iterate version

fix: water shader under LÖVE 12 — make effect()'s parameter precision a define

.github/workflows/release.yml

@@ -0,0 +1,200 @@
+name: Release
+
+# Packs the mod into an installable .zip and publishes it as a GitHub Release,
+# once per push to main.
+#
+# Archive layout: every mod file at the archive root, manifest.json included.
+# That is one of the two shapes the game accepts on MODS > Import mod .zip
+# (src/mods/LauncherMods.lua locateRoot: manifest at the root, or inside a
+# single top-level folder). Nothing else is added, so the archive stays
+# installable by hand too.
+#
+# Versioning, first rule that applies wins:
+#   1. the "version" input of a manual run,
+#   2. "[release X.Y.Z]" anywhere in the commit message,
+#   3. manifest.json's own version, when it is ahead of every existing tag,
+#      so bumping the manifest is the normal way to cut a release,
+#   4. otherwise the newest vX.Y.Z tag with its patch incremented
+#      (0.2.99 rolls over to 0.3.0).
+# Whichever wins is written into the manifest.json inside the archive, so a
+# shipped mod never reports a different version than the release it came from.
+#
+# Generated by: python3 tools/modkit.py add-release-workflow <mod-id>
+# MOD_ID below is stamped to this mod's id when the file is copied.
+
+on:
+  push:
+    branches: [master]
+    paths-ignore:
+      - '.github/**'
+      - '**.md'
+  workflow_dispatch:
+    inputs:
+      version:
+        description: "Exact version to release (e.g. 0.3.0). Leave blank to auto-resolve."
+        required: false
+        default: ""
+
+permissions:
+  contents: write
+
+concurrency:
+  group: release
+  cancel-in-progress: false
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Determine version
+        id: ver
+        env:
+          DISPATCH_VERSION: ${{ github.event.inputs.version }}
+        run: |
+          set -euo pipefail
+          python3 - <<'PY' >> "$GITHUB_OUTPUT"
+          import json, os, re, subprocess, sys
+
+          SEMVER = re.compile(r"^(\d+)\.(\d+)\.(\d+)$")
+
+          def sh(*args):
+              return subprocess.run(args, capture_output=True, text=True).stdout.strip()
+
+          def parse(text):
+              m = SEMVER.match(text)
+              return tuple(int(p) for p in m.groups()) if m else None
+
+          def die(msg):
+              print(f"::error::{msg}", file=sys.stderr)
+              raise SystemExit(1)
+
+          with open("manifest.json", encoding="utf-8") as fh:
+              manifest_version = str(json.load(fh).get("version", ""))
+
+          released = sorted(
+              v for v in (parse(tag[1:]) for tag in sh("git", "tag", "-l", "v*").splitlines()) if v
+          )
+          latest = released[-1] if released else None
+
+          override = os.environ.get("DISPATCH_VERSION", "").strip()
+          if not override:
+              found = re.search(r"\[release\s+(\d+\.\d+\.\d+)\]", sh("git", "log", "-1", "--pretty=%B"))
+              override = found.group(1) if found else ""
+
+          manifest_ver = parse(manifest_version)
+          if override:
+              version = parse(override) or die(f"invalid version override {override!r} (expected X.Y.Z)")
+              source = "the override"
+          elif manifest_ver and (latest is None or manifest_ver > latest):
+              version = manifest_ver
+              source = "manifest.json"
+          elif latest:
+              major, minor, patch = latest
+              patch += 1
+              if patch > 99:
+                  minor, patch = minor + 1, 0
+              version = (major, minor, patch)
+              source = "a patch bump on v%d.%d.%d" % latest
+          else:
+              die(f"manifest.json version {manifest_version!r} is not X.Y.Z "
+                  "and there is no vX.Y.Z tag to count from")
+
+          text = "%d.%d.%d" % version
+          print(f"Releasing {text}, from {source}.", file=sys.stderr)
+          print(f"version={text}")
+          print(f"tag=v{text}")
+          PY
+
+      - name: Refuse to clobber an existing release
+        env:
+          GH_TOKEN: ${{ github.token }}
+          TAG: ${{ steps.ver.outputs.tag }}
+        run: |
+          set -euo pipefail
+          if git rev-parse -q --verify "refs/tags/$TAG" >/dev/null; then
+            echo "::error::Tag $TAG already exists. Pick a different version."
+            exit 1
+          fi
+          if gh release view "$TAG" >/dev/null 2>&1; then
+            echo "::error::Release $TAG already exists. Pick a different version."
+            exit 1
+          fi
+
+      - name: Build the mod .zip
+        env:
+          VERSION: ${{ steps.ver.outputs.version }}
+          MOD_ID: "DRAMATIC_SHAPE"
+        run: |
+          set -euo pipefail
+          staging="$RUNNER_TEMP/pkg"
+          out="$GITHUB_WORKSPACE/dist"
+          rm -rf "$staging" "$out"
+          mkdir -p "$staging" "$out"
+
+          git archive HEAD | tar -x -C "$staging"
+
+          rm -rf "$staging/.github" "$staging/.gitattributes" \
+                 "$staging/.gitignore" "$staging/.luarc.json"
+
+          python3 - "$staging/manifest.json" "$VERSION" <<'PY'
+          import json, sys
+          path, version = sys.argv[1], sys.argv[2]
+          with open(path, encoding="utf-8") as fh:
+              manifest = json.load(fh)
+          manifest["version"] = version
+          with open(path, "w", encoding="utf-8") as fh:
+              json.dump(manifest, fh, indent=2, ensure_ascii=False)
+              fh.write("\n")
+          PY
+
+          zip_path="$out/${MOD_ID}-${VERSION}.zip"
+          (cd "$staging" && zip -qr "$zip_path" .)
+          unzip -l "$zip_path"
+
+          unzip -p "$zip_path" manifest.json > "$RUNNER_TEMP/packed-manifest.json"
+          python3 - "$RUNNER_TEMP/packed-manifest.json" "$VERSION" <<'PY'
+          import json, sys
+          path, expected = sys.argv[1], sys.argv[2]
+          with open(path, encoding="utf-8") as fh:
+              version = json.load(fh)["version"]
+          if version != expected:
+              raise SystemExit(f"::error::packed manifest says {version}, expected {expected}")
+          print(f"manifest.json is at the archive root and reports {version}")
+          PY
+
+          (cd "$out" && sha256sum "${MOD_ID}"-*.zip > sha256sums.txt)
+          cat "$out/sha256sums.txt"
+
+      - name: Publish GitHub Release
+        env:
+          GH_TOKEN: ${{ github.token }}
+          VERSION: ${{ steps.ver.outputs.version }}
+          TAG: ${{ steps.ver.outputs.tag }}
+          MOD_ID: "DRAMATIC_SHAPE"
+        run: |
+          set -euo pipefail
+
+          prev="$(git tag -l 'v*' --sort=-v:refname | grep -v "^${TAG}$" | head -1 || true)"
+          range="${prev:+${prev}..}$GITHUB_SHA"
+          changes="$(git log --no-merges --pretty='- %s' "$range" | head -50 || true)"
+
+          notes=$'Download the .zip and install it from the game: MODS > Import mod .zip.'
+          if [ -n "$changes" ]; then
+            notes+=$'\n\n## Changes\n\n'"$changes"
+          fi
+          printf 'Release notes:\n%s\n' "$notes"
+
+          gh release create "$TAG" \
+            --target "$GITHUB_SHA" \
+            --title "$VERSION" \
+            --notes "$notes" \
+            "dist/${MOD_ID}-${VERSION}.zip" \
+            "dist/sha256sums.txt"
+
+          echo "Published release $TAG"

.gitignore

@@ -5,3 +5,43 @@ __pycache__/
 
 # agent worktrees and local scratch
 .claude/
+
+# ------- Pokemon Stadium data
+#
+# NONE OF THIS SHIPS, and none of it is in the repository. The battle models
+# are Pokemon Stadium's own data: what the mod carries is the READER for them
+# (lib/StadiumRom, StadiumFragment, StadiumFx, StadiumBuild) and the player
+# supplies the cartridge, exactly as this engine already asks them to supply
+# the Game Boy ROM it is a recompilation of.
+#
+# So the ROM itself, everything model_extract/pipeline extracts out of it, and
+# the packs tools/stadium_pack.py builds from those are all ignored. What IS
+# tracked is the pipeline, the notes, and the two READMEs that say where to
+# put a ROM.
+#
+# At runtime the packs are built on the player's own machine, on first run,
+# into the save directory -- never into the mod folder (see StadiumInstall).
+
+# the cartridge, wherever it is dropped, and the checksum note that comes
+# with one. The Zone.Identifier pattern has no colon in it on purpose: it is
+# an NTFS alternate data stream, and the separator reaches git as U+F03A
+# rather than as ':' -- so matching on the suffix alone is what actually works
+*.z64
+*.n64
+*.v64
+*Zone.Identifier
+model_extract/baseroms/**/checksum.md5
+
+# everything the pipeline extracts from it
+model_extract/glb/
+model_extract/js/
+model_extract/textures/
+model_extract/manifest.json
+model_extract/moves.json
+model_extract/viewer.html
+
+# and the packed models built from those -- the local oracle the Lua
+# extractor is diffed against (tests/stadium_extract_test.lua), rebuilt with
+# tools/stadium_pack.py whenever it is wanted
+assets/stadium/
+pocket-voxel/

.modkitignore

@@ -4,6 +4,10 @@
 # The SDK suite and the probes it grew out of. A shipped test that requires
 # an engine module reads as a private require against the archive
 # (CONTRIBUTING-mods.md "What the PR must contain", 2).
+tests/arena_config.lua
+tests/arena_editor.lua
+tests/arena_pick.lua
+tests/battle_shots.lua
 tests/dramatic_shape_test.lua
 tests/voxel_anim_probe.lua
 tests/voxel_door_probe.lua
@@ -19,6 +23,7 @@ tests/voxel_void_probe.lua
 # ROM, read the local cache, and emit assets/voxels/*.lua; the carved models
 # are what a player installs, the carving is not.
 tools/build_voxels.py
+tools/contact_sheets.py
 tools/building_images.py
 tools/building_voxels.py
 tools/voxel-survey.md

README.md

@@ -3,16 +3,8 @@
 A mod for the [Pokémon Gen 1 Recompilation
 Project](https://github.com/bryanthaboi/pokemon-gen1-recomp-project).
 
-The overworld as a 3D diorama. Terrain is extruded into real geometry,
-occlusion comes from a depth buffer rather than a y-sort, characters stand
-as leaning sprite slabs, a shadow map throws real cast shadows across
-whatever they land on, and an optional tilt-shift pass sells the
-miniature-model look.
-
-Purely presentational. Nothing here reaches collision, movement, triggers
-or scripts — it changes what the world *looks* like and nothing about what
-it *is*. Battles, menus and cutscenes are untouched; only the free-roam
-overworld draws differently.
+The overworld as a voxelized 3D diorama. Also supports experimental
+first-person, third-person and VR.
 
 ## Controls
 
@@ -21,12 +13,284 @@ menu.
 
 | control | does |
 | --- | --- |
-| `3`, or the **VOXEL** options row | OFF → 15 → 35 → 50 → 75 → OFF (camera pitch) |
+| `3`, or the **VOXEL** options row | OFF → 15 → 35 → 50 → 75 → 1ST → 3RD → OFF (camera pitch) |
+| `SELECT` (pad / touch) | the same step as `3` — for the machines with no number row |
 | `5`, or the **V-GRID** options row | OFF / ON — a one-pixel wireframe on every voxel |
 | `6`, or the **T-SHIFT** options row | OFF → 1 → 2 → 3 → OFF (miniature blur) |
-| `7`, or the **V-CURVE** options row | OFF → 1 → 2 → 3 — bend the world over the horizon |
+| `7`, or the **V-CURVE** options row | OFF → 1 → 2 → 3 → 4 → 5 — bend the world over the horizon; 5 is a half sphere |
+| the **RENDER DIST** options row | FIT / WIDE / WIDER / WIDEST / OFF — how much of the map the camera bothers to draw. **FIT** is exactly the ground on screen and no more: the trapezoid a tilted camera really frames, which reaches well north of you and flares wide out there — not the square the flat game shows. A connected map falling entirely outside it is skipped before it is drawn, terrain, water, grass and shadows together, which is most of the frame's geometry at the high rungs. Below about 63° that is all the row does and the picture is untouched; at **75** the camera sees to the horizon, so something has to name a distance — FIT is the closest, the wider rungs push the world's edge out, **OFF** stops cutting. Not on **1ST** or **3RD**: you are standing in the world there, and the box opens out and away as the camera dives in. **FULL** sets it to FIT |
+| `8`, or the **3D-BTL** options row | 2D-3D A / 2D-3D B / STADIUM A / STADIUM B / OFF — fight in 3D instead of on a white field. **A** stages it on the map, **B** on two discs against the sky; **2D-3D** uses the game's own battle pics and **STADIUM** the Pokémon Stadium battle models |
+| `9`, or the **WATER** options row | FULL / SKY / OFF — waves and reflections on water. **SKY** gives the surface its pixel-tall wave columns and puts the sky, the sun, the moon and the cast in them; **FULL** adds a screen-space ray march that also reflects the shoreline, the trees and the buildings standing behind it |
+| the **BACK SPRITES** options row | OFF / ON — keep your own Pokémon on the battle menu, seen from behind in its classic slot, instead of standing it on the map; the foe is still out there. Only on the menu while **3D-BTL** is on, because it decides nothing without it |
+| the **AA** options row | OFF / 2X / 4X — smooth the stair-stepped edges of the 3D world by rendering the diorama larger than the window and folding it back down. The ladder is samples per display pixel: 2X is a canvas root-two wider and taller, 4X one exactly twice the size. Every edge in the projected picture softens with the silhouettes — the tileset's own texels are quads in a perspective view and cross the pixel grid at the same arbitrary angles — so the diorama reads smoother rather than sharper. The most expensive row in the mod, so it is OFF by default and **FULL** leaves it alone |
+| the **DAYTIME** options row | SYNC / DAY / NIGHT / DUSK / DAWN / CYCLE — what time it is outdoors, on the diorama *and* on the flat 2D world; held at SYNC (and off the menu) while VOXEL is FULL |
 
-Two of those keys are taken off the engine: `3` was **TILT** and `5` was
-**GBC FX**. Neither is reachable by key while this mod is enabled, and both
-are still on the OPTIONS menu. Pressing `3` also switches both off — they
-fight the diorama, and it is the way back from having left one on.
+## Free-roam cameras (1ST / 3RD)
+
+The last two rungs of the **VOXEL** ladder are experimental, and they are
+the same camera: **1ST** stands it in the player's own eyes, **3RD** pulls
+it back onto a boom behind their shoulder. Both steer, and on both the grid
+walk is replaced by continuous camera-relative movement — push in any
+direction and you go there, at any angle, not just along the four compass
+lines. Collision, warps, ledges, encounters and scripts all still run
+through the engine's own machinery.
+
+| control | does |
+| --- | --- |
+| mouse | look (the cursor is captured; left click is A, right click is B) |
+| right stick | look |
+| a touch drag off the overlay's controls | look |
+| left stick / touch d-pad / arrow keys | walk, relative to where the camera looks |
+| wheel, `Q` / `E`, pinch, or a stick click | **3RD only** — let the boom out and pull it in (`Q` and left stick click out, `E` and right stick click in) |
+
+On an **orbit rung** the same wheel, `Q`/`E` and pinch drive the engine's own
+survey zoom. On **1ST** they do nothing at all: the eye is in your head, and
+there is no distance to change.
+
+On **3RD** the boom shortens against whatever is behind you, so backing into
+a wall walks the camera in to your shoulders rather than through it — squeeze
+it all the way in and the view is 1ST until you step clear. The character
+turns to face where they are walking, and every sprite in the world — yours,
+the NPCs', the figures drawn into the furniture — turns to face the camera
+and shows the frame it would look like from where the camera actually
+stands, so walking behind someone shows you their back.
+
+## The battle camera
+
+A fight staged on the map (**3D-BTL**, on by default) is shot with a solved
+over-the-shoulder rig — and you can steer it.
+
+| control | does |
+| --- | --- |
+| right stick, a touch drag, or the mouse | swing the shot around the arena (→) and raise the seat (↑) |
+| wheel, `Q` / `E`, pinch, or a stick click | the lens (`Q` / left stick click out, `E` / right stick click in) |
+
+Both axes stop where the composition does. Left stops at the shot the rig was
+solved for — there is nothing to the left of it. Right ends **side-on**: the
+eye square to the arena's axis, both Pokémon at the same distance instead of
+one behind the other. Down stops at the rig's own low stance; up is 45° above
+it. The lens opens as you swing or climb, by exactly the amount the two
+Pokémon spread apart, so they stay framed at every angle. Move animations
+follow the pair's position *and* its separation, so a beam still lands on the
+Pokémon it was aimed at.
+
+Where you leave the camera is where the next battle opens.
+
+**BACK SPRITES locks it.** That setting pins your own Pokémon to the GB's slot
+on the menu while the foe stands out on the map, and no angle holds a
+composition that is half frame and half world — so with it on, the shot holds
+the one the rig was solved for.
+
+## STADIUM battles
+
+The **3D-BTL** row has five rungs, which are two choices — what is standing
+there, and where:
+
+| rung | the fight |
+| --- | --- |
+| **2D-3D A** | staged on the map, with the Game Boy's own pics stood up on their tiles |
+| **2D-3D B** | those same pics on two discs against the sky, with no map drawn |
+| **STADIUM A** | staged on the map, with the Pokémon Stadium battle models |
+| **STADIUM B** | those models on the discs |
+| **OFF** | the engine's own battle screen |
+
+**A** is the map — real ground, in that place's own weather and light. **B**
+is the carried stage, which works everywhere, including the caves and shop
+floors that have nowhere to put a fight. Only the STADIUM rungs need a ROM;
+**2D-3D B** is generated in Lua and uses the game's own art.
+
+Skinned and animated, playing the animation the move being used actually
+calls for — the Stadium ROM's own per-species move table, so **DIG** really
+does put Diglett into the ground. Fainting plays the faint and holds there, a
+send-out grows the Pokémon out of the ball as it opens and plays the entrance,
+and between all of that the standby loop runs. Eyes blink and go dizzy;
+Charmander's tail flame and Weezing's gas are drawn over the body.
+
+Taking damage plays nothing, because the set has no damage reaction in it —
+the slot that looked like one is each species' default attack, which is why
+being hit used to look like swinging. The engine's own screen flash, pic blink
+and HP drain are what say "that hurt".
+
+148 of the 151 have models. Exeggutor, Tangela and Magmar come out of the ROM
+with corrupt standby loops and stand as their Game Boy battle sprites
+instead, on their own tile, in the same arena — the same per-Pokémon fallback
+a substitute doll and the pre-send-out trainer pic already take.
+
+**B is for the maps that cannot host a fight.** Half of Kanto's interiors are
+furniture, a cave floor can be nothing but corridors, and a map where neither
+Pokémon can be *seen* from a low camera is declined outright — which drops you
+back to the flat battle screen. B carries its stage, so it works everywhere
+and looks the same every time. It is abstracted from the ground, not from the
+world: the sky behind the discs is the hour's own, and a fight in a cave is
+under that cave's void and its own flat light.
+
+### Getting the models
+
+**They are not in this mod, and they cannot be** — they are Pokémon Stadium's
+data. What ships is the reader; you supply the cartridge, exactly as this
+engine already asks you to supply the Game Boy ROM it is a recompilation of.
+
+> **You must supply a Pokémon Stadium (US) 1.0 ROM.** Not Stadium 2, not
+> another region, not a later revision. Every offset in the reader was
+> measured against that one cartridge, and nothing else is promised: a
+> different file is either refused outright or builds models that are subtly
+> wrong. The mod checks, and says so — on the console, and on the loading
+> screen itself if it built from something unexpected.
+>
+> The reference dump is **md5 `ed1378bc12115f71209a77844965ba50`**, 32 MB.
+> The mod does not tell you where to get one, and none ships with it.
+
+1. Open **OPTIONS** and press the **STADIUM ROM** row. It opens your system's
+   file picker; choose your **Pokémon Stadium (US) 1.0** ROM. `.z64`, `.n64`
+   and `.v64` all work — the byte order is detected, and the wrong file is
+   refused with a reason rather than half-built.
+2. The 151 models are built on a loading screen that says so and shows a
+   progress bar, in about ten seconds. The row then reads **READY**.
+
+The ROM itself is **not kept** — it is read, built from, and forgotten, so
+the cartridge does not sit in your save directory alongside the models it
+produced. Press the row again any time to import a different one.
+
+There is no picker on Android, or on a Linux install with neither `zenity`
+nor `kdialog`. Those keep the original route, which still works everywhere:
+
+- Put the **US 1.0** ROM in a `baseroms/` folder beside the game — straight
+  in it, not in a subfolder — and start the game.
+- In a packaged build (and on Android) `baseroms/` goes in the save
+  directory; the mod logs the exact path on startup when it cannot find one.
+  On Android that is the app's external-files folder, reachable over USB or
+  any file manager without root.
+
+Either way, the two STADIUM rungs appear on the 3D-BTL row when it's done.
+
+The built models live in the save directory, not in the mod folder, and are
+rebuilt automatically if the format changes or the ROM does. Until they exist
+the STADIUM rungs are simply not on the row — skipped rather than shown and
+refused, because a setting you can select that then does nothing is worse than
+one that is not there.
+
+**This works on mobile.** The extraction is pure Lua — no FFI, no native
+helper, no second process — so it runs anywhere LÖVE does. It peaks at about
+68 MB of Lua heap (32 MB of that the cartridge itself) with a working set that
+does not grow across the run, and `tests/stadium_budget_test.lua` fails if
+either stops being true. On Android the save directory is the app's
+external-files folder, so `baseroms/` there is reachable over USB or a file
+manager without root; the build is slower than a desktop's ~7 s but runs one
+species a frame behind the progress bar either way.
+
+Developers can pre-build them with `tools/stadium_pack.py`, which reads the
+same ROM through `model_extract/pipeline`. That path is also the *oracle*:
+`tests/stadium_extract_test.lua` runs it and the in-game Lua extractor over
+the same cartridge and requires all 151 packed files to come out byte for byte
+identical.
+
+## VR
+
+The **VR** options row (OFF / STANDARD / DIORAMA / DIORAMA-MR, off by
+default) drives a PCVR headset through OpenXR on Windows — SteamVR,
+Oculus or WMR.
+
+**STANDARD** follows the VOXEL ladder. Both free-roam rungs put the
+headset in the player's *head*: a boom that seats its wearer three cells
+behind their own body is a reliable way to make people ill, so **3RD** in
+VR is **1ST** in VR. The rung still changes the walk and the sprites the
+same way.
+
+### DIORAMA
+
+**DIORAMA** is one presentation instead of a ladder: the world is always a
+model on the table, and the model is a *thing in the room*.
+
+- **A viewport.** Everything outside an invisible **box** centred on the
+  view is not drawn — a square slab of Kanto sitting in the air rather
+  than a map running off to a horizon, cut with a hard edge, because a
+  flat world is a thing with sides and the sides are what say so. The sky
+  behind is the same one the flat screen has.
+- **V-CURVE changes its shape.** With the bend on the world is not flat
+  any more, and a square cut through a little globe is a lie about what is
+  being looked at — so the box becomes a **ball** whose rim is a
+  **gradient** dissolving into the sky. One click of the left stick throws
+  the row and swaps between the two readings of the same model.
+- **A staged fight** ignores both and cuts a vertical pillar about the
+  arena, always with the dissolved rim, which lifts the fight out of the
+  map as a floating disc.
+- **The grips** take hold of it: one hand carries the model anywhere in
+  the room, both hands turn it and open the viewport out to whatever you
+  spread your hands to.
+- **The left stick's click** throws **V-CURVE** to its top rung and back,
+  rather than stepping views — there is no 2D diorama and no first-person
+  one, so the ladder is held on an orbit rung while the mode runs.
+
+**DIORAMA-MR** is the same mode with the background keyed pure green, for
+a mixed-reality capture that composites the model into your own room.
+
+### VR controls
+
+Suggested onto Touch, Index and WMR controllers (rebindable in the
+runtime's own binding UI); pad, keyboard and mouse all keep working
+alongside.
+
+| control | does |
+| --- | --- |
+| left stick | move — grid-walks the diorama, free-walks 1ST |
+| A / B (X / Y on the left hand) | A / B |
+| either trigger | START |
+| left stick click | *STANDARD* — step the VOXEL angle ladder (same as the "3" key); *DIORAMA* — throw **V-CURVE** to its top rung and back |
+| right stick up / down | *tabletop* — zoom the model |
+| right stick left / right | *1ST only* — snap-turn 45°, or turn smoothly with **SMOOTH TURN** on |
+| one grip squeezed | *STANDARD* — drag the table's height; *DIORAMA* — carry the model wherever that hand goes |
+| both grips squeezed | *DIORAMA only* — turn the model with your hands, and open or close the viewport by spreading them |
+| head | *1ST and battles* — look; FreeMove walks where you look |
+| left hand | *1ST and battles* — the Pokédex: menus, dialogs and the 2D battle screen on its screen |
+
+## Licenses
+
+It redistributes one third-party binary:
+
+- **`assets/vr/openxr_loader.dll`** — the Khronos OpenXR loader
+  (version 1.0.10.2, x64, unmodified), © The Khronos Group Inc.,
+  licensed under the **Apache License 2.0**. The full license text ships
+  alongside the DLL at
+  [`assets/vr/LICENSE-openxr_loader.txt`](assets/vr/LICENSE-openxr_loader.txt),
+  as the license requires; keep the two files together if you
+  redistribute this mod. Source:
+  [KhronosGroup/OpenXR-SDK](https://github.com/KhronosGroup/OpenXR-SDK).
+
+Everything else in this mod is original to it, except that the voxel
+geometry and shape profiles are derived from the tile and sprite data of
+the original game, as documented by the
+[pret/pokered](https://github.com/pret/pokered) disassembly. No ROM
+data, artwork or audio is included; the mod reads the assets the host
+game already has.
+
+### Acknowledgements — pret/pokestadium
+
+The STADIUM battle models are read out of the player's own Pokémon Stadium
+(US) 1.0 cartridge by original code in [`lib/`](lib) and
+[`model_extract/`](model_extract). **That code exists because of
+[pret/pokestadium](https://github.com/pret/pokestadium)**, the community
+decompilation of that game, which is the reference this mod's reader was
+written against. Specifically, it is where the following came from:
+
+- the bone matrix chain, and the fact that scale is kept *out* of it and
+  applied only at draw time (`func_800143C0`) — the single most important
+  thing to get right in the whole rig, and not guessable from the data
+- the rotation basis and its row-vector `Rx·Ry·Rz` order
+  (`func_8000F730`, `src/F420.c`)
+- the animation player's frame counter and loop-start behaviour
+  (`func_80016FBC`), and the texture-animation sampler that *clamps* past
+  the end of its stream rather than wrapping (`func_80017540`) — which is
+  the difference between a Pokémon blinking and twitching
+- the battle system's per-species animation context slots and the routines
+  that select them (`func_8432B0A4`, `func_8430506C`, `func_84305A74`)
+- the move-id constants the per-species move table is keyed by
+
+**No code, data or asset from that project is included in or redistributed
+by this mod**, and none is needed to build or run it. What was taken is an
+understanding of the file formats, re-expressed in this mod's own Lua and
+Python. If you want to reuse anything from the decompilation itself, get it
+from upstream and follow that project's own terms.
+
+No Pokémon Stadium ROM data ships here either. The models are built on the
+player's own machine, from a cartridge they supply, into their own save
+directory — see [Getting the models](#getting-the-models).

assets/docs/buidling_to_voxel/sprite_to_voxel_methodology.md

@@ -61,6 +61,10 @@ cues generalize:
 | Band containing window/door frames | Vertical facade | Straight extrusion |
 | Full-width band with a black underline sitting above an inset band | Ledge / awning overhang | Extrusion + protrusion |
 | Dark `#555` runs beside a facade under a taper | Shadow on the wall beneath an eave | Leave as wall — the geometry above produces the shadow's meaning |
+| Scattered light shapes on a dark field, bracketed by TWO full-width black rims, shallow band below the lower rim | The **inside of an open container** seen from above, with contents lying in it | Hollow tray: walls to the rims, floor slab, air between — never an extrusion |
+| Ellipse drawn wider than tall (e.g. 9x5) | A horizontal circle seen from above — a mouth, a lid, a pot rim | Cut face of a round hull; the aspect ratio is the proof of the top view |
+| Arcs above/below a round object's straight flanks, lowest point at the centre column, often a 1px #555 halo outside | The SAME circles seen curving — ground contact and mouth back-edge, i.e. depth, not narrowing | Strip them from the revolve; run the last body row's disc to the floor |
+| A side band shearing sideways as it descends (¾-view) | The projection sliding a receding wall, not the wall's position | Un-project: the wall goes where the plan says |
 
 The band table for Red's house, which Blue's house shares verbatim:
 
@@ -156,9 +160,12 @@ Tooling: `voxel_build_verify.py` (builds, asserts, renders previews).
 
 1. Obtain the sprite; sample to native resolution via block centers.
 2. Extract palette + silhouette (light-only flood fill, threshold 130);
-   review the ASCII mask.
-3. Segment rows into bands using the Stage-2 cues; write the band table
-   before writing any geometry code.
+   review the ASCII mask — rendered large, not hand-counted.
+3. Name the real object first (including whether it is hollow, round or
+   thin — see "Beyond the house"), then segment rows into bands using the
+   Stage-2 cues; write the band table as prose, one line per row range
+   with where each band lands, before writing any geometry code. The
+   correct reading makes the row arithmetic land exactly.
 4. Measure taper rates from the mask; derive `T(x)`, `YTOP`, overhangs, `D`.
 5. Build: extrude verticals (de-outlined interiors) → ledges → recesses →
    flat top (mid-row cycling) → sloped solids (overwrite, then trim) →
@@ -214,3 +221,75 @@ right for the raw GB palette but comes out white once the atlas is
 recoloured, turning every sloped end into a black-and-white zip. The
 drawing's own eave is black / `#555` / black, and using that reads correctly
 under every palette.
+
+## Beyond the house: the forms later objects added
+
+The house is all solid masses — every band either lies flat or extrudes.
+Later objects forced the taxonomy open, and each addition came from the
+same root move: **name the real 3D form first, then ask which surfaces the
+drawing shows.** The recurring failure at every step was the *extruded
+picture* — and it has a second-order form that survives re-segmentation.
+The Bike Shop's toolbox was re-read from "a prop" into "a cabinet with a
+pump beside it": named parts, correct plot, de-outlined sides, and still
+wrong, because the region read as a cabinet *front* was the inside of an
+open box seen from above. Naming the parts is not enough; every REGION
+must answer "what surface of the real object is this?" The reliable
+arbiter is arithmetic: the correct reading makes the drawn row counts land
+exactly (the toolbox: 1 back-wall rim + 6 interior rows + 1 front rim = 8
+= the one-tile plot depth). Forcing rows to fit means the reading is wrong.
+
+**Hollow forms.** An open container is the one shape whose model must
+contain AIR, which no band table or extrusion can produce. The tray
+treatment builds four walls to the drawn rims, lays the top-view band on
+the floor of the cavity (its contents — a wrench — come along free, since
+they are just pixels of that band), and leaves the space between empty.
+Two rules only containers hit: the pane-recess pass must never run on a
+one-voxel wall (it deletes the front voxel to expose the one behind, and
+there is nothing behind — the wall becomes a hole), and the hollowness
+needs its own verification assert, because a later change that refills the
+cavity leaves every count looking plausible.
+
+**Round forms.** A drawn ellipse wider than tall is a horizontal circle
+seen from above — that one aspect-ratio measurement settles the whole
+reading. Straight flanks give diameter and height at once (round in plan,
+so drawn width IS depth — the one depth never authored). The arcs above
+and below the straight run are the same top and base circles seen curving:
+ground contact and mouth edge, not narrowing — revolving them puts the
+object on a stem. The hull's chord representation stores one z-interval
+per column/row, so a taper is expressible (re-cut the chords, squeeze the
+art into the narrowed span so the rim outline survives) but a hollow ring
+needs a second chord. Voxel resolution bounds taste: on an 11-wide object
+a one-step taper reads as damage and two steps as a cone; pick the step
+count and derive the amount.
+
+**Thin forms.** A line drawing cannot be thick. The air inside a bicycle's
+frame is what makes it read as a bicycle; extrude each stroke 5 voxels and
+the side faces of neighbouring strokes close every gap off-axis — six
+bikes become one dark mass. Standee thickness is a vocabulary
+(`PINNED_DEPTH`: 1 for paper, 2 for plates and side-on vehicles, 5 for
+silhouettes, 10 for objects with a body), and when a standee looks wrong
+the first move is to dump the detector's mask — if the mask is a clean
+object, thickness is the problem, not segmentation.
+
+**Authored masks.** When a drawing shares its tiles and shades with what
+it is painted into, nothing automatic can separate them; the profile
+carries a pixel mask instead. A person becomes a `figures` card (flat,
+leaning with the camera, standing on its feet — because GB character art
+is face-on iconography); an object becomes a `mounted` slab (fixed in the
+world, holding the wall's plane, keeping its drawn elevation — because a
+side-on drawing is a plane parallel to the wall). And when the backdrop is
+a *regular* pattern, the mask should be MEASURED, not hand-drawn:
+composite the plain backdrop tile over the same grid and flood from the
+border through pixels that still match it — what the flood cannot reach is
+the object, sprite-pure and exact.
+
+**Verification, extended.** Isometric previews miss what only the game
+shows: shoot in-game at both the ¾ rung and the low rung (front-face holes
+and proportion errors are invisible from above), crop and NEAREST-upscale
+before judging, and remember the flat rung renders no model at all. Two
+cheap renders beat argument: the front-most voxel per (x, y) laid beside
+the composited drawing catches anchoring and texel leaks instantly, and
+the same render with sunk voxels flagged turns the recess pass into
+something you look at. When shared builder code moves, a saved count
+baseline diffed after every edit (mind the line endings) is what proves a
+generalization is an identity for every model that already shipped.

assets/vr/LICENSE-openxr_loader.txt

@@ -0,0 +1,188 @@
+openxr_loader.dll -- the Khronos OpenXR loader (x64, unmodified)
+Version 1.0.10.2, from the "OpenXR.Loader" NuGet package published by
+The Khronos Group. Source: https://github.com/KhronosGroup/OpenXR-SDK
+
+Copyright (c) The Khronos Group Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License"); the full
+text of the License follows, as its terms require a copy to accompany
+redistribution.
+
+-----------------------------------------------------------------------
+
+                                 Apache License
+                           Version 2.0, January 2004
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+
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data/battle_arenas.lua

@@ -0,0 +1,220 @@
+-- Where each map's battles happen.
+--
+-- One authored spot per area, rather than whichever clearing happens to be
+-- nearest the step the fight started on. A battle on Route 1 should look the
+-- same every time it happens on Route 1 -- and, more importantly, "open
+-- ground" is not the same question as "you can see the two of them": the
+-- battle camera sits low and a long way back, so a hedge, a ledge lip or the
+-- corner of a house anywhere along that sightline hides a Pokemon completely
+-- while every cell it is standing on is perfectly walkable.
+--
+-- Each entry is the arena's north-west corner in map CELLS, and which of
+-- BattleArena.SHAPES it is. Picked by tools/arena_pick (BattleArena.search
+-- with the clearance test on, from the middle of the map) and then looked at,
+-- one screenshot per map -- these are eyeballed answers, not just passing
+-- ones. Grass and flowers around a mon's feet are fine and wanted; anything
+-- that cuts into a body is not.
+--
+-- A map with no entry here falls back to the nearest-clear search at battle
+-- time, so a mod that adds maps, or an entry that goes stale against an
+-- edited map, degrades to the old behaviour rather than to no battle.
+--
+-- The entries below are generated; regenerate with
+--
+--   SHOT_DIR=.scratchpad/arenas \
+--   POKEPORT_DRIVER=mods/DramaticShapeVoxelMod/tests/arena_pick.lua love .
+--
+-- To change ONE map's spot, or to go over these by eye, run the editor
+-- instead -- it is the same choice made in front of the map rather than in a
+-- batch. It slides the arena around on a plan of the map with the fit, the
+-- clearance and the camera's own sightlines answering live, stages a real
+-- battle on the spot when asked, and writes this file back a map at a time,
+-- replacing only the lines that changed and leaving every comment here alone:
+--
+--   POKEPORT_DRIVER=mods/DramaticShapeVoxelMod/tests/arena_editor.lua lovec .
+--
+-- Its export lands in .scratchpad/arena_editor/ to be diffed and copied over;
+-- ARENA_WRITE=1 points it at this file directly. A comment above an entry it
+-- moved describes where that spot USED to be, and it says so by name at
+-- export time -- those are the lines to re-word by hand.
+
+-- `cam = "wide"` on an entry swaps the long default lens for the 44-degree
+-- one (BattleCam.RIGS). Both frame the same composition -- the two mons land
+-- on the same screen anchors either way -- so it is purely a choice about how
+-- much of the place is in shot, at the cost of a smaller pair. Rooms the long
+-- lens cannot stand back from NEED it; anywhere that simply reads better with
+-- more of itself visible may ask for it.
+--
+-- Tall grass is never part of an arena (BattleArena.openCell rejects it), so
+-- a route's spot is always its bare path rather than the field beside it --
+-- grass is knee-high geometry to a Pokemon and this camera is nearly level
+-- with the floor, so tufts on the mon's own tile stand between it and the
+-- lens. Flowers are left alone: they are ankle height and read as ground.
+
+return {
+  -- ------- routes
+  -- narrow, deliberately: the route's interior is a 3-cell-wide lane and the
+  -- wide shape only fits in the western connection border, which staged every
+  -- fight at the edge of the world instead of on the road.
+  --
+  -- Of the seventeen spots the route has outside that border, fourteen are
+  -- this one mid-route clearing and the other three bury the near mon behind
+  -- a hedge -- which the clearance test passes, since it measures terrain
+  -- height along the sightline and a hedge in the apron row is not terrain.
+  -- So the choice is where in the clearing, and this is its west end: tree
+  -- line square behind the pair, nothing crossing either of them.
+  ["ROUTE_1"] = { x = 10, y = 16, shape = "narrow", turn = 90 },
+  ["ROUTE_2"] = { x = 1, y = 49, shape = "wide" },
+  ["ROUTE_3"] = { x = 52, y = 10, shape = "wide", turn = 90 },
+  ["ROUTE_4"] = { x = 46, y = 4, shape = "wide" },
+  ["ROUTE_5"] = { x = 7, y = 0, shape = "wide", turn = 270 },
+  ["ROUTE_6"] = { x = 4, y = 15, shape = "narrow" },
+  ["ROUTE_7"] = { x = 4, y = 3, shape = "narrow", cam = "wide" },
+  ["ROUTE_8"] = { x = 24, y = 5, shape = "wide", turn = 90 },
+  -- the whole route admits six bare wide arenas, all in the west cliff
+  -- corridor; this is the best of them. A flower cluster crosses the far
+  -- mon's hind legs, which the brief allows -- every alternative put a
+  -- terrace through the near mon's waist, which it does not.
+  ["ROUTE_9"] = { x = 1, y = 11, shape = "wide", cam = "wide" },
+  ["ROUTE_10"] = { x = 7, y = 40, shape = "wide" },
+  ["ROUTE_11"] = { x = 9, y = 6, shape = "wide" },
+  ["ROUTE_12"] = { x = 10, y = 71, shape = "wide", turn = 90 },
+  ["ROUTE_13"] = { x = 51, y = 5, shape = "narrow" },
+  ["ROUTE_14"] = { x = 11, y = 24, shape = "wide" },
+  ["ROUTE_15"] = { x = 30, y = 10, shape = "wide", turn = 90 },
+  ["ROUTE_16"] = { x = 8, y = 10, shape = "wide", turn = 90 },
+  ["ROUTE_17"] = { x = 14, y = 70, shape = "wide" },
+  ["ROUTE_18"] = { x = 11, y = 3, shape = "wide" },
+
+  -- ------- buildings and caves
+  --
+  -- Indoors the narrow shape earns its keep: a room with furniture, machinery
+  -- or gravestones in it rarely holds a 3x6 clearing whose whole width is
+  -- also SEEN, and giving up the apron is usually the difference between a
+  -- fight in the open and one behind a console.
+  ["POKEMON_MANSION_1F"] = { x = 4, y = 12, shape = "wide", cam = "wide" },
+  ["POKEMON_MANSION_2F"] = { x = 10, y = 1, shape = "wide", cam = "wide" },
+  ["POKEMON_MANSION_3F"] = { x = 24, y = 3, shape = "narrow", cam = "wide" },
+  ["POKEMON_MANSION_B1F"] = { x = 6, y = 19, shape = "wide", turn = 90 },
+  ["POKEMON_TOWER_2F"] = { x = 4, y = 7, shape = "narrow" },
+  ["POKEMON_TOWER_3F"] = { x = 4, y = 6, shape = "wide" },
+  -- every one of 4F's thirty candidate spots puts a gravestone through a
+  -- mon; the floor below is the same tower and has the room, so the fight
+  -- is shot there
+  ["POKEMON_TOWER_4F"] = { map = "POKEMON_TOWER_3F", x = 4, y = 6,
+                           shape = "wide" },
+  ["POKEMON_TOWER_5F"] = { x = 8, y = 9, shape = "narrow", cam = "wide" },
+  ["POKEMON_TOWER_6F"] = { x = 14, y = 6, shape = "narrow", cam = "wide" },
+  ["POKEMON_TOWER_7F"] = { x = 9, y = 5, shape = "wide" },
+  ["POWER_PLANT"] = { x = 18, y = 5, shape = "narrow" },
+  ["ROCK_TUNNEL_1F"] = { x = 14, y = 15, shape = "wide" },
+  ["ROCK_TUNNEL_B1F"] = { x = 20, y = 17, shape = "wide" },
+  ["ROCKET_HIDEOUT_B1F"] = { x = 20, y = 18, shape = "narrow" },
+  ["ROCKET_HIDEOUT_B2F"] = { x = 20, y = 10, shape = "narrow", cam = "wide" },
+  ["ROCKET_HIDEOUT_B3F"] = { x = 24, y = 15,
+                             shape = "narrow", turn = 90, cam = "wide" },
+  ["ROCKET_HIDEOUT_B4F"] = { x = 19, y = 17, shape = "wide", cam = "wide" },
+  ["SAFARI_ZONE_CENTER"] = { x = 1, y = 8, shape = "wide" },
+  ["SAFARI_ZONE_EAST"] = { x = 16, y = 8,
+                           shape = "wide", turn = 90, cam = "wide" },
+  ["SAFARI_ZONE_NORTH"] = { x = 22, y = 12, shape = "wide", turn = 90 },
+  ["SAFARI_ZONE_WEST"] = { x = 20, y = 2, shape = "wide" },
+  ["SEAFOAM_ISLANDS_1F"] = { x = 14, y = 7, shape = "wide" },
+  ["SEAFOAM_ISLANDS_B1F"] = { x = 9, y = 8,
+                              shape = "wide", turn = 90, cam = "wide" },
+  ["SEAFOAM_ISLANDS_B2F"] = { x = 15, y = 9, shape = "wide", turn = 90 },
+  ["SEAFOAM_ISLANDS_B3F"] = { x = 26, y = 7, shape = "wide", turn = 180 },
+  ["SEAFOAM_ISLANDS_B4F"] = { x = 9, y = 7, shape = "narrow" },
+  -- Silph Co is office floors partitioned into small rooms, so the long lens
+  -- often lands outside the walls it is meant to be looking between; the
+  -- floors that could not be framed any other way ask for the wide one.
+  ["SILPH_CO_2F"] = { x = 4, y = 9, shape = "narrow", turn = 270 },
+  ["SILPH_CO_4F"] = { x = 14, y = 14, shape = "narrow", turn = 90 },
+  ["SILPH_CO_5F"] = { x = 16, y = 7, shape = "wide" },
+  ["SILPH_CO_6F"] = { x = 19, y = 2,
+                      shape = "narrow", turn = 90, cam = "wide" },
+  ["SILPH_CO_7F"] = { x = 1, y = 2, shape = "wide", cam = "wide" },
+  ["SILPH_CO_8F"] = { x = 8, y = 6, shape = "narrow" },
+  ["SILPH_CO_9F"] = { x = 20, y = 11, shape = "wide", cam = "wide" },
+  ["SS_ANNE_1F_ROOMS"] = { x = 11, y = 1, shape = "narrow", cam = "wide" },
+  -- the ship is all two-cell corridors, so the wide arena shape fits nowhere
+  -- aboard and the long lens always lands outside the hull
+  ["SS_ANNE_2F"] = { x = 36, y = 8, shape = "narrow", cam = "wide" },
+  -- these two decks are byte-identical geometry, so they take the same spot
+  ["SS_ANNE_2F_ROOMS"] = { x = 11, y = 12, shape = "narrow", cam = "wide" },
+  ["SS_ANNE_B1F_ROOMS"] = { x = 11, y = 12, shape = "narrow", cam = "wide" },
+  ["SS_ANNE_BOW"] = { x = 8, y = 3, shape = "wide" },
+  ["VICTORY_ROAD_2F"] = { x = 16, y = 6, shape = "wide", cam = "wide" },
+  ["VICTORY_ROAD_3F"] = { x = 20, y = 1, shape = "wide", cam = "wide" },
+
+  -- ------- towns and the last interiors
+  ["CERULEAN_CITY"] = { x = 15, y = 16, shape = "wide" },
+  ["GAME_CORNER"] = { x = 8, y = 5, shape = "wide" },
+  -- the lab is ten cells by twelve, so the long lens is always off-map, and
+  -- on it a desk clipped one mon and a pillar the other
+  ["OAKS_LAB"] = { x = 1, y = 3, shape = "narrow", turn = 90, cam = "wide" },
+  -- Saffron's gym is a grid of small walled cells: no wide shape exists
+  -- anywhere in it, and the long lens sits inside a divider
+  ["SAFFRON_GYM"] = { x = 9, y = 7, shape = "narrow", cam = "wide" },
+  ["SILPH_CO_3F"] = { x = 18, y = 11, shape = "wide", cam = "wide" },
+  ["SILPH_CO_10F"] = { x = 1, y = 1, shape = "wide", cam = "wide" },
+  ["SILPH_CO_11F"] = { x = 10, y = 6,
+                       shape = "wide", turn = 180, cam = "wide" },
+  -- the upper corridor (cols 4-5, rows 1-4) is sealed at runtime by the
+  -- gym's barrier, so arenas there silently fail the fit test
+  ["VERMILION_GYM"] = { x = 3, y = 2,
+                        shape = "narrow", turn = 90, cam = "wide" },
+  ["VICTORY_ROAD_1F"] = { x = 11, y = 5, shape = "narrow", cam = "wide" },
+  ["VIRIDIAN_FOREST"] = { x = 16, y = 34, shape = "narrow" },
+
+  -- ------- the remaining routes
+  ["ROUTE_19"] = { x = 8, y = 31, shape = "narrow" },
+  -- the two surf routes fight AFLOAT, in the middle of their own sea rather
+  -- than on the rim of beach the land search would otherwise find
+  ["ROUTE_20"] = { x = 23, y = 7, shape = "wide" },
+  ["ROUTE_21"] = { x = 8, y = 46, shape = "wide" },
+  ["ROUTE_22"] = { x = 35, y = 7, shape = "wide", cam = "wide" },
+  ["ROUTE_23"] = { x = 2, y = 34, shape = "wide", cam = "wide" },
+  ["ROUTE_24"] = { x = 6, y = 9, shape = "wide", turn = 270, cam = "wide" },
+  ["ROUTE_25"] = { x = 32, y = 2, shape = "wide", cam = "wide" },
+
+  -- ------- caves, gyms and the Elite Four
+  --
+  -- None of these tilesets has a grass tile at all, so the no-grass rule
+  -- constrained nothing here; what constrains them is furniture, rock
+  -- pillars and how small the rooms are.
+  ["AGATHAS_ROOM"] = { x = 4, y = 2, shape = "narrow", cam = "wide" },
+  ["BRUNOS_ROOM"] = { x = 2, y = 1, shape = "wide", turn = 90 },
+  ["CELADON_GYM"] = { x = 3, y = 4,
+                      shape = "narrow", turn = 90, cam = "wide" },
+  ["CERULEAN_CAVE_1F"] = { x = 12, y = 8, shape = "narrow", cam = "wide" },
+  -- 2F is a maze of one-cell rock corridors; all 24 of its candidate spots
+  -- hide a mon, so it borrows the floor below -- the same cave
+  ["CERULEAN_CAVE_2F"] = { map = "CERULEAN_CAVE_B1F", x = 2, y = 0,
+                           shape = "wide" },
+  ["CERULEAN_CAVE_B1F"] = { x = 2, y = 0, shape = "wide", cam = "wide" },
+  ["CERULEAN_GYM"] = { x = 4, y = 2, shape = "wide" },
+  ["CHAMPIONS_ROOM"] = { x = 2, y = 2, shape = "narrow", cam = "wide" },
+  ["CINNABAR_GYM"] = { x = 9, y = 16,
+                       shape = "narrow", turn = 90, cam = "wide" },
+  ["DIGLETTS_CAVE"] = { x = 14, y = 26,
+                        shape = "wide", turn = 90, cam = "wide" },
+  ["FIGHTING_DOJO"] = { x = 3, y = 5,
+                        shape = "narrow", turn = 90, cam = "wide" },
+  ["LANCES_ROOM"] = { x = 4, y = 2, shape = "wide", cam = "wide" },
+  ["LORELEIS_ROOM"] = { x = 4, y = 2, shape = "narrow" },
+  ["MT_MOON_1F"] = { x = 25, y = 16, shape = "wide" },
+  ["MT_MOON_B1F"] = { x = 4, y = 11, shape = "wide" },
+  ["MT_MOON_B2F"] = { x = 8, y = 20, shape = "wide" },
+
+  -- The three gyms the default rig cannot stand back from. Five blocks is
+  -- further than these rooms are wide, so the eye landed outside the map and
+  -- the border ring -- extruded into a cliff by this mode -- crossed the near
+  -- mon wherever it stood. `cam = "wide"` swaps in the 44-degree lens (see
+  -- BattleCam), which fits inside the room; the mons come out smaller and all
+  -- three became stageable. It is asked for HERE, per map, so every area that
+  -- does not ask keeps the long lens it was framed for.
+  ["FUCHSIA_GYM"] = { x = 8, y = 6, shape = "narrow", cam = "wide" },
+  ["PEWTER_GYM"] = { x = 4, y = 1, shape = "narrow", turn = 90, cam = "wide" },
+  ["VIRIDIAN_GYM"] = { x = 10, y = 8, shape = "narrow", cam = "wide" },
+}

data/map_atmosphere.lua

@@ -0,0 +1,63 @@
+-- What hangs in the air of each map.
+--
+-- One entry per map that has an ATMOSPHERE: a ground fog the scene shader
+-- folds every surface into, and volumetric god rays -- light let down
+-- through an INVISIBLE canopy hanging above the map's real geometry, as
+-- if the trees drawn are only the understorey of something taller. The
+-- rays are not placed: a per-pixel march (see ForestAtmos) reads the
+-- frame's own depth and the sun's own shadow map, so the beams stand
+-- exactly where light really breaks between the tree hulls, trees and
+-- characters carve dark columns through them, and a wind-blown leaf
+-- field at the canopy plane opens and closes them like foliage moving
+-- overhead. The light leans along the mod's fixed noon shear (the one
+-- light a canopy map ever gets -- see DayNight.CANOPY); only its COLOUR
+-- and STRENGTH follow the clock: gold spears of sun by day, silver moon
+-- rays after dark, pollen adrift in the day's beams and fireflies once
+-- they cool.
+--
+-- A map with no entry here has no atmosphere at all: no fog uniform is
+-- raised, no march runs, nothing is spent. That is the contract a new
+-- map opts into by adding a line, and what a stale entry degrades to if
+-- its map id ever stops existing.
+--
+-- The knobs, in world pixels unless said otherwise (a map cell is 16):
+--
+--   canopyY   where the invisible canopy hangs. MUST clear the tallest
+--             real geometry under it (Viridian's carved tree hulls top
+--             at y = 32) -- a beam is alpha ZERO at this height and only
+--             fades in below it, so a canopy at or under the tree tops
+--             would cut every ray off before it cleared the leaves.
+--   fadeTo    the height by which a descending ray reaches full strength.
+--   fog       density  how fast distance dissolves into the haze
+--                      (1 - exp(-density * distance-past-start))
+--             start    how many pixels out the dissolve begins
+--             heightK  how quickly the fog thins with ALTITUDE
+--                      (exp(-y * heightK): 0.02 halves it by y = 35)
+--   rays      strength  overall in-scatter gain on the march
+--             reach     how far out the march walks, in world px
+--   motes     count of pollen/dust flecks adrift in the daylight beams
+--   fireflies count of the night shift
+--   seed      the xorshift seed the particle deal runs on
+--
+-- Two caveats for maps opting in later: the water pass has no fog term,
+-- so a lake under heavy haze stays clear-day sharp in its reflections;
+-- and the march runs after the water's mirror copy, so beams will not
+-- appear IN those reflections either. Neither can bite in a map without
+-- water.
+
+return {
+  ["VIRIDIAN_FOREST"] = {
+    canopyY = 56,
+    fadeTo = 28,
+    fog = { density = 0.0045, start = 64, heightK = 0.02 },
+    -- strength is calibrated against the march's real integral: the
+    -- under-canopy stretch of an orbit ray is short and thinly dense, so
+    -- the raw accumulation for a fully lit beam core is a few percent --
+    -- this gain lands it near +0.3 on screen. Halve it for a whisper,
+    -- double it for cathedral light.
+    rays = { strength = 16, reach = 380 },
+    motes = { count = 96 },
+    fireflies = { count = 48 },
+    seed = 0x51D,
+  },
+}

lib/AntiAlias.lua

@@ -0,0 +1,244 @@
+-- Voxel world mode: anti-aliasing, by supersampling.
+--
+-- Everything else in this mod is flat art blitted at whole pixels; this one
+-- pass is real geometry seen through a perspective camera, and a polygon
+-- edge that lands at an angle across the pixel grid is the one place in the
+-- game where a hard stair-step is not a stylistic choice. A roof ridge, a
+-- ledge lip, a tree's silhouette against the sky and the leaning card of a
+-- character are all cut by an edge that has no reason to line up with
+-- anything, and at the shallow rungs -- where the diorama reads most like a
+-- photograph of a model -- they crawl as the camera drifts.
+--
+-- SUPERSAMPLING, not MSAA and not a filter over the finished frame, for two
+-- reasons that both come out of what the pass already is:
+--
+--   MSAA would take the water with it. The reflections read the frame's own
+--   DEPTH buffer as a texture (Voxel3D.beginWater), and a multisampled depth
+--   attachment is not a thing a fragment shader in this dialect can sample.
+--   The row would have quietly switched the other row off.
+--
+--   An edge filter (FXAA and its relatives) works from the finished colour
+--   alone, and would be GUESSING where the edges are out of one sample per
+--   pixel -- inventing detail it never rendered, and unable to tell a
+--   geometry edge from the boundary between two texels of a tileset.
+--
+-- Rendering the pass larger and folding it back down has neither problem:
+-- the depth buffer stays an ordinary texture, every pass in the frame keeps
+-- working in the canvas it was handed, and the fold is an average of samples
+-- that were each rendered honestly. It antialiases everything at once --
+-- geometry, the alpha-cut outline of a sprite card, the wireframe, the
+-- water's ray march -- because none of them know it is happening.
+--
+-- Be clear about what "everything" means: the artwork softens too. A tileset
+-- texel out here is not a screen pixel, it is a quad in a perspective view,
+-- and its boundary crosses the pixel grid at the same arbitrary angle a roof
+-- ridge does -- so the fold averages across it exactly as it averages across
+-- the ridge. That is what an honest extra sample says about that pixel, and
+-- it is also the trade the row IS: the diorama comes out smoother, not
+-- sharper. Which is why this is a row and not something that is simply on.
+--
+-- What it costs is pixels, which is the whole of why this is a row and not
+-- something that is simply on: 2X is half again as many in each direction,
+-- 4X is twice, and the scene pass is the most expensive thing in the frame.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local ModSetting = V.require("ModSetting")
+
+local AntiAlias = {}
+
+-- the key under options.modOptions.DRAMATIC_SHAPE, shared by the row in
+-- OPTIONS and the mod manager's own settings page for this mod
+AntiAlias.KEY = "aa"
+AntiAlias.LABEL = "AA"
+
+-- The ladder is SAMPLES PER DISPLAY PIXEL, which is how an AA setting reads
+-- everywhere else, and the canvas scale each rung costs is its square root:
+-- 2 samples is a canvas 1.41x wider and taller, 4 is one exactly twice the
+-- size. OFF is the default -- this is a cost knob, and a mod should not
+-- quietly spend four times the fill rate of the machine it lands on.
+AntiAlias.setting = ModSetting.new(AntiAlias.KEY, AntiAlias.LABEL,
+                                   { 0, 2, 4 }, { "OFF", "2X", "4X" })
+
+-- The scale the pass currently open was actually expanded by (see expand).
+-- 1 while there is no supersampling in force, which is also what every
+-- reader gets on a frame that never opened a pass at all.
+local live = 1
+
+function AntiAlias.samples()
+  return tonumber(AntiAlias.setting:get()) or 0
+end
+
+-- What the row ASKS for. The scale in force is `factor()`, which is this
+-- clamped to what the driver will actually allocate.
+local function wanted()
+  local n = AntiAlias.samples()
+  if n <= 1 then return 1 end
+  return math.sqrt(n)
+end
+
+-- The biggest canvas this driver admits to, or nil where it will not say.
+-- A 4K window at 4X asks for 7680 across, which is past the limit on plenty
+-- of hardware and every phone -- and a refused canvas is not a softer
+-- diorama, it is beginScene returning false and the whole mode falling back
+-- to the flat 2D path.
+local function textureLimit()
+  if not (love.graphics and love.graphics.getSystemLimits) then return nil end
+  local ok, limits = pcall(love.graphics.getSystemLimits)
+  return (ok and limits and limits.texturesize) or nil
+end
+
+-- The size to render `w` x `h` display pixels at, and the size everything
+-- inside the pass then measures itself in.
+--
+-- Also where `live` is set, which is why this must be called once per pass
+-- immediately before beginScene: the wireframe's line width and the FX
+-- overlay's sprite scale are both quoted in DISPLAY pixels and have to be
+-- multiplied up into canvas ones, and the honest multiplier is the one this
+-- returned rather than the one the row asked for.
+function AntiAlias.expand(w, h)
+  local s = wanted()
+  local max = textureLimit()
+  if max and max > 0 then
+    -- clamped rather than abandoned: a window too big for 4X can usually
+    -- still carry some of it, and half a rung of smoothing is worth more
+    -- than a row that silently does nothing at that size
+    s = math.min(s, max / math.max(1, w), max / math.max(1, h))
+  end
+  if not (s > 1.01) then
+    live = 1
+    return w, h
+  end
+  local ew, eh = math.floor(w * s + 0.5), math.floor(h * s + 0.5)
+  live = ew / math.max(1, w)
+  return ew, eh
+end
+
+-- The scale the open pass was expanded by; 1 when it was not.
+function AntiAlias.factor()
+  return live
+end
+
+-- ------- the fold
+--
+-- One target per pass (the free-roam world and the battle's arena are alive
+-- at different moments but reallocating on every battle entry and exit is
+-- what the scene canvas's own slots exist to avoid), reallocated only when
+-- that pass's DISPLAY size changes -- a window resize, or the row itself
+-- moving, which changes the source and not this.
+
+local targets = {}
+
+local function targetFor(slot, w, h)
+  local t = targets[slot]
+  if not (t and t.w == w and t.h == h) then
+    local ok, c = pcall(love.graphics.newCanvas, w, h)
+    if not (ok and c) then return nil end
+    -- nearest, like the canvas it stands in for: this one is composited a
+    -- canvas pixel to a display pixel, and the smoothing has already happened
+    pcall(c.setFilter, c, "nearest", "nearest")
+    if t and t.canvas and t.canvas.release then pcall(t.canvas.release, t.canvas) end
+    t = { canvas = c, w = w, h = h }
+    targets[slot] = t
+  end
+  return t.canvas
+end
+
+-- The box filter, and the whole of why it is a shader rather than a scaled
+-- draw with linear filtering on.
+--
+-- The void this pass renders into is cleared to a TRANSPARENT BLACK, and at
+-- the rungs below FULL a good deal of the frame is still that. Averaging a
+-- straight-alpha edge against it drags the result toward black as well as
+-- toward transparent, and then the engine's own composite multiplies by that
+-- alpha a second time -- so every silhouette against the void would come out
+-- ringed with a dark fringe, which is exactly the artefact the row is here to
+-- remove.
+--
+-- So the taps are premultiplied before they are averaged and divided back out
+-- after, which is the arithmetic that makes an edge pixel mean "half covered
+-- by this colour" instead of "covered by half of this colour".
+--
+-- Four taps, half a source texel from the destination centre. At 4X those
+-- land dead on the four texel centres the destination pixel covers, so it is
+-- an exact 2x2 box; at 2X the source grid does not divide, and the bilinear
+-- fetch under each tap widens the box a little rather than missing samples.
+local SHADER = [[
+  uniform vec2 tap;        // half a SOURCE texel, in uv
+  vec4 effect(vec4 color, Image tex, vec2 tc, vec2 sc) {
+    vec4 a = Texel(tex, tc + vec2(-tap.x, -tap.y));
+    vec4 b = Texel(tex, tc + vec2( tap.x, -tap.y));
+    vec4 c = Texel(tex, tc + vec2(-tap.x,  tap.y));
+    vec4 d = Texel(tex, tc + vec2( tap.x,  tap.y));
+    float al = (a.a + b.a + c.a + d.a) * 0.25;
+    if (al <= 0.0) return vec4(0.0);
+    vec3 sum = a.rgb * a.a + b.rgb * b.a + c.rgb * c.a + d.rgb * d.a;
+    return vec4(sum * 0.25 / al, al) * color;
+  }
+]]
+
+local shader = nil            -- nil = untried, false = unavailable
+
+local function getShader()
+  if shader == nil then
+    local ok, sh = pcall(love.graphics.newShader, SHADER)
+    shader = (ok and sh) or false
+  end
+  return shader or nil
+end
+
+-- Fold `canvas` down to `w` x `h` and hand back the result.
+--
+-- Returns the input untouched when there is nothing to fold -- the row is
+-- off, or the canvas already IS that size -- so a caller can run it
+-- unconditionally, and so can a headless test run. A target that would not
+-- allocate is the same answer: the pass is lost either way if this hands back
+-- something the wrong size, so it hands back the input and the frame draws at
+-- the size it was rendered.
+function AntiAlias.resolve(canvas, w, h, slot)
+  if not canvas then return canvas end
+  local ok, cw, ch = pcall(canvas.getDimensions, canvas)
+  if not ok or (cw == w and ch == h) then return canvas end
+  local target = targetFor(slot or "world", w, h)
+  if not target then return canvas end
+
+  local sh = getShader()
+  local prevBlend, prevAlpha = love.graphics.getBlendMode()
+  -- the scene canvas filters nearest for its usual 1:1 blit; the taps want
+  -- linear, put back below so every other pass finds what it expects
+  pcall(canvas.setFilter, canvas, "linear", "linear")
+  love.graphics.setColor(1, 1, 1, 1)
+  -- replace, not alpha-blend: this is an image-processing copy, and the alpha
+  -- the shader worked out has to land as itself rather than be composited
+  -- against whatever the target held
+  love.graphics.setBlendMode("replace", "premultiplied")
+  if sh then
+    love.graphics.setShader(sh)
+    pcall(sh.send, sh, "tap", { 0.5 / cw, 0.5 / ch })
+  end
+  local drew = pcall(function()
+    love.graphics.setCanvas(target)
+    love.graphics.clear(0, 0, 0, 0)
+    love.graphics.draw(canvas, 0, 0, 0, w / cw, h / ch)
+  end)
+  love.graphics.setCanvas()
+  love.graphics.setShader()
+  love.graphics.setBlendMode(prevBlend or "alpha", prevAlpha)
+  pcall(canvas.setFilter, canvas, "nearest", "nearest")
+  return drew and target or canvas
+end
+
+-- Drop the GPU objects (window resize, hot reload).
+function AntiAlias.invalidate()
+  for slot, t in pairs(targets) do
+    if t.canvas and t.canvas.release then pcall(t.canvas.release, t.canvas) end
+    targets[slot] = nil
+  end
+end
+
+function AntiAlias.row()
+  return AntiAlias.setting:row()
+end
+
+return AntiAlias

lib/BattleArena.lua

@@ -0,0 +1,427 @@
+-- Overworld battles: where the fight is staged.
+--
+-- A battle in this mod happens ON THE MAP, so it needs a patch of ground
+-- clear enough to stand two Pokemon on and point a camera down. This module
+-- finds it: the nearest patch of open cells, in the shape below.
+--
+--     x x x
+--     x O x        O   the enemy's mon
+--     x x x
+--     x x x
+--     x P x        P   the player's mon
+--     x x x
+--
+-- Every `x` is an OPEN cell -- one with no obstruction, i.e. one the player
+-- could walk onto. The two mons stand three cells apart down the middle
+-- column, with a one-cell apron all round so the camera looks across floor
+-- rather than into a wall.
+--
+-- When no map has room for that -- a corridor, a cave, a shop floor -- the
+-- search relaxes to the narrow shape, which is the same three-cell gap with
+-- the apron given up:
+--
+--     O
+--     x
+--     x
+--     P
+--
+-- and if even that will not fit, the caller gets nil and the battle draws
+-- the way it always did. A mod that cannot find a stage does not invent
+-- one.
+--
+-- Nothing here MOVES anybody: the arena is where the CAMERA goes and where
+-- the two mons are staged for the shot. The player's own cell, the party,
+-- every script and flag are exactly where the battle left them, which is
+-- what keeps a trainer's post-battle dialogue talking to someone still
+-- standing in front of them.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local BattleArena = {}
+
+-- ------- the authored spot
+--
+-- Every map gets ONE place its battles happen, chosen once and written down
+-- in data/battle_arenas.lua, rather than whatever clearing happens to be
+-- nearest to wherever the fight started. Two reasons.
+--
+-- A fight should look the same every time it happens somewhere. Picking the
+-- nearest patch means Route 1 has a dozen different battle scenes depending
+-- on which step of the grass you were on, some of them behind a tree.
+--
+-- And "open ground" is not the same question as "you can SEE the two of
+-- them". The camera is low and a long way back, so a hedge, a ledge lip or a
+-- building corner anywhere along that line hides a mon completely while the
+-- cells it stands on are perfectly walkable. That is what `clearance` below
+-- measures, and it is what the authored list is chosen against.
+--
+-- A map with no entry falls back to the search, so a mod that adds maps, or
+-- an entry that goes stale, degrades to the old behaviour rather than to no
+-- battle.
+-- An entry may also name ANOTHER MAP to stage on:
+--
+--   ["MT_MOON_B2F"] = { map = "MT_MOON_1F", x = 12, y = 8, shape = "wide" }
+--
+-- because some maps simply have nowhere to put a fight. A cave's lower floor
+-- can be nothing but two-cell-wide corridors between rock walls; a gym is a
+-- room full of furniture. Rather than stage a battle there badly -- both
+-- Pokemon behind a boulder -- the fight is shot on a floor of the SAME cave,
+-- or a floor of the same building, that does have the room for it. It is the
+-- same place, and no worse a fiction than a battle happening on ground the
+-- player is not standing on, which is what every one of these already is.
+local authored = nil
+local overrides = {}
+
+local function authoredFor(mapId)
+  -- `~= nil`, not truthiness: `false` is a meaningful entry here (an
+  -- authored refusal), so it has to reach the caller rather than read as
+  -- "nothing set" and fall through to the data file
+  local forced = overrides[mapId]
+  if forced ~= nil then return forced end
+  if authored == nil then
+    local ok, list = pcall(V.data, "battle_arenas")
+    authored = (ok and type(list) == "table") and list or false
+  end
+  if not authored then return nil end
+  return authored[mapId]
+end
+
+BattleArena.authoredFor = authoredFor
+
+-- Force one map's entry at runtime, ahead of the data file. The authoring
+-- tool's handle: it is how a spot chosen by eye is staged and photographed
+-- before it is written down, and the only way to check a cross-floor entry
+-- without editing the shipped list first. Pass nil to drop it again.
+function BattleArena.setOverride(mapId, entry)
+  overrides[mapId] = entry
+end
+
+-- Cell size in world pixels, the unit every coordinate here is in when it
+-- crosses into the renderer (Map's walk grid is 16px cells).
+local CELL = 16
+
+-- The two shapes, in preference order. `w`/`h` are in cells; `enemy` and
+-- `player` are the offsets, from the shape's north-west corner, of the two
+-- cells a mon stands on.
+BattleArena.SHAPES = {
+  { id = "wide",   w = 3, h = 6, enemy = { 1, 1 }, player = { 1, 4 } },
+  { id = "narrow", w = 1, h = 4, enemy = { 0, 0 }, player = { 0, 3 } },
+}
+
+-- ------- which way round the fight stands
+--
+-- Both shapes above are drawn north-south, with the foe at the top and the
+-- player below it, and the camera is solved for that: it sits off the
+-- player's shoulder, low and back down the arena's own axis. `turn` swings
+-- the WHOLE staging a quarter at a time -- the footprint, the two cells, and
+-- the camera with them -- so the composition on screen is identical and only
+-- the ground under it is different.
+--
+-- It buys two things.
+--
+-- A footprint that FITS. The wide shape is three cells by six; an east-west
+-- corridor two cells deep has no room for it standing up and all the room in
+-- the world for it lying down. Half the maps in Kanto run the other way from
+-- the one shape this mode was drawn in.
+--
+-- And a BACKDROP. A quarter turn moves the camera to a different side of the
+-- same patch of ground, so the wall behind the pair becomes the window
+-- behind them, or the cliff becomes the valley. Nothing about the shot's
+-- geometry changes -- the mons land on the same two screen anchors at the
+-- same size -- so this is purely a choice about what is behind them, made
+-- per map by somebody looking at it.
+--
+-- Written in DEGREES in data/battle_arenas.lua (`turn = 90`) because that is
+-- what it is; handled as quarter turns everywhere below.
+local function quarters(turn)
+  local q = math.floor(((tonumber(turn) or 0) / 90) + 0.5)
+  return ((q % 4) + 4) % 4
+end
+
+BattleArena.quarters = quarters
+
+-- The footprint a shape covers once turned: a quarter or three of a turn
+-- swaps how far it reaches in each direction, which is the whole reason a
+-- corridor takes one and not the other.
+function BattleArena.extent(shape, turn)
+  if quarters(turn) % 2 == 1 then return shape.h, shape.w end
+  return shape.w, shape.h
+end
+
+-- Where a cell offset inside the shape ends up under the same turn, measured
+-- from the turned footprint's own north-west corner -- so the corner an entry
+-- names stays the corner, whichever way the fight faces from it.
+local function spin(shape, turn, ox, oy)
+  local q = quarters(turn)
+  if q == 1 then return shape.h - 1 - oy, ox end
+  if q == 2 then return shape.w - 1 - ox, shape.h - 1 - oy end
+  if q == 3 then return oy, shape.w - 1 - ox end
+  return ox, oy
+end
+
+-- Whether a cell is open ground for the purpose above.
+--
+-- "Open" is the walk test the player themselves answer to, so an arena can
+-- never be laid over a wall, a counter, a tree or a ledge face. Water counts
+-- only for a surfer, which is the one case where the player is standing on
+-- it too -- a sea battle staged on the beach half a route away would read as
+-- a teleport.
+--
+-- Warp cells are excluded on top of that. They are walkable by definition
+-- (they are the doormat), and a fight framed in a doorway both looks wrong
+-- and puts the camera inside the building's geometry.
+--
+-- And TALL GRASS is excluded, which is the surprising one, because grass is
+-- where wild battles come from and standing in it is the obvious place to
+-- have one. It does not survive contact with the camera. Grass is real
+-- geometry in this mode -- a row of tufts about knee height on a Pokemon --
+-- drawn with the same camera-ward bias that lets it overdraw a walking
+-- character's feet in the free-roam world. From a camera nearly level with
+-- the floor that bias stops being feet-deep: the tufts on and around a mon's
+-- own tile stand between it and the lens and eat most of the sprite.
+--
+-- So the arena is laid on bare ground -- the whole footprint, not just the
+-- two cells a mon stands on, because the apron south of the near mon is
+-- exactly the row whose grass would cover it. Grass FURTHER back toward the
+-- camera is fine and stays: it is far enough forward to project low and wide
+-- across the bottom of the frame, where it reads as a field rather than as
+-- something in the way.
+local function openCell(map, cx, cy, surfing)
+  if not map:inBounds(cx, cy) then return false end
+  if map:warpAtCell(cx, cy) then return false end
+  if map:isWarpTileCell(cx, cy) then return false end
+  if map.isGrassCell and map:isGrassCell(cx, cy) then return false end
+  if map:isWalkableCell(cx, cy) then return true end
+  return (surfing and map:isWaterCell(cx, cy)) or false
+end
+
+BattleArena.openCell = openCell
+
+-- The map's open cells as one flat boolean grid, so the rectangle test
+-- below is a lookup rather than a tileset walk per cell. Built once per
+-- search; a battle asks for one.
+local function openGrid(map, surfing)
+  local w, h = map.widthCells, map.heightCells
+  local grid = {}
+  for cy = 0, h - 1 do
+    local row = cy * w
+    for cx = 0, w - 1 do
+      grid[row + cx] = openCell(map, cx, cy, surfing)
+    end
+  end
+  return grid, w, h
+end
+
+local function fits(grid, gw, x, y, w, h)
+  for cy = y, y + h - 1 do
+    local row = cy * gw
+    for cx = x, x + w - 1 do
+      if not grid[row + cx] then return false end
+    end
+  end
+  return true
+end
+
+-- Build the record the renderer reads: the two mons' cells and, in world
+-- pixels, the centre of each and of the pair.
+local function place(shape, x, y, turn)
+  local eox, eoy = spin(shape, turn, shape.enemy[1], shape.enemy[2])
+  local pox, poy = spin(shape, turn, shape.player[1], shape.player[2])
+  local ex, ey = x + eox, y + eoy
+  local px, py = x + pox, y + poy
+  local w, h = BattleArena.extent(shape, turn)
+  local arena = {
+    shape = shape.id,
+    -- carried in degrees, so everything downstream that reasons about the
+    -- shot -- the camera's base yaw above all -- reads the same number the
+    -- data file was written with
+    turn = quarters(turn) * 90,
+    x = x, y = y, w = w, h = h,
+    enemyCell = { ex, ey },
+    playerCell = { px, py },
+    -- world-pixel centres of the two cells a mon stands on
+    enemy = { ex * CELL + CELL / 2, ey * CELL + CELL / 2 },
+    player = { px * CELL + CELL / 2, py * CELL + CELL / 2 },
+  }
+  arena.mid = { (arena.enemy[1] + arena.player[1]) / 2,
+                (arena.enemy[2] + arena.player[2]) / 2 }
+  return arena
+end
+
+-- ------- can the two of them actually be SEEN there
+--
+-- The camera sits low and far back on one side, so what hides a mon is not
+-- what is on its own tile -- it is anything TALL between the camera and it.
+-- A tree two cells to the south-east blocks the near mon completely while
+-- every cell of the arena is open ground.
+--
+-- So the line from the eye to each mon is walked in short steps and the
+-- terrain height under each step is compared with how high the line is
+-- there. Three lines per mon -- to its feet, its middle and its head --
+-- because a hedge that clears the head still cuts the body in half.
+--
+-- Grass and flowers are deliberately not obstacles: they stand at ankle
+-- height, they are what a field looks like, and a mon standing in them
+-- reads as standing in a field rather than as being hidden by one.
+BattleArena.SAMPLE_STEP = 4      -- world pixels along the line
+BattleArena.MON_H = 16           -- how tall a mon stands, in world pixels
+BattleArena.CLEAR_EPS = 1.5      -- slack, so a flush kerb is not an obstacle
+
+local function heightAt(map, wx, wz)
+  local cx, cy = math.floor(wx / CELL), math.floor(wz / CELL)
+  if not map:inBounds(cx, cy) then
+    -- off the map the border ring is drawn, and on most outdoor maps that
+    -- ring is trees; treat it as solid so an arena is never framed through it
+    return 32
+  end
+  local ok, h = pcall(V.require("VoxelScene").groundAt, map, cx, cy)
+  return (ok and h) or 0
+end
+
+-- Whether the segment from `eye` to (tx, ty, tz) clears the terrain.
+local function lineClear(map, eye, tx, ty, tz)
+  local dx, dy, dz = tx - eye[1], ty - eye[2], tz - eye[3]
+  local len = math.sqrt(dx * dx + dy * dy + dz * dz)
+  if len <= 1 then return true end
+  local steps = math.ceil(len / BattleArena.SAMPLE_STEP)
+  -- skip the ends: the eye is in open air by construction and the last step
+  -- is the mon's own tile, which it is standing on
+  for i = 1, steps - 1 do
+    local t = i / steps
+    local wx = eye[1] + dx * t
+    local wy = eye[2] + dy * t
+    local wz = eye[3] + dz * t
+    if heightAt(map, wx, wz) > wy + BattleArena.CLEAR_EPS then return false end
+  end
+  return true
+end
+
+-- Whether both mons would be in plain view from the battle camera.
+function BattleArena.clearance(map, arena)
+  local BattleCam = V.require("BattleCam")
+  -- the CANONICAL shot: whether a fight fits somewhere is a fact about the
+  -- ground, so it must not depend on the drift's phase or on where the
+  -- player last swung the camera (see BattleCam.rig's third argument)
+  local ok, rig = pcall(BattleCam.rig, arena, 0, true)
+  if not (ok and rig and rig.eye) then return true end
+  local eye = rig.eye
+  local H = BattleArena.MON_H
+  for _, mark in ipairs({ arena.player, arena.enemy }) do
+    for _, hy in ipairs({ 1, H * 0.5, H }) do
+      if not lineClear(map, eye, mark[1], hy, mark[2]) then return false end
+    end
+  end
+  return true
+end
+
+-- The nearest arena to (fromX, fromY) -- the player's cell -- or nil when
+-- the map has room for neither shape.
+--
+-- Distance is measured from the player to the arena's MIDPOINT, so "nearest"
+-- means the fight is staged as close to where it was triggered as the ground
+-- allows, rather than merely having a corner nearby.
+--
+-- Both shapes are searched over the whole map before the next one is tried:
+-- a wide arena on the far side of a route still beats a narrow one
+-- underfoot, because the wide one is the shot this mode is framed for.
+function BattleArena.find(map, fromX, fromY, surfing)
+  if not (map and map.widthCells) then return nil end
+
+  -- the authored spot wins outright when the map has one and it still holds
+  local pick = authoredFor(map.id)
+  -- `false` is an authored REFUSAL: a map looked at and found to have nowhere
+  -- a fight can be seen, with no other floor to borrow. Declining is the
+  -- honest answer -- the battle draws on the plain screen -- and it has to be
+  -- said explicitly, because the fallback search below would otherwise go and
+  -- find one of the bad spots that were already rejected by eye.
+  if pick == false then return nil end
+  if pick then
+    local shape = nil
+    for _, s in ipairs(BattleArena.SHAPES) do
+      if s.id == (pick.shape or "wide") then shape = s end
+    end
+    -- an entry may point at another floor of the same cave or building; the
+    -- arena is then measured against THAT map, and carries it
+    local host = map
+    if shape and pick.map and pick.map ~= map.id then
+      local ok, other = pcall(function()
+        local Game = require("src.core.Game")
+        return require("src.world.MapLoader").load(Game.data, pick.map)
+      end)
+      host = (ok and other) or nil
+    end
+    if shape and host then
+      -- An authored spot is checked with WATER COUNTING AS GROUND, whatever
+      -- the player is doing. The surfing test exists to stop the automatic
+      -- search staging a walker's fight out at sea; an authored entry was
+      -- chosen and looked at by a person, so if it is on water that is the
+      -- point of it -- the surf routes fight in the middle of their own
+      -- ocean rather than on a scrap of beach at the edge of the map. Land
+      -- entries are unaffected: land passes the test either way.
+      local grid, gw = openGrid(host, true)
+      -- measured against the TURNED footprint: an entry that lies the arena
+      -- down an east-west corridor covers different ground from the one that
+      -- stands it up, and the fit test is the thing that has to know
+      local fw, fh = BattleArena.extent(shape, pick.turn)
+      if fits(grid, gw, pick.x, pick.y, fw, fh) then
+        local arena = place(shape, pick.x, pick.y, pick.turn)
+        arena.map = host
+        -- which camera rig this spot is framed for; nil is the default long
+        -- lens, "close" the short one small rooms need (see BattleCam)
+        arena.cam = pick.cam
+        return arena
+      end
+    end
+  end
+
+  local found = BattleArena.search(map, fromX, fromY, surfing)
+  if found then found.map = map end
+  return found
+end
+
+-- The arena at a given north-west corner, whatever the map says about it.
+-- The authoring tool's manual override: a spot chosen by eye rather than by
+-- the search, so it can be photographed and judged before it is written down.
+function BattleArena.at(x, y, shapeId, turn)
+  for _, shape in ipairs(BattleArena.SHAPES) do
+    if shape.id == (shapeId or "wide") then
+      return place(shape, x, y, turn)
+    end
+  end
+  return nil
+end
+
+-- The nearest arena the map can offer, preferring one the pair can be SEEN
+-- in. Two passes rather than one score: a clear arena on the far side of a
+-- route beats an obstructed one underfoot, because being able to see the
+-- fight is the point, but an obstructed one still beats no battle at all.
+function BattleArena.search(map, fromX, fromY, surfing, wantClear)
+  local grid, gw, gh = openGrid(map, surfing)
+  for _, shape in ipairs(BattleArena.SHAPES) do
+    for _, needClear in ipairs({ true, false }) do
+      local best, bestD = nil, nil
+      for y = 0, gh - shape.h do
+        for x = 0, gw - shape.w do
+          if fits(grid, gw, x, y, shape.w, shape.h) then
+            local mx = x + (shape.w - 1) / 2
+            local my = y + (shape.h - 1) / 2
+            local dx, dy = mx - fromX, my - fromY
+            local d = dx * dx + dy * dy
+            if not bestD or d < bestD then
+              local cand = place(shape, x, y)
+              if not needClear or BattleArena.clearance(map, cand) then
+                best, bestD = cand, d
+              end
+            end
+          end
+        end
+      end
+      if best then return best end
+      if wantClear and needClear then return nil end
+    end
+  end
+  return nil
+end
+
+return BattleArena

lib/BattleBillboard.lua

@@ -0,0 +1,137 @@
+-- Overworld battles: the two mons, as geometry standing on the map.
+--
+-- Not pics composited over a picture of the world -- quads INSIDE it, drawn
+-- in the same 3D pass as the terrain, from the same camera, through the same
+-- shader. Which means they get everything the world gets and nothing has to
+-- be faked for them: the depth buffer decides what is in front of what, the
+-- sun pass sees them and throws their real silhouettes across the ground,
+-- and their size on screen is whatever standing on that tile at that
+-- distance actually looks like.
+--
+-- One quad, standing upright with its feet on the cell and yawed to face the
+-- camera. Upright rather than leaned back, unlike the free-roam mode's
+-- character cards: those lean because that camera looks DOWN and a standing
+-- card would foreshorten to nothing, and this one looks along the ground
+-- from about a foot above it, where a card standing up is simply correct.
+--
+-- The shader's alpha discard cuts the mon's exact outline out of the quad,
+-- so a Pokemon is its own silhouette against the world with no matte, no
+-- billboard edge and no sorting to get wrong.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Mat4 = V.require("Mat4")
+local Voxel3D = V.require("Voxel3D")
+
+local BattleBillboard = {}
+
+-- How wide a full-size (7x7 tile) mon stands, in world pixels. One overworld
+-- square, so a Pokemon covers the tile it is on and no more; a species whose
+-- pic is smaller than the full buffer comes out proportionally smaller,
+-- which is how the artwork's own size differences survive the trip.
+BattleBillboard.FULL_W = 16
+BattleBillboard.FULL_PIC = 56     -- the pic size FULL_W refers to
+
+-- A hair of camera-ward bias, so a card standing ON the ground plane wins
+-- the depth test against it instead of z-fighting the tile it is rooted to.
+BattleBillboard.PULL = 1.5
+
+local quad = nil                  -- nil = untried, false = unavailable
+
+-- The unit card: x in -0.5..0.5, y in 0..1, z = 0, UV over the whole
+-- texture. Feet on the model origin, so the model matrix only has to say
+-- where the mon is standing and how big it is.
+--
+-- Which puts this card OFF the voxel grid, alone among the meshes in this
+-- mode: the rest are built one unit per voxel in their own model space --
+-- terrain in world pixels, a character's card in the sprite's own pixels --
+-- and the wireframe is the integer planes of that space (see VoxelGrid).
+-- One unit here is the whole card, so the only integer plane inside it is
+-- x = 0, which is the pic's centre column: a single stray line straight
+-- down the middle of every Pokemon and no seams anywhere else.
+--
+-- The card stays a unit card, because a mon's size on screen is decided by
+-- the artwork's own dimensions and the distance it is standing at, and a
+-- unit card is what lets one matrix say both. Whoever draws it turns the
+-- wireframe off instead (Voxel3D.seams) -- a mesh that is not on the voxel
+-- grid does not get a voxel grid drawn on it.
+local function unitQuad()
+  if quad ~= nil then return quad or nil end
+  local verts = {
+    { -0.5, 0, 0, 0, 1, 1 },
+    { 0.5, 0, 0, 1, 1, 1 },
+    { 0.5, 1, 0, 1, 0, 1 },
+    { -0.5, 1, 0, 0, 0, 1 },
+  }
+  local indices = {}
+  Voxel3D.pushQuad(indices, 0)
+  local mesh = Voxel3D.newMesh(verts, indices)
+  quad = mesh or false
+  return quad or nil
+end
+
+BattleBillboard.mesh = unitQuad
+
+-- The yaw that turns the card's face toward the eye. The quad's normal is
+-- +Z before rotation, so this is just the bearing from the mon to the
+-- camera -- flattened to the horizontal, because a card that also tipped to
+-- face a camera above it would lift its feet off the floor.
+function BattleBillboard.yawToward(x, z, eye)
+  if not eye then return 0 end
+  return math.atan2(eye[1] - x, eye[3] - z)
+end
+
+-- Stand a `w` x `h` card with its feet centred on world (x, y, z).
+function BattleBillboard.matrix(x, y, z, w, h, yaw)
+  return Mat4.mul(Mat4.mul(Mat4.translate(x, y, z), Mat4.rotateY(yaw)),
+                  Mat4.scale(w, h, 1))
+end
+
+-- The world size a pic of `pw` x `ph` texture pixels stands at.
+function BattleBillboard.sizeFor(pw, ph)
+  if not (pw and ph and pw > 0 and ph > 0) then return 0, 0 end
+  local scale = BattleBillboard.FULL_W / BattleBillboard.FULL_PIC
+  return pw * scale, ph * scale
+end
+
+-- Draw one mon. `tex` is the pic already rendered to a texture (see
+-- OverworldBattle, which lets the engine's own battler draw produce it, so
+-- every faint slide, blink and squish comes along), `grow` the send-out
+-- animation's scale or nil.
+function BattleBillboard.draw(tex, x, y, z, grow)
+  local mesh = unitQuad()
+  if not (mesh and tex) then return false end
+  local pw, ph = tex:getDimensions()
+  local w, h = BattleBillboard.sizeFor(pw, ph)
+  if grow then w, h = w * grow, h * grow end
+  if w <= 0 or h <= 0 then return false end
+  local yaw = BattleBillboard.yawToward(x, z, Voxel3D.eye)
+  -- off the voxel grid, so no wireframe on it (see unitQuad)
+  Voxel3D.seams(false)
+  Voxel3D.draw(mesh, tex, BattleBillboard.matrix(x, y, z, w, h, yaw),
+               BattleBillboard.PULL)
+  Voxel3D.seams(true)
+  return true
+end
+
+-- The same card, as the SUN sees it: no camera-ward pull (that is a trick
+-- for the view's own depth buffer and would drag the shadow off its owner)
+-- and no draw call of its own, because the shadow pass has its own.
+function BattleBillboard.caster(shadowMap, tex, x, y, z, grow)
+  local mesh = unitQuad()
+  if not (mesh and tex) then return false end
+  local pw, ph = tex:getDimensions()
+  local w, h = BattleBillboard.sizeFor(pw, ph)
+  if grow then w, h = w * grow, h * grow end
+  if w <= 0 or h <= 0 then return false end
+  local yaw = BattleBillboard.yawToward(x, z, Voxel3D.eye)
+  shadowMap.draw(mesh, tex, BattleBillboard.matrix(x, y, z, w, h, yaw))
+  return true
+end
+
+function BattleBillboard.invalidate()
+  quad = nil
+end
+
+return BattleBillboard

lib/BattleCam.lua

@@ -0,0 +1,514 @@
+-- Overworld battles: the over-the-shoulder camera and its parallax drift.
+--
+-- The two mons are PINNED to their cells: each pic is drawn wherever its
+-- patch of ground projects to, not at a fixed screen slot. So the camera is
+-- not decoration -- it is the thing that decides where the fight appears,
+-- and it has to put those two patches of ground exactly where the battle
+-- screen wants its two pics:
+--
+--     the player's mon   (26, 96)    back pic, feet on the text box, well left
+--     the enemy's mon   (124, 56)    front pic, bottom of the 7x7 slot
+--
+-- Four screen coordinates, so four equations. The rig below is the solution:
+-- SIDE / BACK / HEIGHT place the eye relative to the arena's midpoint, LOOK
+-- aims it, and FRAME_H sets the lens, and together they land both marks
+-- within a thousandth of a pixel of the targets. They are not hand-picked
+-- numbers that looked about right -- they came out of a solver, and the
+-- suite reprojects them so a future edit either still lands or says so.
+--
+-- East is what decides which mon is on which side. The arena axis runs north
+-- (the enemy) to south (the player's mon), and a camera east of that axis
+-- sees the near end swing LEFT and the far end RIGHT -- the layout arrived
+-- at by standing in the right place rather than by mirroring anything.
+--
+-- ------- and two more equations, from the pixels
+--
+-- The pics are pixel art and their size on screen is not something the mod
+-- gets to choose: 56 pixels for a front pic, 64 for a back one. And a mon has
+-- to stand in ONE OVERWORLD SQUARE, or it towers over the houses and gives
+-- away that the world behind it is a picture. Together those say the square
+-- each mon stands on must project to about the width of its own pic, which is
+-- two more equations for the same six unknowns -- and they are what set the
+-- distance.
+--
+-- The answer is a LONG LENS FROM A LOW STANCE: twelve degrees above the
+-- floor, twelve degrees wide, from five blocks back. Not a stylistic choice
+-- -- it is what a 56-pixel sprite standing on a 16-pixel tile forces on a
+-- 160-pixel screen. Roughly three tiles fit across the frame, so the camera
+-- has to be far away and zoomed in rather than near and wide. That is the
+-- DEFAULT rig, and every map that can take it gets it.
+--
+-- ------- the exception: rooms too small to stand back from
+--
+-- Five blocks back is further than some rooms are wide. A gym is about ten
+-- cells across, so on one the eye lands OUTSIDE the map, where the border
+-- ring the engine draws round every map -- extruded into a cliff by this mode
+-- -- crosses the near Pokemon wherever it stands. Three gyms could not be
+-- staged anywhere at all for that reason.
+--
+-- So there is a second rig, and an arena asks for it by name (cam = "wide"
+-- in data/battle_arenas.lua). It comes in to about four cells with the lens
+-- opened up to match: an ordinary 44-degree shot that fits inside the room.
+-- The mons render smaller for it -- a bit over half a tile rather than a
+-- whole one -- which is the price. Both rigs are solved against the SAME four
+-- anchors, so the composition is identical either way; only the lens and the
+-- distance differ, which is what makes it safe to pick per map.
+--
+-- Rooms too small for the long lens are the reason it exists, but it is not
+-- only for them: an area that simply reads better with more of itself in
+-- shot can ask for it too.
+--
+-- Purely presentational, like everything else in this mod: the camera looks
+-- at the map, and nothing it does reaches collision, movement or scripts.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local BattleCam = {}
+
+-- ------- the rig, in world pixels (a map cell is 16, a block 32)
+--
+-- Solved against the four anchors and two spans above, with the two mons 48
+-- world pixels (three cells) apart -- BattleArena.SHAPES is where that gap is
+-- set, and changing it invalidates these.
+
+-- `frameH` is how much world the frame is tall enough to hold at the aim
+-- distance, which together with that distance is the lens.
+-- Named for the LENS, because that is what an author is choosing between
+-- when they look at a shot and decide it wants more room in it.
+BattleCam.RIGS = {
+  -- the default: a long 11.5-degree lens from five blocks back, which is
+  -- what makes one tile big enough to stand a 56-pixel mon on
+  tele = {
+    side = 78.79, back = 144.96, height = 37.88,
+    lookX = -0.26, lookY = 0.34, frameH = 34.11,
+  },
+  -- 44 degrees from four cells: fits inside a room the long lens cannot
+  -- stand back from, and shows more of anywhere else, at the cost of a
+  -- smaller pair
+  wide = {
+    side = 41.98, back = 41.16, height = 28.48,
+    lookX = -3.24, lookY = -1.35, frameH = 55.62,
+  },
+}
+
+BattleCam.DEFAULT_RIG = "tele"
+
+-- The rig an arena asks for, falling back to the default for anything that
+-- does not ask (and for a name that is not one of the two).
+function BattleCam.rigFor(arena)
+  local want = arena and arena.cam
+  return BattleCam.RIGS[want] or BattleCam.RIGS[BattleCam.DEFAULT_RIG]
+end
+
+-- ------- the drift
+--
+-- A slow orbit about the arena's vertical axis. Rotating about a point
+-- BETWEEN the two mons is what makes it parallax rather than a pan: the mons
+-- are pinned to the ground, so the near one slides one way across the frame
+-- and the far one slides the OTHER, by the amount their difference in
+-- distance implies. Over a full swing that is about eight pixels of relative
+-- movement -- plainly visible as depth, far too slow to fight the fight.
+-- The angle is small because the lens is long: two degrees of orbit is seven
+-- pixels of travel through an eleven-degree field of view.
+--
+-- Under it, a much smaller breath in and out along the same line, on an
+-- unrelated period, so the pair never returns to the same pose on any cycle
+-- a battle is long enough to show. A DOLLY rather than a pan of the aim:
+-- moving the aim point would slide both mons the same way, which with pinned
+-- pics is just the whole picture walking sideways. Changing the DISTANCE
+-- moves them apart and back together about the frame's centre, which is the
+-- same depth cue the orbit gives, from the other axis.
+BattleCam.PAN_YAW = math.rad(2)   -- half-angle of the orbit
+BattleCam.PAN_PERIOD = 26         -- seconds for one there-and-back
+BattleCam.PAN_DOLLY = 0.02        -- how far the eye breathes, as a fraction
+BattleCam.DOLLY_PERIOD = 37
+
+-- ------- the player's own orbit
+--
+-- The drift above is the shot breathing. THIS is the player steering it:
+-- a right stick, a drag across the screen or the mouse walks the eye
+-- around the arena's axis, and it stops at both ends.
+--
+-- 0 is the shot the rig was solved for and the LEFT stop, because there is
+-- nothing to the left of it -- the composition below is what the whole
+-- module exists to land, and past it the two mons start swapping sides.
+--
+-- 1 is SIDE-ON: the eye swung round until it is square to the arena's
+-- north-south axis, where the two mons stand at the same distance instead
+-- of one behind the other. That is as far as the picture stays a battle
+-- rather than a diorama with two Pokemon in it, and it is a different angle
+-- for each rig -- the tele lens starts 28 degrees off the axis and the wide
+-- one 45 -- so the stop is COMPUTED from the rig rather than written down,
+-- and retuning either moves its own stop with it.
+--
+-- The input is deliberately not 1:1 with the pixels: it accumulates into
+-- `orbitGoal` and the live angle eases after it, so a flick reads as the
+-- camera being pushed rather than as the camera being dragged.
+BattleCam.ORBIT_TIME = 0.22       -- seconds for the eye to catch its goal
+BattleCam.ORBIT_DRAG = 1.15       -- fraction of the range per screen width
+BattleCam.ORBIT_STICK = 0.9       -- fraction of the range per second, full tilt
+BattleCam.ORBIT_MOUSE = 0.0011    -- fraction of the range per mouse count
+BattleCam.STICK_DEAD = 0.2
+
+-- ------- and the height it is watched from
+--
+-- The same steering on the other axis, with the same shape of stop at each
+-- end: 0 is the rig's own stance -- the low, near-floor seat the whole
+-- composition is solved around, and the DOWN stop, because below it the
+-- camera starts looking up the arena's nose -- and 1 is 45 degrees above
+-- it, which is high enough to read the ground the fight is standing on
+-- without becoming the diorama's own top-down.
+--
+-- Raised about the FOCUS rather than about the eye, so the aim stays on
+-- the two mons and only the seat climbs; and at a constant radius, so
+-- climbing never changes how big anything is -- that is the zoom's job.
+BattleCam.PITCH_RANGE = math.rad(45)
+BattleCam.PITCH_TIME = 0.22
+BattleCam.PITCH_DRAG = 1.6        -- fraction of the range per screen HEIGHT
+BattleCam.PITCH_STICK = 0.9
+BattleCam.PITCH_MOUSE = 0.0016
+
+-- ------- and the player's own zoom
+--
+-- How much world the frame holds, as a multiple of the rig's own frameH:
+-- BELOW one is zoomed in. It has to be the LENS rather than the distance,
+-- because the rig derives its field of view from frameH and the distance
+-- together -- so moving the eye alone changes the perspective and not the
+-- framing, which is exactly what the dolly breath above is for.
+BattleCam.ZOOM_MIN = 0.45         -- the pair filling the frame
+BattleCam.ZOOM_MAX = 2.0          -- the fight in its own landscape
+BattleCam.ZOOM_STEP = 1.15
+BattleCam.ZOOM_TIME = 0.18
+
+BattleCam.orbit = 0
+BattleCam.orbitGoal = 0
+BattleCam.pitch = 0
+BattleCam.pitchGoal = 0
+BattleCam.zoom = 1
+BattleCam.zoomGoal = 1
+
+-- Whether the player may steer at all. BACK SPRITES clears it: that
+-- setting pins the player's own mon to the GB's own slot on the menu
+-- (OverworldBattle.backPinned) instead of standing it out on the map, so
+-- half the picture is nailed to the frame and half of it is geometry. Swing
+-- the camera under that and the two halves come apart -- the foe walks
+-- around an arena its opponent is not standing in, and the move animations
+-- that reach between them stretch across the gap. There is no angle that
+-- composition survives, so the answer is not to allow one.
+--
+-- Only the STEER is withheld: the slow drift stays, because it was always
+-- there under BACK SPRITES and two degrees is not a composition problem.
+BattleCam.steerable = true
+
+-- Hold the rig perfectly still (VR sets this while a session runs). The
+-- drift exists to give a FLAT screen the depth cue the picture cannot
+-- have; a headset gets real parallax from the player's own head, and a
+-- picture that sways on its own inside VR reads as the world lurching --
+-- on the floating panel especially, where the battle screen is watched
+-- from a fixed seat.
+BattleCam.still = false
+
+BattleCam.t = 0
+
+-- Only the DRIFT's phase, so every fight opens on the same breath. Where
+-- the player last put the camera is deliberately NOT reset: an angle and a
+-- lens they chose are how they want to watch battles, not a thing about
+-- this battle, and having to re-find them every encounter would make them
+-- not worth setting. They are session state -- a fresh run opens on the
+-- rig's own shot, which is the one the composition is solved for.
+function BattleCam.reset()
+  BattleCam.t = 0
+end
+
+-- Back to the solved shot, for anything that wants the composition as
+-- authored rather than as steered.
+function BattleCam.recentre()
+  BattleCam.orbit, BattleCam.orbitGoal = 0, 0
+  BattleCam.pitch, BattleCam.pitchGoal = 0, 0
+  BattleCam.zoom, BattleCam.zoomGoal = 1, 1
+end
+
+-- How far the eye may swing, in radians, before it is square to the arena's
+-- axis. The rig's own stance decides it: `side` and `back` are the offset
+-- it starts at, so the bearing it starts on is atan2(side, back) and what
+-- is left to a quarter turn is the room the player has.
+function BattleCam.orbitRange(arena)
+  local R = BattleCam.rigFor(arena)
+  return math.max(0, math.pi / 2 - math.atan2(R.side, R.back))
+end
+
+-- ------- what the player's inputs reach
+--
+-- All four take a signed amount and clamp; positive is RIGHTWARD, toward
+-- the side-on stop. Returning whether the goal actually moved lets a
+-- caller tell "steered" from "already against the stop".
+
+-- Both axes go through here, so the "nothing while BACK SPRITES holds the
+-- composition" rule and the two stops live in one place each.
+local function setAxis(key, goal)
+  if not BattleCam.steerable then return false end
+  local was = BattleCam[key]
+  BattleCam[key] = math.max(0, math.min(1, goal))
+  return BattleCam[key] ~= was
+end
+
+-- A drag, in fractions of the screen's width (orbit) or height (pitch).
+function BattleCam.dragOrbit(fraction)
+  return setAxis("orbitGoal",
+                 BattleCam.orbitGoal + (fraction or 0) * BattleCam.ORBIT_DRAG)
+end
+
+function BattleCam.dragPitch(fraction)
+  return setAxis("pitchGoal",
+                 BattleCam.pitchGoal + (fraction or 0) * BattleCam.PITCH_DRAG)
+end
+
+-- Relative mouse motion, in counts.
+function BattleCam.mouseOrbit(dx)
+  return setAxis("orbitGoal",
+                 BattleCam.orbitGoal + (dx or 0) * BattleCam.ORBIT_MOUSE)
+end
+
+function BattleCam.mousePitch(dy)
+  return setAxis("pitchGoal",
+                 BattleCam.pitchGoal + (dy or 0) * BattleCam.PITCH_MOUSE)
+end
+
+-- A stick held for `dt` seconds, as a rate with a squared response -- the
+-- first half of the throw aims and the rest travels, the same curve the
+-- free-roam look uses.
+local function curve(v)
+  local a = math.abs(v or 0)
+  if a < BattleCam.STICK_DEAD then return 0 end
+  a = (a - BattleCam.STICK_DEAD) / (1 - BattleCam.STICK_DEAD)
+  return ((v < 0) and -1 or 1) * a * a
+end
+
+function BattleCam.stickOrbit(x, dt)
+  local v = curve(x)
+  if v == 0 then return false end
+  return setAxis("orbitGoal",
+                 BattleCam.orbitGoal + v * BattleCam.ORBIT_STICK * (dt or 0))
+end
+
+function BattleCam.stickPitch(y, dt)
+  local v = curve(y)
+  if v == 0 then return false end
+  return setAxis("pitchGoal",
+                 BattleCam.pitchGoal + v * BattleCam.PITCH_STICK * (dt or 0))
+end
+
+-- The zoom, in notches (positive pulls OUT, like every other zoom here).
+function BattleCam.stepZoom(notches)
+  if not BattleCam.steerable then return false end
+  local was = BattleCam.zoomGoal
+  BattleCam.zoomGoal = math.max(BattleCam.ZOOM_MIN,
+                        math.min(BattleCam.ZOOM_MAX,
+                                 was * (BattleCam.ZOOM_STEP ^ (notches or 0))))
+  return BattleCam.zoomGoal ~= was
+end
+
+-- How far apart the two mons READ from the current orbit, as a multiple of
+-- how far apart they read from the solved shot.
+--
+-- The arena's axis runs from one mon to the other, and the solved shot
+-- looks along it at a shallow 28 degrees, which foreshortens that gap to
+-- less than half its length. Swing round to square-on and the
+-- foreshortening is gone: the same two cells now read at their full
+-- separation, better than twice as wide. Left alone, that threw the pair
+-- out to the edges of the frame -- half of each mon off-screen at the
+-- side-on stop, which made the whole far end of the range unusable.
+--
+-- Climbing does the same thing on the other axis -- a raised camera looks
+-- less along the ground and more across it, which un-foreshortens the gap
+-- again -- so the correction has to answer to both.
+--
+-- What it measures is how much of the arena's axis survives projection:
+-- the axis runs due north-south, the view line points back at the arena at
+-- plan bearing `beta` and elevation `elev`, and the part of a unit axis
+-- that lands across the frame rather than along the view is the sine of
+-- the angle between them. The ratio of that to the solved shot's own is
+-- the factor the lens opens by -- 1 at the solved shot by construction,
+-- about 1.9 at side-on, about 1.7 fully raised.
+--
+-- Analytic rather than measured off the built rig, so nothing has to
+-- reason about a camera to ask the question, and so the sun's box (which
+-- asks through frameH) gets the identical number the lens does.
+--
+-- Measured off the STEER alone, deliberately: the drift's own two degrees
+-- moved this before and must keep moving it by exactly as much, or every
+-- battle shot that has ever been taken shifts.
+local function axisSpan(beta, elev)
+  local c = math.cos(elev)
+  local s = math.sin(beta) * c
+  local v = math.sin(elev)
+  return math.sqrt(s * s + v * v)
+end
+
+function BattleCam.spread(arena)
+  local R = BattleCam.rigFor(arena)
+  local beta = math.atan2(R.side, R.back)
+  local elev = math.atan2(R.height - R.lookY,
+                          math.sqrt((R.side - R.lookX) ^ 2 + R.back ^ 2))
+  local home = axisSpan(beta, elev)
+  if home < 1e-6 then return 1 end
+  return axisSpan(beta + BattleCam.orbit * BattleCam.orbitRange(arena),
+                  elev + BattleCam.pitch * BattleCam.PITCH_RANGE) / home
+end
+
+-- How much world the frame holds right now: the rig's own reach at the
+-- player's zoom and at whatever the orbit has done to the pair's spacing,
+-- or the rig's own alone whenever both are being withheld (VR's fixed
+-- seat, BACK SPRITES' pinned composition). The sun's box is fitted to this
+-- too, so a zoomed shot lights exactly the ground it shows -- which is why
+-- BattleScene asks this rather than multiplying for itself.
+function BattleCam.frameH(arena)
+  local base = BattleCam.rigFor(arena).frameH
+  if BattleCam.still or not BattleCam.steerable then return base end
+  return base * BattleCam.zoom * BattleCam.spread(arena)
+end
+
+local function chase(now, goal, dt, time)
+  if now == goal then return goal end
+  local v = now + (goal - now) * math.min(1, (dt or 0) / time)
+  return (math.abs(goal - v) < 1e-4) and goal or v
+end
+
+-- Real frame time, like every other presentational tween in this mod: a
+-- fast-forwarded battle must not spin the camera.
+function BattleCam.update(dt)
+  BattleCam.t = BattleCam.t + (dt or 0)
+  -- keep the phase small forever rather than letting a long session lose
+  -- float precision in the sines below
+  local wrap = BattleCam.PAN_PERIOD * BattleCam.DOLLY_PERIOD
+  if BattleCam.t > wrap then BattleCam.t = BattleCam.t - wrap end
+  -- and the steered three easing after whatever the player last asked for,
+  -- which is what keeps a flick of the stick from being a cut
+  BattleCam.orbit = chase(BattleCam.orbit, BattleCam.orbitGoal, dt,
+                          BattleCam.ORBIT_TIME)
+  BattleCam.pitch = chase(BattleCam.pitch, BattleCam.pitchGoal, dt,
+                          BattleCam.PITCH_TIME)
+  BattleCam.zoom = chase(BattleCam.zoom, BattleCam.zoomGoal, dt,
+                         BattleCam.ZOOM_TIME)
+end
+
+local function phase(t, period)
+  return math.sin(2 * math.pi * t / period)
+end
+
+-- The camera for `arena` this instant: the record Voxel3D.camera takes, plus
+-- the pitch the pull and the sun frustum want (measured from straight down,
+-- the same convention Voxel.angle uses).
+--
+-- `fov` here frames the GB's 160x144. A caller rendering at window
+-- resolution widens it for the extra picture around that frame -- see
+-- BattleScene.letterboxFov, which is what keeps the pins exact at any window
+-- size.
+--
+-- `groundY` is the height of the arena floor, so a fight staged on a ledge
+-- or a raised walkway is shot from above THAT rather than from inside it.
+-- `canonical` asks for the shot the rig was SOLVED for -- no drift, no
+-- breath, no steer, no zoom -- from a caller that is reasoning about the
+-- arena rather than drawing it. BattleArena's clearance test is the one
+-- that needs it: whether a fight can be staged somewhere is a fact about
+-- the ground, and answering it through whatever angle the player happened
+-- to leave the last battle on would pick a different arena depending on
+-- where they had swung the camera an hour ago.
+function BattleCam.rig(arena, groundY, canonical)
+  groundY = groundY or 0
+  local R = BattleCam.rigFor(arena)
+  local mx, mz = arena.mid[1], arena.mid[2]
+  -- VR asks for the same stillness for its own reason (see BattleCam.still)
+  local fixed = BattleCam.still or canonical
+  -- and the steer is withheld a second way, on its own: BACK SPRITES holds
+  -- the composition and the DRIFT still runs under it (see steerable)
+  local steered = (not fixed) and BattleCam.steerable
+
+  -- The drift, plus wherever the player has steered to. The steer is
+  -- NEGATIVE because the rotation below runs the other way from the bearing
+  -- it turns: rotating (side, back) by +yaw carries the eye back toward the
+  -- arena's own axis, and the room the player has is all on the far side of
+  -- that -- out toward square-on. (orbitRange measures exactly that room.)
+  local steer = steered and -BattleCam.orbit * BattleCam.orbitRange(arena) or 0
+  -- ------- and the quarter turn the arena itself is standing at
+  --
+  -- An arena may be laid down any of the four ways (BattleArena's `turn`),
+  -- and the rig is solved for ONE of them: eye off the player's shoulder,
+  -- back down an axis that runs north-south. So the whole offset is turned
+  -- with the ground under it, which leaves the camera in exactly the same
+  -- place RELATIVE to the two mons -- same distance, same height, same
+  -- angle -- and therefore lands them on the same two screen anchors at the
+  -- same size. A turn is a fact about the map, never about the shot.
+  --
+  -- It goes in with the drift and the steer rather than beside them because
+  -- it is the same rotation about the same point; the player's own orbit is
+  -- then measured from wherever the arena starts, so both stops travel with
+  -- it and side-on stays side-on.
+  local base = math.rad(arena.turn or 0)
+  local yaw = base + steer + (fixed and 0
+              or BattleCam.PAN_YAW * phase(BattleCam.t, BattleCam.PAN_PERIOD))
+  local c, s = math.cos(yaw), math.sin(yaw)
+  -- the breath scales the whole offset, height included, so the eye moves
+  -- along its own line to the arena and the pitch of the shot never changes
+  local k = fixed and 1
+            or 1 + BattleCam.PAN_DOLLY
+                   * phase(BattleCam.t, BattleCam.DOLLY_PERIOD)
+  local dx = (R.side * c - R.back * s) * k
+  local dz = (R.side * s + R.back * c) * k
+
+  local eye = { mx + dx, groundY + R.height * k, mz + dz }
+  -- the aim's own offset turns with the arena too, and with the BASE alone --
+  -- the drift and the steer swing the eye about the focus, so a focus that
+  -- followed them would take the thing being orbited around with it
+  local bc, bs = math.cos(base), math.sin(base)
+  local focus = { mx + R.lookX * bc, groundY + R.lookY, mz + R.lookX * bs }
+
+  -- and the climb: the eye swung UP about the focus, at a constant radius.
+  -- About the focus so the aim stays nailed to the two mons and only the
+  -- seat moves, and at a constant radius so climbing never changes how big
+  -- anything is -- that is the lens's job below, and a rig that did both at
+  -- once would have no way to do either on purpose.
+  local lift = steered and BattleCam.pitch * BattleCam.PITCH_RANGE or 0
+  if lift > 0 then
+    local vx, vy, vz = eye[1] - focus[1], eye[2] - focus[2], eye[3] - focus[3]
+    local flat = math.sqrt(vx * vx + vz * vz)
+    local r = math.sqrt(flat * flat + vy * vy)
+    if flat > 1e-6 and r > 1e-6 then
+      local a = math.atan2(vy, flat) + lift
+      -- short of straight down, always: the placed camera's up vector is
+      -- world up, which degenerates against a view looking exactly along it
+      a = math.min(a, math.rad(85))
+      local nf = r * math.cos(a)
+      eye[1] = focus[1] + vx / flat * nf
+      eye[3] = focus[3] + vz / flat * nf
+      eye[2] = focus[2] + r * math.sin(a)
+    end
+  end
+
+  local ex = eye[1] - focus[1]
+  local ey = eye[2] - focus[2]
+  local ez = eye[3] - focus[3]
+  local dist = math.max(1, math.sqrt(ex * ex + ey * ey + ez * ez))
+  local horiz = math.sqrt(ex * ex + ez * ez)
+
+  -- The lens carries the player's zoom: how much world the frame holds is
+  -- the one thing that actually changes the framing here, because the field
+  -- of view is DERIVED from that reach and the distance. Moving the eye
+  -- instead would leave the picture the same size and only change its
+  -- perspective -- which is what the dolly breath above is deliberately
+  -- for, and is not what "zoom" means to anyone holding a wheel.
+  local frameH = fixed and R.frameH or BattleCam.frameH(arena)
+  return {
+    eye = eye,
+    focus = focus,
+    fov = 2 * math.atan((frameH / 2) / dist),
+    -- the world curve is a free-roam flourish that bends the horizon away
+    -- from the player; a fixed camera on a staged shot has no player to bend
+    -- around, and the bend would tip the arena floor out from under the mons
+    -- the pics are pinned to
+    curve = 0,
+  }, math.atan2(horiz, math.max(1e-3, ey))
+end
+
+return BattleCam

lib/BattleDOF.lua

@@ -0,0 +1,187 @@
+-- Overworld battles: the depth-of-field pass over the arena.
+--
+-- A photographic lens focused on two subjects three cells apart holds a
+-- narrow slab of the world sharp and loses everything in front of and
+-- behind it. On this shot that slab is a BAND ACROSS THE FRAME, because the
+-- camera is fixed and looking down at a floor: distance from the lens runs
+-- monotonically up the picture, so screen height IS depth, and a band of
+-- rows is a slab of world. The floor the mons stand on stays sharp, the
+-- middle distance and the horizon soften, and the foreground the camera is
+-- leaning over softens the other way.
+--
+-- BOTH MONS ARE IN FOCUS, and not by tuning: they are drawn as the battle
+-- screen's own pics AFTER this runs, so they are never blurred at all. This
+-- pass only ever touches the world behind them -- which is exactly the
+-- separation a real shot of two subjects at the same distance would have.
+--
+-- Two separable gaussian passes over a 160x144 image: two full-frame draws
+-- of 23,040 pixels, which is nothing, and it buys the one cue that stops a
+-- 3D backdrop reading as wallpaper.
+
+local BattleDOF = {}
+
+-- Switched off for now. The pass is kept whole -- band maths, shader,
+-- canvases -- because the reason to have it has not gone away: it is the one
+-- cue that separates the pair from the ground behind them. It is off because
+-- the mons are geometry in the scene now rather than pics over it, and a blur
+-- that softens their own tile softens THEM, which the pinned-pic version
+-- never had to answer for. Turning it back on means solving that first.
+BattleDOF.ENABLED = false
+
+-- Fallbacks for the band, in canvas uv. The caller normally measures it off
+-- the two ground marks -- the whole point is that the slab in focus is the
+-- one the mons are standing in -- and these are what a caller that cannot
+-- gets instead.
+BattleDOF.FOCUS_Y = 0.52
+BattleDOF.BAND = 0.16
+BattleDOF.RANGE = 0.32
+
+-- How much floor either side of the two marks stays sharp, as a fraction of
+-- the gap between them: a mon is taller than the patch it stands on, and the
+-- ground just in front of and behind it belongs to the same slab.
+BattleDOF.BAND_MARGIN = 0.55
+
+-- How far past the band it takes to reach full blur, in the same units as
+-- the band itself.
+BattleDOF.RANGE_SCALE = 2.0
+
+-- Tap spacing at full blur, as a fraction of the canvas height, so the blur
+-- is the same depth of field in a window and fullscreen. The gaussian's
+-- reach is four taps and the two passes compound, so a little goes a long
+-- way.
+BattleDOF.SPACING = 0.0095
+
+-- A touch of saturation on the way out, the same trick the tilt-shift pass
+-- uses: a blurred background reads as further away when it is also a
+-- little richer than the sharp subject in front of it.
+BattleDOF.SATURATION = 1.12
+
+local SHADER = [[
+  uniform vec2 dir;        // one texel step along the axis being blurred
+  uniform float focusY;
+  uniform float band;
+  uniform float range;
+  uniform float spacing;
+  uniform float boost;     // 0 = plain blur pass, 1 = final pass (colour pop)
+  uniform float saturation;
+  vec4 effect(vec4 color, Image tex, vec2 tc, vec2 sc) {
+    float d = abs(tc.y - focusY) - band;
+    float s = clamp(d / range, 0.0, 1.0);
+    s = s * s;             // ease in, so the band edge has no visible seam
+    vec2 o = dir * (s * spacing);
+    vec4 sum = Texel(tex, tc) * 0.2270270270;
+    sum += (Texel(tex, tc + o) + Texel(tex, tc - o)) * 0.1945945946;
+    sum += (Texel(tex, tc + 2.0 * o) + Texel(tex, tc - 2.0 * o)) * 0.1216216216;
+    sum += (Texel(tex, tc + 3.0 * o) + Texel(tex, tc - 3.0 * o)) * 0.0540540541;
+    sum += (Texel(tex, tc + 4.0 * o) + Texel(tex, tc - 4.0 * o)) * 0.0162162162;
+    if (boost > 0.5) {
+      float luma = dot(sum.rgb, vec3(0.299, 0.587, 0.114));
+      sum.rgb = mix(vec3(luma), sum.rgb, saturation);
+    }
+    return sum * color;
+  }
+]]
+
+local shader = nil            -- nil = untried, false = unavailable
+local ping, pong, cw, ch = nil, nil, 0, 0
+
+local function getShader()
+  if shader == nil then
+    local ok, sh = pcall(love.graphics.newShader, SHADER)
+    shader = (ok and sh) or false
+  end
+  return shader or nil
+end
+
+-- Its own pair of canvases rather than the tilt-shift pass's: those are
+-- sized to the window and this is sized to the GB frame, and sharing them
+-- would reallocate both every time a battle started or ended.
+local function getCanvases(w, h)
+  if not ping or cw ~= w or ch ~= h then
+    local ok, a = pcall(love.graphics.newCanvas, w, h)
+    if not ok then return nil end
+    local okB, b = pcall(love.graphics.newCanvas, w, h)
+    if not okB then return nil end
+    -- the gaussian's fractional tap offsets need linear filtering
+    a:setFilter("linear", "linear")
+    b:setFilter("linear", "linear")
+    ping, pong, cw, ch = a, b, w, h
+  end
+  return ping, pong
+end
+
+-- The sharp band for a shot whose two ground marks land at canvas rows
+-- `y1` and `y2`, as (focusY, band, range) in uv. This is the depth of field
+-- proper: the band is the slab of world the two mons occupy, and everything
+-- nearer or further softens away from it.
+function BattleDOF.bandFor(y1, y2, h)
+  if not (y1 and y2 and h and h > 0) then
+    return BattleDOF.FOCUS_Y, BattleDOF.BAND, BattleDOF.RANGE
+  end
+  local mid = (y1 + y2) / 2 / h
+  local half = math.abs(y1 - y2) / 2 / h
+  local band = half * (1 + BattleDOF.BAND_MARGIN)
+  return math.min(1, math.max(0, mid)),
+         band,
+         math.max(1e-3, band * BattleDOF.RANGE_SCALE)
+end
+
+-- Run the pass over `canvas` and return the result, or the input unchanged
+-- when it cannot run (headless, no shader support) -- so the caller always
+-- has something to composite. `focusY`, `band` and `range` are in canvas uv;
+-- omit them for the fixed fallback band.
+function BattleDOF.apply(canvas, focusY, band, range)
+  if not (canvas and BattleDOF.ENABLED) then return canvas end
+  local sh = getShader()
+  if not sh then return canvas end
+  local w, h = canvas:getDimensions()
+  local a, b = getCanvases(w, h)
+  if not a then return canvas end
+  focusY = focusY or BattleDOF.FOCUS_Y
+  band = band or BattleDOF.BAND
+  range = range or BattleDOF.RANGE
+
+  local prevBlend, prevAlpha = love.graphics.getBlendMode()
+  local prevCanvas = love.graphics.getCanvas()
+
+  -- the scene canvas filters nearest for its 1:1 blit; the taps need linear,
+  -- restored below so the composite sees what it expects
+  canvas:setFilter("linear", "linear")
+  love.graphics.setShader(sh)
+  love.graphics.setColor(1, 1, 1, 1)
+  -- replace, not alpha-blend: these are image-processing copies
+  love.graphics.setBlendMode("replace", "premultiplied")
+  pcall(sh.send, sh, "focusY", focusY)
+  pcall(sh.send, sh, "band", band)
+  pcall(sh.send, sh, "range", range)
+  pcall(sh.send, sh, "spacing", math.max(0.75, h * BattleDOF.SPACING))
+  pcall(sh.send, sh, "saturation", BattleDOF.SATURATION)
+
+  local ok = pcall(function()
+    love.graphics.setCanvas(a)
+    pcall(sh.send, sh, "dir", { 1 / w, 0 })
+    pcall(sh.send, sh, "boost", 0)
+    love.graphics.draw(canvas)
+    love.graphics.setCanvas(b)
+    pcall(sh.send, sh, "dir", { 0, 1 / h })
+    pcall(sh.send, sh, "boost", 1)
+    love.graphics.draw(a)
+  end)
+
+  if prevCanvas then
+    love.graphics.setCanvas(prevCanvas)
+  else
+    love.graphics.setCanvas()
+  end
+  love.graphics.setShader()
+  love.graphics.setBlendMode(prevBlend or "alpha", prevAlpha)
+  canvas:setFilter("nearest", "nearest")
+  return ok and b or canvas
+end
+
+-- Drop the GPU objects (window resize, hot reload).
+function BattleDOF.invalidate()
+  ping, pong, cw, ch = nil, nil, 0, 0
+end
+
+return BattleDOF

lib/BattleExit.lua

@@ -0,0 +1,201 @@
+-- Leaving a battle: the fade the way back to the map never had.
+--
+-- Going IN is a whole production -- one of the original's eight wipes, picked by
+-- three bits, over a flash (src/render/BattleTransition.lua). Coming OUT was a
+-- hard cut: BattleState:finish pops itself and the map is simply THERE on the
+-- next frame. On the flat battle screen that is a cut between a white field and
+-- a tile map, which the original got away with. In this mode it is a cut between
+-- a placed camera looking across an arena and a diorama looking down on a
+-- walking player, and a jump that big reads as a glitch rather than as an edit.
+--
+-- So the battle fades out, closes behind the black, and the map fades up out of
+-- it. The timing is a transitions record this mod registers rather than a
+-- constant in here, so it is retunable in data like the engine's own eight.
+--
+-- WHEN. Only while voxel mode is on: this is the diorama's own exit, and a
+-- vanilla battle keeps the cut it always had. While the mode IS on, every battle
+-- gets it -- including one that found no arena and drew on the flat battle
+-- screen -- because what is being smoothed over is the return to the MAP, and
+-- the map is a diorama either way.
+--
+-- HOW IT IS DRAWN, which is the part worth reading. Not by this state: it draws
+-- nothing at all. It owns a NUMBER, and one black rectangle over the FINISHED
+-- composite in a wrap around Renderer:endFrame paints it -- after the world
+-- blit, after the letterbox, after the UI blit, which is the only point where a
+-- single rect covers everything on screen at once.
+--
+-- The renderer's own fade (worldFadeAlpha, which the warp fade uses) is painted
+-- BETWEEN the world and the UI, because a warp has no UI over it. A fade that
+-- borrowed it would darken the arena and leave the battle's text box sitting
+-- bright on top of the black -- and the letterbox bars of a flat battle screen,
+-- painted by the renderer's clear before any state draws, would not darken at
+-- all.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local BattleExit = {}
+BattleExit.__index = BattleExit
+
+-- The battle underneath keeps drawing while this is up -- what fades is its own
+-- last live frame, camera drift, HUD and all. Only the top state UPDATES, so
+-- nothing the battle does can outrun the fade either.
+BattleExit.isOpaque = false
+
+-- The registered record's id, and the fallback timing if it is missing (a
+-- headless caller, or a total conversion that dropped the namespace). Per HALF,
+-- matching the engine's warp fade, so the whole edit is 24 frames.
+BattleExit.ID = "voxel_battle_exit"
+BattleExit.FRAMES = 12
+
+-- The fade in progress, or nil. Kept here rather than on the state so the
+-- endFrame wrap has one place to look and nothing can go stale the frame after
+-- the state leaves the stack.
+local live = nil
+
+-- How black the composite is this frame: 0 on the battle's last live frame, 1 at
+-- the cut, 0 again once the map is up. nil when no fade is running, which is
+-- every other frame the game ever draws.
+function BattleExit.veil()
+  if not live then return nil end
+  -- A fade can be taken off the stack by something that is not the fade: a
+  -- script or a shot driver popping down to the overworld, a state teardown.
+  -- Then it is not running, whatever its counter says -- and a veil left behind
+  -- would black the game out for good, because nothing is going to fade it back
+  -- in. Checked here rather than trusted, because this is the one place the
+  -- answer is used. The walk only happens while a fade is live.
+  local stack = live.game and live.game.stack
+  local states = stack and stack.states
+  local onStack = false
+  for i = #(states or {}), 1, -1 do
+    if states[i] == live then onStack = true break end
+  end
+  if not onStack then live = nil; return nil end
+  local a = live.t / live.frames
+  if live.phase == "in" then a = 1 - a end
+  return math.max(0, math.min(1, a))
+end
+
+local function framesFor(game)
+  local records = game and game.data and game.data.transitions
+  local record = records and records[BattleExit.ID]
+  local frames = record and record.frames
+  if type(frames) == "number" and frames > 0 then return frames end
+  return BattleExit.FRAMES
+end
+
+function BattleExit.new(game, battle, onMidpoint)
+  return setmetatable({ game = game, battle = battle, onMidpoint = onMidpoint,
+                        frames = framesFor(game), t = 0, phase = "out" },
+                      BattleExit)
+end
+
+-- Push the fade over the battle it is closing.
+function BattleExit.start(battle, onMidpoint)
+  local game = battle.game
+  local self = BattleExit.new(game, battle, onMidpoint)
+  live = self
+  game.stack:push(self)
+  return self
+end
+
+function BattleExit:update()
+  self.t = self.t + 1
+  if self.t < self.frames then return end
+  self.t = 0
+
+  if self.phase == "in" then
+    live = nil
+    self.game.stack:pop()
+    return
+  end
+
+  -- ------- the cut, at full black
+  --
+  -- Off the stack FIRST. BattleState:finish pops whatever is on TOP, and while
+  -- this fade is up that is the fade -- so a fade that stayed would eat the
+  -- battle's own pop and leave the battle running underneath, finished but
+  -- still on the stack. Popping ourselves hands the top back to the battle so
+  -- its pop lands on itself.
+  self.phase = "in"
+  local stack = self.game.stack
+  stack:pop()
+  if self.onMidpoint then self.onMidpoint() end
+  if stack:top() == self.game.overworld then
+    stack:push(self)                       -- and the map comes up out of it
+    return
+  end
+
+  -- We are not going back to the map after all. Either the battle did not
+  -- actually leave -- finish() can be a false start, and wanted() mirrors the
+  -- one the engine has today -- or something else took the screen on the way
+  -- out: a blackout's own warp fade, an evolution prompt. Whatever it is owns
+  -- the transition from here, so this one ends at the cut instead of fading in
+  -- over the top of it. The flag goes back too, so a second finish() that does
+  -- leave gets its own fade.
+  live = nil
+  if self.battle then self.battle.dramaticShapeLeaving = nil end
+end
+
+-- "Voxel mode is on", as the ENGINE answers it: switched on, not retired by a
+-- fault, and runnable on this machine. A function on the table rather than an
+-- inline call so a driver or a headless test can pin it -- the test harness has
+-- no depth buffer, where the honest answer is no on every rung.
+function BattleExit.modeOn()
+  return require("src.render.Pipelines").eligible("voxel") and true or false
+end
+
+-- Whether this ending gets the fade.
+function BattleExit.wanted(battle)
+  local game = battle and battle.game
+  if not (game and game.stack) then return false end
+  -- finish() is not always the end: an unpaid PAY DAY prints its takings and
+  -- comes back through here a moment later (BattleState:finish's first branch).
+  -- Mirrored read-only, so the fade starts on the call that really leaves rather
+  -- than fading to black and snapping back for one more message.
+  if battle.payDay and battle.result == "win" then return false end
+  return BattleExit.modeOn()
+end
+
+-- ------- engine seams
+--
+-- Two wraps, each idempotent so a hot reload cannot stack them.
+function BattleExit.install()
+  local BattleState = require("src.battle.BattleState")
+  if not BattleState.dramaticShapeExitHook then
+    local inner = BattleState.finish
+    -- The one place a battle ends. Wrapped rather than listened for: the
+    -- battle.ended event is emitted AFTER the pop, and by then the battle
+    -- screen is gone and there is nothing left to fade out.
+    function BattleState:finish()
+      if self.dramaticShapeLeaving or not BattleExit.wanted(self) then
+        return inner(self)
+      end
+      self.dramaticShapeLeaving = true
+      BattleExit.start(self, function() inner(self) end)
+    end
+    BattleState.dramaticShapeExitHook = true
+  end
+
+  local Renderer = require("src.render.Renderer")
+  if not Renderer.dramaticShapeExitHook then
+    local inner = Renderer.endFrame
+    function Renderer:endFrame(zones, worldZones)
+      inner(self, zones, worldZones)
+      local a = BattleExit.veil()
+      if not a or a <= 0 then return end
+      -- The composite is on the screen by now, in LOVE units, so one rect over
+      -- the window darkens the world, the letterbox bars, the text box and
+      -- anything a present pass put on top, all by the same amount. Left to
+      -- last on purpose: this is a shutter closing on the finished frame, not a
+      -- layer inside it.
+      local w, h = love.graphics.getDimensions()
+      love.graphics.setColor(0, 0, 0, a)
+      love.graphics.rectangle("fill", 0, 0, w, h)
+      love.graphics.setColor(1, 1, 1, 1)
+    end
+    Renderer.dramaticShapeExitHook = true
+  end
+end
+
+return BattleExit

lib/BattleHud.lua

@@ -0,0 +1,231 @@
+-- Overworld battles: the HUD's footing on a world that is not white.
+--
+-- Gen 1 draws its battle HUDs as black glyphs and bar tiles straight onto
+-- the white field, with no box around them -- the field IS the backing. Take
+-- the field away and put a route underneath and the name, the level and the
+-- HP numbers are black on grass, which is not readable.
+--
+-- So each HUD block gets a panel: the world behind it, blurred to frosted
+-- glass and laid back down translucent, with a tint that pushes it away from
+-- whatever colour the text is about to be. Frosted rather than opaque
+-- because the point of the mode is that you can see where you are standing,
+-- and an opaque slab in the corner of the frame is the white field back
+-- again by another name.
+--
+-- The ink does NOT change. There was a pass here that measured each panel's
+-- average brightness and flipped the glyphs to white over a dark one, with
+-- hysteresis so a drifting camera could not strobe them. It worked, and it
+-- was still wrong: the battle menu is the one part of the frame the player
+-- reads constantly, and having its colour depend on what the camera happens
+-- to be pointing at makes it an unreliable piece of furniture. Gen 1's
+-- battle text is black, so it is black -- and the panel's tint is what
+-- earns that its contrast, on a cave floor as much as on a meadow.
+--
+-- Removing it also took out a one-pixel GPU readback that ran several times
+-- a second purely to answer a question nothing asks any more.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local BattleHud = {}
+
+-- How solid the frost is over the world behind it, and how far the tint
+-- pushes it toward the far end from the text.
+--
+-- Both deliberately light. The panel is there to make glyphs legible, not to
+-- put a slab in the corner of the frame: at these values the sharp world
+-- still reads through it and the blur registers as a pane of glass rather
+-- than as a second background.
+BattleHud.FROST = 0.55
+BattleHud.TINT = 0.26
+
+-- The frost buffer's height; width follows the source's aspect. Small on
+-- purpose: the downscale is most of the blur.
+BattleHud.FROST_H = 72
+
+local frost, frostW, frostH = nil, 0, 0
+local blurA, blurB = nil, nil
+local frame = 0
+
+local SHADER = [[
+  uniform vec2 dir;
+  vec4 effect(vec4 color, Image tex, vec2 tc, vec2 sc) {
+    vec4 sum = Texel(tex, tc) * 0.2270270270;
+    sum += (Texel(tex, tc + dir) + Texel(tex, tc - dir)) * 0.1945945946;
+    sum += (Texel(tex, tc + 2.0 * dir) + Texel(tex, tc - 2.0 * dir)) * 0.1216216216;
+    sum += (Texel(tex, tc + 3.0 * dir) + Texel(tex, tc - 3.0 * dir)) * 0.0540540541;
+    sum += (Texel(tex, tc + 4.0 * dir) + Texel(tex, tc - 4.0 * dir)) * 0.0162162162;
+    return sum * color;
+  }
+]]
+
+local shader = nil            -- nil = untried, false = unavailable
+
+local function getShader()
+  if shader == nil then
+    local ok, sh = pcall(love.graphics.newShader, SHADER)
+    shader = (ok and sh) or false
+  end
+  return shader or nil
+end
+
+local function canvasOf(w, h, filter)
+  local ok, c = pcall(love.graphics.newCanvas, w, h)
+  if not ok then return nil end
+  c:setFilter(filter or "linear", filter or "linear")
+  return c
+end
+
+-- Build (or rebuild) the frosted copy of `src` for this frame.
+--
+-- Two steps, because one is not enough: the downscale to a 72-row buffer
+-- averages the world down to something that no longer reads as terrain, and
+-- the separable gaussian over that turns the remaining structure into
+-- frosted glass rather than a mosaic of the tiles it came from.
+function BattleHud.build(src)
+  if not src then return nil end
+  local blur = getShader()
+  local sw, sh = src:getDimensions()
+  if sw <= 0 or sh <= 0 then return nil end
+  local h = BattleHud.FROST_H
+  local w = math.max(1, math.floor(sw * h / sh + 0.5))
+  if not frost or frostW ~= w or frostH ~= h then
+    frost = canvasOf(w, h)
+    blurA = canvasOf(w, h)
+    blurB = canvasOf(w, h)
+    if not (frost and blurA and blurB) then
+      frost, blurA, blurB, frostW, frostH = nil, nil, nil, 0, 0
+      return nil
+    end
+    frostW, frostH = w, h
+  end
+
+  local prevCanvas = love.graphics.getCanvas()
+  local prevBlend, prevAlpha = love.graphics.getBlendMode()
+  local prevFilter = { src:getFilter() }
+  src:setFilter("linear", "linear")
+  love.graphics.setColor(1, 1, 1, 1)
+  love.graphics.setBlendMode("replace", "premultiplied")
+
+  local ok = pcall(function()
+    love.graphics.setCanvas(frost)
+    love.graphics.draw(src, 0, 0, 0, w / sw, h / sh)
+    if blur then
+      love.graphics.setShader(blur)
+      love.graphics.setCanvas(blurA)
+      pcall(blur.send, blur, "dir", { 2.5 / w, 0 })
+      love.graphics.draw(frost)
+      love.graphics.setCanvas(blurB)
+      pcall(blur.send, blur, "dir", { 0, 2.5 / h })
+      love.graphics.draw(blurA)
+      love.graphics.setShader()
+      frost, blurB = blurB, frost   -- the blurred one is the frost now
+    end
+  end)
+
+  love.graphics.setShader()
+  if prevCanvas then
+    love.graphics.setCanvas(prevCanvas)
+  else
+    love.graphics.setCanvas()
+  end
+  love.graphics.setBlendMode(prevBlend or "alpha", prevAlpha)
+  src:setFilter(prevFilter[1] or "nearest", prevFilter[2] or "nearest")
+  frame = frame + 1
+  return ok and frost or nil
+end
+
+function BattleHud.frame()
+  return frame
+end
+
+-- Map a GB-frame rect onto the frost canvas, given where the letterbox sits
+-- in the source the frost was built from.
+local function frostRect(rect, box)
+  local kx = frostW / box.pw
+  local ky = frostH / box.ph
+  local fx = (box.lx + rect[1] * box.scale) * kx
+  local fy = (box.ly + rect[2] * box.scale) * ky
+  local fw = rect[3] * box.scale * kx
+  local fh = rect[4] * box.scale * ky
+  return fx, fy, math.max(1, fw), math.max(1, fh)
+end
+
+-- The same map for a rect that is ALREADY in world-canvas pixels. A HUD
+-- snapped out to the window's edge has left the GB frame, so it has no GB
+-- coordinates to be placed from -- see OverworldBattle.snapRects.
+local function frostRectWorld(rect, box)
+  local kx = frostW / box.pw
+  local ky = frostH / box.ph
+  return rect[1] * kx, rect[2] * ky,
+         math.max(1, rect[3] * kx), math.max(1, rect[4] * ky)
+end
+
+-- Which of the two the caller's rects are in. One frost buffer, one panel
+-- draw, two coordinate spaces: the GB frame (rects land in the 160x144 UI
+-- canvas) or world pixels (rects land in the window-resolution world image).
+local function mapper(world)
+  return world and frostRectWorld or frostRect
+end
+
+-- Draw one HUD panel into the current target, in that target's own
+-- coordinates: GB ones for the 160x144 UI canvas, world pixels (world = true)
+-- for a panel laid straight onto the world image.
+--
+-- The tint always pushes toward WHITE, away from the black ink that is about
+-- to land on it, so the contrast is guaranteed rather than hoped for -- and
+-- it is the whole of what makes a fixed ink colour workable over any ground.
+function BattleHud.panel(rect, box, world)
+  if not (frost and box and box.scale and box.scale > 0) then return false end
+  local fx, fy, fw, fh = mapper(world)(rect, box)
+  local ok = pcall(function()
+    local quad = love.graphics.newQuad(fx, fy, fw, fh, frostW, frostH)
+    love.graphics.setColor(1, 1, 1, BattleHud.FROST)
+    love.graphics.draw(frost, quad, rect[1], rect[2], 0,
+                       rect[3] / fw, rect[4] / fh)
+    love.graphics.setColor(1, 1, 1, BattleHud.TINT)
+    love.graphics.rectangle("fill", rect[1], rect[2], rect[3], rect[4])
+    love.graphics.setColor(1, 1, 1, 1)
+  end)
+  return ok
+end
+
+-- ------- the whole HUD layer as a texture
+--
+-- The two blocks do not sit in the same place any more: each is snapped to its
+-- own side of the WINDOW, which is outside the 160x144 canvas the engine draws
+-- them in (see OverworldBattle.snapRects). A draw cannot be aimed at two
+-- places at once, so the layer is rendered ONCE into a GB-sized canvas and
+-- each block is then blitted out of it as a quad.
+--
+local hudLayer = nil
+
+function BattleHud.layerTexture(w, h, fn)
+  if not hudLayer or hudLayer:getWidth() ~= w or hudLayer:getHeight() ~= h then
+    hudLayer = canvasOf(w, h, "nearest")
+    if not hudLayer then return nil end
+  end
+  local g = love.graphics
+  local prevCanvas = g.getCanvas()
+  local prevBlend, prevAlpha = g.getBlendMode()
+  local ok, err = pcall(function()
+    g.setCanvas(hudLayer)
+    g.clear(0, 0, 0, 0)
+    g.setBlendMode("alpha")
+    g.setColor(1, 1, 1, 1)
+    fn()
+  end)
+  if prevCanvas then g.setCanvas(prevCanvas) else g.setCanvas() end
+  g.setBlendMode(prevBlend or "alpha", prevAlpha)
+  g.setColor(1, 1, 1, 1)
+  if not ok then error(err, 0) end
+  return hudLayer
+end
+
+function BattleHud.invalidate()
+  frost, blurA, blurB = nil, nil, nil
+  frostW, frostH = 0, 0
+  hudLayer = nil
+end
+
+return BattleHud

lib/BattlePics.lua

@@ -0,0 +1,347 @@
+-- Overworld battles: giving a battle pic its paper back.
+--
+-- Gen 1 battle pics are two-bit art whose lightest shade is WHITE, and the
+-- engine's decoded PNGs key that shade to alpha 0 -- which was free, because
+-- the field behind them was white too. A transparent belly on a white page
+-- is a white belly.
+--
+-- Put a route behind it and the belly is grass. Charizard's chest, the whites
+-- of every eye, the highlight down a Pikachu's cheek: all of it turns into a
+-- hole with the world showing through, and the mon reads as a stencil.
+--
+-- So the paper is put back, and only where the paper was. Which pixels those
+-- are is the whole problem, and it has to be ANSWERED rather than looked up:
+-- the hardware drew the mon's white belly and the white field behind it with
+-- the same shade, the decoder keyed both to the same alpha, and nothing in the
+-- image says which was which. There is no distinction to recover; there is one
+-- to draw.
+--
+-- The rule is a flood fill from OUTSIDE the figure: whatever the background
+-- can reach is background, and whatever it cannot is paper. What makes that
+-- work is where the flood is allowed to start.
+--
+-- Start it at the image border and it fills everything and answers nothing.
+-- Gen 1 figures are open drawings and a belly is not a sealed room: it walks
+-- out between two legs and off the bottom of the frame. Run over all 352 of
+-- this game's battle pics, that finds an enclosed hole in NONE of them -- so
+-- it left every mon a stencil, which is the bug this file exists to fix and
+-- for a long time did not.
+--
+-- So the flood is started at the edges of the artwork's own BOUNDING BOX, and
+-- the left, the right and the top are seeded whole. The sky between a pair of
+-- ears reaches the top edge and stays sky; the gap between a body and a raised
+-- tail reaches the side and stays gap.
+--
+-- The BOTTOM is the interesting one, because two completely different things
+-- meet the underside of a figure and they have to be told apart.
+--
+--   A DRAIN is where the drawing simply ran out -- a belly whose white carries
+--   on down until the artist stopped, leaking to the outside through the inch
+--   between a body and a leg. Seal it: what is above it is the mon.
+--
+--   A MOUTH is the space BETWEEN two legs, or under an arch. It is background
+--   that happens to be enclosed on three sides. Leave it open: the world
+--   should show through the gap in a trainer's stride.
+--
+-- What separates them is how WIDE the opening is, and on this game's art that
+-- is not a close call. Measured along the bottom of every battle pic: the
+-- drains run 3 and 4 pixels (Clefairy's back, Wartortle's back, Red's back)
+-- and the mouths run 10, 12, 14 and 17 (a Rattata's underbelly, Blue's stride,
+-- Brock's, a Pikachu's back). Nothing lands between 4 and 10, so the cut is
+-- taken at 6 with room either side rather than tuned to a single sprite.
+--
+-- Apart from that one number the rule is exact: no pixel is filled for what
+-- surrounds it, only because the background provably cannot get to it. And it
+-- needs no idea whether it is holding a front pic, a back one or a trainer --
+-- fronts are near-solid silhouettes with almost nothing inside them to fill,
+-- and they come back untouched because that is what their own shape says, not
+-- because they were special-cased.
+--
+-- The drain/mouth cut is for a pic STANDING ON THE MAP, where a mouth is a
+-- real hole with real ground behind it. A pic PINNED TO THE MENU has no such
+-- hole to be: under BACK SPRITES the player's mon is drawn in the GB's own
+-- slot with its feet flush on the text box (BattleState.backPlacement pins
+-- row 96), so the only thing under its lowest row is white box. Nothing can
+-- reach it from below, whatever the opening's width, and the caller says so
+-- by asking for a SEALED BOTTOM -- for which the rule stops being a heuristic
+-- and becomes exact: paper is whatever the background cannot walk to from the
+-- left, the right or the top.
+--
+-- That is the difference between a Pikachu that reads as a mon and one that
+-- reads as wireframe. The pale-bodied back pics -- Pikachu, Seel, Dewgong,
+-- Chansey, Jigglypuff -- are drawn as OUTLINES: everything inside the ink is
+-- shade 0 and every one of them is keyed away, so the figure is a rim with the
+-- arena showing through it. Each one also has a wide opening along its bottom,
+-- which the drain cut correctly reads as a mouth and the sealed bottom
+-- correctly does not. Twelve of this game's 151 back pics turn on it; the
+-- other 139 come back byte-identical either way, because they had nothing
+-- under them the flood was getting in through.
+--
+-- The silhouette is untouched, so the mon still cuts cleanly against the
+-- world; only its insides stop being see-through.
+--
+-- Read back off the GPU rather than off the asset, deliberately. What comes
+-- back is the pic the engine actually decided to draw -- species palette,
+-- forced-mono rebuild, shiny recolour, a mod's replacement art -- so this
+-- needs to know nothing about how any of that was arrived at. Once per pic
+-- per session, cached on the image itself.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local BattlePics = {}
+
+-- Cached by the image the engine handed over, one table per bottom rule --
+-- the same pic answers differently sealed and unsealed, and a single table
+-- would hand the wrong twin back to whichever caller asked second. Weak keys,
+-- so a pic that goes out of scope takes its filled twin with it rather than
+-- pinning a texture for the session.
+local function newCache()
+  return {
+    [false] = setmetatable({}, { __mode = "k" }),
+    [true]  = setmetatable({}, { __mode = "k" }),
+  }
+end
+local cache = newCache()
+
+-- What an enclosed hole is filled with when the pic itself offers nothing
+-- better. White, because white is what the battle field was: this restores the
+-- pixel the artist drew and the engine then keyed away, it does not invent a
+-- new one.
+BattlePics.FILL = { 1, 1, 1, 1 }
+
+-- Anything at or under this alpha counts as keyed-out rather than drawn.
+local CUT = 0.5
+
+-- Read the pixels the engine would actually blit. A LOVE Image does not hand
+-- its data back, so it is drawn into a canvas of its own size and the canvas
+-- is read -- which is also what makes this work for every path that produces
+-- a pic, without knowing which one produced this one.
+--
+-- The canvas is forced to dpiscale = 1, and that is the whole difference
+-- between a pic and a MONSTER. love.graphics.newCanvas defaults its dpiscale
+-- to the surface's, conf.lua turns highdpi on for Android and iOS, and
+-- Android's density is routinely 2.75 -- so newCanvas(56, 56) hands back a
+-- 154x154 texture there, the pic is drawn into it magnified to fill it, and
+-- newImageData reads the magnified copy back at its own PIXEL size. The image
+-- built from that is 2.75x the artwork, drawPicsLayer draws it at 1:1 because
+-- it trusts getWidth(), and the mon stands on the map nearly three times the
+-- size of the square it is supposed to cover. Desktop never saw it: dpiscale
+-- is already 1 there. Nor did every species, because only a pic with an
+-- enclosed hole in it comes back through here at all (see `changed` below) --
+-- so a Pidgey came out giant and the mon beside it did not, which is what
+-- makes this read as a sprite bug rather than a scale one. See the engine's
+-- own src/render/PixelCanvas.lua, which exists for exactly this reason.
+local function readBack(img)
+  local w, h = img:getDimensions()
+  if w <= 0 or h <= 0 then return nil end
+  local prevCanvas = love.graphics.getCanvas()
+  local prevBlend, prevAlpha = love.graphics.getBlendMode()
+  local prevR, prevG, prevB, prevA = love.graphics.getColor()
+  local data = nil
+  local ok = pcall(function()
+    local canvas = love.graphics.newCanvas(w, h, { dpiscale = 1 })
+    love.graphics.setCanvas(canvas)
+    love.graphics.clear(0, 0, 0, 0)
+    love.graphics.setBlendMode("replace", "premultiplied")
+    love.graphics.setColor(1, 1, 1, 1)
+    love.graphics.draw(img, 0, 0)
+    love.graphics.setCanvas()
+    data = canvas:newImageData()
+    if canvas.release then pcall(canvas.release, canvas) end
+  end)
+  if prevCanvas then
+    love.graphics.setCanvas(prevCanvas)
+  else
+    love.graphics.setCanvas()
+  end
+  love.graphics.setBlendMode(prevBlend or "alpha", prevAlpha)
+  love.graphics.setColor(prevR or 1, prevG or 1, prevB or 1, prevA or 1)
+  return ok and data or nil
+end
+
+-- The box the artwork actually occupies, or nil for a pic with no ink in it.
+--
+-- Not the image: a pic is centred in a 7x7-tile buffer and a small mon leaves
+-- whole rows and columns of nothing around itself. The bottom of THIS box is
+-- the cut the rule below turns on, and the bottom of the image is just empty
+-- frame some distance under it.
+local function inkBounds(data, w, h)
+  local x0, y0, x1, y1 = w, h, -1, -1
+  for y = 0, h - 1 do
+    for x = 0, w - 1 do
+      local _, _, _, a = data:getPixel(x, y)
+      if a > CUT then
+        if x < x0 then x0 = x end
+        if x > x1 then x1 = x end
+        if y < y0 then y0 = y end
+        if y > y1 then y1 = y end
+      end
+    end
+  end
+  if x1 < x0 then return nil end
+  return x0, y0, x1, y1
+end
+
+-- The colour the keyed-away shade would have had: the LIGHTEST colour still
+-- standing in the pic.
+--
+-- Pure white is only the right answer while the pic is still grays, and by the
+-- time it reaches here it usually is not. picImage hands a pic over AFTER the
+-- bake -- a species SGB colour, a BGP fade mid-animation, PAL_BLACK for the
+-- whole screen while the blackout text is up -- and shade 0 travels with the
+-- rest. A white belly inside a blacked-out mon would be the one lit thing on a
+-- dark screen; inside a warm-palette mon it would be a cold patch the artist
+-- never drew.
+--
+-- So the paper is read off the pic rather than assumed, which needs shade 0 to
+-- have survived somewhere in it. It always has: every one of this game's 151
+-- back pics keeps at least one opaque shade-0 pixel -- a highlight down a
+-- cheek, the white of an eye -- because only the shade-0 pixels the decoder
+-- could reach were keyed. So what comes back is the baked shade 0 itself, not
+-- an approximation of it, and it tracks every palette the engine picks without
+-- being told which one that was.
+--
+-- Ranked by channel sum, which orders four DMG shades exactly: a palette maps
+-- all three channels monotonically, so lightest by sum is lightest full stop.
+local function paperColor(data, x0, y0, x1, y1)
+  local best, pr, pg, pb = -1, nil, nil, nil
+  for y = y0, y1 do
+    for x = x0, x1 do
+      local r, g, b, a = data:getPixel(x, y)
+      if a > CUT then
+        local lum = r + g + b
+        if lum > best then best, pr, pg, pb = lum, r, g, b end
+      end
+    end
+  end
+  if best < 0 then return nil end
+  return pr, pg, pb
+end
+
+-- The widest opening along the bottom of a figure that still counts as a drain
+-- rather than a mouth. See the header for the measurements either side of it.
+BattlePics.DRAIN = 6
+
+-- Mark every transparent pixel the BACKGROUND can reach, flooding inward from
+-- the edges of the artwork's box: the left, the right and the top whole, and
+-- along the bottom only those openings wide enough to be background rather
+-- than the underside of a figure the drawing ran out of -- or none of them at
+-- all, for a pic whose feet are on the text box and which therefore has
+-- nothing behind its lowest row to let in.
+--
+-- Confined to the box as well as seeded from it, so the empty frame under a
+-- short pic cannot walk around a sealed drain and come back up through it.
+--
+-- An explicit stack rather than recursion: a 56x56 pic is three thousand
+-- pixels and a keyed-out background is most of them, which is a deeper call
+-- chain than is worth risking for no gain.
+local function markOutside(data, w, h, x0, y0, x1, y1, sealBottom)
+  local outside = {}
+  local stack, top = {}, 0
+  local function clear(x, y)
+    local _, _, _, a = data:getPixel(x, y)
+    return a <= CUT
+  end
+  local function push(x, y)
+    if x < x0 or y < y0 or x > x1 or y > y1 then return end
+    local key = y * w + x
+    if outside[key] then return end
+    if not clear(x, y) then return end
+    outside[key] = true
+    top = top + 1
+    stack[top] = key
+  end
+  for x = x0, x1 do push(x, y0) end
+  for y = y0, y1 do
+    push(x0, y)
+    push(x1, y)
+  end
+  -- the bottom, run by run: a wide one is the gap between two legs and lets
+  -- the world through, a narrow one is where a belly ran out and is sealed.
+  -- Skipped whole for a pic on the box, where even the widest of them has
+  -- white paper behind it rather than arena.
+  if not sealBottom then
+    local x = x0
+    while x <= x1 do
+      if clear(x, y1) then
+        local from = x
+        while x <= x1 and clear(x, y1) do x = x + 1 end
+        if (x - from) > BattlePics.DRAIN then
+          for k = from, x - 1 do push(k, y1) end
+        end
+      else
+        x = x + 1
+      end
+    end
+  end
+  while top > 0 do
+    local key = stack[top]
+    top = top - 1
+    local x, y = key % w, math.floor(key / w)
+    push(x - 1, y)
+    push(x + 1, y)
+    push(x, y - 1)
+    push(x, y + 1)
+  end
+  return outside
+end
+
+-- The pic with its enclosed holes filled, or the pic itself when that could
+-- not be done (no pixel access, a driver that refused the readback). Never
+-- nil for a non-nil argument: a caller must always have something to draw.
+--
+-- sealBottom for a pic pinned to the text box rather than standing on the map:
+-- see the header. A caller that does not say defaults to the map, which is
+-- where all but one of this mod's pics are.
+function BattlePics.filled(img, sealBottom)
+  if not img then return img end
+  sealBottom = sealBottom and true or false
+  local slot = cache[sealBottom]
+  local hit = slot[img]
+  if hit ~= nil then return hit or img end
+
+  local made = nil
+  local ok = pcall(function()
+    local data = readBack(img)
+    if not data then return end
+    local w, h = data:getDimensions()
+    local x0, y0, x1, y1 = inkBounds(data, w, h)
+    if not x0 then return end          -- a pic with nothing drawn in it
+    local outside = markOutside(data, w, h, x0, y0, x1, y1, sealBottom)
+    local fill = BattlePics.FILL
+    local pr, pg, pb = paperColor(data, x0, y0, x1, y1)
+    local fr = pr or fill[1]
+    local fg = pg or fill[2]
+    local fb = pb or fill[3]
+    local changed = false
+    -- only inside the box: everything beyond it is frame the artist never
+    -- reached, and filling that would put the mon in a white rectangle
+    for y = y0, y1 do
+      local row = y * w
+      for x = x0, x1 do
+        if not outside[row + x] then
+          local _, _, _, a = data:getPixel(x, y)
+          if a <= CUT then
+            data:setPixel(x, y, fr, fg, fb, fill[4])
+            changed = true
+          end
+        end
+      end
+    end
+    -- nothing enclosed: hand the original back rather than a copy of it
+    if not changed then return end
+    local out = love.graphics.newImage(data)
+    out:setFilter("nearest", "nearest")
+    made = out
+  end)
+
+  slot[img] = (ok and made) or false
+  return made or img
+end
+
+function BattlePics.invalidate()
+  cache = newCache()
+end
+
+return BattlePics

lib/BattleScene.lua

@@ -0,0 +1,740 @@
+-- Overworld battles: one frame of the arena, as geometry.
+--
+-- The same world the free-roam mode draws, from a placed camera instead of
+-- the orbit, at the WINDOW's own pixel resolution -- not the GB's. The
+-- backdrop reaches the screen through Renderer's worldOverride, the seam a
+-- render pipeline's finished world image already composites through, which
+-- is drawn one canvas pixel to one screen pixel; the 160x144 battle screen
+-- then blits over it in the classic letterbox. So the world is as crisp as
+-- the free-roam diorama and the pics, HUDs and text box stay exactly the
+-- chunky GB art they are.
+--
+-- Rendering the whole window rather than just the letterbox means the
+-- framing has to be split in two. The RIG frames the GB's 160x144 (see
+-- BattleCam, which is solved against coordinates in that frame); this
+-- module widens the lens by exactly the ratio the window bears to the
+-- letterbox, so the letterbox sub-rectangle of what gets rendered is
+-- bit-for-bit the framing the rig asked for, and everything outside it is
+-- extra picture. That is what lets the two mons be PINNED: their cells
+-- project to the same GB coordinates at any window size or zoom.
+--
+-- Characters are deliberately absent. The overworld cast is culled for the
+-- length of the battle (see OverworldBattle), so this pass has terrain,
+-- grass and flowers and nothing that walks -- the arena is empty, which is
+-- what makes it an arena.
+--
+-- Everything expensive is shared with the free-roam mode rather than
+-- duplicated: the same chunk meshes out of ChunkMesher, the same palette
+-- atlas out of TerrainAtlas, the same sun out of ShadowMap. A battle on a
+-- map already meshed for walking around costs the frame it draws and
+-- nothing else.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Mat4 = V.require("Mat4")
+local Voxel3D = V.require("Voxel3D")
+local ShadowMap = V.require("ShadowMap")
+local ChunkMesher = V.require("ChunkMesher")
+local TerrainAtlas = V.require("TerrainAtlas")
+local VoxelScene = V.require("VoxelScene")
+local BattleCam = V.require("BattleCam")
+local BattleBillboard = V.require("BattleBillboard")
+local VoxelGrid = V.require("VoxelGrid")
+local DayNight = V.require("DayNight")
+local AntiAlias = V.require("AntiAlias")
+local PaletteFX = require("src.render.PaletteFX")
+local Map = require("src.world.Map")
+
+local BattleScene = {}
+
+-- The GB frame the battle screen is drawn in, and the frame BattleCam's rig
+-- is solved against.
+BattleScene.GB_W = 160
+BattleScene.GB_H = 144
+
+-- A map cell in world pixels: the overworld square a mon stands on, which is
+-- both what the arena is measured in and what a mon is sized to.
+BattleScene.CELL = 16
+
+-- How far into black a shadow goes in the arena, against the free-roam
+-- mode's own lighter setting.
+--
+-- Darker on purpose, and only here. Walking around, a shadow is scenery and
+-- wants to stay out of the way of reading the map. In a battle it is doing
+-- one specific job: the two mons are flat cards, and the ONLY thing telling
+-- the eye they are standing on that floor rather than hanging in front of it
+-- is the shadow they put on it. A faint one leaves them floating.
+BattleScene.SHADOW_ALPHA = 0.68
+
+-- Which rung of the sky ramp an indoor void is painted with. A room has no
+-- sky, but it does have somewhere the geometry stops, and leaving that
+-- transparent would show the letterbox clear through the gaps.
+local INDOOR_SHADE = 4
+
+-- ------- where the GB frame sits inside the window
+--
+-- Renderer blits worldOverride one canvas pixel to one screen pixel and then
+-- blits the 160x144 UI canvas into a centred, integer-scaled letterbox. So
+-- these have to agree with Renderer:endFrame exactly, or the pins land off
+-- the mons by however much they disagree.
+function BattleScene.letterbox()
+  local Renderer = require("src.render.Renderer")
+  local pw, ph = BattleScene.pixelSize()
+  local s = Renderer:fitScale()
+  return math.floor((pw - BattleScene.GB_W * s) / 2),
+         math.floor((ph - BattleScene.GB_H * s) / 2),
+         s, pw, ph
+end
+
+-- The window in FRAMEBUFFER pixels, which is what the override blit works
+-- in. love.graphics.getDimensions is in LOVE units and differs from this by
+-- the display density on mobile.
+function BattleScene.pixelSize()
+  if love.graphics.getPixelDimensions then
+    local pw, ph = love.graphics.getPixelDimensions()
+    if pw and ph and pw > 0 and ph > 0 then return pw, ph end
+  end
+  return love.graphics.getDimensions()
+end
+
+-- Widen the rig's vertical field of view from the GB frame to the whole
+-- window, so the letterbox rows show exactly what the rig framed.
+--
+-- The horizontal falls out of it: at aspect pw/ph the window's half-width is
+-- tan(fov/2) * pw/ph, and the letterbox is 160*s of those pw pixels, which
+-- works back out to the GB frame's own 160/144. So one scale on the vertical
+-- pins both axes.
+function BattleScene.letterboxFov(fovGB, ph, s)
+  local span = BattleScene.GB_H * s
+  if span <= 0 then return fovGB end
+  return 2 * math.atan(math.tan(fovGB / 2) * ph / span)
+end
+
+-- ------- palette
+--
+-- The world palette a map draws under, in the shape VoxelScene's colour
+-- helpers take. Rebuilt per frame from the overworld state, which is where
+-- the engine's own pipeline context gets it too (OverworldController's
+-- ctx.paletteFor).
+local function paletteFor(state, home)
+  return function(map)
+    return PaletteFX.pal(require("src.core.Game").data,
+                         state:paletteNameFor(map or home))
+  end
+end
+
+-- ------- the map the fight is staged on
+--
+-- Normally the one the player is standing on. An authored arena may name
+-- another floor of the same cave or building (see BattleArena), and then the
+-- scene is THAT map: its terrain, its palette, its sky. Nothing else in the
+-- battle changes -- the fight, the party, the player's own position are all
+-- exactly where they were.
+--
+-- A foreign floor is meshed alone, with no connected neighbours: connections
+-- are the player's neighbourhood, and the map the camera has gone to visit is
+-- not standing in it. Both maps are kept live so neither the arena's mesh nor
+-- the one waiting to be walked back onto is evicted mid-battle.
+local function prefetchArena(state, host)
+  if host == state.map then return VoxelScene.prefetch(state) end
+  local live = { [host.id] = true, [state.map.id] = true }
+  for _, nb in ipairs(state.neighbors or {}) do live[nb.map.id] = true end
+  ChunkMesher.setLive(live)
+  TerrainAtlas.setLive(live)
+  ChunkMesher.request(host, false, nil, true)
+  local terrain, water = ChunkMesher.pair(host, false)
+  if not terrain then terrain, water = ChunkMesher.pair(host, true) end
+  return terrain, {}, water, {}
+end
+
+-- ------- the sun
+--
+-- Only has to be drawn once per battle: the arena does not move, and neither
+-- does the light. So the signature is the map, the arena and the meshes --
+-- not the camera, which is the one thing that IS moving and the one thing
+-- the sun does not care about.
+-- ------- the two mons, hung on their cells
+--
+-- The billboard texture is the battle screen's own 160x144 pics layer with
+-- one side rendered into it (see OverworldBattle.sideTexture), so the quad is
+-- that whole frame stood up on the map -- which is what carries every pic
+-- effect the engine applies without any of them being reimplemented here.
+--
+-- Its size follows from one number: a full 7x7-tile mon covers one overworld
+-- square, so a canvas pixel is FULL_W / FULL_PIC world pixels and the card is
+-- the canvas at that scale. Its placement follows from the anchor the
+-- texture reports -- the column the pic was centred on and the row its feet
+-- were put on -- which is translated onto the cell before the card is stood
+-- up, so a mon of any size in any pose has its feet on the ground.
+-- `mirror` flips the card about its own anchor column. Both mons wear their
+-- FRONT pic, which is drawn facing out of the screen -- so dropped into the
+-- world unaltered the pair stand back to back, both looking the same way past
+-- each other. Mirroring the near one turns it to face the far one, which is
+-- what a fight looks like; and because it is a flip about the pic's own
+-- centre the feet do not move off the tile.
+--
+-- The player's TRAINER pic is the exception, and it is exempted below. That
+-- one is a BACK view -- the player seen from behind, already turned to face
+-- up the field -- so it arrives pointing the right way and mirroring it would
+-- turn it around to face the camera it is standing in front of.
+local function monMatrix(tex, x, groundY, z, mirror)
+  local k = BattleBillboard.FULL_W / BattleBillboard.FULL_PIC
+  local w = BattleScene.GB_W * k
+  local h = BattleScene.GB_H * k
+  local ox = -((tex.ax / BattleScene.GB_W) - 0.5) * w
+  local oy = -((BattleScene.GB_H - tex.ay) / BattleScene.GB_H) * h
+  local yaw = BattleBillboard.yawToward(x, z, Voxel3D.eye)
+  local card = Mat4.mul(Mat4.translate(ox, oy, 0), Mat4.scale(w, h, 1))
+  if mirror then card = Mat4.mul(Mat4.scale(-1, 1, 1), card) end
+  return Mat4.mul(Mat4.mul(Mat4.translate(x, groundY, z), Mat4.rotateY(yaw)),
+                  card)
+end
+
+-- Every mon that has something to show this frame, as (texture, matrix).
+local function monCards(arena, groundY, textures)
+  local out = {}
+  if not textures then return out end
+  for _, side in ipairs({ "enemy", "player" }) do
+    local tex = textures[side]
+    local cell = (side == "player") and arena.player or arena.enemy
+    if tex and tex.canvas and cell then
+      local mirror = (side == "player") and not tex.trainer
+      out[#out + 1] = { tex = tex.canvas,
+                        model = monMatrix(tex, cell[1], groundY, cell[2],
+                                          mirror) }
+    end
+  end
+  return out
+end
+
+BattleScene.monCards = monCards
+
+-- The MOVE-ANIMATION layer's place in the world: a BILLBOARD facing the
+-- eye, for the GB-frame effects texture OverworldBattle.animTexture
+-- renders (the engine's own drawAnimLayer, caught on a canvas).
+--
+-- Effects are 2D drawings like the pics, and the pics' answer holds for
+-- them too: a drawing must FACE the eye that is looking (the mon cards
+-- yaw toward it per eye -- see monMatrix). So the frame stands on the
+-- arena's midpoint, yawed at the eye like the cards are, and the classic
+-- layout's two slot marks are pinned where each CELL lands on that plane
+-- along this very eye's own ray -- so from the eye that is looking, a
+-- burst authored at a slot sits exactly over the mon standing in for it,
+-- and a projectile crossing the frame crosses the arena. The vertical
+-- scale is the mon cards' own (FULL_W / FULL_PIC), so an effect is sized
+-- like the pics it plays over.
+--
+-- An eye standing (nearly) ON the arena's axis sees the two cells in
+-- line and the pinning degenerates; the frame then falls back to the
+-- fixed plane through both cells, which that eye views edge-on anyway.
+--
+-- Reads Voxel3D.eye at CALL time, like the cards -- call it per eye.
+-- Returns the model matrix for BattleBillboard's unit card (x -0.5..0.5,
+-- y 0..1 up, v flipped), or nil where the anchors are degenerate.
+function BattleScene.fxCard(arena, groundY, anchors)
+  local p, e = anchors.player, anchors.enemy
+  local dgb = e[1] - p[1]
+  if math.abs(dgb) < 1 then return nil end
+  local GW, GH = BattleScene.GB_W, BattleScene.GB_H
+  local Px, Py, Pz = arena.player[1], groundY, arena.player[2]
+  local Ex, Ey, Ez = arena.enemy[1], groundY, arena.enemy[2]
+  local s = BattleBillboard.FULL_W / BattleBillboard.FULL_PIC
+  local Mx, My, Mz = (Px + Ex) / 2, groundY, (Pz + Ez) / 2
+
+  local eye = Voxel3D.eye
+  local yaw = BattleBillboard.yawToward(Mx, Mz, eye)
+  local nx, nz = math.sin(yaw), math.cos(yaw)     -- out of the frame, at the eye
+  local rx, rz = math.cos(yaw), -math.sin(yaw)    -- the frame's own right
+
+  -- where a world point sits ON the billboard, as (right, up) coordinates
+  -- about the midpoint: slid along the eye's ray onto the plane, so the
+  -- mark and the mon line up from exactly the seat that is looking
+  local function inPlane(qx_, qy_, qz_)
+    if eye then
+      local dqx, dqy, dqz = qx_ - eye[1], qy_ - eye[2], qz_ - eye[3]
+      local denom = dqx * nx + dqz * nz
+      if math.abs(denom) > 1e-6 then
+        local t = ((Mx - eye[1]) * nx + (Mz - eye[3]) * nz) / denom
+        qx_ = eye[1] + dqx * t
+        qy_ = eye[2] + dqy * t
+        qz_ = eye[3] + dqz * t
+      end
+    end
+    return (qx_ - Mx) * rx + (qz_ - Mz) * rz, qy_ - My
+  end
+  local pax, pay = inPlane(Px, Py, Pz)
+  local eax, eay = inPlane(Ex, Ey, Ez)
+
+  if math.abs(eax - pax) < 4 then
+    -- edge-on: the fixed plane through both cells, world-axis mapping
+    local ux = (Ex - Px) / dgb
+    local uy = (Ey - Py - s * (p[2] - e[2])) / dgb
+    local uz = (Ez - Pz) / dgb
+    local cx = Px + ux * (0.5 * GW - p[1])
+    local cy = Py + uy * (0.5 * GW - p[1]) + s * (p[2] - GH)
+    local cz = Pz + uz * (0.5 * GW - p[1])
+    local nl = math.sqrt(ux * ux + uz * uz)
+    local fx, fz = 0, 1
+    if nl > 1e-9 then fx, fz = uz / nl, -ux / nl end
+    return { ux * GW, 0, fx, cx,
+             uy * GW, s * GH, 0, cy,
+             uz * GW, 0, fz, cz,
+             0, 0, 0, 1 }
+  end
+
+  -- in-plane travel per GB pixel of frame x, solved so both marks land:
+  -- inPlane(gb) = (pax, pay) + U * (gbx - p.x) + (0, s) * (p.y - gby)
+  local ux = (eax - pax) / dgb
+  local uy = (eay - pay - s * (p[2] - e[2])) / dgb
+  local cxp = pax + ux * (0.5 * GW - p[1])
+  local cyp = pay + uy * (0.5 * GW - p[1]) + s * (p[2] - GH)
+  return { rx * ux * GW, 0, nx, Mx + rx * cxp,
+           uy * GW, s * GH, 0, My + cyp,
+           rz * ux * GW, 0, nz, Mz + rz * cxp,
+           0, 0, 0, 1 }
+end
+
+-- The sun has to see the mons too, or they stand on the ground without
+-- putting anything on it. They are the one thing in this scene that MOVES,
+-- so `token` -- a counter the caller bumps whenever a pic could have changed
+-- -- goes in the signature; the terrain half of the answer would otherwise
+-- keep a stale pass alive and freeze the shadows in whatever pose they were
+-- first drawn in.
+local function shadowSignature(state, arena, terrain, nbMesh, token)
+  local host = arena.map or state.map
+  -- `turn` is in the signature with the corner and the shape: the same corner
+  -- turned a quarter is a different footprint standing on different ground,
+  -- and a cast kept from the other one freezes the shadows across it
+  local parts = { "battle", host.id, arena.x, arena.y, arena.shape,
+                  tostring(arena.turn or 0),
+                  tostring(terrain), tostring(token or 0),
+                  -- the cycle keeps running through a fight, and an arena lit
+                  -- from somewhere new must be re-cast from there
+                  math.floor(ShadowMap.KX * 128),
+                  math.floor(ShadowMap.KZ * 128) }
+  for i = 1, #nbMesh do parts[#parts + 1] = tostring(nbMesh[i]) end
+  return table.concat(parts, ",")
+end
+
+local function castShadows(state, arena, terrain, nbMesh, cx, cy, vw, vh,
+                           atlasFor, cards, token, host, neighbors,
+                           water, nbWater, groundY)
+  if not ShadowMap.available() then return end
+  local sig = shadowSignature(state, arena, terrain, nbMesh, token)
+  if not ShadowMap.stale(sig) then return end
+  if not ShadowMap.begin(cx, cy, vw, vh) then return end
+
+  -- A DISC RUNG: the two discs are the only ground there is, so they are the
+  -- only thing the sun has to see besides the Pokemon themselves. Everything
+  -- below this is a map that is not in the shot.
+  if arena.discs then
+    pcall(function()
+      V.require("StadiumStage").cast(ShadowMap, arena, groundY or 0)
+    end)
+    pcall(function() V.require("Stadium").cast(ShadowMap) end)
+    ShadowMap.finish(sig)
+    return
+  end
+
+  ShadowMap.draw(terrain, atlasFor(host), nil)
+  for i, nb in ipairs(neighbors) do
+    ShadowMap.draw(nbMesh[i], atlasFor(nb.map), Mat4.translate(nb.ox, 0, nb.oy))
+  end
+  -- the water surface is its own reflective pass now (see Water) and so is
+  -- no longer inside the terrain mesh; the sun still has to see it, or the
+  -- light's map has a hole at every lake
+  ShadowMap.draw(water, atlasFor(host), nil)
+  for i, nb in ipairs(neighbors) do
+    ShadowMap.draw(nbWater and nbWater[i], atlasFor(nb.map),
+                   Mat4.translate(nb.ox, 0, nb.oy))
+  end
+  -- thin cards are snugged toward the sun (ShadowMap.snug) so their shadows
+  -- keep contact with their bases instead of starting a bias-width away
+  ShadowMap.draw(ChunkMesher.flowers(host), atlasFor(host),
+                 ShadowMap.snug(nil))
+  for _, nb in ipairs(neighbors) do
+    ShadowMap.draw(ChunkMesher.flowers(nb.map), atlasFor(nb.map),
+                   ShadowMap.snug(Mat4.translate(nb.ox, 0, nb.oy)))
+  end
+
+  -- the mons themselves, as the same cards the camera will see. Their alpha
+  -- is the silhouette, so what lands on the ground is the shape of the
+  -- Pokemon rather than a blob standing in for one.
+  -- marked as the CAST, so a fight staged at the water's edge does not lay a
+  -- cut-out of a Pokemon across the lake (see ShadowMap.sprites); the arena's
+  -- own floor still takes them, which is the shadow that matters here
+  ShadowMap.sprites(true)
+  for _, card in ipairs(cards or {}) do
+    ShadowMap.draw(BattleBillboard.mesh(), card.tex,
+                   ShadowMap.snug(card.model))
+  end
+  ShadowMap.sprites(false)
+  -- and the STADIUM models, when that rung is the one running. NOT marked
+  -- as sprites: that flag exists so a flat card's cut-out is kept off the
+  -- water (see ShadowMap.sprites), and these are real geometry standing in
+  -- the world -- a Gyarados at the water's edge should put a Gyarados on
+  -- the water. Un-snugged for the same reason: snug is a bias for a card
+  -- rooted to the ground plane, and a model has thickness of its own.
+  pcall(function() V.require("Stadium").cast(ShadowMap) end)
+
+  ShadowMap.finish(sig)
+end
+
+-- The height of the arena floor: the ground the two mons stand on. Both
+-- cells are open, so they are normally the same; take the player's, which is
+-- the one nearer the camera and therefore the one a mismatch would show up
+-- against.
+function BattleScene.groundY(map, arena)
+  -- A disc rung's discs are carried, not found: their tops ARE the ground
+  -- plane, so there is no terrain height to read and reading one would put
+  -- the stage at whatever elevation the map happens to have at a spot the
+  -- fight is not actually happening on
+  if arena and arena.discs then return 0 end
+  local ok, h = pcall(VoxelScene.groundAt, map,
+                      arena.playerCell[1], arena.playerCell[2])
+  return (ok and h) or 0
+end
+
+-- Where a world point lands in GB frame coordinates under `vp`, or nil when
+-- it is behind the camera. This is the function the pins are built on: it
+-- takes the window-resolution clip position and divides the letterbox back
+-- out of it, so the answer is in the same 160x144 space the battle screen
+-- draws its pics in.
+function BattleScene.toGB(vp, wx, wy, wz, lx, ly, s, pw, ph)
+  local cx = vp[1] * wx + vp[2] * wy + vp[3] * wz + vp[4]
+  local cy = vp[5] * wx + vp[6] * wy + vp[7] * wz + vp[8]
+  local cw = vp[13] * wx + vp[14] * wy + vp[15] * wz + vp[16]
+  if cw <= 1e-6 then return nil end
+  -- viewProjection already flipped clip Y into LOVE's Y-down convention
+  local px = (cx / cw * 0.5 + 0.5) * pw
+  local py = (cy / cw * 0.5 + 0.5) * ph
+  return (px - lx) / s, (py - ly) / s
+end
+
+-- Render the arena and hand back { canvas, player = {x,y}, enemy = {x,y} },
+-- the two marks in GB coordinates -- or nil when there is nothing to draw
+-- yet (the terrain mesh is still building, the driver has no depth support).
+-- nil is not a failure: the caller simply leaves the battle screen as the
+-- engine drew it for that frame.
+-- White, for the hit flash, and how far toward it the card goes.
+--
+-- The shader replaces the card's colour rather than multiplying it, so at
+-- full strength this is the sprite turned into a solid white silhouette --
+-- which is what the effect is on a flat GB screen and far too much on a
+-- sprite standing in a lit world. Held well short of 1, the mon's own
+-- shading still reads through the flash: it looks struck rather than
+-- deleted.
+BattleScene.FLASH_COLOR = { 1, 1, 1 }
+BattleScene.FLASH_STRENGTH = 0.5
+
+-- ------- the tile clock, while the overworld is not the one drawing
+--
+-- Water and flowers animate off TileRenderer's 60Hz counter, and the ENGINE
+-- only advances it from OverworldState:drawWorld -- which runs under dialogs
+-- and menus, but not under a battle, because a battle draws instead of the
+-- overworld rather than over it. So for the length of a staged fight the
+-- counter stood still: the water tiles stopped rotating their pixels and the
+-- wave field, which is driven off the same number so the two cannot drift
+-- (see Water), stopped with them. A lake in the background of a battle was a
+-- photograph.
+--
+-- Ticked HERE rather than from the mod's update hook, because here is the
+-- one place that means "a staged battle is drawing this frame, and the
+-- overworld is not". From the update hook the condition would have to be
+-- guessed at, and a frame where both ran would double the rate.
+local function tickTiles()
+  local Game = require("src.core.Game")
+  local ow = Game and Game.overworld
+  local top = Game and Game.stack and Game.stack:top()
+  -- during the wipe INTO a battle the overworld can still be the one
+  -- drawing, and it is ticking the clock itself; two ticks in a frame would
+  -- run the water at double speed
+  if top and ow and top == ow then return end
+  pcall(require("src.render.TileRenderer").tick)
+end
+
+function BattleScene.render(state, arena, textures, token)
+  if not (state and state.map and arena) then return nil end
+  if not Voxel3D.available() then return nil end
+  tickTiles()
+
+  -- the floor the fight is staged on: normally the player's own, sometimes
+  -- another floor of the same cave or building (see BattleArena)
+  local host = arena.map or state.map
+  local neighbors = (host == state.map) and (state.neighbors or {}) or {}
+
+  -- the hour's light reaches the arena exactly as it reaches free-roam: the
+  -- shared rig follows the clock on an outdoor floor and stays at noon on an
+  -- indoor one, and the same tint multiplies the staged shot -- with the
+  -- same window glass on whatever buildings stand in the background
+  local outdoor = host.def and Map.isOutdoor(host.def) or false
+  DayNight.applyRig(outdoor)
+  -- a canopy floor (Viridian Forest) fights under the hour's tint too,
+  -- with the rig and the void exactly as they were
+  Voxel3D.tint = DayNight.tint(outdoor or DayNight.isCanopy(host))
+  local GlassMask = V.require("GlassMask")
+  Voxel3D.glassMask = outdoor and GlassMask.texture(host.tileset) or nil
+  Voxel3D.glassNight = outdoor and DayNight.windowLight() or 0
+  -- no glint in the arena: the drift is the shot breathing, not the player
+  -- moving, and a shimmer on background windows would fight the mons
+  Voxel3D.glassGlint = 0
+  -- the host floor's atmosphere reaches the staged shot at HALF density --
+  -- a fight in Viridian Forest sits in the same haze the walk there did,
+  -- thinned so neither mon goes soft -- and its god rays stay out of it:
+  -- this camera is low and long, and a bright blade across a combatant
+  -- reads as a rendering fault, not weather. nil almost everywhere.
+  local ForestAtmos = V.require("ForestAtmos")
+  local atmos = ForestAtmos.frame(host)
+  Voxel3D.fog = atmos and { color = atmos.fog.color,
+                            density = atmos.fog.density * 0.5,
+                            start = atmos.fog.start,
+                            heightK = atmos.fog.heightK } or nil
+
+  -- A B RUNG stands the fight on two carried discs against the sky, with no
+  -- map in the shot at all (see StadiumStage). Everything below still runs --
+  -- the letterbox, the camera solve, the sun, the pins, the tint, the depth
+  -- of field -- because none of it is about the terrain; what changes is
+  -- which geometry the two passes draw.
+  local discs = arena.discs and true or false
+
+  -- shares the free-roam mode's request/evict bookkeeping, so a battle warms
+  -- exactly the meshes walking around would have and nothing extra
+  local terrain, nbMesh, water, nbWater
+  if discs then
+    -- and nothing is meshed for a disc fight, which is the other half of why
+    -- the rung works everywhere: there is no waiting for a chunk to build, so
+    -- the first frame of the first battle on a cold map is the finished shot
+    nbMesh, water, nbWater = {}, nil, {}
+  else
+    terrain, nbMesh, water, nbWater = prefetchArena(state, host)
+    if not terrain then return nil end
+  end
+
+  local lx, ly, s, pw, ph = BattleScene.letterbox()
+  if not (pw > 0 and ph > 0 and s > 0) then return nil end
+
+  local palette = paletteFor(state, host)
+  local function atlasFor(map)
+    return TerrainAtlas.forMap(map, VoxelScene._modeColors(palette, map))
+  end
+
+  local groundY = BattleScene.groundY(host, arena)
+  local cam, pitch = BattleCam.rig(arena, groundY)
+  cam.fov = BattleScene.letterboxFov(cam.fov, ph, s)
+
+  local cx, cy = arena.mid[1], arena.mid[2]
+  -- the world extents the sun frustum is fitted to; the camera itself is
+  -- framed by cam.fov, so these only have to describe the ground in shot
+  -- the player's zoom is part of this: the sun's box is fitted to what the
+  -- frame holds, so a shot pulled wide has to light the ground it just
+  -- brought into view rather than the ground the rig alone would have
+  local vh = BattleCam.frameH(arena) * ph / (BattleScene.GB_H * s)
+  local vw = vh * pw / ph
+
+  -- the cards need the camera's eye to face it, so the rig has to be live
+  -- before they are built; Voxel3D.eye is set by viewProjection, which
+  -- beginScene calls -- so a provisional one is taken here for the sun pass
+  -- and the real one is rebuilt inside the scene below.
+  Voxel3D.camera = cam
+  Voxel3D.viewProjection(cx, cy, vw, vh)
+  local cards = monCards(arena, groundY, textures)
+  Voxel3D.camera = nil
+  castShadows(state, arena, terrain, nbMesh, cx, cy, vw, vh, atlasFor,
+              cards, token, host, neighbors, water, nbWater, groundY)
+
+  -- An opaque void either way. Outdoors the camera is low enough that the
+  -- horizon is genuinely in frame, so it is sky; indoors it is the dark end
+  -- of the same ramp, which is a room's "past the wall". Transparent -- the
+  -- free-roam default -- would let the letterbox clear through wherever the
+  -- geometry stops.
+  local sky = VoxelScene.skyColor(host, 1)
+             or VoxelScene.skyShade(INDOOR_SHADE, 1)
+  -- On a disc rung the void is not a backdrop behind the scenery -- it IS the
+  -- scenery, because the map is not drawn. So outdoors it gets the full
+  -- treatment the free-roam camera gets: the banded gradient and the hour's
+  -- own sun or moon hanging in it (Voxel3D.beginScene paints those when the
+  -- sky it is handed carries bands). Indoors there is nothing to dress: a
+  -- room's void is one flat shade, which is what a room looks like past the
+  -- wall, and the disc fight in a cave is lit and coloured as that cave.
+  if discs and VoxelScene.skyColor(host, 1) then
+    local Sky = V.require("Sky")
+    local okDress, dressed = pcall(Sky.dress, sky)
+    if okDress and dressed then sky = dressed end
+  end
+
+  Voxel3D.camera = cam
+  -- the sun is turned up for the arena and put back afterwards, so the
+  -- free-roam world it shares this module with keeps its own weight -- and
+  -- the hour still has the last word: a sunset fades the arena's shadows
+  -- out and the moon presses more softly, exactly as it does outside
+  local sunWas = Voxel3D.SHADOW_ALPHA
+  Voxel3D.SHADOW_ALPHA = BattleScene.SHADOW_ALPHA
+                         * DayNight.shadowScale(outdoor)
+  -- and the wireframe is ON for a battle whatever the V-GRID row says. The
+  -- arena is a staged shot rather than the world being walked through, and
+  -- the seams are what make it read as built rather than photographed. Forced
+  -- through the override so the player's own row is never written to.
+  local gridWas = VoxelGrid.override
+  VoxelGrid.override = true
+  local out = nil
+  local ok, err = pcall(function()
+    -- its own canvas slot: this renders at the window's pixel size and the
+    -- free-roam pass does too, but the two are alive at different moments
+    -- and a shared slot would reallocate on every battle entry and exit
+    --
+    -- AA, if the row asks for it, renders it larger still and folds it back
+    -- to pw x ph below (see AntiAlias). The framing is untouched by that:
+    -- the lens was widened by the window's RATIO to the letterbox and the
+    -- rig solved in the GB's own frame, so a bigger canvas is more samples
+    -- of the identical shot -- which is why the pins below still measure in
+    -- pw and ph, and why the HUDs and the depth of field, drawn onto the
+    -- folded canvas afterwards, stay the chunky GB art they are.
+    local rw, rh = AntiAlias.expand(pw, ph)
+    if not Voxel3D.beginScene(rw, rh, cx, cy, vw, vh, sky, "battle") then
+      return
+    end
+    if discs then
+      -- discs: the two platforms, and nothing else. No terrain, no
+      -- neighbouring maps, no water, no grass and no flowers -- see the
+      -- matching skips further down. What is behind them is the sky the
+      -- clear painted.
+      V.require("StadiumStage").draw(arena, groundY)
+    else
+    Voxel3D.draw(terrain, atlasFor(host), nil)
+    for i, nb in ipairs(neighbors) do
+      Voxel3D.draw(nbMesh[i], atlasFor(nb.map),
+                   Mat4.translate(nb.ox, 0, nb.oy))
+    end
+    -- and the water over it -- PLAIN, always: the flat animated tiles, never
+    -- the reflective pass, whatever the WATER row says. The reflection is
+    -- tuned for the overworld's ladder of cameras; this shot's is PLACED --
+    -- low, tilted and framed like a picture -- and under it the pass reads
+    -- wrong: Fresnel opens all the way up, the leaned sky lands on bands the
+    -- framing never shows, and a lake-sized arena comes out as murk wearing
+    -- the tile art. The battle is a stage set, and stage water is painted.
+    -- (No mirror also means the mons need no second draw into one -- they
+    -- just composite over the water below, like everything else on the set.)
+    if water then Voxel3D.draw(water, atlasFor(host)) end
+    for i, nb in ipairs(neighbors) do
+      if nbWater and nbWater[i] then
+        Voxel3D.draw(nbWater[i], atlasFor(nb.map),
+                     Mat4.translate(nb.ox, 0, nb.oy))
+      end
+    end
+    end
+    -- The mons, standing on their tiles. Depth-tested like everything else,
+    -- so a ledge or a tree between the camera and a Pokemon really is in
+    -- front of it, and the alpha discard cuts the sprite's own outline out of
+    -- the card. A small camera-ward pull keeps a card rooted to the ground
+    -- plane from z-fighting the tile it is standing on.
+    -- The engine's hit flash is a full-screen white rectangle, which on a
+    -- white battle field is a flash and over a world is a whiteout of the
+    -- map, the HUD and the text box alike. It is dropped on the way past
+    -- (see OverworldBattle) and put back HERE, on the two things it was ever
+    -- about: the mons themselves go solid white for those frames.
+    local flashing = textures and textures.flash
+    if flashing then
+      Voxel3D.flatten(BattleScene.FLASH_COLOR, BattleScene.FLASH_STRENGTH)
+    end
+    -- and no voxel wireframe on the pair. Everything else in this frame is
+    -- built a unit per voxel and wears the seams that fall out of that; a
+    -- mon's card is one quad wearing the battle screen (see
+    -- BattleBillboard), so it is off the grid and has no seams to draw.
+    Voxel3D.seams(false)
+    -- and no glass either: the cards wear the battle screen, not the
+    -- tileset atlas, so the mask's coordinates mean nothing on them
+    Voxel3D.glass(false)
+    for _, card in ipairs(monCards(arena, groundY, textures)) do
+      -- the sun stored this card snugged (castShadows), so its own shadow
+      -- lookup must read the same snugged transform -- see ShadowMap.snug
+      Voxel3D.draw(BattleBillboard.mesh(), card.tex, card.model,
+                   BattleBillboard.PULL, ShadowMap.snug(card.model))
+    end
+    Voxel3D.glass(true)
+    Voxel3D.seams(true)
+    -- and the STADIUM models, inside the same flash window and with the
+    -- same camera-ward pull, so a Pokemon standing on its tile still wins
+    -- the depth test against the tile. They manage the wireframe and the
+    -- glass mask around their own draws (StadiumRig), which is why this
+    -- sits outside the pair above rather than inside it.
+    local okStadium, stadiumErr = pcall(function()
+      V.require("Stadium").draw(BattleBillboard.PULL)
+    end)
+    if not okStadium then V.require("Stadium").report(stadiumErr) end
+    if flashing then Voxel3D.flatten(nil) end
+    -- grass and flowers ride the same camera-ward pull the free-roam pass
+    -- gives them, measured against THIS camera's pitch rather than the
+    -- orbit's -- there is no character here for them to overdraw, but the
+    -- pull is also what keeps a tuft from z-fighting the floor it stands on
+    local pull = VoxelScene.pull(math.max(pitch, 0.05))
+    if not discs then
+      Voxel3D.draw(ChunkMesher.grass(host), atlasFor(host), nil, pull)
+      for _, nb in ipairs(neighbors) do
+        Voxel3D.draw(ChunkMesher.grass(nb.map), atlasFor(nb.map),
+                     Mat4.translate(nb.ox, 0, nb.oy), pull)
+      end
+      local fpull = math.max(0, pull - 8 * math.sin(math.max(pitch, 0.05)))
+      Voxel3D.draw(ChunkMesher.flowers(host), atlasFor(host), nil, fpull,
+                   ShadowMap.snug(nil))
+      for _, nb in ipairs(neighbors) do
+        Voxel3D.draw(ChunkMesher.flowers(nb.map), atlasFor(nb.map),
+                     Mat4.translate(nb.ox, 0, nb.oy), fpull,
+                     ShadowMap.snug(Mat4.translate(nb.ox, 0, nb.oy)))
+      end
+    end
+    local canvas = AntiAlias.resolve(Voxel3D.endScene(), pw, ph, "battle")
+    if not canvas then return end
+
+    local vp = Voxel3D.vp
+    local pmx, pmy = BattleScene.toGB(vp, arena.player[1], groundY,
+                                      arena.player[2], lx, ly, s, pw, ph)
+    local emx, emy = BattleScene.toGB(vp, arena.enemy[1], groundY,
+                                      arena.enemy[2], lx, ly, s, pw, ph)
+    if not (pmx and emx) then return end
+    -- How wide one overworld square is on screen where each mon stands, in
+    -- GB pixels. This is what the pics are scaled to: a mon covers its own
+    -- square and no more, at whatever the drift has done to the distance.
+    local half = BattleScene.CELL / 2
+    local pl = BattleScene.toGB(vp, arena.player[1] - half, groundY,
+                                arena.player[2], lx, ly, s, pw, ph)
+    local pr = BattleScene.toGB(vp, arena.player[1] + half, groundY,
+                                arena.player[2], lx, ly, s, pw, ph)
+    local el = BattleScene.toGB(vp, arena.enemy[1] - half, groundY,
+                                arena.enemy[2], lx, ly, s, pw, ph)
+    local er = BattleScene.toGB(vp, arena.enemy[1] + half, groundY,
+                                arena.enemy[2], lx, ly, s, pw, ph)
+    if not (pl and pr and el and er) then return end
+    out = {
+      canvas = canvas,
+      player = { pmx, pmy },
+      enemy = { emx, emy },
+      playerSpan = math.abs(pr - pl),
+      enemySpan = math.abs(er - el),
+      -- the letterbox, so the depth-of-field pass can put its sharp band on
+      -- the two marks rather than on a fraction of the window
+      lx = lx, ly = ly, scale = s, pw = pw, ph = ph,
+      -- and the hour's light, for anything drawn over this shot that is NOT
+      -- geometry and so never went past the shader that applied it -- the back
+      -- pic pinned to the menu (see OverworldBattle.backPinned). Neutral
+      -- indoors, which is what DayNight.tint answers for a room.
+      tint = Voxel3D.tint,
+    }
+  end)
+  -- the placed camera is ours for exactly this pass; anything else that
+  -- renders (the free-roam pipeline, next frame) must find the orbit back
+  Voxel3D.camera = nil
+  Voxel3D.SHADOW_ALPHA = sunWas
+  VoxelGrid.override = gridWas
+  if not ok then
+    -- endScene never ran, so the canvas is still bound and the shader still
+    -- set; put the frame back the way it was found before rethrowing
+    pcall(love.graphics.setShader)
+    pcall(love.graphics.setDepthMode)
+    pcall(love.graphics.setCanvas)
+    error(err, 0)
+  end
+  return out
+end
+
+return BattleScene

lib/Buildings.lua

@@ -68,6 +68,47 @@ local RECESS_MAX = 24
 local SHADE = { top = 0.95, south = 1.0, north = 0.68,
                 side = 0.78, bottom = 0.5 }
 
+-- ------- how far a merged run may reach: the tile lattice
+--
+-- Merging is what keeps a 90k-voxel house down to ~2k quads, and under a
+-- straight projection a run may be as long as it likes -- a straight line
+-- is a straight line however finely it is cut. THE WORLD CURVE IS NOT
+-- STRAIGHT. It drops every vertex by the square of its distance from the
+-- focus (see WorldCurve), so a quad's interior is the CHORD of a parabola
+-- its neighbours draw the arc of: a run of length L hangs k*L^2/4 below
+-- the short quads butted against it, and the join tears open.
+--
+-- Nothing bounded a run's length before, and the runs that ran away were
+-- the ones wearing a CONSTANT texel -- the roof's black eave outline, its
+-- fascia, the shaded underside -- because a flat run has no art to break
+-- it. Those reached 102px across a gym, which at V-CURVE 3 hangs some
+-- three world pixels under the roof surface beside it: the eave tore off
+-- the roof and the drop showed the building's dark interior through the
+-- slot. (Strip runs, the drawing marching along the atlas, break at the
+-- tileset's own boundaries and were never the problem.)
+--
+-- So a run stops at the next 8px lattice line. Buildings are stamped at
+-- tx*8 (see stamp), so the model's lattice IS the map's: every quad in the
+-- scene -- terrain, props, this -- now ends on the same lines, every join
+-- is vertex-for-vertex, and the bend carries them together. What is left
+-- is the sag WITHIN one cell, k*64/4, which is under a twentieth of a
+-- world pixel at any rung.
+--
+-- It costs quads on a dense city map (Cerulean's object stream goes from
+-- 35.7k to 41.6k, and its longest edge from 102px to 8px) and it costs them
+-- whether the curve is on or not, which is the deliberate trade: the mesh
+-- is cached per map and built asynchronously over seconds, so meshing for
+-- the curve's sake only when the curve is on would mean rebuilding every
+-- live map on a keypress.
+local CELL = 8
+
+-- How far a run starting at `a` may go before it crosses the next lattice
+-- line. Floor-mod, so the awning's negative z lands on the same lines the
+-- positive side does.
+local function runCap(a)
+  return CELL - a % CELL
+end
+
 local function keyOf(tx, ty)
   return (ty + 64) * 4096 + (tx + 64)
 end
@@ -170,6 +211,39 @@ local function read(t, data, perRow)
 
   local inside = {}
   for i = 0, W * H - 1 do inside[i] = not outside[i] end
+
+  -- `scrub` names pixel rects where the drawing paints an object standing
+  -- ON the surface (Red's potted plant on the dining tabletop). The object
+  -- keeps its own standee -- the template's `keep` leaves its tiles
+  -- unclaimed -- so the band beneath it is the one surface the drawing
+  -- implies but never paints clear: every rect pixel takes the field
+  -- shade, sourced from the first field texel outside the rects, and the
+  -- model's top comes out as the plain surface the object sat on.
+  if t.scrub then
+    local function inRect(x, y)
+      for _, r in ipairs(t.scrub) do
+        if x >= r[1] and x <= r[3] and y >= r[2] and y <= r[4] then
+          return true
+        end
+      end
+      return false
+    end
+    local donor = nil
+    for i = 0, W * H - 1 do
+      if col[i] == GREY and inside[i]
+         and not inRect(i % W, math.floor(i / W)) then
+        donor = i
+        break
+      end
+    end
+    for i = 0, W * H - 1 do
+      if inRect(i % W, math.floor(i / W)) then
+        col[i] = GREY
+        ax[i], ay[i] = ax[donor], ay[donor]
+        inside[i] = true
+      end
+    end
+  end
   return { W = W, H = H, col = col, ax = ax, ay = ay, inside = inside }
 end
 
@@ -190,7 +264,24 @@ local function measure(sp, t)
     top[x] = r
   end
 
-  local wallH = H - roofRows
+  -- The drawing's own ground line: the row after the last drawn one. A
+  -- building ends on the black threshold row it stands on (ground == H),
+  -- but furniture is drawn standing on open floor -- the lab table's
+  -- legs stop two rows short of its grid -- and extruding against H
+  -- would float it that far above its own plot.
+  local ground = roofRows
+  for sy = H - 1, roofRows, -1 do
+    local drawn = false
+    for sx = 0, W - 1 do
+      if sp.inside[sy * W + sx] then drawn = true break end
+    end
+    if drawn then
+      ground = sy + 1
+      break
+    end
+  end
+
+  local wallH = ground - roofRows
   local ytop = wallH - 1 + t.slab
 
   -- Side faces must not come out as slabs of outline black: where the
@@ -259,6 +350,14 @@ local function measure(sp, t)
     end
   end
 
+  -- The pane rule reads a LIGHT region the drawing seals behind a BLACK
+  -- frame. A drawing built the other way round -- the healing machine's
+  -- dark screens sealed behind their own white bezels -- inverts under
+  -- it: every lit edge sinks and the black panes stand proud, a black
+  -- lattice a voxel off the face. `panes = false` says the drawing does
+  -- not carry the rule's polarity, so the facade stays flush.
+  if t.panes == false then recess = {} end
+
   -- One representative texel per shade, taken from the building's own art:
   -- the roof's fascia and its undersides are geometry the drawing implies
   -- but never paints, and they must still wear its palette (and pick up
@@ -279,20 +378,599 @@ local function measure(sp, t)
   -- sprite taller than its footprint -- the tower's 16-row drawing
   -- stands on the 8 rows of it that are actually on the map, and D = H
   -- would have pushed its body 64px south into the town plaza.
-  return { top = top, ytop = ytop, D = #t.tiles * 8,
+  -- `depth` (in tile rows) names the plot when the grid runs PAST it
+  -- onto ground the drawing merely stands its legs on: the lab table's
+  -- third row is the walkable cell the player faces it from, and the
+  -- full-grid depth would stand the model in their path.
+  -- `depth` names the plot in TILE ROWS, which is the right grain for a
+  -- building. `depthPx` names it in voxels, for an object whose real
+  -- depth is not a whole tile row -- the Bike Shop toolbox is a box
+  -- standing in the middle of its own cell, not a thing that fills a plot.
+  return { top = top, ytop = ytop,
+           D = t.depthPx or ((t.depth or #t.tiles) * 8),
+           ground = ground,
            recess = recess, interior = interior, shadeTexel = shadeTexel }
 end
 
 -- ----------------------------------------------------------------- build --
 
+-- A desk with separately-classified objects on it (a template's `parts`
+-- list): the methodology's region classification at part granularity.
+-- Upright parts anchor their drawn bottom row to the desk's top plane
+-- and wear their own drawn tops as lids; flat parts (a keyboard, a
+-- sheet of paper) lie one voxel proud at drawn row = depth row -- the
+-- same 1:1 the tabletop itself is drawn with, so an object's height ON
+-- the drawing is its position ON the desk. The desk is the lab-table
+-- slab + base; its lid is the one synthesized surface in the model
+-- (the objects cover every drawn pixel of the tabletop), continued
+-- from the sibling tables' pattern in the drawing's own shades.
+-- tools/building_voxels.py `build_desk_set` is the reference twin.
+local function deskSetModel(sp, pr, t)
+  local W, H, D = sp.W, sp.H, pr.D
+  local ground = pr.ground
+  local col, inside = sp.col, sp.inside
+  local vox = {}
+  local function key(x, y, z) return (y * D + z) * W + x end
+  local function put(x, y, z, i) vox[key(x, y, z)] = i end
+
+  -- de-outline walk bounded to the part, so a part's side faces show
+  -- its own material and never the neighbour's (the sprite-wide walk
+  -- the facade path uses would cross the black seam between units)
+  local function interiorAt(sx, sy, lo, hi)
+    local i = sy * W + sx
+    if col[i] ~= BLACK then return sx end
+    local step = sx < math.floor((lo + hi) / 2) and 1 or -1
+    for d = 1, 3 do
+      local nx = sx + step * d
+      if nx >= lo and nx <= hi then
+        local ni = sy * W + nx
+        if inside[ni] and col[ni] ~= BLACK then return nx end
+      end
+    end
+    return sx
+  end
+
+  -- The parts list, shared by every base piece: a desk plane or an
+  -- open tray rim alike, `plane` is simply the height they ride.
+  local ytop = 0
+  local function buildParts(plane)
+    for _, p in ipairs(t.parts) do
+      Budget.tick()
+      local x0 = p.x and p.x[1] or 0
+      local x1 = p.x and p.x[2] or (W - 1)
+      if p.kind == "flat" then
+        -- drawn row = depth row by default; `z` renames the origin when
+        -- the flat sits below the desk's own drawn top span (the Center
+        -- PC's keyboard). `at` names the sheet's own height when it does
+        -- not lie on the desk plane (the healing machine's keyboard is a
+        -- shelf mounted on the cabinet's side); `thick` gives it a body
+        -- -- layers below the sheet repeating each column's own texel,
+        -- the same continuation rule every synthesized surface follows.
+        local r0 = p.rows[1]
+        local z0 = p.z or r0
+        local atY = p.at or plane
+        local thick = p.thick or 1
+        if atY > ytop then ytop = atY end
+        for sy = r0, p.rows[2] do
+          local z = z0 + (sy - r0)
+          if z >= 0 and z < D then
+            for sx = x0, x1 do
+              if inside[sy * W + sx] then
+                for y = math.max(0, atY - thick + 1), atY do
+                  put(sx, y, z, sy * W + sx)
+                end
+              end
+            end
+          end
+        end
+      elseif p.kind == "box" then
+        -- A BOX part is a drawn rect standing at its own drawn
+        -- elevation -- equipment attached to the machine rather than an
+        -- object on the desk plane. The rows are face-on art: the top
+        -- row's drawn height IS the box's top (ground - 1 - r0,
+        -- measured), and the box runs down to `base` (default the drawn
+        -- extent; 0 continues it to the floor, the legs-continue rule).
+        -- Height beyond the drawn rows fills the way a roof band does:
+        -- rows before `cycle` map 1:1 from the top, rows after it 1:1
+        -- from the bottom -- the healing machine hoses' foot lands ON
+        -- the floor -- and the cycle window repeats between.
+        local r0, r1 = p.rows[1], p.rows[2]
+        local c0 = p.cycle and p.cycle[1] or r1
+        local c1 = p.cycle and p.cycle[2] or r1
+        local pz = p.z or 0
+        local pd = p.depth
+        local top = pr.ground - 1 - r0
+        local bot = p.base or (pr.ground - 1 - r1)
+        local nTop, nBot = c0 - r0, r1 - c1
+        if top > ytop then ytop = top end
+        for y = bot, top do
+          local k, j = top - y, y - bot
+          local sy
+          if k < nTop then
+            sy = r0 + k
+          elseif j < nBot then
+            sy = r1 - j
+          else
+            sy = c0 + (k - nTop) % (c1 - c0 + 1)
+          end
+          for sx = x0, x1 do
+            local i = sy * W + sx
+            if inside[i] then
+              local ix = interiorAt(sx, sy, x0, x1)
+              for z = pz, pz + pd - 1 do
+                if z >= 0 and z < D then
+                  local px = (z == pz or z == pz + pd - 1) and sx or ix
+                  put(sx, y, z, sy * W + px)
+                end
+              end
+            end
+          end
+        end
+      elseif p.kind == "iso" then
+        -- An ISO part is drawn in 2:1 isometric -- a box TURNED 45
+        -- degrees to the map, so one rhombus carries its top, its front
+        -- and its side at once and no band or facade split can reach
+        -- them. Un-projecting it is that projection run backwards: the
+        -- box stands as a real diamond in plan and every voxel wears the
+        -- texel the drawing paints where that voxel projects TO. The
+        -- drawn top lands on the top, the screen on the screen-facing
+        -- side and the flank on the flank, and nothing is segmented by
+        -- hand -- which is the only way to get this right, because the
+        -- three faces meet on a diagonal no rectangle can name.
+        --
+        -- Everything but the depth centre falls out of the drawn rect,
+        -- because the projection fixes it: the half-width is the drawn
+        -- rhombus's x radius, HALF that again its z radius (2:1 is what
+        -- makes it isometric), the near corner's drawn row is the base
+        -- rhombus's front tip, and whatever drawn height is left once
+        -- that rhombus is accounted for is the box's own height. Bill's
+        -- computer: rx 6, rz 3, base centre row 10, and 6 voxels tall --
+        -- which puts its left corner's vertical edge at drawn rows
+        -- 4..10, exactly where the drawing paints one.
+        --
+        -- `plan` is the one thing the drawing CANNOT state: 2:1 is the
+        -- projection, not the object, so reading rz as the plan radius
+        -- too builds a box half as deep as it is wide -- a slab, not the
+        -- cube the drawing depicts. `plan` names the real z radius and
+        -- the drawn row is scaled into it, so a cube is `plan = rx` and
+        -- the drawing still lands on it pixel for pixel.
+        local pr0, pr1 = p.rows[1], p.rows[2]
+        local rx = math.floor((x1 - x0 + 1) / 2)
+        local rz = math.floor(rx / 2)
+        local plan = p.plan or rz
+        local oy = pr1 - rz
+        local h = oy - rz - pr0
+        local ytp = plane + h
+        if ytp > ytop then ytop = ytp end
+        for sx = x0, x1 do
+          -- doubled, so a rect of even width keeps its centre between
+          -- two columns instead of limping one to the left
+          local dx2 = 2 * sx - (x0 + x1)
+          for dz = -plan, plan do
+            local z = p.z + dz
+            local d2 = math.abs(dx2) * plan + 2 * math.abs(dz) * rx
+            if z >= 0 and z < D and d2 <= (2 * rx + 1) * plan then
+              -- the plan row scaled back into the drawn rhombus
+              local dzs = math.floor((2 * dz * rz + plan) / (2 * plan))
+              for y = 0, h do
+                local sy = oy + dzs - y
+                local i = sy * W + sx
+                if sy >= pr0 and sy <= pr1 and inside[i] then
+                  put(sx, plane + y, z, i)
+                end
+              end
+            end
+          end
+        end
+      elseif p.kind == "plan" then
+        -- A PLAN part is a slab whose plan IS the drawn top view: the
+        -- band's silhouette becomes the footprint pixel for pixel
+        -- (drawn row = depth row, the same 1:1 every tabletop is drawn
+        -- with), so an octagonal top stands as an octagon rather than
+        -- the box no rectangular band can escape. The top layer wears
+        -- the band itself, outline and all; the rim layers below wear
+        -- the drawn fascia rows folded down the edge (x clamped into
+        -- the drawn fascia's span), and the slab's unseen interior the
+        -- field's dark texel.
+        local r0, r1 = p.rows[1], p.rows[2]
+        local f0, f1 = p.fascia[1], p.fascia[2]
+        local fx0, fx1 = p.fasciaX[1], p.fasciaX[2]
+        local rise = p.rise or 0
+        local h = (f1 - f0 + 1) + 1
+        if rise + h > ytop then ytop = rise + h end
+        local function drawn(sx, z)
+          return sx >= x0 and sx <= x1 and z >= 0 and z <= r1 - r0
+                 and inside[(r0 + z) * W + sx]
+        end
+        for z = 0, r1 - r0 do
+          if z >= 0 and z < D then
+            local sy = r0 + z
+            for sx = x0, x1 do
+              if inside[sy * W + sx] then
+                put(sx, rise + h - 1, z, sy * W + sx)
+                local edge = not (drawn(sx - 1, z) and drawn(sx + 1, z)
+                                  and drawn(sx, z - 1) and drawn(sx, z + 1))
+                for y = rise, rise + h - 2 do
+                  if edge then
+                    local fsx = math.max(fx0, math.min(fx1, sx))
+                    put(sx, y, z, (f0 + (rise + h - 2 - y)) * W + fsx)
+                  else
+                    put(sx, y, z, pr.shadeTexel[DARK])
+                  end
+                end
+              end
+            end
+          end
+        end
+      elseif p.kind == "disc" then
+        -- A DISC part is ROUND IN PLAN -- the pedestal column and base
+        -- the projection can only draw from the front. Centre and
+        -- radius are measured off the drawn widths (a flattened arc is
+        -- a horizontal circle seen from above); the circular footprint
+        -- is synthesized like any continued geometry, and every voxel
+        -- still wears the drawing: the side folds the drawn face-on
+        -- rows around the hull (x clamped into the drawn span, rows
+        -- repeating up the height), and `cap` lays the drawn top-view
+        -- rows over the top layer's interior, drawn north rows to the
+        -- plan's north. `cx2`/`cz2` are DOUBLED plan centres, so an
+        -- even diameter keeps its centre between two voxels instead of
+        -- limping one off.
+        local r, rise, h = p.r, p.rise or 0, p.h
+        local s0, s1 = p.side.rows[1], p.side.rows[2]
+        local sa0, sa1 = p.side.x[1], p.side.x[2]
+        local sn = s1 - s0 + 1
+        if rise + h > ytop then ytop = rise + h end
+        local function inDisc(x, z)
+          local dx = 2 * x + 1 - p.cx2
+          local dz = 2 * z + 1 - p.cz2
+          return dx * dx + dz * dz <= 4 * r * r
+        end
+        local zlo = math.floor((p.cz2 - 2 * r) / 2)
+        for x = math.floor((p.cx2 - 2 * r) / 2),
+                math.floor((p.cx2 + 2 * r) / 2) do
+          for z = math.max(0, zlo),
+                  math.min(D - 1, math.floor((p.cz2 + 2 * r) / 2)) do
+            if inDisc(x, z) then
+              local edge = not (inDisc(x - 1, z) and inDisc(x + 1, z)
+                                and inDisc(x, z - 1) and inDisc(x, z + 1))
+              for y = rise, rise + h - 1 do
+                local sx, sy
+                if p.cap and y == rise + h - 1 and not edge then
+                  local c0, c1 = p.cap.rows[1], p.cap.rows[2]
+                  sy = math.min(c1, c0 + math.floor((z - zlo)
+                                                    * (c1 - c0 + 1)
+                                                    / (2 * r)))
+                  sx = math.max(p.cap.x[1], math.min(p.cap.x[2], x))
+                else
+                  sy = s0 + (rise + h - 1 - y) % sn
+                  sx = math.max(sa0, math.min(sa1, x))
+                end
+                put(x, y, z, sy * W + sx)
+              end
+            end
+          end
+        end
+      else
+        local tr0, tr1 = p.top[1], p.top[2]
+        local fr0, fr1 = p.facade[1], p.facade[2]
+        local pd = p.depth
+        -- `rise` lifts a part off the desk's top plane and `z` names its
+        -- back-most depth row (the field a flat part already carries). An
+        -- object STANDING on a desk needs neither: it starts on the plane
+        -- at the plot's back. The healing machine's console needs both --
+        -- it stands in the FRONT map row of a grid whose back row is the
+        -- wall band it leans against, and its screen head is MOUNTED on
+        -- the console's front two voxels above the body's top. Both come
+        -- off the drawing, not off taste.
+        local base = plane + (p.rise or 0)
+        local pz = p.z or 0
+        local ytp = base + (fr1 - fr0)
+        if ytp > ytop then ytop = ytp end
+        -- `inset` sinks an authored pane one voxel: the pane rule
+        -- applied by hand, for a part whose screen IS sealed behind its
+        -- own black frame while the template's `panes = false` (set for
+        -- the polarity-inverted panel elsewhere in the same drawing)
+        -- blocks the global pass. Same mechanism as a recess: the front
+        -- voxel is simply not placed.
+        local ins = p.inset
+        for sx = x0, x1 do
+          -- the lid: the part's drawn top laid across its depth from the
+          -- back, last row continuing forward; the front lid row is the
+          -- facade's own top row -- the drawn front-top edge.  `stretch`
+          -- maps the drawn band over the whole depth instead, the tray's
+          -- rule: for a part authored DEEPER than its drawing (the house
+          -- stool grown past its drawn seat), clamping would print the
+          -- last row as a long smear off the back band's edge.
+          for z = pz, pz + pd - 1 do
+            local front = z == pz + pd - 1
+            local sy
+            if front then
+              sy = fr0
+            elseif p.stretch then
+              sy = math.min(tr0 + math.floor((z - pz) * (tr1 - tr0 + 1)
+                                             / (pd - 1)), tr1)
+            else
+              sy = math.min(tr0 + z - pz, tr1)
+            end
+            while sy <= tr1 and not inside[sy * W + sx] do sy = sy + 1 end
+            local ok = sy <= tr1 or (front and inside[fr0 * W + sx])
+            if ok and z >= 0 and z < D then
+              put(sx, ytp, z, (front and fr0 or sy) * W + sx)
+            end
+          end
+          -- the body: facade rows anchored to the part's own base
+          for sy = fr0 + 1, fr1 do
+            local y = base + (fr1 - sy)
+            local i = sy * W + sx
+            if inside[i] then
+              local ix = interiorAt(sx, sy, x0, x1)
+              for z = pz, pz + pd - 1 do
+                if z >= 0 and z < D then
+                  if z == pz + pd - 1 then
+                    local sunk = ins and sx >= ins.x[1] and sx <= ins.x[2]
+                                 and sy >= ins.rows[1] and sy <= ins.rows[2]
+                    if not sunk and not pr.recess[i] then put(sx, y, z, i) end
+                  elseif z == pz then
+                    put(sx, y, z, i)
+                  else
+                    put(sx, y, z, sy * W + ix)
+                  end
+                end
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+
+  -- A TRAY is an open container -- the drawing looks down INTO it, so its
+  -- top-view band is not a lid but the inside of the box, and the model
+  -- has to be hollow. Bands, all measured 1:1 like any other band table:
+  -- `top` is the opening (drawn row -> depth row), `front` the near wall
+  -- seen face-on (drawn row -> elevation), `x` the box's outer span and
+  -- `inner` the opening's, so the difference between them is the wall.
+  -- Four walls stand to the rim, the floor slab lies `floor` voxels thick
+  -- under the opening, and the cavity between them is left as AIR -- which
+  -- is the whole point, and what an extruded facade can never be. Parts (a
+  -- standing lid) then ride the rim like any object on a desk's plane.
+  if t.tray then
+    local tr = t.tray
+    local top0 = tr.top[1]
+    local fr0, fr1 = tr.front[1], tr.front[2]
+    local bx0, bx1 = tr.x[1], tr.x[2]
+    local ix0, ix1 = tr.inner[1], tr.inner[2]
+    local floor = tr.floor or 0
+    local plane = fr1 - fr0 + 1            -- the rim: the wall's height
+    -- Which drawn row lies at depth z. The far rim is the band's first
+    -- row and the near rim the front wall's own, and the drawn inside
+    -- STRETCHES over whatever depth is between them: a box deeper than
+    -- its drawing has rows to spare is the ordinary case once the plot
+    -- stops being the grid, and the alternative -- running out of rows
+    -- and repeating the last one -- would print the wrench twice.
+    local lo, hi = top0 + 1, tr.top[2] - 1     -- the drawn inside
+    local span = math.max(1, D - 3)            -- interior depth rows - 1
+    local function trayRow(z)
+      if z == 0 then return top0 end
+      if z == D - 1 then return fr0 end
+      return lo + math.floor((z - 1) * (hi - lo) / span)
+    end
+    for sx = bx0, bx1 do
+      Budget.tick()
+      for z = 0, D - 1 do
+        local hollow = sx >= ix0 and sx <= ix1 and z > 0 and z < D - 1
+        for y = 0, (hollow and floor or plane - 1) do
+          if hollow or y == plane - 1 then
+            -- the opening seen from above: the tray's own floor and
+            -- whatever lies in it -- and the rim is the same band where
+            -- the wall meets it
+            local i = trayRow(z) * W + sx
+            if inside[i] then put(sx, y, z, i) end
+          else
+            -- the wall below the rim: the front band folded up it, the
+            -- drawn face on the front and back layers and the de-outlined
+            -- interior between, exactly as a facade extrudes.
+            --
+            -- NO recess pass here, and it must stay that way: a pane sinks
+            -- by DELETING its front voxel so the one behind becomes the
+            -- pane, and a container's wall is one voxel thick -- there is
+            -- nothing behind it, so the front panel simply opened a hole
+            -- straight into the box and you could see the wrench through it.
+            local sy = fr1 - y
+            local i = sy * W + sx
+            if inside[i] then
+              local px = (z == 0 or z == D - 1) and sx
+                         or interiorAt(sx, sy, bx0, bx1)
+              put(sx, y, z, sy * W + px)
+            end
+          end
+        end
+      end
+    end
+    if plane > ytop then ytop = plane end
+    buildParts(plane)
+    return { at = function(x, y, z)
+               if x < 0 or x >= W or y < 0 or z < 0 or z >= D then
+                 return nil
+               end
+               return vox[key(x, y, z)]
+             end,
+             W = W, ytop = ytop, zmin = 0, zmax = D - 1 }
+  end
+
+  -- No base piece at all: the drawing IS its parts (the house stool -- a
+  -- seat and its legs, nothing under them but floor). The plane the parts
+  -- anchor to is the ground itself.
+  if not t.desk then
+    buildParts(0)
+    return { at = function(x, y, z)
+               if x < 0 or x >= W or y < 0 or z < 0 or z >= D then
+                 return nil
+               end
+               return vox[key(x, y, z)]
+             end,
+             W = W, ytop = ytop, zmin = 0, zmax = D - 1 }
+  end
+
+  -- The desk's top plane. Usually the drawing states it: the fascia and
+  -- base rows it paints below the objects ARE the front face, and their
+  -- row count is the height. Bill's desk paints neither inside its grid
+  -- -- its apron is drawn into the WALKABLE cell in front, and that cell
+  -- is left out on purpose so the chair standing there keeps its own
+  -- tiles -- so `plane` names the height directly and the body below the
+  -- lid is synthesized: the band table's own rim treatment, a shaded box
+  -- closed by the outline where it meets the floor, in the drawing's
+  -- shades via shadeTexel.
+  local f0, f1 = t.desk.fascia[1], t.desk.fascia[2]
+  local b0, b1 = t.desk.base[1], t.desk.base[2]
+  local plane = (b1 - b0 + 1) + (f1 - f0 + 1)
+
+  -- The desk's own PLOT, when the grid holds more than the desk. Bill's
+  -- grid runs on into the walkable cell, because the drawing puts the
+  -- desk's apron AND the chair pushed up to it in the same tiles -- so
+  -- the desk box has to stop at its own cell (`depth`) and stand on its
+  -- own ground line rather than the grid's, which the chair's feet set
+  -- eight rows lower. The base band's last row IS that ground line by
+  -- definition, and for every desk drawn inside its own grid it is the
+  -- measured one to the row (lab table, lab computers, Center PC, the
+  -- Bike Shop toolbox), so this changes nothing for them.
+  -- ...and in voxels (`depthPx`) plus a back origin (`z`) when the desk
+  -- is shallower than a tile row and leans against something: the
+  -- healing machine's cabinet is 10 deep -- its drawn top band's 9 rows
+  -- plus the front edge -- standing against the wall band, so its box
+  -- runs z 16..25 of a 32-deep plot.
+  local deskD = t.desk.depthPx or (t.desk.depth and t.desk.depth * 8) or D
+  local dz0 = t.desk.z or 0
+  local dz1 = dz0 + deskD - 1
+  local deskG = b1 + 1
+  -- ...and the desk's COLUMNS (`x`), when the grid is wider than the
+  -- desk: the healing machine's grid carries its flanking hoses and
+  -- keyboard, and the cabinet is only the middle 16 columns.
+  local dx0 = t.desk.x and t.desk.x[1] or 0
+  local dx1 = t.desk.x and t.desk.x[2] or W - 1
+
+  -- The WALL element: the band the machine backs onto, whose tiles this
+  -- grid claims. The drawing shows it only as the stripe background
+  -- around the tower (the same standing as the potted plants' floor),
+  -- so the block cycles the drawing's own stripe unit -- real pixels of
+  -- column `x`, rows `cycle` -- at wall-band height over the back plot,
+  -- exactly what the neighbouring cells' `wall` pins render.
+  if t.wall then
+    local wl = t.wall
+    local c0, c1 = wl.cycle[1], wl.cycle[2]
+    local cn = c1 - c0 + 1
+    local wx = wl.x or 0
+    for y = 0, wl.h - 1 do
+      Budget.tick()
+      local sy = c0 + (wl.h - 1 - y) % cn
+      for sx = 0, W - 1 do
+        for z = 0, wl.depthPx - 1 do
+          put(sx, y, z, sy * W + wx)
+        end
+      end
+    end
+  end
+
+  -- the base band, extruded exactly like every lab table's
+  for sy = b0, b1 do
+    Budget.tick()
+    local y = deskG - 1 - sy
+    for sx = dx0, dx1 do
+      if inside[sy * W + sx] then
+        local ix = interiorAt(sx, sy, dx0, dx1)
+        for z = dz0, dz1 do
+          local px = (z == dz0 or z == dz1) and sx or ix
+          put(sx, y, z, sy * W + px)
+        end
+      end
+    end
+  end
+  for i in pairs(pr.recess) do
+    local sy = math.floor(i / W)
+    local sx = i % W
+    if sy >= b0 and sy <= b1 and sx >= dx0 and sx <= dx1 then
+      vox[key(sx, deskG - 1 - sy, dz1)] = nil
+    end
+  end
+
+  -- the slab: fascia rows wrap every side
+  for sy = f0, f1 do
+    Budget.tick()
+    local y = plane - 1 - (sy - f0)
+    for sx = dx0, dx1 do
+      for z = dz0, dz1 do put(sx, y, z, sy * W + sx) end
+    end
+  end
+
+  if t.desk.top then
+    -- The lid wears the desk's own drawn top band -- the drawing DOES
+    -- paint this tabletop (the healing machine's white top face with
+    -- its lit west and shaded east strips), so nothing is synthesized
+    -- where it is visible: band rows map back-to-front, the first
+    -- fascia row is the drawn front-top edge, same rule as an upright
+    -- part's lid. Where a part's drawing occludes the band (the monitor
+    -- standing on it), the lid continues the nearest strip BESIDE the
+    -- part -- still the drawing's own pixels, the same sibling-pattern
+    -- rule every synthesized lid follows.
+    local tr0, tr1 = t.desk.top[1], t.desk.top[2]
+    for z = dz0, dz1 do
+      Budget.tick()
+      local sy = z == dz1 and f0 or math.min(tr0 + (z - dz0), tr1)
+      for sx = dx0, dx1 do
+        local px = sx
+        for _, p in ipairs(t.parts) do
+          local px0, px1 = p.x[1], p.x[2]
+          local r0, r1
+          if p.kind == "flat" or p.kind == "iso" or p.kind == "box" then
+            r0, r1 = p.rows[1], p.rows[2]
+          else
+            r0, r1 = p.top[1], p.facade[2]
+          end
+          if sx >= px0 and sx <= px1 and sy >= r0 and sy <= r1 then
+            px = (sx - px0 < px1 - sx) and (px0 - 1) or (px1 + 1)
+            px = math.max(dx0, math.min(dx1, px))
+            break
+          end
+        end
+        put(sx, plane - 1, z, sy * W + px)
+      end
+    end
+  else
+    -- the lid continues the sibling tables' top -- black rim, white
+    -- highlight courses along the north and west, grey field
+    local field = t.desk.lid == "white" and WHITE or GREY
+    for sx = dx0, dx1 do
+      for z = dz0, dz1 do
+        local shade = field
+        if sx == dx0 or sx == dx1 or z == dz0 or z == dz1 then
+          shade = BLACK
+        elseif sx == dx0 + 1 or z == dz0 + 1 then
+          shade = WHITE
+        end
+        put(sx, plane - 1, z, pr.shadeTexel[shade])
+      end
+    end
+  end
+
+  if plane > ytop then ytop = plane end
+  buildParts(plane)
+
+  return { at = function(x, y, z)
+             if x < 0 or x >= W or y < 0 or z < 0 or z >= D then return nil end
+             return vox[key(x, y, z)]
+           end,
+           W = W, ytop = ytop, zmin = 0, zmax = D - 1 }
+end
+
 -- The voxel model as a lookup: `at(x, y, z)` is the index of the sprite
 -- pixel that voxel wears, or nil. Build ORDER is expressed as lookup
 -- order -- roof first, so it overwrites the walls it intersects, and walls
 -- are trimmed to its underside so nothing pokes through the surface.
 local function model(sp, pr, t)
+  if t.parts then return deskSetModel(sp, pr, t) end
   local W, H, D = sp.W, sp.H, pr.D
   local slab, roofRows = t.slab, t.roofRows
-  local top, ytop = pr.top, pr.ytop
+  local top, ytop, ground = pr.top, pr.ytop, pr.ground
 
   -- The roof's drawn span. A sprite inset from its box (B03) leaves outer
   -- columns undrawn in the roof band; they carry no roof at all, and the
@@ -367,16 +1045,18 @@ local function model(sp, pr, t)
 
     -- the awning: the band juts two voxels past the walls, front and back
     if ledge0 and (z == -2 or z == -1 or z == D or z == D + 1) then
-      local sy = H - 1 - y
+      local sy = ground - 1 - y
       if sy >= ledge0 and sy <= ledge1 and sp.inside[sy * W + x] then
         return sy * W + x
       end
       return nil
     end
 
-    -- the facade, extruded straight back over the footprint
+    -- the facade, extruded straight back over the footprint. Rows map
+    -- against the measured ground line, not the grid's last row: the two
+    -- differ only for furniture standing on open floor (see measure).
     if z < 0 or z >= D then return nil end
-    local sy = H - 1 - y
+    local sy = ground - 1 - y
     local i = sy * W + x
     if y == 0 and not sp.inside[i] and sy > 0 and sp.inside[i - W] then
       -- the drawing's last row is the ground the building stands on, so
@@ -464,7 +1144,8 @@ local function emit(m, sp, atlasW, atlasH)
   local function runX(y, z, dx, dy, dz, x)
     local i0 = ci(x, y, z)
     local strip, n = nil, 1
-    while true do
+    local cap = runCap(x)
+    while n < cap do
       local nx = x + n
       local i = ci(nx, y, z)
       if not i or ci(nx + dx, y + dy, z + dz) then break end
@@ -556,8 +1237,8 @@ local function emit(m, sp, atlasW, atlasH)
         while z <= zmax do
           local i = ci(x, y, z)
           if i and not ci(x + d, y, z) then
-            local n = 1
-            while z + n <= zmax do
+            local n, cap = 1, runCap(z)
+            while n < cap and z + n <= zmax do
               local j = ci(x, y, z + n)
               if j ~= i or ci(x + d, y, z + n) then break end
               n = n + 1
@@ -666,7 +1347,7 @@ function Buildings.build(S, map, data, perRow)
               end
               built = models[key]
             end
-            Buildings.stamp(S, map, built, tx, ty, bw, bh)
+            Buildings.stamp(S, map, built, tx, ty, bw, bh, t)
           end
         end
       end
@@ -676,9 +1357,24 @@ end
 
 -- One placement: claim its tiles (so the detector leaves them alone and
 -- the mesher paints ground under them) and copy the model into place.
-function Buildings.stamp(S, map, quads, tx, ty, bw, bh)
-  local shape = { class = "building", h = 0, art = "building",
-                  flat = false, authored = true }
+--
+-- Two template fields alter what a claim means, for a drawing that
+-- carries a STANDEE on its surface (Red's potted plant on the dining
+-- table). `keep` names tile ids the stamp must NOT claim: their authored
+-- pins stay live, so the standee scan still stands the object exactly as
+-- it always did. `support` is the model's top plane in voxels: the claim
+-- shape carries it as its height, which is what tells that scan the
+-- standee's shelf -- a plain claim stays at h = 0, and Structures treats
+-- a building claim with height as a full model (skip, never a second
+-- box; see its support branches).
+function Buildings.stamp(S, map, quads, tx, ty, bw, bh, t)
+  local shape = { class = "building", h = (t and t.support) or 0,
+                  art = "building", flat = false, authored = true }
+  local keep = nil
+  if t and t.keep then
+    keep = {}
+    for _, id in ipairs(t.keep) do keep[id] = true end
+  end
 
   -- the ground the building stands on: the commonest flat tile around its
   -- feet, so a house on a path keeps its path
@@ -704,9 +1400,18 @@ function Buildings.stamp(S, map, quads, tx, ty, bw, bh)
   for r = 0, bh - 1 do
     for c = 0, bw - 1 do
       local k = keyOf(tx + c, ty + r)
-      S.shapeAt[k] = shape
-      S.skip[k] = true
-      S.ground[k] = best or false
+      if keep and keep[S.tileAt[k]] then
+        -- unclaimed by request: the tile keeps its pin (the plant's
+        -- cutout pool) and the standee scan finds it there. Only the
+        -- ground is set now, so the scan's own claim of these tiles has
+        -- the building's floor to paint when no flat tile touches a
+        -- cluster ringed by its own furniture.
+        S.ground[k] = best or false
+      else
+        S.shapeAt[k] = shape
+        S.skip[k] = true
+        S.ground[k] = best or false
+      end
     end
   end
 

lib/CamControl.lua

@@ -0,0 +1,415 @@
+-- The player's own camera controls: zoom everywhere, and the battle's orbit.
+--
+-- This mod has four cameras, and by the time a wheel notch arrives they all
+-- want it. So one module owns the INPUTS and answers the only question that
+-- matters -- which camera is this aimed at -- rather than each camera
+-- growing its own wheel handler and racing the others for the event:
+--
+--   a staged battle      the camera the fight is shot with (BattleCam): the
+--                        wheel and Q/E work its lens, and the right stick,
+--                        a drag or the mouse walk it around the arena.
+--
+--   the 3RD rung         the boom behind the player's shoulder
+--                        (ThirdPerson): the wheel, Q/E and a pinch let it
+--                        out and pull it in.
+--
+--   an orbit rung        the engine's own survey zoom, which the wheel has
+--                        always driven -- so here the module mostly gets
+--                        out of the way, and only ADDS the two keys and the
+--                        pinch that the engine has no handler for.
+--
+--   the 1ST rung         nothing. The eye is in the player's head; there is
+--                        no distance to change, and a pinch there would
+--                        silently wind the survey zoom for whenever they
+--                        stepped back out. Inputs pass through untouched.
+--
+-- Every claim is answered by a GATE rather than by a mode flag, and every
+-- wrap forwards whatever it does not claim -- so with voxel mode off, and
+-- on every screen that is not the overworld or a battle, each byte flows
+-- exactly where it always did.
+--
+-- Installed AFTER FirstPerson (see main.lua), which makes these wraps the
+-- outer ones: a battle's controls get first refusal on the mouse and the
+-- touch screen, which is right, because while a fight is staged the
+-- free-roam look is not driving anyway.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Voxel = V.require("VoxelState")
+local Voxel3D = V.require("Voxel3D")
+local FirstPerson = V.require("FirstPerson")
+local ThirdPerson = V.require("ThirdPerson")
+local BattleCam = V.require("BattleCam")
+
+local CamControl = {}
+
+-- ------- tuning
+--
+-- PINCH_SLACK is how far apart two fingers must travel, as a ratio of
+-- their starting gap, before the gesture counts as a pinch at all -- below
+-- it a two-finger tap wobbles rather than zooms.
+--
+-- SURVEY_PINCH is how many of the engine's integer survey steps one
+-- doubling of the finger gap is worth. The survey ladder is coarse (whole
+-- pixels per world pixel), so a pinch has to be geared down or the first
+-- centimetre of travel crosses the whole range.
+CamControl.PINCH_SLACK = 0.02
+CamControl.SURVEY_PINCH = 2.2
+
+-- ------- gates
+
+-- A fight staged on the map, drawn and on screen. Asked of the shot rather
+-- than of the battle state, because the shot is exactly "there is a 3D
+-- battle in front of the player right now" -- with 3D-BTL off, or on a map
+-- with no arena, the engine's own flat battle screen is up and its camera
+-- is not ours to steer.
+-- BACK SPRITES also closes it, through BattleCam.steerable: that setting
+-- nails the player's own mon to the GB's slot on the menu while the foe
+-- stands out on the map, and no camera angle holds a composition that is
+-- half frame and half world (see BattleCam.steerable, which is where the
+-- reasoning lives and which the RIG answers to as well -- so a stored
+-- angle from before the setting was switched on stands down with it).
+local function battleLive()
+  local ok, shot = pcall(function()
+    return V.require("OverworldBattle").shot()
+  end)
+  return (ok and shot and BattleCam.steerable) and true or false
+end
+
+CamControl.battleLive = battleLive
+
+-- The free-roam overworld, with the 3D pass carrying it: the gate every
+-- zoom that is not a battle's answers to.
+local function roaming()
+  return Voxel.active() and Voxel3D.available() and FirstPerson.onTop()
+end
+
+-- Which camera a zoom is aimed at: "battle", "boom", "survey", or nil for
+-- nothing that zooms (1ST, or a screen with no camera of ours behind it).
+function CamControl.zoomTarget()
+  if battleLive() then return "battle" end
+  if not roaming() then return nil end
+  if Voxel.isThirdPerson(Voxel.level) then return "boom" end
+  if Voxel.isFirstPerson(Voxel.level) then return nil end
+  return "survey"
+end
+
+-- ------- zoom
+--
+-- `notches` is signed the way every zoom in this file is: POSITIVE pulls
+-- the camera OUT. The engine's own survey step runs the other way, and is
+-- negated at the one place it is called rather than everywhere else being
+-- bent to match it.
+--
+-- Returns true when the input was ours, which is what tells a wrap to stop
+-- rather than forward.
+
+local function surveyStep(notches)
+  local ok = pcall(function()
+    local Game = require("src.core.Game")
+    Game:zoomStep(notches > 0 and -1 or 1)
+  end)
+  return ok
+end
+
+function CamControl.zoomBy(notches)
+  if not notches or notches == 0 then return false end
+  local target = CamControl.zoomTarget()
+  if target == "battle" then
+    BattleCam.stepZoom(notches)
+    return true
+  elseif target == "boom" then
+    ThirdPerson.stepZoom(notches)
+    return true
+  elseif target == "survey" then
+    -- one call per notch: the engine's ladder is integer rungs, and a
+    -- wheel spun hard should climb them all rather than one
+    for _ = 1, math.min(8, math.abs(notches)) do surveyStep(notches) end
+    return true
+  end
+  return false
+end
+
+-- A pinch's own scale: > 1 is fingers spreading, which means zoom IN
+-- (pull the world closer), which is a NEGATIVE notch count.
+function CamControl.pinchBy(factor)
+  if not (factor and factor > 0) then return false end
+  local target = CamControl.zoomTarget()
+  if target == "boom" then
+    return ThirdPerson.scaleZoom(1 / factor)
+  elseif target == "battle" then
+    -- battles take a pinch too: the wheel and the keys reach this camera
+    -- and a phone has neither, so without it the lens would be the one
+    -- control a touch screen could not work
+    return BattleCam.stepZoom(math.log(1 / factor)
+                              / math.log(BattleCam.ZOOM_STEP))
+  elseif target == "survey" then
+    CamControl.surveyAccum = (CamControl.surveyAccum or 0)
+      + math.log(factor) / math.log(2) * CamControl.SURVEY_PINCH
+    local moved = false
+    while CamControl.surveyAccum >= 1 do
+      CamControl.surveyAccum = CamControl.surveyAccum - 1
+      surveyStep(-1)
+      moved = true
+    end
+    while CamControl.surveyAccum <= -1 do
+      CamControl.surveyAccum = CamControl.surveyAccum + 1
+      surveyStep(1)
+      moved = true
+    end
+    return moved
+  end
+  return false
+end
+
+CamControl.surveyAccum = 0
+
+-- ------- the battle's orbit
+--
+-- Only ever the battle's: the free-roam rungs already steer their own look
+-- through FirstPerson, and these wraps sit outside it precisely so a fight
+-- can borrow the same devices without either of them growing a mode check.
+
+-- The right stick, read as a rate off the axes FirstPerson's own wrap is
+-- already recording (it records whatever the rung, so a battle can read
+-- them without a second wrap on the same seam). Ticked from
+-- OverworldBattle.update, which runs whatever is on top of the stack.
+--
+-- X walks the shot round the arena, Y raises the seat. The Y is NEGATED:
+-- a stick pushed forward reads as negative on SDL's axis, and pushing
+-- forward should send the camera UP and over -- the same "push the camera
+-- where you want it" the drag and the mouse below use.
+function CamControl.tick(dt)
+  if not battleLive() then return end
+  local x, y = FirstPerson.stickX(), FirstPerson.stickY()
+  if x ~= 0 then BattleCam.stickOrbit(x, dt) end
+  if y ~= 0 then BattleCam.stickPitch(-y, dt) end
+end
+
+-- ------- the wraps
+
+local installed = false
+
+function CamControl.install()
+  if installed then return end
+  installed = true
+
+  local Game = require("src.core.Game")
+
+  -- ------- the wheel
+  --
+  -- The engine's own handler is the survey zoom, so the wrap only has to
+  -- take the notch away when some OTHER camera wants it; "survey" falls
+  -- through to exactly the code that always ran.
+  do
+    local inner = Game.wheelmoved
+    function Game:wheelmoved(dx, dy)
+      local target = CamControl.zoomTarget()
+      if (target == "battle" or target == "boom") and dy and dy ~= 0 then
+        CamControl.zoomBy(dy > 0 and -1 or 1)
+        return
+      end
+      return inner(self, dx, dy)
+    end
+  end
+
+  -- ------- the stick clicks
+  --
+  -- Q and E, on the pad: the left stick's click pulls the camera out and the
+  -- right stick's pulls it in. A controller has no wheel and no number row,
+  -- and the two clicks are the only buttons a Gen 1 pad layout leaves free
+  -- (SELECT already walks the angle ladder).
+  --
+  -- Claimed for the two cameras a pad player can actually be looking at
+  -- while pressing them -- the third-person boom and a staged battle's lens
+  -- -- and forwarded untouched everywhere else, so a player who has rebound
+  -- either click keeps it on every other screen, a rebind capture included.
+  -- Not on the orbit rungs: the survey zoom has the OPTIONS row and the
+  -- wheel already, and taking a pad button for it would be taking one from
+  -- a player who never asked.
+  local CLICK_ZOOMS = { boom = true, battle = true }
+  do
+    local inner = Game.gamepadpressed
+    function Game:gamepadpressed(joystick, button)
+      if (button == "leftstick" or button == "rightstick")
+         and CLICK_ZOOMS[CamControl.zoomTarget() or ""] then
+        CamControl.zoomBy(button == "leftstick" and 1 or -1)
+        return
+      end
+      return inner(self, joystick, button)
+    end
+  end
+
+  -- ------- the mouse
+  --
+  -- Battle only. The free-roam look already owns relative motion through
+  -- FirstPerson's own wrap (this one is outside it, so what is claimed here
+  -- never reaches it) and a fight is exactly when that look is not driving.
+  --
+  -- Bare motion, no button held: moving the mouse moves the shot.
+  --
+  -- Each event's contribution is CLAMPED, though, because not every motion
+  -- event is a hand moving. The pointer entering the window, a warp back to
+  -- centre, an alt-tab -- each arrives as ONE event carrying the whole
+  -- distance from wherever the cursor was last seen, and in testing that
+  -- was a couple of hundred counts: enough to swing the shot a quarter of
+  -- the way to side-on before the player had touched anything. A real hand
+  -- delivers its travel as a stream of small events and is unaffected; a
+  -- teleport delivers it as one and is cut down to the size of a flick.
+  local MOUSE_STEP = 40
+  local function clamp(v)
+    return math.max(-MOUSE_STEP, math.min(MOUSE_STEP, v or 0))
+  end
+  do
+    local inner = love.mousemoved
+    love.mousemoved = function(x, y, dx, dy, istouch)
+      if battleLive() and not istouch then
+        -- dy is NEGATED for the same reason the stick's is: moving the
+        -- mouse away from you sends the camera up and over
+        if dx and dx ~= 0 then BattleCam.mouseOrbit(clamp(dx)) end
+        if dy and dy ~= 0 then BattleCam.mousePitch(-clamp(dy)) end
+        -- forwarded anyway: the cursor still has UI to point at, and the
+        -- steer is a read of the motion rather than a claim on it
+      end
+      if inner then return inner(x, y, dx, dy, istouch) end
+    end
+  end
+
+  -- ------- the touch screen
+  --
+  -- Two gestures, told apart by how many fingers are down on OPEN screen
+  -- (the overlay's own d-pad and buttons are never either):
+  --
+  --   one finger, in a battle    drags the shot around the arena
+  --   two fingers               pinch to zoom, wherever zooming means
+  --                             something -- and while they are down the
+  --                             free-roam look stands aside, so a pinch in
+  --                             3RD does not also spin the view
+  local TouchControls = require("src.core.TouchControls")
+
+  local free = {}          -- id -> {x, y} for every finger on open screen
+  local pinch = nil        -- { a, b, gap } while two of them are pinching
+
+  local function freeCount()
+    local n = 0
+    for _ in pairs(free) do n = n + 1 end
+    return n
+  end
+
+  local function gapOf(a, b)
+    local dx, dy = free[a].x - free[b].x, free[a].y - free[b].y
+    return math.sqrt(dx * dx + dy * dy)
+  end
+
+  -- Two free fingers and a camera that zooms: start measuring. The look
+  -- drag is dropped for the duration -- FirstPerson never sees the moves
+  -- below -- and re-seated on whichever finger survives, so the view does
+  -- not jump by however far the pinch travelled.
+  local function startPinch()
+    if pinch or freeCount() < 2 then return end
+    local ids = {}
+    for id in pairs(free) do ids[#ids + 1] = id end
+    local gap = gapOf(ids[1], ids[2])
+    if gap < 16 then return end
+    pinch = { a = ids[1], b = ids[2], gap = gap }
+    CamControl.surveyAccum = 0
+    pcall(FirstPerson.dropLook)
+  end
+
+  local function endPinch(lifted)
+    if not pinch then return end
+    local survivor = nil
+    for id in pairs(free) do
+      if id ~= lifted then survivor = id break end
+    end
+    pinch = nil
+    if survivor and free[survivor] then
+      pcall(FirstPerson.reseatLook, survivor,
+            free[survivor].x, free[survivor].y)
+    end
+  end
+
+  local function onControl(x, y)
+    local hit = nil
+    pcall(function() hit = TouchControls:hitTest(x, y) end)
+    return hit
+  end
+
+  -- Whether this module has any interest in touches at all this frame.
+  -- Kept deliberately wide -- a battle, or anything that zooms -- because
+  -- the wrap forwards everything it does not claim regardless.
+  local function wantsTouch()
+    return battleLive() or CamControl.zoomTarget() ~= nil
+  end
+
+  do
+    local inner = Game.touchpressed
+    function Game:touchpressed(id, x, y)
+      if wantsTouch() and not onControl(x, y) then
+        free[id] = { x = x, y = y }
+        if CamControl.zoomTarget() then startPinch() end
+        -- forwarded even so: a single free finger is the free-roam look's
+        -- to claim (FirstPerson's wrap is inside this one), and in a
+        -- battle it is nobody's until it MOVES
+      end
+      return inner(self, id, x, y)
+    end
+  end
+
+  do
+    local inner = Game.touchmoved
+    function Game:touchmoved(id, x, y)
+      local f = free[id]
+      if f then
+        local px, py = f.x, f.y
+        f.x, f.y = x, y
+        if pinch and (id == pinch.a or id == pinch.b) then
+          local gap = gapOf(pinch.a, pinch.b)
+          local factor = gap / math.max(1, pinch.gap)
+          if math.abs(factor - 1) > CamControl.PINCH_SLACK then
+            CamControl.pinchBy(factor)
+            pinch.gap = gap
+          end
+          return                       -- claimed: never a look drag too
+        end
+        if battleLive() and not pinch then
+          local w, h = 1280, 720
+          pcall(function()
+            w, h = love.graphics.getWidth(), love.graphics.getHeight()
+          end)
+          BattleCam.dragOrbit((x - px) / math.max(320, w))
+          -- dragged UP sends the camera up and over, the same way the
+          -- stick and the mouse do
+          BattleCam.dragPitch(-(y - py) / math.max(240, h))
+          return
+        end
+      end
+      return inner(self, id, x, y)
+    end
+  end
+
+  do
+    local inner = Game.touchreleased
+    function Game:touchreleased(id, x, y)
+      if free[id] then
+        if pinch and (id == pinch.a or id == pinch.b) then endPinch(id) end
+        free[id] = nil
+      end
+      return inner(self, id, x, y)
+    end
+  end
+
+  -- a reset that drops held input state drops ours with it, exactly as the
+  -- free-roam look's does
+  do
+    local inner = Game.focus
+    function Game:focus(f)
+      free, pinch = {}, nil
+      CamControl.surveyAccum = 0
+      return inner(self, f)
+    end
+  end
+end
+
+return CamControl

lib/ChunkMesher.lua

@@ -221,8 +221,18 @@ end
 -- Kept free of any GPU call so it can be exercised headless -- the
 -- geometry is the part with the interesting invariants, and a suite that
 -- needed a real GL context to check them would never run in CI.
-local function runGeometry(map, bodyOnly, masks, sink)
+-- `waterSink`, when given, takes the WATER SURFACE quads instead of the
+-- main sink -- the one class in this world that is drawn as its own pass
+-- (see Water: a mirror cannot be drawn until what it reflects exists).
+-- Nothing else moves: the quads are the same quads, emitted by the same
+-- corner and uv arithmetic at the same recessed height, and the shoreline
+-- faces around them still belong to the GROUND that exposes them.
+--
+-- Omitted, water stays in the terrain mesh exactly as it always did, which
+-- is what the headless geometry() below and the sun's own pass both want.
+local function runGeometry(map, bodyOnly, masks, sink, waterSink)
   local push = sink.push
+  local waterPush = waterSink and waterSink.push or nil
   local tileset = map.tileset
   local S = Structures.forMap(map)
   local perRow = tileset.tilesPerRow or 16
@@ -358,12 +368,14 @@ local function runGeometry(map, bodyOnly, masks, sink)
     return aoSide
   end
 
-  local function topQuad(x0, z0, h, tile, shade)
+  -- `to` routes the quad somewhere other than the main sink -- the water
+  -- surface is the only caller that ever does (see runGeometry's header).
+  local function topQuad(x0, z0, h, tile, shade, to)
     local u0, u1, v0, v1 = uvRect(tile, 0, 8)
-    push({ { x0, h, z0 }, { x0 + 8, h, z0 },
-           { x0 + 8, h, z0 + 8 }, { x0, h, z0 + 8 } },
-         { { u0, v0 }, { u1, v0 }, { u1, v1 }, { u0, v1 } },
-         aoShades(x0 / 8, z0 / 8, h, shade))
+    ;(to or push)({ { x0, h, z0 }, { x0 + 8, h, z0 },
+                    { x0 + 8, h, z0 + 8 }, { x0, h, z0 + 8 } },
+                  { { u0, v0 }, { u1, v0 }, { u1, v1 }, { u0, v1 } },
+                  aoShades(x0 / 8, z0 / 8, h, shade))
   end
 
   -- vertical quad for face direction `d` of the tile column at (x0, z0),
@@ -427,6 +439,18 @@ local function runGeometry(map, bodyOnly, masks, sink)
         s = nil
       end
 
+      -- Under the TREES fill the border wall is MODELLED or it is not there
+      -- (see Structures' hullRingOnly): a ring cell nothing claimed would
+      -- be a flat-topped box standing beside carved trunks, which reads as
+      -- a painted-on plateau rather than forest. Structures already stops
+      -- the ring at the carve distance; this catches the odd cell inside it
+      -- that the 2x2 grouping could not take -- a canopy whose partners
+      -- fall outside the shortened ring is left unclaimed, and one strip of
+      -- boxes along an edge is the whole artefact this avoids.
+      if not inBody and S.hideBareRing and not S.skip[k] then
+        s = nil
+      end
+
       if s and S.skip[k] then
         -- an object stands here; paint its synthesized ground and let the
         -- prebuilt prism quads (appended below) carry the art
@@ -546,8 +570,14 @@ local function runGeometry(map, bodyOnly, masks, sink)
             end
             topTile = S.tileAt[keyOf(tx, row)]
           end
+          -- water's surface, and only water's: the recessed sheet itself,
+          -- never the ground's shoreline bands around it. A cell an object
+          -- stands on took the branch above and paints synthesized GROUND,
+          -- which is right -- a sign at the waterline stands on a plot, not
+          -- on the pond.
           topQuad(x0, z0, h, topTile,
-                  s.art == "upright" and VOLUME_TOP_SHADE or 1)
+                  s.art == "upright" and VOLUME_TOP_SHADE or 1,
+                  (s.class == "water") and waterPush or nil)
         end
 
         -- sides: 8px bands wherever the neighbour is lower. Band k spans
@@ -752,18 +782,34 @@ end
 -- The raw geometry for `map`: (vertex list, triangle index list, quad
 -- count). Synchronous and GPU-free -- the headless suite and the probes
 -- exercise the invariants through this.
-function ChunkMesher.geometry(map, bodyOnly, masks)
+--
+-- `split` lifts the water surface out, as it is lifted out for the
+-- reflective pass, and appends that sink's own three values -- so the suite
+-- can check the same separation the GPU path relies on without a GPU.
+-- Without it the water is in the first list, which is what every existing
+-- caller reads.
+function ChunkMesher.geometry(map, bodyOnly, masks, split)
   local sink = newTableSink()
-  runGeometry(map, bodyOnly, masks, sink)
-  return sink.results()
+  local waterSink = split and newTableSink() or nil
+  runGeometry(map, bodyOnly, masks, sink, waterSink)
+  if not waterSink then return sink.results() end
+  local v, i, n = sink.results()
+  local wv, wi, wn = waterSink.results()
+  return v, i, n, wv, wi, wn
 end
 
 -- Build the mesh for `map` synchronously. Returns nil when there is
 -- nothing to draw or meshes are unavailable (headless).
-function ChunkMesher.build(map, bodyOnly, masks)
+--
+-- `split` asks for the water surface as a SECOND mesh, returned after the
+-- terrain one -- the shape the reflective pass needs (see Water). Without
+-- it the water is inside the terrain mesh, which is the historical
+-- contract and what every other caller still wants.
+function ChunkMesher.build(map, bodyOnly, masks, split)
   local sink = newSink()
-  runGeometry(map, bodyOnly, masks, sink)
-  return sink.finish()
+  local waterSink = split and newSink() or nil
+  runGeometry(map, bodyOnly, masks, sink, waterSink)
+  return sink.finish(), waterSink and waterSink.finish() or nil
 end
 
 local function quadsMesh(quads)
@@ -801,6 +847,43 @@ local function buildFlowerMesh(map)
   return quadsMesh(Structures.forMap(map).flowerQuads)
 end
 
+-- Authored FIGURES (a person drawn into furniture) as one mesh each, in
+-- the card's own local space -- because each one is placed by its own
+-- matrix at draw time, leaned back by the camera pitch exactly like a
+-- character card (VoxelScene). A figure baked into the terrain mesh could
+-- not lean, and a shared mesh could not carry per-figure placement.
+--
+-- A list, not a mesh: `{ mesh, wx, wz, y, w }` per figure. Maps have one
+-- or none, so the loop that draws them is shorter than the terrain's.
+-- `w` is the card's own width in its local space (its quads start at
+-- x = 0), measured here because the first-person pass yaws a card about
+-- its middle -- a card yawed about its left edge swings off its seat.
+local function buildFigureMeshes(map)
+  local out = {}
+  for _, f in ipairs(Structures.forMap(map).figures or {}) do
+    local mesh = quadsMesh(f.quads)
+    if mesh then
+      local w = 0
+      for _, q in ipairs(f.quads) do
+        for c = 1, 4 do
+          local x = q[c] and q[c][1]
+          if x and x > w then w = x end
+        end
+      end
+      out[#out + 1] = { mesh = mesh, wx = f.wx, wz = f.wz, y = f.y, w = w }
+    end
+  end
+  return out
+end
+
+-- Figure lists hold their meshes one level down, so the generic slot
+-- release cannot reach them.
+local function releaseFigures(list)
+  for _, f in ipairs(type(list) == "table" and list or {}) do
+    if f.mesh and f.mesh.release then pcall(f.mesh.release, f.mesh) end
+  end
+end
+
 -- Replace a cached slot, releasing whatever mesh it held.
 local function swapSlot(c, slot, mesh)
   local old = c[slot]
@@ -819,12 +902,23 @@ local function entry(id)
   return c
 end
 
+-- The water surface that came out of a terrain slot's own build. Kept
+-- beside it rather than in a slot of its own because the two are ONE
+-- answer: a full mesh drawn beside a body build's water would draw the
+-- ring's ponds twice and miss the body's own.
+local function waterSlot(slot)
+  return slot .. "Water"
+end
+
 local function releaseEntry(c)
-  for _, slot in ipairs({ "full", "body", "grass", "flowers" }) do
+  for _, slot in ipairs({ "full", "body", "fullWater", "bodyWater",
+                          "grass", "flowers" }) do
     local mesh = c[slot]
     if mesh and mesh.release then pcall(mesh.release, mesh) end
     c[slot] = nil
   end
+  releaseFigures(c.figures)
+  c.figures = nil
   c.stale = nil
 end
 
@@ -863,28 +957,37 @@ end
 local function runJob(job)
   local map = job.map
   local c = entry(job.id)
-  if c.grass == nil or c.flowers == nil or (c.stale and c.stale.aux) then
+  if c.grass == nil or c.flowers == nil or c.figures == nil
+     or (c.stale and c.stale.aux) then
     local okG, grass = pcall(buildGrassMesh, map)
     local okF, flowers = pcall(buildFlowerMesh, map)
+    local okX, figures = pcall(buildFigureMeshes, map)
     if (gen[job.id] or 0) ~= job.gen then
       if okG and grass and grass.release then pcall(grass.release, grass) end
       if okF and flowers and flowers.release then
         pcall(flowers.release, flowers)
       end
+      if okX then releaseFigures(figures) end
       return
     end
     swapSlot(c, "grass", (okG and grass) or false)
     swapSlot(c, "flowers", (okF and flowers) or false)
+    releaseFigures(c.figures)
+    c.figures = (okX and figures) or false
     if c.stale then c.stale.aux = nil end
   end
   local sink = newSink()
-  runGeometry(map, job.slot == "body", job.masks, sink)
+  local waterSink = newSink()
+  runGeometry(map, job.slot == "body", job.masks, sink, waterSink)
   local mesh = sink.finish()
+  local water = waterSink.finish()
   if (gen[job.id] or 0) ~= job.gen then
     if mesh and mesh.release then pcall(mesh.release, mesh) end
+    if water and water.release then pcall(water.release, water) end
     return
   end
   swapSlot(c, job.slot, mesh or false)
+  swapSlot(c, waterSlot(job.slot), water or false)
   if c.stale then
     c.stale[job.slot] = nil
     if not (c.stale.full or c.stale.body or c.stale.aux) then
@@ -986,12 +1089,14 @@ function ChunkMesher.get(map, bodyOnly, masks)
     if c.stale then c.stale.aux = nil end
   end
   if c[slot] == nil or (c.stale and c.stale[slot]) then
-    local ok, mesh = pcall(ChunkMesher.build, map, bodyOnly, masks)
+    local ok, mesh, water = pcall(ChunkMesher.build, map, bodyOnly, masks,
+                                  true)
     if not ok then
       print("[warn] voxel mesh build failed for " .. tostring(map.id)
             .. ": " .. tostring(mesh))
     end
     swapSlot(c, slot, (ok and mesh) or false)
+    swapSlot(c, waterSlot(slot), (ok and water) or false)
     if c.stale then
       c.stale[slot] = nil
       if not (c.stale.full or c.stale.body or c.stale.aux) then
@@ -1012,6 +1117,21 @@ function ChunkMesher.peek(map, bodyOnly)
   return mesh or nil
 end
 
+-- A slot's terrain mesh AND the water surface lifted out of it, as one
+-- answer. Never builds, like peek.
+--
+-- Both or neither, always from the SAME slot: the water was cut out of that
+-- exact geometry, so pairing a full mesh with a body build's water would
+-- draw the border ring's ponds twice and leave the body's as holes. Callers
+-- that fall back from one variant to the other fall back through this, so
+-- there is nowhere for the two to be chosen separately.
+function ChunkMesher.pair(map, bodyOnly)
+  local c = cache[map.id]
+  if not c then return nil, nil end
+  local slot = bodyOnly and "body" or "full"
+  return c[slot] or nil, c[waterSlot(slot)] or nil
+end
+
 function ChunkMesher.grass(map)
   local c = cache[map.id]
   return c and c.grass or nil
@@ -1022,6 +1142,14 @@ function ChunkMesher.flowers(map)
   return c and c.flowers or nil
 end
 
+-- Authored figures as `{ mesh, wx, wz, y, w }` records -- each placed by
+-- its own leaning matrix at draw time, so they cannot share one mesh.
+function ChunkMesher.figures(map)
+  local c = cache[map.id]
+  local list = c and c.figures
+  return (type(list) == "table") and list or nil
+end
+
 -- Rebuild a map's meshes IN PLACE: the stale meshes keep drawing while
 -- replacements cook, and each slot swaps as its build lands. This is
 -- the block-edit path (a cut tree, a door stamp) -- invalidate() drops

lib/DayNight.lua

@@ -0,0 +1,499 @@
+-- Voxel world mode: the day/night cycle -- one clock, and everything the
+-- frame asks it.
+--
+-- THE CLOCK is twenty minutes around: ten of day, ten of night. The DAYTIME
+-- row either PINS it -- DAY, NIGHT, DUSK and DAWN are fixed times on that
+-- dial, not separate looks -- or lets it run (CYCLE), in which case the pin
+-- the player left is where the cycle picks up. Everything below is a pure
+-- function of the clock, so the pinned settings and the running cycle can
+-- never drift apart: DUSK is simply the cycle stopped at sunset.
+--
+-- THE SUN's noon is this mod's existing sun, exactly: shear (-0.85, -0.55),
+-- hanging in the southeast about 45 degrees up. That is the DAY setting and
+-- the default, so a player who never touches the row sees the mod they
+-- already had. From there the arc swings NORTH at both ends -- rising 70
+-- degrees north of east, setting the mirror of that -- because the camera
+-- looks north and the northern sky is the only sky it ever frames: a sun
+-- that rose due east would light the world for ten minutes without once
+-- being seen. Swung north, the disc stands in frame through dawn and dusk
+-- (the hours worth looking at) and passes overhead-behind-the-camera
+-- through midday, which is where a noon sun belongs.
+--
+-- THE MOON arcs entirely through the northern sky -- rising northeast, due
+-- north at mid-night, setting northwest -- so it hangs over the diorama all
+-- night and the pinned NIGHT setting puts it dead centre. Its shadows fall
+-- softly south, away from it, at about two-thirds the sun's weight.
+--
+-- SHADOWS are the shear the light throws: direction opposite the body's
+-- bearing, length its elevation's cotangent (clamped -- a rising sun throws
+-- a long shadow, not an infinite one), strength fading to nothing over the
+-- last twelve degrees before the horizon so the handoff between sun and
+-- moon is a soft gap rather than a snap. Face shading (Voxel3D.FACE_SHADE)
+-- deliberately stays the noon bake: it is a subtle angle term baked into
+-- every mesh, and rebaking the world's geometry per phase buys less than
+-- the cast shadows, the sky and the tint already say.
+--
+-- OUTDOOR ONLY. Indoors keeps the noon rig, the untinted world and no sky:
+-- a cave at midnight is exactly as dark as a cave at noon, which is what a
+-- room with no windows looks like. Map.isOutdoor is the same test the sky
+-- already rests on; the caller passes its answer in (applyRig/tint).
+--
+-- Persistence: the running cycle's clock is written into the mod's own
+-- save-file bucket (save.modData.DRAMATIC_SHAPE, via mod.save) on the
+-- engine's save.writing event, and read back on save.loaded/created. A save
+-- with no clock in it starts at noon.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local ModSetting = V.require("ModSetting")
+local PaletteFX = require("src.render.PaletteFX")
+
+local DayNight = {}
+
+-- ------- the dial
+
+DayNight.CYCLE = 1200         -- seconds around the whole dial
+DayNight.DAY_LEN = 600        -- the sun's half; the moon has the rest
+DayNight.BLEND = 75           -- seconds of palette blend either side of a twilight
+
+-- where the pinned settings stop the clock
+DayNight.T = { dawn = 0, day = 300, dusk = 600, night = 900 }
+
+DayNight.KEY = "daytime"
+DayNight.LABEL = "DAYTIME"
+
+-- "sync" first: an unset or unreadable value follows the machine's own
+-- clock, per the row's contract (ModSetting values[1] is the default) --
+-- and forceSync below reaches for it by the same position.
+DayNight.setting = ModSetting.new(DayNight.KEY, DayNight.LABEL,
+                                  { "sync", "day", "night", "dusk",
+                                    "dawn", "cycle" },
+                                  { "SYNC", "DAY", "NIGHT", "DUSK",
+                                    "DAWN", "CYCLE" })
+
+-- The one writer for the FULL pin. While VOXEL sits on FULL the DAYTIME
+-- row is off the menu with the rest of the rows the preset owns, and the
+-- value is held HERE at SYNC -- the diorama preset's sky follows the clock
+-- on the wall, whatever was chosen before. Called from every path that can
+-- arrive at or act under FULL (main.lua: the preset itself, the rows hook,
+-- the manager's options_changed), mirroring OverworldBattle.forceOG.
+function DayNight.forceSync(game)
+  if DayNight.setting:get() ~= "sync" then
+    DayNight.setting:setIndex(1, game)
+  end
+end
+
+DayNight.clock = DayNight.T.day     -- the running cycle's own position
+
+-- ------- the two arcs
+--
+-- Bearings in DEGREES from east toward south (the world's +X is east, +Z
+-- south), elevations in degrees up from the ground plane.
+
+-- noon IS the existing sun: shear (-0.85, -0.55) hangs it at
+-- atan2(0.55, 0.85) south of east, atan(1/hypot) = 44.65 degrees up
+local NOON_KX, NOON_KZ = -0.85, -0.55
+local TH_NOON = math.deg(math.atan2(-NOON_KZ, -NOON_KX))
+local EL_NOON = math.deg(math.atan(1 / math.sqrt(NOON_KX * NOON_KX
+                                                 + NOON_KZ * NOON_KZ)))
+
+local TH_RISE, TH_SET = -70, 250            -- north of east / north of west
+local TH_MRISE, TH_MMID, TH_MSET = -20, -90, -160
+local EL_MOON = 40
+
+DayNight.K_MAX = 2.0          -- shear clamp: a shadow at most twice its height
+DayNight.ALPHA_SUN = 0.40     -- the existing midday shadow weight
+DayNight.ALPHA_MOON = 0.26    -- moonlight is a softer press
+DayNight.FADE_DEG = 12        -- shadows fade out over the last degrees of a rise/set
+
+-- disc PLACEMENT only: the true elevation would put the noon sun far above
+-- any frame, so the arc the discs ride is squashed toward the horizon. The
+-- shadows always use the true elevation.
+DayNight.ELEV_SQUASH = 0.14
+
+-- three-point arc: a at s=0, b at s=0.5, c at s=1
+local function arc(a, b, c, s)
+  if s < 0.5 then return a + (b - a) * 2 * s end
+  return b + (c - b) * (2 * s - 1)
+end
+
+-- The body lighting the world at clock `t`: bearing and elevation in
+-- degrees, and whether it is the moon. The t == DAY_LEN boundary belongs to
+-- the SUN, so the pinned DUSK setting is the sun half-set in the northwest,
+-- not the moon rising.
+function DayNight.bodyAt(t)
+  t = t % DayNight.CYCLE
+  if t <= DayNight.DAY_LEN then
+    local s = t / DayNight.DAY_LEN
+    return arc(TH_RISE, TH_NOON, TH_SET, s),
+           EL_NOON * math.sin(math.pi * s), false
+  end
+  local s = (t - DayNight.DAY_LEN) / (DayNight.CYCLE - DayNight.DAY_LEN)
+  return arc(TH_MRISE, TH_MMID, TH_MSET, s),
+         EL_MOON * math.sin(math.pi * s), true
+end
+
+-- The shadow shear that body throws: drift per pixel of height, opposite
+-- the bearing, cot(elevation) long, clamped.
+function DayNight.shearAt(t)
+  local th, el, moon = DayNight.bodyAt(t)
+  if el < 0.5 then el = 0.5 end
+  local k = math.min(DayNight.K_MAX, 1 / math.tan(math.rad(el)))
+  return -math.cos(math.rad(th)) * k, -math.sin(math.rad(th)) * k, moon
+end
+
+-- How much shadow the light can press right now, 0..1 of the body's own
+-- weight: full up high, gone at the horizon, so sunset hands off to
+-- moonrise through a soft shadowless gap instead of snapping.
+function DayNight.strengthAt(t)
+  local _, el = DayNight.bodyAt(t)
+  local s = el / DayNight.FADE_DEG
+  if s < 0 then return 0 end
+  return s < 1 and s or 1
+end
+
+-- ------- the palettes
+--
+-- Sky bands, lightest FIRST (the horizon end), exactly the shape Sky.bands
+-- reads. Six bands, not four: twilight is the whole show here, and six rungs
+-- of it is what keeps a sunset reading as a gradient rather than as stripes.
+-- Every channel is a multiple of 8 -- the 5-bit GBC lattice -- including
+-- after blending, which re-quantises onto it.
+-- `golden` and `violet` are not pins -- they are WAYPOINTS the blends pass
+-- through. Day's blue horizon and dusk's gold one are near-complements, and
+-- a straight lerp between complements bottoms out in grey: mid-transition
+-- the whole sky went the colour of dishwater, and gold-to-navy did the same
+-- on the far side of sunset. So the evening bends through a golden hour
+-- (horizon warming, zenith still blue -- late afternoon), and both edges of
+-- the night bend through a violet civil twilight (rose horizon under a
+-- violet sky -- the real colour of that half hour).
+DayNight.PALETTES = {
+  day = { { 184, 216, 248 }, { 144, 192, 248 }, { 104, 160, 240 },
+          { 72, 128, 224 }, { 48, 96, 200 }, { 40, 72, 168 } },
+  golden = { { 248, 216, 144 }, { 232, 184, 136 }, { 176, 152, 168 },
+             { 120, 128, 192 }, { 80, 104, 184 }, { 56, 80, 152 } },
+  dawn = { { 248, 216, 152 }, { 248, 176, 136 }, { 232, 136, 144 },
+           { 176, 104, 168 }, { 112, 80, 168 }, { 64, 64, 136 } },
+  dusk = { { 248, 200, 112 }, { 248, 152, 96 }, { 232, 104, 96 },
+           { 184, 80, 136 }, { 120, 64, 152 }, { 56, 48, 120 } },
+  violet = { { 200, 136, 160 }, { 152, 104, 160 }, { 112, 80, 152 },
+             { 72, 56, 128 }, { 40, 40, 96 }, { 16, 24, 64 } },
+  night = { { 88, 104, 160 }, { 64, 80, 136 }, { 48, 56, 112 },
+            { 32, 40, 88 }, { 16, 24, 64 }, { 8, 8, 40 } },
+}
+
+-- what the world's own colours are multiplied by, per phase (0..255)
+DayNight.TINTS = {
+  day = { 255, 255, 255 },
+  golden = { 255, 232, 208 },
+  dawn = { 255, 216, 192 },
+  dusk = { 255, 192, 168 },
+  violet = { 184, 160, 200 },
+  night = { 120, 136, 192 },
+}
+
+-- the twilight glow around the low sun, and the discs' own four-shade
+-- palettes (lightest first, so a display mode transforms them like any
+-- other palette)
+DayNight.GLOWS = { dawn = { 248, 232, 176 }, dusk = { 248, 224, 168 } }
+DayNight.SUN_COLORS = { { 248, 240, 200 }, { 248, 208, 96 },
+                        { 248, 144, 80 }, { 216, 96, 64 } }
+DayNight.MOON_COLORS = { { 240, 244, 248 }, { 224, 232, 240 },
+                         { 168, 184, 208 }, { 120, 136, 168 } }
+
+-- The dial as keyframes: a repeated name is a plateau, a change is a
+-- BLEND-wide ramp. Laid out so DUSK and DAWN proper land exactly on their
+-- pinned times, and so the evening approaches dusk THROUGH the golden-hour
+-- waypoint rather than straight across the grey between blue and gold. The
+-- morning side needs no waypoint of its own: dawn's pinks into day's blues
+-- share a family and blend clean.
+local DIAL
+local function dial()
+  if DIAL then return DIAL end
+  local B, D, C = DayNight.BLEND, DayNight.DAY_LEN, DayNight.CYCLE
+  DIAL = {
+    { 0, "dawn" }, { B, "day" },
+    { D - 2 * B, "day" }, { D - B, "golden" }, { D, "dusk" },
+    { D + B / 2, "violet" }, { D + B, "night" },
+    { C - B, "night" }, { C - B / 2, "violet" }, { C, "dawn" },
+  }
+  return DIAL
+end
+
+-- Phase weights at clock `t`, off the dial above.
+function DayNight.mix(t)
+  t = t % DayNight.CYCLE
+  local d = dial()
+  for i = 1, #d - 1 do
+    local a, b = d[i], d[i + 1]
+    if t >= a[1] and t < b[1] then
+      if a[2] == b[2] then return { [a[2]] = 1 } end
+      local u = (t - a[1]) / (b[1] - a[1])
+      return { [a[2]] = 1 - u, [b[2]] = u }
+    end
+  end
+  return { dawn = 1 }
+end
+
+-- back onto the 5-bit lattice after any blend
+local function q8(v)
+  v = math.floor(v / 8 + 0.5) * 8
+  if v < 0 then return 0 end
+  return v > 248 and 248 or v
+end
+
+local function blend3(key, mix, fallback)
+  local r, g, b = 0, 0, 0
+  for name, w in pairs(mix) do
+    local c = key[name] or fallback
+    r = r + c[1] * w
+    g = g + c[2] * w
+    b = b + c[3] * w
+  end
+  return { q8(r), q8(g), q8(b) }
+end
+
+-- The sky palette for clock `t`, blended between the phase palettes and
+-- re-quantised to the lattice. Memoised per whole second: the answer only
+-- moves as the cycle runs, and the cycle moves it slowly.
+local palCache = { key = nil, pal = nil }
+
+function DayNight.palette(t)
+  t = t or DayNight.time()
+  local key = math.floor(t % DayNight.CYCLE)
+  if palCache.key == key then return palCache.pal end
+  local mix = DayNight.mix(t)
+  local pal = {}
+  for i = 1, #DayNight.PALETTES.day do
+    local r, g, b = 0, 0, 0
+    for name, w in pairs(mix) do
+      local c = DayNight.PALETTES[name][i]
+      r = r + c[1] * w
+      g = g + c[2] * w
+      b = b + c[3] * w
+    end
+    pal[i] = { q8(r), q8(g), q8(b) }
+  end
+  palCache.key, palCache.pal = key, pal
+  return pal
+end
+
+-- The world tint for clock `t`, {r, g, b} in 0..1. Neutral indoors -- the
+-- caller answers for where it is standing (see the header).
+local tintCache = { key = nil, tint = nil }
+local NEUTRAL = { 1, 1, 1 }
+
+function DayNight.tint(outdoor, t)
+  if not outdoor then return NEUTRAL end
+  t = t or DayNight.time()
+  local key = math.floor(t % DayNight.CYCLE)
+  if tintCache.key ~= key then
+    -- NOT re-quantised: this is a light level the shader multiplies by, not
+    -- a palette colour, and the lattice's 248 ceiling would make even noon
+    -- fractionally dim
+    local mix = DayNight.mix(t)
+    local r, g, b = 0, 0, 0
+    for name, w in pairs(mix) do
+      local c = DayNight.TINTS[name] or DayNight.TINTS.day
+      r = r + c[1] * w
+      g = g + c[2] * w
+      b = b + c[3] * w
+    end
+    tintCache.key = key
+    tintCache.tint = { r / 255, g / 255, b / 255 }
+  end
+  return tintCache.tint
+end
+
+-- The twilight glow: how strongly (0..1) and in what colour the sky warms
+-- around the low sun. Only the SUN glows -- a moonrise is silver, not gold.
+function DayNight.glow(t)
+  t = t or DayNight.time()
+  local _, _, moon = DayNight.bodyAt(t)
+  if moon then return 0, nil end
+  local mix = DayNight.mix(t)
+  local amt = (mix.dawn or 0) + (mix.dusk or 0)
+  if amt <= 0 then return 0, nil end
+  return amt, blend3(DayNight.GLOWS, mix, DayNight.GLOWS.dusk)
+end
+
+-- ------- the clock itself
+
+local lastMode = nil
+
+local function mode()
+  return DayNight.setting:get() or "day"
+end
+
+-- Where SYNC reads the real clock: local hours, 0..24 with the minutes as
+-- fraction. A named seam rather than a bare os.date call, so the suite can
+-- hand it a fixed hour.
+function DayNight.hours()
+  local d = os.date("*t")
+  return d.hour + d.min / 60 + d.sec / 3600
+end
+
+-- SYNC: the machine's own time of day laid onto the dial. Local noon is
+-- the DAY pin, midnight the NIGHT pin, six and eighteen the twilights --
+-- an hour of the real day is fifty seconds of dial, and Kanto's evening
+-- falls when the player's does.
+function DayNight.syncTime()
+  return ((DayNight.hours() - 6) * (DayNight.CYCLE / 24)) % DayNight.CYCLE
+end
+
+-- The effective time: the pin, the running clock under CYCLE, or the wall
+-- clock under SYNC.
+function DayNight.time()
+  local m = mode()
+  if m == "cycle" then return DayNight.clock end
+  if m == "sync" then return DayNight.syncTime() end
+  return DayNight.T[m] or DayNight.T.day
+end
+
+-- Advance the cycle. Runs every frame from the voxel pipeline's update hook
+-- (which ticks through battles and menus too, so night falls during a long
+-- fight exactly as it does on a walk). Stepping ONTO cycle picks up from
+-- the pin the player was just looking at: DUSK then CYCLE rolls on into
+-- night rather than teleporting the sky.
+function DayNight.update(dt)
+  local m = mode()
+  if m ~= lastMode then
+    if m == "cycle" then
+      -- from a pin, its time; from SYNC, wherever the real sky already was
+      DayNight.clock = DayNight.T[lastMode]
+                       or (lastMode == "sync" and DayNight.syncTime())
+                       or DayNight.clock
+    end
+    lastMode = m
+  end
+  if m == "cycle" and dt and dt > 0 then
+    DayNight.clock = (DayNight.clock + dt) % DayNight.CYCLE
+  end
+end
+
+-- The clock the RIG runs on: quantised, so the shadow map redraws a few
+-- times a minute as the sun crawls rather than every frame.
+DayNight.STEP = 2
+
+function DayNight.rigTime()
+  local t = DayNight.time()
+  return math.floor(t / DayNight.STEP) * DayNight.STEP
+end
+
+-- ------- what the frame reads
+
+-- Point the shared light rig at the clock -- or at noon, indoors. This
+-- writes the same fields everything already reads (ShadowMap.KX/KZ for the
+-- sun pass and its frustum, Voxel3D.SHADOW_* for the decal fallback and the
+-- sunDark uniform), so no draw path changes to follow the sun; they follow
+-- the rig, and the rig follows the clock.
+function DayNight.applyRig(outdoor)
+  local ShadowMap = V.require("ShadowMap")
+  local Voxel3D = V.require("Voxel3D")
+  local t = outdoor and DayNight.rigTime() or DayNight.T.day
+  local kx, kz, moon = DayNight.shearAt(t)
+  ShadowMap.KX, ShadowMap.KZ = kx, kz
+  Voxel3D.SHADOW_KX, Voxel3D.SHADOW_KZ = kx, kz
+  local base = moon and DayNight.ALPHA_MOON or DayNight.ALPHA_SUN
+  Voxel3D.SHADOW_ALPHA = base * DayNight.strengthAt(t)
+  return t
+end
+
+-- How much of a pass's OWN shadow weight the hour leaves it, 0..1 -- for a
+-- caller that sets its own alpha (the battle arena) and should still lose
+-- its shadows to a sunset.
+function DayNight.shadowScale(outdoor, t)
+  if not outdoor then return 1 end
+  t = t or DayNight.rigTime()
+  local _, _, moon = DayNight.bodyAt(t)
+  local s = DayNight.strengthAt(t)
+  return moon and s * (DayNight.ALPHA_MOON / DayNight.ALPHA_SUN) or s
+end
+
+-- The disc to hang in the sky, or nil when the body is set or behind the
+-- camera's half of the sky. Returns a direction for the PLACEMENT arc --
+-- true bearing, squashed elevation (see ELEV_SQUASH) -- plus which body it
+-- is; the caller projects it through its own camera.
+function DayNight.body(t)
+  t = t or DayNight.time()
+  local th, el, moon = DayNight.bodyAt(t)
+  if el < -2 then return nil end
+  local e = math.rad(el * DayNight.ELEV_SQUASH)
+  local b = math.rad(th)
+  return {
+    dx = math.cos(b) * math.cos(e),
+    dy = math.sin(e),
+    dz = math.sin(b) * math.cos(e),
+    moon = moon,
+  }
+end
+
+-- Maps under a CANOPY: not outdoor -- there is no sky to paint and no sun
+-- or moon to see, so the shadow rig stays the mod's fixed noon light,
+-- which is all that ever filtered through the leaves -- but not a sealed
+-- room either: night still FALLS in them. Of everything the clock does,
+-- exactly one thing reaches a canopy map: the hour's tint.
+DayNight.CANOPY = { VIRIDIAN_FOREST = true }
+
+function DayNight.isCanopy(map)
+  return (map and map.id and DayNight.CANOPY[map.id]) and true or false
+end
+
+-- How lit the WINDOWS are, 0..1 -- the lamps behind the glass, not the sky.
+-- They come on through dusk (a lit window against a sunset is half the point
+-- of having either), burn all night, and are mostly out again by dawn:
+-- people wake before it is bright, they do not read at sunrise.
+local LAMPS = { night = 1, violet = 1, dusk = 0.7, dawn = 0.25 }
+
+function DayNight.windowLight(t)
+  local mix = DayNight.mix(t or DayNight.time())
+  local lit = 0
+  for name, w in pairs(mix) do
+    lit = lit + (LAMPS[name] or 0) * w
+  end
+  return lit
+end
+
+-- The period name for the engine's world.tod hook (map.palette ctx.tod,
+-- music.select): the dominant phase, in the vocabulary day/night mods use.
+local TOD = { day = "DAY", golden = "DAY", night = "NIGHT",
+              violet = "NIGHT", dawn = "MORNING", dusk = "EVENING" }
+
+function DayNight.tod(t)
+  local mix = DayNight.mix(t or DayNight.time())
+  local best, bestW = "day", -1
+  for name, w in pairs(mix) do
+    if w > bestW then best, bestW = name, w end
+  end
+  return TOD[best] or "DAY"
+end
+
+-- ------- persistence
+--
+-- The clock rides the SAVE SLOT, not the options file: what time it is in
+-- Kanto is a fact about that journey, like where the player is standing.
+-- mod.save is the loader's per-mod bucket in save.modData, which persists
+-- with the slot on its own -- writing the value is all there is to do.
+
+DayNight.SAVE_KEY = "clock"
+
+function DayNight.store()
+  local saveApi = V.mod and V.mod.save
+  if not (saveApi and saveApi.set) then return end
+  pcall(saveApi.set, saveApi, DayNight.SAVE_KEY, DayNight.clock)
+end
+
+function DayNight.restore()
+  local saveApi = V.mod and V.mod.save
+  local stored = nil
+  if saveApi and saveApi.get then
+    local ok, got = pcall(saveApi.get, saveApi, DayNight.SAVE_KEY)
+    if ok then stored = got end
+  end
+  -- no time set: it is day (the requirement, verbatim)
+  DayNight.clock = type(stored) == "number"
+                   and stored % DayNight.CYCLE or DayNight.T.day
+end
+
+return DayNight

lib/DayTint.lua

@@ -0,0 +1,169 @@
+-- The hour's light on the FLAT world.
+--
+-- The clock already reaches everything the 3D pass draws: VoxelScene and
+-- BattleScene multiply the whole scene by DayNight.tint, so walking around a
+-- route at dusk warms the diorama and midnight turns it blue. Switch voxel
+-- mode off and none of that happens -- the tint is a uniform in a shader the
+-- flat tile path never runs -- so the same evening that fell on the diorama
+-- left the 2D world at permanent noon. One clock, two worlds, one of them
+-- ignoring it.
+--
+-- So the flat composite gets the same multiply, painted as one rectangle.
+--
+-- ------- WHERE, which is the only difficult part
+--
+-- Not on the world canvas. In a colorized mode that canvas is grayscale art
+-- and the blit that puts it on screen runs it through the palette shader,
+-- which classifies each pixel into a shade BY ITS RED CHANNEL. Multiply a
+-- night blue over it first and every shade lands in the wrong bucket -- the
+-- world would not darken, it would change colour into whatever the palette
+-- said the wrong bucket was.
+--
+-- So it goes on AFTER that pass, on the composited world. And not after the
+-- whole frame either: the UI blit is next, and the dialog boxes, the menus and
+-- the HUD are paper held up in front of the world rather than part of it --
+-- the same reason the tilt-shift blur is a worldPresent and not a present.
+--
+-- Which leaves one instant: between the world blit and the UI blit, inside
+-- Renderer:endFrame. There is no seam there -- worldPresent, the engine's own
+-- hook for exactly this, only runs when a PIPELINE produced the world, which
+-- in flat mode is the one thing that did not happen. So endFrame is wrapped
+-- and the UI canvas's own draw call is watched for: `blit` passes the canvas
+-- as the first argument, so the first draw of Renderer.canvas IS the boundary,
+-- by identity rather than by counting or guessing.
+--
+-- The shader and scissor that call arrives under belong to the UI blit already
+-- in progress, so both are put aside for the rectangle and handed straight
+-- back -- otherwise the tint would be palette-remapped and clipped to a zone.
+--
+-- ------- WHEN
+--
+-- Outdoors, on the flat path, when the hour is not neutral. Each of those is
+-- load-bearing:
+--
+--   the flat path   a pipeline that rendered the world already applied the
+--                   tint inside its own shader; painting it again would apply
+--                   the hour twice. worldOverride is exactly "a pipeline drew
+--                   this frame".
+--   outdoors        a room has no sky to take its light from, which is the
+--                   same answer DayNight.tint gives on its own and the same
+--                   one applyRig gives the sun.
+--   not neutral     midday is a multiply by white. Skipped rather than drawn,
+--                   so a game with the clock at DAY issues not one extra call.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local DayNight = V.require("DayNight")
+
+local DayTint = {}
+
+-- Below this the tint is close enough to white that the rectangle would not
+-- change a pixel, and the frame is left exactly as it was.
+DayTint.NEUTRAL = 0.999
+
+local function outdoorNow()
+  local ok, Game = pcall(require, "src.core.Game")
+  if not ok then return false end
+  local ow = Game and Game.overworld
+  local map = ow and ow.map
+  if not map then return false end
+  local okMap, Map = pcall(require, "src.world.Map")
+  if not okMap then return false end
+  local outdoor = map.def and Map.isOutdoor(map.def) or false
+  -- a canopy floor takes the hour's colour and nothing else of it, exactly as
+  -- it does in the 3D pass (BattleScene, VoxelScene)
+  return outdoor or DayNight.isCanopy(map)
+end
+
+-- The colour this frame's world should be multiplied by, or nil to leave the
+-- frame alone.
+function DayTint.forFrame(renderer)
+  if not renderer then return nil end
+  if renderer.worldOverride then return nil end   -- a pipeline drew, and tinted
+  if not renderer.worldActive then return nil end -- no world on screen at all
+  if not outdoorNow() then return nil end
+  local tint = DayNight.tint(true)
+  if not tint then return nil end
+  local r, g, b = tint[1] or 1, tint[2] or 1, tint[3] or 1
+  if r > DayTint.NEUTRAL and g > DayTint.NEUTRAL and b > DayTint.NEUTRAL then
+    return nil
+  end
+  return r, g, b
+end
+
+-- One rectangle over the window, multiplied into whatever is under it.
+--
+-- The whole window rather than the world's own rect, which is what the
+-- engine's warp fade does from the same place and for the same reason: the
+-- border fill, the letterbox bars and the world are all "the world" as far as
+-- the hour is concerned, and black multiplied by anything is still black.
+-- Every read of the graphics state is optional, because a headless driver
+-- ships some of these and not others -- the same reason TerrainAtlas reads the
+-- engine's seams guarded. What cannot be read cannot be put back either, and a
+-- missing accessor must cost the tint rather than the frame.
+local function saved(name, ...)
+  local fn = love.graphics[name]
+  if not fn then return nil end
+  local ok, a, b, c, d = pcall(fn, ...)
+  if not ok then return nil end
+  return a, b, c, d
+end
+
+function DayTint.paint(r, g, b)
+  local gfx = love.graphics
+  local shader = saved("getShader")
+  local sx, sy, sw, sh = saved("getScissor")
+  local blend, alpha = saved("getBlendMode")
+  local pr, pg, pb, pa = saved("getColor")
+  local w, h = gfx.getDimensions()
+
+  if gfx.setShader then gfx.setShader() end
+  if gfx.setScissor then gfx.setScissor() end
+  gfx.setBlendMode("multiply", "premultiplied")
+  gfx.setColor(r, g, b, 1)
+  gfx.rectangle("fill", 0, 0, w, h)
+
+  gfx.setBlendMode(blend or "alpha", alpha)
+  gfx.setColor(pr or 1, pg or 1, pb or 1, pa or 1)
+  if gfx.setScissor then
+    if sx then gfx.setScissor(sx, sy, sw, sh) else gfx.setScissor() end
+  end
+  if shader and gfx.setShader then gfx.setShader(shader) end
+end
+
+function DayTint.install()
+  local Renderer = require("src.render.Renderer")
+  if Renderer.dramaticShapeTintHook then return end
+  local inner = Renderer.endFrame
+
+  function Renderer:endFrame(zones, worldZones)
+    local r, g, b = DayTint.forFrame(self)
+    if not r then return inner(self, zones, worldZones) end
+
+    local gfx = love.graphics
+    local draw = gfx.draw
+    local ui = self.canvas
+    local painted = false
+    gfx.draw = function(tex, ...)
+      -- the UI canvas reaching the screen: the world is finished, the paper
+      -- in front of it has not started. Restored FIRST so the rectangle's own
+      -- drawing cannot re-enter this, and so a UI blit that draws one quad per
+      -- SGB zone only triggers it once.
+      if not painted and tex == ui then
+        painted = true
+        gfx.draw = draw
+        DayTint.paint(r, g, b)
+      end
+      return draw(tex, ...)
+    end
+
+    local ok, err = pcall(inner, self, zones, worldZones)
+    gfx.draw = draw
+    if not ok then error(err, 0) end
+  end
+
+  Renderer.dramaticShapeTintHook = true
+end
+
+return DayTint

lib/Diorama.lua

@@ -0,0 +1,344 @@
+-- The DIORAMA modes: Kanto as a model you can pick up.
+--
+-- STANDARD VR presents whatever rung the player is on -- the orbit rungs
+-- become a tabletop, 1ST stands you inside the world (see lib/VR.lua).
+-- DIORAMA is a different promise, and it is one promise rather than a
+-- ladder: the world is ALWAYS the model on the table, seen from outside,
+-- and what the headset adds is that the model is a THING IN THE ROOM --
+-- grab it, turn it, set it down somewhere else, decide how much of it you
+-- want to be holding.
+--
+-- Two pieces make that read, and this file owns both.
+--
+--   THE VIEWPORT. Everything outside an invisible BOX centred on the view
+--   is simply not drawn -- the Final Fantasy Tactics read, a square slab
+--   of the world sitting in the air rather than a map running off to a
+--   horizon. A square cut with a HARD edge, because a flat world is a
+--   thing with sides and the sides are what say so.
+--
+--   V-CURVE is what changes its shape. With the bend on, the world is not
+--   flat any more -- it is a little globe curling away over its own
+--   horizon -- and a square cut through a globe is a lie about what is
+--   being looked at. So the box becomes a BALL, and its rim becomes a
+--   GRADIENT that dissolves into the sky rather than an edge that
+--   guillotines it. One click of the left stick (which throws V-CURVE --
+--   see lib/VR) swaps between the two readings of the same model.
+--
+--   A staged fight ignores both and cuts a vertical PILLAR about the
+--   arena, which lifts the fight out of the map as a floating disc.
+--
+--   (A BASE was built under all this once -- the ground extruded a tile
+--   deep, cut to the viewport's shape, wearing Mt Moon's cave floor down
+--   its sides -- and it was REMOVED at the user's request. The cut ends at
+--   the ground plane now; don't put a plinth back under it.)
+--
+--   THE GRIP. Squeeze one and the model follows that hand through the
+--   room; squeeze both and it turns with them and the viewport resizes
+--   to whatever you open your hands to. All of it is arithmetic on the
+--   XR-to-world mapping lib/VRRig already had (an anchor, a yaw and a
+--   scale), so nothing about the world's own geometry knows this is
+--   happening.
+--
+-- DIORAMA-MR is the same mode with the background keyed pure green, for
+-- a mixed-reality capture that composites the model into the room the
+-- player is actually standing in.
+--
+-- Nothing here reaches the flat screen: every field is set by lib/VR for
+-- the length of one headset frame and cleared with the session.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Diorama = {}
+
+-- ------- the viewport
+--
+-- The half-size at rest, as a fraction of the view height the flat screen
+-- frames. Sized off the VIEW rather than fixed in world pixels so the zoom
+-- rows keep meaning what they mean -- a zoomed-in rung frames less world
+-- and gets a smaller model, exactly as it frames a smaller picture.
+--
+-- The BOX takes half of it, so the square is exactly the view the standard
+-- rung would have shown, edge to edge. The BALL takes rather more: a ball
+-- inscribed in that square holds noticeably less world (its corners are
+-- the four biggest pieces of it), and the point of the V-CURVE throw is to
+-- see the same model curl, not to lose a quarter of it.
+Diorama.BOX_FRAC = 0.5
+Diorama.BALL_FRAC = 0.62
+
+-- How far the grips may open and close it, as a multiplier on that.
+Diorama.SCALE_MIN = 0.3
+Diorama.SCALE_MAX = 4
+
+-- The rim under V-CURVE, as a fraction of the radius: where the world
+-- starts fading and where it has finished. Wide enough to read as a
+-- dissolve rather than an edge, narrow enough that the middle of the model
+-- is solid. The BOX has no fade at all -- see fadeFor.
+Diorama.FADE_FRAC = 0.16
+
+-- The staged fight's disc: the arena's own half-length plus an apron, in
+-- world pixels (a map cell is 16). The two mons stand three cells apart,
+-- so this is a disc about seven cells across -- the fight, the ground it
+-- is fought on, and nothing else.
+Diorama.ARENA_APRON = 32
+
+-- ------- what the live frame is
+--
+-- All three set by lib/VR for the length of one headset frame, and by
+-- nothing else. `on` is the whole mode's gate; VoxelScene reads it once
+-- per frame and every diorama-shaped thing hangs off that read.
+Diorama.on = false
+Diorama.keyed = false
+Diorama.cull = nil        -- { x, y, z, r, invFade, kind }
+
+-- Chroma green, and PURE green deliberately: a keyer wants the one colour
+-- nothing in the picture can accidentally be, and no palette this mod can
+-- paint the world in reaches 0,255,0.
+Diorama.KEY_COLOR = { 0, 1, 0 }
+
+-- ------- what the grips have done to it
+--
+-- Kept across frames (this is where the model IS, as far as the player is
+-- concerned) and cleared only when the session ends. `offset` is in LOCAL
+-- metres and rides the mapping's anchor, `yaw` turns the mapping, `zoom`
+-- multiplies the viewport's radius.
+Diorama.offset = { 0, 0, 0 }
+Diorama.yaw = 0
+Diorama.zoom = 1
+
+function Diorama.reset()
+  Diorama.on, Diorama.keyed, Diorama.cull = false, false, nil
+  Diorama.offset = { 0, 0, 0 }
+  Diorama.yaw, Diorama.zoom = 0, 1
+  Diorama.release()
+end
+
+-- ------- which way a staged fight lies on the table
+--
+-- The disc's bearing while a battle is up: the player's own hand-turn, with
+-- the ARENA's quarter turn taken back out of it.
+--
+-- An arena may be laid down any of the four ways (BattleArena's `turn`), and
+-- the promise that field makes everywhere else is that turning it changes the
+-- GROUND under the fight and never the fight itself -- the two Pokemon land
+-- on the same marks, seen the same way round. Every other camera keeps that
+-- promise by construction: the flat shot and the standard VR mount are both
+-- built from BattleCam's eye, which turns with the arena, so the composition
+-- follows it round.
+--
+-- This one is not built from that eye. It is a disc of map lifted onto the
+-- table, and its bearing is the arena's bearing in the WORLD -- so a fight
+-- staged on a turned arena arrived on the table lying across the head that
+-- was looking at it, while the same fight on an unturned one faced properly.
+-- Same fight, same composition everywhere else, sideways here.
+--
+-- So the turn comes back out. Subtracted, matching the sign the standard
+-- mount already lands on: its yaw is atan2 of (eye - focus), and rotating
+-- that pair by +turn takes the bearing to (bearing - turn). One rule, two
+-- seats.
+--
+-- The hand-turn stays on top of it, because that is the player moving the
+-- model and is theirs to keep.
+function Diorama.battleYaw(arena)
+  local turn = (arena and arena.turn) or 0
+  if turn == 0 then return Diorama.yaw end
+  local yaw = Diorama.yaw - math.rad(turn)
+  -- kept in (-pi, pi] like the grips leave it, so nothing downstream has to
+  -- care which way round it came
+  return (yaw + math.pi) % (2 * math.pi) - math.pi
+end
+
+-- Open a diorama frame. `mode` is VR.mode()'s answer; anything that is
+-- not a diorama mode closes it.
+function Diorama.begin(mode)
+  Diorama.on = (mode == "diorama" or mode == "diorama-mr")
+  Diorama.keyed = Diorama.on and mode == "diorama-mr"
+  if not Diorama.on then Diorama.cull = nil end
+  return Diorama.on
+end
+
+function Diorama.stop()
+  Diorama.on, Diorama.keyed, Diorama.cull = false, false, nil
+end
+
+-- What the world's background must be cleared to, or nil to leave the sky
+-- alone. Only ever a colour in DIORAMA-MR, and only while a frame is open.
+function Diorama.keyColor()
+  if not (Diorama.on and Diorama.keyed) then return nil end
+  return Diorama.KEY_COLOR
+end
+
+-- ------- the viewport, as the shaders take it
+--
+-- `kind` is the shader's own switch: 0 no cut, 1 the box, 2 the ball, 3
+-- the fight's pillar. `invFade` is one over the fade band in world pixels,
+-- so the rim is a single multiply out there -- and a hard edge is simply a
+-- band under a pixel wide, which costs the shader no branch of its own.
+Diorama.BOX = 1
+Diorama.BALL = 2
+Diorama.PILLAR = 3
+
+-- The half-size the viewport stands at right now, for a view `vh` world
+-- pixels tall -- the flat framing this rung would have shown -- and for
+-- the shape it is currently in.
+function Diorama.radius(vh, curved)
+  local frac = curved and Diorama.BALL_FRAC or Diorama.BOX_FRAC
+  return math.max(24, (vh or 288) * frac * Diorama.zoom)
+end
+
+-- Whether the world is BENT right now, which is the whole of what decides
+-- the viewport's shape: a square cut suits a flat slab of map, and a
+-- curved world rolling away over its own horizon wants a ball with a
+-- dissolve. Asked of the row rather than remembered, so the V-CURVE the
+-- stick click throws (and the "7" key, and the OPTIONS row) all reach it.
+function Diorama.curved()
+  local ok, on = pcall(function()
+    return V.require("WorldCurve").active()
+  end)
+  return ok and on or false
+end
+
+-- The fade band for a cut of half-size `r`: the curve's dissolve, or a
+-- hard edge (band 0) for the box.
+function Diorama.fadeFor(r, curved)
+  if not curved then return 0 end
+  return math.max(1, r * Diorama.FADE_FRAC)
+end
+
+local function volume(kind, x, y, z, r, fade)
+  return { x = x, y = y, z = z, r = r,
+           -- The BOX kind is rectangular in the shader, because the flat
+           -- screen's box is the WINDOW's own footprint and a window is not
+           -- square (lib/ViewBox). A headset's model has no window to be
+           -- shaped like, so this one is: the same half-size twice.
+           rx = r, rz = r,
+           -- a zero band is a hard edge: half a pixel of ramp, which is
+           -- one pixel of antialiasing rather than a stair
+           invFade = 1 / math.max(fade or 0, 0.5), kind = kind }
+end
+
+-- The viewport this frame, centred on the world point the model is pinned
+-- by: the BOX ordinarily, and the BALL while the world is curved.
+function Diorama.viewport(cx, cy, vh)
+  local curved = Diorama.curved()
+  local r = Diorama.radius(vh, curved)
+  Diorama.cull = volume(curved and Diorama.BALL or Diorama.BOX,
+                        cx, 0, cy, r, Diorama.fadeFor(r, curved))
+  return Diorama.cull
+end
+
+-- The staged fight's disc: a vertical pillar about the arena's midpoint,
+-- wide enough for both mons and their apron. Vertical means UNBOUNDED --
+-- a tree standing on the disc keeps all of its height, which is what
+-- makes the cut read as the ground having been lifted out rather than as
+-- the world having been sliced through at eye level.
+function Diorama.pillar(arena)
+  if not (arena and arena.mid) then return nil end
+  local mx, mz = arena.mid[1], arena.mid[2]
+  local r = Diorama.ARENA_APRON
+  if arena.player and arena.enemy then
+    local dx = arena.player[1] - mx
+    local dz = arena.player[2] - mz
+    r = r + math.sqrt(dx * dx + dz * dz)
+  end
+  -- Round whatever the curve is doing -- a fight is a disc, and a square
+  -- arena tile floating in the air is not the picture -- and ALWAYS
+  -- dissolved at the rim, curve or no curve. The box's hard edge is there
+  -- to say "this is a flat slab of map with sides"; a fight is a thing
+  -- lifted out of the world and hanging in the air, and a hard edge on it
+  -- reads as a cookie cutter rather than as a piece of ground.
+  Diorama.cull = volume(Diorama.PILLAR, mx, 0, mz, r,
+                        Diorama.fadeFor(r, true))
+  return Diorama.cull
+end
+
+-- ------- the grips
+--
+-- One hand carries the model; two turn it and open the viewport. The
+-- gesture is measured as a DELTA per frame rather than from where the
+-- squeeze started, so letting go and taking hold again never snaps
+-- anything -- the model simply stops following and starts again.
+
+Diorama.GRIP = 0.6              -- squeezed past this counts as holding on
+Diorama.SPREAD_MIN = 0.08       -- hands closer than this give no scale
+
+local lastOne = nil             -- the carrying hand's position, last frame
+local lastMid = nil             -- both hands' midpoint
+local lastAngle = nil           -- and the bearing of the line between them
+local lastSpread = nil          -- and its length
+
+local function clearGrab()
+  lastOne, lastMid, lastAngle, lastSpread = nil, nil, nil, nil
+end
+
+Diorama.releaseGrab = clearGrab
+
+-- Advance the grab from this frame's controller state (lib/VRXR's table:
+-- gripL/gripR in 0..1, handl/handr as { pos, quat } when tracked).
+-- Returns true while the model is being held.
+function Diorama.gesture(ctl)
+  if not ctl then
+    clearGrab()
+    return false
+  end
+  local gl, gr = ctl.gripL or 0, ctl.gripR or 0
+  local hl = (gl > Diorama.GRIP) and ctl.handl or nil
+  local hr = (gr > Diorama.GRIP) and ctl.handr or nil
+
+  if hl and hr then
+    lastOne = nil
+    local lp, rp = hl.pos, hr.pos
+    local mid = { (lp[1] + rp[1]) / 2, (lp[2] + rp[2]) / 2,
+                  (lp[3] + rp[3]) / 2 }
+    local dx, dy, dz = rp[1] - lp[1], rp[2] - lp[2], rp[3] - lp[3]
+    local spread = math.sqrt(dx * dx + dy * dy + dz * dz)
+    -- the bearing of the line between the hands, in the same convention
+    -- the mapping's yaw turns through (see VRRig.eyeCamera): atan2 of the
+    -- x component over the z one, so a hand-over-hand turn and the model's
+    -- turn are the same number
+    local angle = math.atan2(dx, dz)
+    if lastMid then
+      for i = 1, 3 do
+        Diorama.offset[i] = Diorama.offset[i] + (mid[i] - lastMid[i])
+      end
+    end
+    if lastAngle then
+      local d = (angle - lastAngle + math.pi) % (2 * math.pi) - math.pi
+      Diorama.yaw = (Diorama.yaw + d + math.pi) % (2 * math.pi) - math.pi
+    end
+    if lastSpread and lastSpread > Diorama.SPREAD_MIN
+       and spread > Diorama.SPREAD_MIN then
+      Diorama.zoom = math.max(Diorama.SCALE_MIN,
+                       math.min(Diorama.SCALE_MAX,
+                                Diorama.zoom * (spread / lastSpread)))
+    end
+    lastMid, lastAngle, lastSpread = mid, angle, spread
+    return true
+  end
+
+  lastMid, lastAngle, lastSpread = nil, nil, nil
+  local one = hl or hr
+  if one then
+    if lastOne then
+      for i = 1, 3 do
+        Diorama.offset[i] = Diorama.offset[i] + (one.pos[i] - lastOne[i])
+      end
+    end
+    lastOne = { one.pos[1], one.pos[2], one.pos[3] }
+    return true
+  end
+  lastOne = nil
+  return false
+end
+
+-- Nothing here owns a GPU object any more (the base did, and it is gone --
+-- see the header), so this is only the grab's own hand-to-hand state: a
+-- window resize or a hot reload should not leave the model following a
+-- delta measured against a frame that no longer exists.
+function Diorama.release()
+  clearGrab()
+end
+
+Diorama.invalidate = Diorama.release
+
+return Diorama

lib/FirstPerson.lua

@@ -0,0 +1,919 @@
+-- Voxel world mode: the free-roam camera -- the 1ST and 3RD rungs.
+--
+-- Every other rung is the same camera at a different pitch: an orbit over
+-- the view centre, described by one number. 1ST is a different rig
+-- entirely: the eye stands in the player's own head, the view direction is
+-- the player's to steer -- mouse, right stick or a touch drag -- and the
+-- rig rides the placed-camera seam (Voxel3D.camera) that the staged battle
+-- already proved out. Everything downstream of that seam -- the shader
+-- uniforms, project(), the sky's vanishing line, the water's lean -- reads
+-- eye and focus the same way it always has.
+--
+-- 3RD is that same rig with the eye pulled back onto a boom behind the
+-- player's shoulder (lib/ThirdPerson.lua). Everything in this file is
+-- already general over where the eye stands -- the attitude, the look
+-- inputs, the move intent, the cards that turn to face the eye -- so the
+-- third-person rung is one number applied at the very end of frame(),
+-- rather than a second camera to keep in step with this one.
+--
+-- What this module owns:
+--
+--   the ATTITUDE   yaw and pitch, fed by whichever look input speaks:
+--                  relative mouse motion, the right stick's rate, or a
+--                  touch dragged across open screen. All three drive the
+--                  same two numbers, so they compose instead of fighting.
+--
+--   the BLEND      easing between the orbit and the head. Stepping onto
+--                  the rung dives the camera from wherever the orbit was
+--                  into the player's eyes over half a second; stepping off
+--                  flies it back out. Mid-blend the rig is a straight lerp
+--                  of the two cameras -- eye, focus, fov, up -- through
+--                  the same placed-camera record.
+--
+--   the MOVE INTENT   the analog vector FreeMove walks the player by,
+--                  gathered here because it is made of the same devices:
+--                  the left stick's raw axes, the touch d-pad's true
+--                  deflection, or the held keys, rotated by this camera's
+--                  yaw so "forward" means "where I am looking".
+--
+-- Deliberately NOT here: movement itself (lib/FreeMove.lua, which owns the
+-- collision walk and the grid the game logic still lives on), and the
+-- billboard math that faces cards at this eye (VoxelScene, which owns
+-- every other card matrix too).
+--
+-- Everything the module reaches -- the mouse's relative mode, the wrapped
+-- love handlers, the touch overlay's hit test -- is pcall-guarded the same
+-- way the 3D pass is: headless runs and drivers without a mouse simply
+-- never see the input, and the rung falls back to holding the 75-degree
+-- orbit.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Mat4 = V.require("Mat4")
+local Voxel = V.require("VoxelState")
+local Voxel3D = V.require("Voxel3D")
+local WorldCurve = V.require("WorldCurve")
+local ThirdPerson = V.require("ThirdPerson")
+
+local FirstPerson = {}
+
+-- ------- the rig's numbers
+--
+-- EYE_HEIGHT stands the eye near the top of the 16px sprite -- the head,
+-- not the hat tip -- above the same ground-plus-lift the character card
+-- stands on, so surfing bobs and ledge hops carry the view with them.
+--
+-- FOV is wider than the diorama's ~53 degrees: inside the world, the
+-- diorama's lens reads as a keyhole. 65 vertical is the modern-shooter
+-- middle ground.
+--
+-- FOCUS_DIST is short on purpose: the placed-camera branch derives its
+-- near plane from |eye - focus| (dist * 0.05), and the eye walks within
+-- 2-3 world pixels of a wall face when sliding along it -- a far focus
+-- would push the near plane through the wall and clip a hole in it.
+FirstPerson.EYE_HEIGHT = 13
+FirstPerson.FOV = math.rad(65)
+FirstPerson.FOCUS_DIST = 24
+
+-- Pitch limits, in radians below horizontal (positive looks DOWN). The
+-- world has no ceiling and the sky's bands sit low, so looking far up
+-- shows the void above the gradient; the up-range is clamped tighter than
+-- the down-range for that reason, not a technical one.
+FirstPerson.PITCH_DOWN = math.rad(70)
+FirstPerson.PITCH_UP = -math.rad(50)
+FirstPerson.PITCH_DEFAULT = math.rad(10)
+
+-- how long the dive into (and out of) the head takes, in seconds
+FirstPerson.BLEND_TIME = 0.45
+
+-- ------- look input tuning
+--
+-- MOUSE_SENS is radians per relative-mode count -- about 0.18 degrees per
+-- count, the conventional shooter default. STICK rates are radians per
+-- second at full deflection, with a squared response curve so small
+-- deflections aim and full ones turn. TOUCH_TURN is what one full screen
+-- width of drag turns, mobile-shooter convention.
+FirstPerson.MOUSE_SENS = 0.0032
+FirstPerson.STICK_YAW = 3.5
+FirstPerson.STICK_PITCH = 2.4
+FirstPerson.STICK_DEAD = 0.18
+FirstPerson.TOUCH_TURN = 2.2 * math.pi
+FirstPerson.MOVE_DEAD = 0.25
+
+-- ------- state
+--
+-- Yaw is a world bearing: 0 faces south (+Z, the way a resting sprite
+-- faces), pi/2 east -- the same convention VoxelScene.YAW uses, so a
+-- facing converts to a yaw by table lookup.
+FirstPerson.yaw = 0
+FirstPerson.pitch = FirstPerson.PITCH_DEFAULT
+FirstPerson.blend = 0
+
+-- A multiplier on the first-person field of view, for anything that wants
+-- to narrow the lens without owning the rig: 1 is the ordinary 65
+-- degrees, and horde mode's iron sights ease it down toward 40 while the
+-- player is looking down them (lib/HordeGun). Kept here rather than in
+-- the caller because the fov is folded into the orbit blend below, and
+-- because signature() has to know -- a lens that narrows while the player
+-- stands still still has to re-fit the shadow box.
+FirstPerson.fovScale = 1
+
+local wasEngaged = false
+local stick = { x = 0, y = 0 }        -- right stick, latest event values
+local mouseDX, mouseDY = 0, 0         -- relative counts since last update
+local lookTouch = nil                 -- { id, x, y } of the claimed finger
+local touchMove = nil                 -- the touch d-pad's analog deflection
+local captured = false                -- mouse relative mode engaged by us
+
+-- the placed-camera record this module last handed to Voxel3D, so passes
+-- that key behaviour off "is the first-person rig the one drawing" (the
+-- billboard yaw, the frame remap) can ask by identity rather than by mode
+-- -- the battle's own placed camera must never read as first person
+local rig = nil
+
+local FACING_ANGLE = {
+  down = 0,
+  right = math.pi / 2,
+  up = math.pi,
+  left = -math.pi / 2,
+}
+local FACING_ORDER = { "down", "right", "up", "left" }
+
+local function wrapPi(a)
+  return (a + math.pi) % (2 * math.pi) - math.pi
+end
+
+local function ease(t)
+  return t * t * (3 - 2 * t)
+end
+
+-- ------- gates
+
+-- Whether a free-roam rung -- 1ST or 3RD -- is selected and the 3D pass can
+-- carry it. Both stand the camera with the player, so both read the look
+-- inputs, both walk free, and both turn the cards; how far behind the head
+-- the eye ends up is ThirdPerson's business alone.
+function FirstPerson.engaged()
+  return Voxel.isFreeCam(Voxel.level) and Voxel3D.available()
+end
+
+-- Whether the overworld is what the player is looking at: nothing pushed
+-- over it, so the buttons are free-roam's. Shared with everything else in
+-- the mod that asks the same question of the same stack (CamControl's
+-- zooms above all), rather than each restating the pcall.
+function FirstPerson.onTop()
+  local ok, top, ow = pcall(function()
+    local Game = require("src.core.Game")
+    return Game.stack and Game.stack:top(), Game.overworld
+  end)
+  return ok and top ~= nil and top == ow
+end
+
+-- Whether first person should be READING the player's inputs right now:
+-- engaged, with the overworld on top of the stack (a menu, a dialog or a
+-- battle above it owns the buttons, exactly as it does for grid walking).
+function FirstPerson.driving()
+  return FirstPerson.engaged() and FirstPerson.onTop()
+end
+
+-- The right stick's live X, for a camera that is not this one: while a
+-- battle is staged the free-roam look is not driving, but the axes are
+-- still arriving on the wrap below (which records whatever the rung), and
+-- the battle's orbit wants them. Reading them here rather than wrapping
+-- the same seam twice.
+function FirstPerson.stickX()
+  return stick.x or 0
+end
+
+function FirstPerson.stickY()
+  return stick.y or 0
+end
+
+-- ------- lending the look finger out
+--
+-- A pinch needs both fingers on the screen, and one of them is very likely
+-- the finger this module claimed as the look drag. Rather than have the
+-- pinch fight for it, CamControl asks for it: dropLook while the gesture
+-- runs, reseatLook on whichever finger survives it. Re-seating rather than
+-- simply releasing is what stops the view snapping by however far the
+-- pinch travelled -- the finger carries on as the look drag from where it
+-- now is, which is what it looks like it should do.
+function FirstPerson.dropLook()
+  lookTouch = nil
+end
+
+function FirstPerson.reseatLook(id, x, y)
+  if id == nil then lookTouch = nil return end
+  lookTouch = { id = id, x = x, y = y }
+end
+
+-- The eased blend, 0 at the orbit and 1 in the head.
+function FirstPerson.blendEased()
+  return ease(FirstPerson.blend)
+end
+
+-- The blend, but only while the free-roam pass's own rig is the placed
+-- camera. The battle scene places a camera of its own through the same
+-- seam, and its cards must keep their stage lean rather than yawing at a
+-- first-person eye that is not looking at them.
+function FirstPerson.cardBlend()
+  if not rig or Voxel3D.camera ~= rig then return 0 end
+  return ease(FirstPerson.blend)
+end
+
+-- A VR eye stepping into the rig's shoes: the VR pass builds its own
+-- placed cameras (one per eye) and hands each one here as it draws, so
+-- everything keyed to "the first-person rig is drawing" -- the billboard
+-- yaw, the frame remap, the hidden player card -- answers for that eye.
+-- In the diorama (blend 0) adoption is inert: cardBlend still reports
+-- zero and the cards keep their lean.
+function FirstPerson.adoptVReye(record)
+  rig = record
+end
+
+-- Whether the player's own card should be left out of the camera draw:
+-- deep enough into the blend that the card would fill the lens from
+-- inside. The sun pass keeps drawing it either way -- a first-person
+-- player still throws a shadow on the ground ahead.
+--
+-- Never while 3RD's boom is genuinely out, whatever the blend: the whole
+-- point of a boom is that the character it is booming away from is on
+-- screen. (Nor the silhouette that rides the same answer -- seeing your own
+-- outline through the building you just walked behind is what a
+-- third-person camera owes the player.) A boom SQUEEZED into the head by a
+-- wall answers false there and the card comes out again, because at that
+-- range it is the first-person problem word for word.
+function FirstPerson.hidePlayer()
+  if ThirdPerson.showsPlayer() then return false end
+  return FirstPerson.cardBlend() > 0.9
+end
+
+-- ------- attitude
+
+-- Apply a look delta, in radians. Everything that turns the head funnels
+-- through here, so the clamps live once.
+function FirstPerson.lookBy(dyaw, dpitch)
+  FirstPerson.yaw = wrapPi(FirstPerson.yaw + dyaw)
+  FirstPerson.pitch = math.max(FirstPerson.PITCH_UP,
+                       math.min(FirstPerson.PITCH_DOWN,
+                                FirstPerson.pitch + dpitch))
+end
+
+-- A bearing as one of the grid's four directions -- the 45-degree
+-- quantisation every facing in this file is made with, in one place so the
+-- compass, the body and the card frames can never disagree about where a
+-- boundary is.
+local function facingOf(a)
+  local s, c = math.sin(a), math.cos(a)
+  if math.abs(s) > math.abs(c) then
+    return s > 0 and "right" or "left"
+  end
+  return c > 0 and "down" or "up"
+end
+
+-- The view direction's flat compass facing, for everything that still
+-- thinks in the grid's four directions: the cell A interacts with, the
+-- sprite the sun sees, the direction a blocked slide bonks in.
+function FirstPerson.compassFacing()
+  return facingOf(FirstPerson.yaw)
+end
+
+-- Which way the BODY points, as a continuous world bearing, given the
+-- world-space direction it is walking (0, 0 while standing). In the head,
+-- the body is the head: you face what you look at. On the boom you can see
+-- yourself, and a character sliding sideways while facing the lens reads as
+-- a bug rather than as a strafe -- so a walking body turns to face its own
+-- travel, and a standing one comes back round to the camera's bearing,
+-- which is the one A talks along.
+function FirstPerson.bodyBearing(wx, wz)
+  if ThirdPerson.extended() and wx and wz and (wx ~= 0 or wz ~= 0) then
+    return math.atan2(wx, wz)
+  end
+  return FirstPerson.yaw
+end
+
+-- The same answer as one of the four facings, which is what the grid game
+-- (and the sprite sheet) reasons in.
+function FirstPerson.bodyFacing(wx, wz)
+  return facingOf(FirstPerson.bodyBearing(wx, wz))
+end
+
+-- ------- the body's live bearing
+--
+-- The bearing the player's own body is actually pointing along RIGHT NOW,
+-- or nil whenever the free walk is not the thing pointing it (a scripted
+-- move, a cutscene, the grid walk with the rung off). FreeMove maintains
+-- it; only the player's own card reads it.
+--
+-- It exists because the card's frame is chosen by the angle BETWEEN the
+-- body and the eye, and quantising the body to a compass direction first
+-- throws away exactly the precision that choice needs. A standing body is
+-- pointed along the camera's own yaw, so the true angle between them is a
+-- flat 180 degrees and the card should show its back and nothing else --
+-- but snap the body to one of four directions on the game tick, then
+-- measure it against an eye that has kept turning since, and the pair can
+-- read as 135 degrees and pick the PROFILE frame instead. Spin the camera
+-- fast and the character flicks to a mirrored side view for a frame or
+-- two. Keeping the bearing continuous gives the measurement a full 45
+-- degrees of slack before it can cross a boundary, which no frame's worth
+-- of turning comes close to spending.
+FirstPerson.bodyYaw = nil
+
+-- Point the body along the direction it is walking (or, standing, along
+-- the camera): records the continuous bearing and hands back the compass
+-- facing the caller wants for p.facing.
+function FirstPerson.pointBody(wx, wz)
+  FirstPerson.bodyYaw = FirstPerson.bodyBearing(wx, wz)
+  return facingOf(FirstPerson.bodyYaw)
+end
+
+-- Hand the body back to whatever else is turning it.
+function FirstPerson.releaseBody()
+  FirstPerson.bodyYaw = nil
+end
+
+-- The unit look direction, and its flat (ground-plane) part.
+local function lookDir()
+  local cp = math.cos(FirstPerson.pitch)
+  return math.sin(FirstPerson.yaw) * cp,
+         -math.sin(FirstPerson.pitch),
+         math.cos(FirstPerson.yaw) * cp
+end
+
+function FirstPerson.lookFlat()
+  return math.sin(FirstPerson.yaw), math.cos(FirstPerson.yaw)
+end
+
+-- ------- billboards seen from inside the world
+--
+-- The diorama's cards face south and lean back by the camera's pitch --
+-- correct for a camera that always stands south. An eye that can stand
+-- ANYWHERE sees a south-facing card edge-on from the east, so in first
+-- person every card yaws about its feet to face the eye (cylindrical
+-- billboarding: upright, never tipping). VoxelScene blends its matrices
+-- between the two by cardBlend.
+
+-- The yaw that turns a card's south-facing normal toward the eye.
+function FirstPerson.cardYaw(wx, wz)
+  local eye = rig and rig.eye
+  if not eye then return 0 end
+  local dx, dz = eye[1] - wx, eye[3] - wz
+  if dx * dx + dz * dz < 1e-9 then return 0 end
+  return math.atan2(dx, dz)
+end
+
+-- Which of the four sprite frames a body at world bearing `phi` shows an
+-- eye looking at (wx, wz): the bearing rotated into the viewer's own frame,
+-- quantised. nil when there is no rig to be seen from.
+local function frameFor(phi, wx, wz)
+  local eye = rig and rig.eye
+  if not (eye and phi) then return nil end
+  local dx, dz = eye[1] - wx, eye[3] - wz
+  if dx * dx + dz * dz < 1e-9 then return nil end
+  local rel = wrapPi(phi - math.atan2(dx, dz))
+  local idx = math.floor((rel + math.pi / 4) / (math.pi / 2)) % 4
+  return FACING_ORDER[idx + 1]
+end
+
+-- Which of the four sprite frames an entity shows THIS eye: its facing
+-- rotated into the viewer's own frame, quantised. The flat game's frames
+-- are "how this pose looks from the south", so the apparent facing is the
+-- pose rotated by where the viewer actually stands -- walk behind an NPC
+-- and you see their back, circle to their flank and you see the profile,
+-- exactly as the four frames Gen 1 drew intend.
+--
+-- An NPC's facing IS one of the four and nothing finer, so this is the
+-- whole story for everyone in the world except the one body the camera is
+-- attached to -- see playerFacing.
+function FirstPerson.apparentFacing(facing, wx, wz)
+  return frameFor(FACING_ANGLE[facing], wx, wz) or facing
+end
+
+-- The PLAYER's own card, which is the one case where the body's bearing is
+-- known to better than a compass point (bodyYaw, above) -- and the one case
+-- where it matters, because the eye is derived FROM that bearing rather
+-- than independent of it. Measured continuously, a standing body reads as
+-- a flat 180 degrees from its own camera and shows its back, steadily,
+-- however fast the camera is spun. Falls back to the four-direction answer
+-- whenever something other than the free walk is turning the body.
+function FirstPerson.playerFacing(facing, wx, wz)
+  return frameFor(FirstPerson.bodyYaw, wx, wz)
+         or FirstPerson.apparentFacing(facing, wx, wz)
+end
+
+-- ------- the move intent
+--
+-- The analog vector FreeMove walks by, in CAMERA space: mx strafes (+
+-- right), mz advances (+ forward). Whichever device is actually deflected
+-- answers -- the left stick's raw axes first (the engine quantises them to
+-- a d-pad; the raw pair is the analog truth), then a touch d-pad finger,
+-- then the held keys. Magnitude caps at 1.
+function FirstPerson.moveVector()
+  local ok, Game = pcall(require, "src.core.Game")
+  local input = ok and Game.input or nil
+
+  local ax = input and input.stickAxis or nil
+  if ax then
+    local mag = math.sqrt(ax.x * ax.x + ax.y * ax.y)
+    if mag > FirstPerson.MOVE_DEAD then
+      local t = math.min(1, (mag - FirstPerson.MOVE_DEAD)
+                            / (1 - FirstPerson.MOVE_DEAD))
+      return ax.x / mag * t, -ax.y / mag * t
+    end
+  end
+
+  if touchMove then
+    local mag = math.sqrt(touchMove.x * touchMove.x
+                          + touchMove.y * touchMove.y)
+    if mag > FirstPerson.MOVE_DEAD then
+      local t = math.min(1, mag)
+      return touchMove.x / mag * t, -touchMove.y / mag * t
+    end
+  end
+
+  if input then
+    local mx = (input:isDown("right") and 1 or 0)
+               - (input:isDown("left") and 1 or 0)
+    local mz = (input:isDown("up") and 1 or 0)
+               - (input:isDown("down") and 1 or 0)
+    if mx ~= 0 or mz ~= 0 then
+      local mag = math.sqrt(mx * mx + mz * mz)
+      return mx / mag, mz / mag
+    end
+  end
+  return 0, 0
+end
+
+-- Rotate a camera-space move into world space: forward is the flat look
+-- direction, strafe-right is its right hand. (cross(forward, up) with
+-- forward = (sin y, 0, cos y) and up = +Y lands right on (-cos y, 0,
+-- sin y): face south and your right hand points west.)
+function FirstPerson.moveWorld(mx, mz)
+  local s, c = math.sin(FirstPerson.yaw), math.cos(FirstPerson.yaw)
+  return -c * mx + s * mz, s * mx + c * mz
+end
+
+-- ------- the tick
+
+-- Runs from the pipeline's update hook, every frame whatever the level --
+-- the same tick VoxelState eases the orbit on. Owns the blend, the mouse
+-- capture lifecycle, and the frame's stick-rate look.
+function FirstPerson.update(dt)
+  local engagedNow = FirstPerson.engaged()
+
+  -- entering the rung: the head starts looking the way the sprite faces,
+  -- pitched gently down -- the reading pose of the flat game
+  if engagedNow and not wasEngaged then
+    local ok, facing = pcall(function()
+      local Game = require("src.core.Game")
+      return Game.overworld and Game.overworld.player
+             and Game.overworld.player.facing
+    end)
+    FirstPerson.yaw = (ok and FACING_ANGLE[facing]) or 0
+    FirstPerson.pitch = FirstPerson.PITCH_DEFAULT
+  end
+  wasEngaged = engagedNow
+
+  -- the blend, held at flat until there is terrain to dive into -- the
+  -- same wait Voxel.update keeps for the orbit tween, for the same reason
+  local target = engagedNow and 1 or 0
+  if target > FirstPerson.blend and FirstPerson.blend == 0
+     and not Voxel.ready then
+    target = 0
+  end
+  local step = dt / FirstPerson.BLEND_TIME
+  if FirstPerson.blend < target then
+    FirstPerson.blend = math.min(target, FirstPerson.blend + step)
+  elseif FirstPerson.blend > target then
+    FirstPerson.blend = math.max(target, FirstPerson.blend - step)
+  end
+  if FirstPerson.blend <= 0 and rig then
+    -- fully out: let go of the placed camera (unless a battle already
+    -- swapped its own in, which is not ours to clear)
+    if Voxel3D.camera == rig then Voxel3D.camera = nil end
+    rig = nil
+  end
+
+  -- the boom, on the same tick and for the same reason: it has to keep
+  -- easing after 3RD is left, and it needs the blend to know whether a
+  -- change of rung is a SLIDE (already inside the world, 1ST <-> 3RD) or
+  -- part of the dive in from the orbit, which carries the eye anyway
+  ThirdPerson.update(dt, FirstPerson.blend)
+
+  -- mouse capture follows engagement: captured whenever the rung is on and
+  -- the window has focus, released the moment either ends. Checked against
+  -- the live mode rather than toggled on edges, so a capture lost to the
+  -- OS (alt-tab) re-arms itself on the next focused frame.
+  local wantCapture = engagedNow
+  if wantCapture and love.window and love.window.hasFocus then
+    local okF, focus = pcall(love.window.hasFocus)
+    wantCapture = okF and focus or false
+  end
+  if love.mouse and love.mouse.setRelativeMode then
+    local okM, isRel = pcall(love.mouse.getRelativeMode)
+    if okM and isRel ~= wantCapture then
+      pcall(love.mouse.setRelativeMode, wantCapture)
+    end
+    captured = wantCapture
+  end
+
+  local driving = FirstPerson.driving()
+
+  -- The mouse's counts, accumulated by the wrapped handler since the last
+  -- tick; dropped unread while something else owns the screen.
+  --
+  -- The yaw sign is NEGATED, here and in every look input below: yaw grows
+  -- south -> east -> north (the world runs +X east, +Z south, and the
+  -- direction is (sin yaw, cos yaw)), which seen from behind the eye is a
+  -- LEFT turn -- so "move the mouse right, look right" means subtracting.
+  local dx, dy = mouseDX, mouseDY
+  mouseDX, mouseDY = 0, 0
+  if driving and (dx ~= 0 or dy ~= 0) then
+    FirstPerson.lookBy(-dx * FirstPerson.MOUSE_SENS,
+                       dy * FirstPerson.MOUSE_SENS)
+  end
+
+  -- the right stick is a rate: radians per second, squared response so
+  -- the first half of the throw aims and the rest turns
+  if driving then
+    local rx, ry = stick.x, stick.y
+    local function curve(v)
+      local a = math.abs(v)
+      if a < FirstPerson.STICK_DEAD then return 0 end
+      a = (a - FirstPerson.STICK_DEAD) / (1 - FirstPerson.STICK_DEAD)
+      return (v < 0 and -1 or 1) * a * a
+    end
+    local cy, cp = curve(rx), curve(ry)
+    if cy ~= 0 or cp ~= 0 then
+      -- negated yaw for the same reason as the mouse above
+      FirstPerson.lookBy(-cy * FirstPerson.STICK_YAW * dt,
+                         cp * FirstPerson.STICK_PITCH * dt)
+    end
+  end
+end
+
+-- ------- the rig itself
+
+-- The orbit camera's eye/focus/fov/up for the frame's centre -- the same
+-- arithmetic Voxel3D.viewProjection runs, restated here because the blend
+-- needs both ends as DATA. Kept textually tiny so the two cannot drift:
+-- focus on the centre, eye FOCAL*vh away at the pitch, up perpendicular
+-- in the YZ plane.
+local function orbitRig(cx, cy, vh)
+  local a = Voxel.angle
+  local dist = Voxel.FOCAL * vh
+  return { cx, dist * math.cos(a), cy + dist * math.sin(a) },
+         { cx, 0, cy },
+         2 * math.atan(1 / (2 * Voxel.FOCAL)),
+         { 0, math.sin(a), -math.cos(a) }
+end
+
+local lastEye = nil                   -- frozen head pose for player-less frames
+
+-- Build this frame's placed camera and hand it to Voxel3D, plus the scene
+-- centre the curve and the depth reference should use. `me` is the
+-- player's posed entry (px, py, gh, lift) or nil (a Fly animation), and
+-- (cx, cy) the orbit's own view centre.
+--
+-- Returns nil with the blend fully out, which is the caller's signal to
+-- leave the orbit in charge.
+function FirstPerson.frame(me, cx, cy, vw, vh)
+  local b = FirstPerson.blend
+  if b <= 0 then
+    if rig and Voxel3D.camera == rig then Voxel3D.camera = nil end
+    rig = nil
+    return nil
+  end
+  local e = ease(b)
+
+  local head
+  if me then
+    head = { me.px + 8,
+             (me.gh or 0) + (me.lift or 0) + FirstPerson.EYE_HEIGHT,
+             me.py + 8 }
+    lastEye = head
+  else
+    head = lastEye or { cx, FirstPerson.EYE_HEIGHT, cy }
+  end
+  local lx, ly, lz = lookDir()
+  local fpFocus = { head[1] + lx * FirstPerson.FOCUS_DIST,
+                    head[2] + ly * FirstPerson.FOCUS_DIST,
+                    head[3] + lz * FirstPerson.FOCUS_DIST }
+
+  -- 3RD: the eye walks back off the head along the very direction it looks,
+  -- as far as the world allows. Fully in (1ST, and every frame of the
+  -- diorama) this hands back the head and the focus untouched, so the two
+  -- rungs are one rig with one number between them.
+  local camEye, camFocus = ThirdPerson.place(head, lx, ly, lz, fpFocus)
+
+  local oEye, oFocus, oFov, oUp = orbitRig(cx, cy, vh)
+  local function mix(p, q)
+    return { p[1] + (q[1] - p[1]) * e,
+             p[2] + (q[2] - p[2]) * e,
+             p[3] + (q[3] - p[3]) * e }
+  end
+  local up = mix(oUp, { 0, 1, 0 })
+  local ul = math.sqrt(up[1] * up[1] + up[2] * up[2] + up[3] * up[3])
+  if ul > 1e-6 then up[1], up[2], up[3] = up[1] / ul, up[2] / ul, up[3] / ul
+  else up = { 0, 1, 0 } end
+
+  -- the world curve eases out with the blend: standing inside the world,
+  -- the bend that sells the diorama reads as the ground falling away. A
+  -- true zero (curve declined) needs the field present -- nil would let
+  -- Voxel3D fall back to the setting
+  local k = WorldCurve.k(vh) * (1 - e)
+
+  rig = {
+    eye = mix(oEye, camEye),
+    focus = mix(oFocus, camFocus),
+    fov = oFov + (FirstPerson.FOV - oFov) * e,
+    up = up,
+    curve = k,
+  }
+  Voxel3D.camera = rig
+
+  -- the scene centre walks from the orbit's view centre to the head, so
+  -- the curve's focus, the depth reference and the glint's travel follow
+  -- the camera that is actually in charge
+  local sx = cx + (head[1] - cx) * e
+  local sy = cy + (head[3] - cy) * e
+  return rig, sx, sy
+end
+
+-- Where the shadow pass should centre its box: pushed along the flat look
+-- so the fitted frustum -- built for an orbit that always looks north --
+-- covers the ground THIS camera sees. The push is strongest looking
+-- south (the direction the orbit's box barely reaches) and scales with
+-- the blend.
+function FirstPerson.shadowCenter(sx, sy, vh)
+  local e = FirstPerson.cardBlend()
+  if e <= 0 then return sx, sy end
+  local fx, fz = FirstPerson.lookFlat()
+  local ShadowMap = V.require("ShadowMap")
+  local cap = (ShadowMap.FAR_CAP or 2.5) * vh
+  return sx + fx * 0.6 * vh * e,
+         sy + fz * (fz > 0 and (cap - vh * 0.5) or vh * 0.4) * e
+end
+
+-- The first-person facts a shadow signature has to include: the sun's
+-- box is fitted around this camera, so turning the head or walking the
+-- blend has to re-fit it even standing still.
+function FirstPerson.signature()
+  local b = FirstPerson.blend
+  if b <= 0 then return "" end
+  return table.concat({
+    math.floor(b * 64),
+    math.floor(FirstPerson.yaw * 64),
+    math.floor(FirstPerson.pitch * 64),
+    -- and how far back the boom stands the eye: a wall shortening it moves
+    -- the camera the sun's box is fitted around, standing still or not
+    ThirdPerson.signature(),
+  }, ",")
+end
+
+-- ------- input capture
+--
+-- The seams: relative mouse motion has no Game handler at all (the
+-- engine's love.mousemoved only feeds the mouse-as-touch debug path), the
+-- right stick's axes are explicitly ignored by Input, and a touch
+-- anywhere off the overlay's controls dies in TouchControls. Each wrap
+-- forwards everything it does not claim, and claims only while first
+-- person is actually driving -- so with the rung off, every byte flows
+-- exactly where it always did.
+
+local installed = false
+
+function FirstPerson.install()
+  if installed then return end
+  installed = true
+
+  local Game = require("src.core.Game")
+
+  -- ------- right stick
+  do
+    local inner = Game.gamepadaxis
+    function Game:gamepadaxis(joystick, axis, value)
+      if axis == "rightx" then stick.x = value
+      elseif axis == "righty" then stick.y = value end
+      return inner(self, joystick, axis, value)
+    end
+  end
+  -- generic (non-gamepad) sticks: axes 1/2 are the left stick by SDL
+  -- convention and Input already claims them; 3/4 are the usual right
+  -- pair on the same class of device. Real gamepads are excluded -- they
+  -- already spoke through the mapped rightx/righty above, and their RAW
+  -- axis 3 is as likely a trigger as a stick.
+  --
+  -- Two more exclusions, both learned the hard way on Android, where this
+  -- wrap runs BEFORE the engine's own generic-joystick guards:
+  --
+  --   the accelerometer arrives as a joystick named for what it is, with
+  --   gravity pinning an axis well past any deadzone -- the same device
+  --   Game:joystickaxis refuses for movement (#459), refused here by the
+  --   same name test, or the view spins on its own the moment 1ST opens.
+  --
+  --   and a raw axis is only BELIEVED after it has been seen near centre
+  --   once. A stick at rest sits at zero, so a real one earns trust with
+  --   its first touch; a gravity-pinned sensor axis or a trigger resting
+  --   at an extreme never centres and so never steers the look.
+  local function isAccelerometer(joystick)
+    local ok, name = pcall(function() return joystick:getName() end)
+    return ok and type(name) == "string"
+           and name:lower():find("accelerometer", 1, true) ~= nil
+  end
+  local rawCentred = {}
+  do
+    local inner = Game.joystickaxis
+    function Game:joystickaxis(joystick, axis, value)
+      local mapped = joystick and joystick.isGamepad and joystick:isGamepad()
+      if not mapped and (axis == 3 or axis == 4)
+         and not isAccelerometer(joystick) then
+        if math.abs(value) < 0.3 then rawCentred[axis] = true end
+        if rawCentred[axis] then
+          if axis == 3 then stick.x = value else stick.y = value end
+        end
+      end
+      return inner(self, joystick, axis, value)
+    end
+  end
+
+  -- ------- mouse
+  --
+  -- love.mousemoved rather than a Game method, because the engine has no
+  -- Game:mousemoved to wrap -- the callback in the project's main.lua is
+  -- the one place relative counts arrive. Claimed only while captured;
+  -- pass-through otherwise, including the mouse-as-touch path.
+  do
+    local inner = love.mousemoved
+    love.mousemoved = function(x, y, dx, dy, istouch)
+      if captured and not istouch then
+        mouseDX = mouseDX + (dx or 0)
+        mouseDY = mouseDY + (dy or 0)
+        return
+      end
+      if inner then return inner(x, y, dx, dy, istouch) end
+    end
+  end
+  -- While the mouse is captured there is no cursor to click UI with, so
+  -- the buttons become GB buttons: left is A, right is B -- through the
+  -- overlay's own press path, which a rebind can never detach. What WE
+  -- pressed is remembered per button, so the release always reaches the
+  -- overlay even if the capture ended while the button was down --
+  -- otherwise a click that outlives the rung strands A held forever.
+  --
+  -- HORDE MODE re-reads the same two buttons as a weapon: left fires,
+  -- right holds the sights. Claimed BEFORE the A/B mapping below rather
+  -- than on top of it, so a click during the mode never also lands as a
+  -- GB button -- otherwise the A that ends the GAME OVER card would be
+  -- spent by the shot that ended the run.
+  local mouseHeld = {}
+  local MOUSE_BTN = { [1] = "a", [2] = "b" }
+  local function hordeMouse(button, down)
+    local Horde = V.require("Horde")
+    if not Horde.playing() then return false end
+    if button == 1 then
+      if down then V.require("HordeGun").fire() end
+      return true
+    elseif button == 2 then
+      V.require("HordeGun").setAds(down)
+      return true
+    end
+    return false
+  end
+  do
+    local inner = love.mousepressed
+    love.mousepressed = function(x, y, button, istouch, presses)
+      if captured and not istouch and hordeMouse(button, true) then return end
+      if captured and not istouch and MOUSE_BTN[button] then
+        local Input = require("src.core.Input")
+        mouseHeld[button] = true
+        Input:overlayPressed(MOUSE_BTN[button])
+        return
+      end
+      if inner then return inner(x, y, button, istouch, presses) end
+    end
+  end
+  do
+    local inner = love.mousereleased
+    love.mousereleased = function(x, y, button, istouch, presses)
+      -- a release always reaches whoever owns the press: the horde's
+      -- aim-hold has to let go even if the mode ended mid-click
+      if not mouseHeld[button] and hordeMouse(button, false) then return end
+      if mouseHeld[button] then
+        local Input = require("src.core.Input")
+        mouseHeld[button] = nil
+        Input:overlayReleased(MOUSE_BTN[button])
+        return
+      end
+      if inner then return inner(x, y, button, istouch, presses) end
+    end
+  end
+
+  -- ------- touch
+  --
+  -- A finger on open screen -- not on the overlay's d-pad or buttons --
+  -- becomes the look drag. One finger owns the look at a time; every
+  -- other touch flows to TouchControls untouched, so a thumb can drag the
+  -- view while the other walks the d-pad. That d-pad finger is also read
+  -- back ANALOG here: TouchControls quantises it to four directions for
+  -- the grid game, but the deflection it quantised is exactly the move
+  -- vector a free walk wants.
+  local TouchControls = require("src.core.TouchControls")
+
+  local function dpadVector(x, y)
+    local ok, v = pcall(function()
+      local L = TouchControls:layout()
+      local dz = L.dpad
+      local half = dz.w * 0.65
+      return { x = math.max(-1, math.min(1, (x - dz.cx) / half)),
+               y = math.max(-1, math.min(1, (y - dz.cy) / half)) }
+    end)
+    return ok and v or nil
+  end
+
+  do
+    local inner = Game.touchpressed
+    function Game:touchpressed(id, x, y)
+      if FirstPerson.driving() then
+        local onControl = nil
+        pcall(function() onControl = TouchControls:hitTest(x, y) end)
+        if not onControl and not lookTouch then
+          -- HORDE MODE: a tap on open screen is a SHOT, fired on the press
+          -- rather than on a release that turned out not to be a drag --
+          -- a shooter that waits to find out whether you meant it is a
+          -- shooter that misses. The same finger still becomes the look
+          -- drag below, so aiming and firing are one gesture.
+          if V.require("Horde").playing() then
+            V.require("HordeGun").fire()
+          end
+          lookTouch = { id = id, x = x, y = y }
+          return
+        end
+        inner(self, id, x, y)
+        if onControl == "dpad" and TouchControls.dpadTouch == id then
+          touchMove = dpadVector(x, y)
+        end
+        return
+      end
+      return inner(self, id, x, y)
+    end
+  end
+  do
+    local inner = Game.touchmoved
+    function Game:touchmoved(id, x, y)
+      if lookTouch and lookTouch.id == id then
+        local w = 1280
+        pcall(function() w = love.graphics.getWidth() end)
+        local per = FirstPerson.TOUCH_TURN / math.max(320, w)
+        if FirstPerson.driving() then
+          -- negated yaw for the same reason as the mouse (see update):
+          -- drag right, look right, the mobile-shooter convention
+          FirstPerson.lookBy(-(x - lookTouch.x) * per,
+                             (y - lookTouch.y) * per)
+        end
+        lookTouch.x, lookTouch.y = x, y
+        return
+      end
+      if touchMove and TouchControls.dpadTouch == id then
+        touchMove = dpadVector(x, y) or touchMove
+      end
+      return inner(self, id, x, y)
+    end
+  end
+  do
+    local inner = Game.touchreleased
+    function Game:touchreleased(id, x, y)
+      if lookTouch and lookTouch.id == id then
+        lookTouch = nil
+        return
+      end
+      if TouchControls.dpadTouch == id then touchMove = nil end
+      return inner(self, id, x, y)
+    end
+  end
+
+  -- a reset that drops held input state drops ours with it
+  do
+    local inner = Game.focus
+    function Game:focus(f)
+      lookTouch, touchMove = nil, nil
+      stick.x, stick.y = 0, 0
+      mouseDX, mouseDY = 0, 0
+      return inner(self, f)
+    end
+  end
+  -- a disconnected controller cannot send the centering event for whatever
+  -- its stick last held -- the engine drops all input state here, and the
+  -- look rate (plus the raw axes' earned trust) goes with it
+  do
+    local inner = Game.joystickremoved
+    function Game:joystickremoved(joystick)
+      stick.x, stick.y = 0, 0
+      rawCentred[3], rawCentred[4] = nil, nil
+      return inner(self, joystick)
+    end
+  end
+end
+
+return FirstPerson

lib/ForestAtmos.lua

@@ -0,0 +1,886 @@
+-- The air under the canopy: fog, god rays, and what drifts through them.
+--
+-- Some maps have an ATMOSPHERE (data/map_atmosphere.lua -- Viridian Forest
+-- today, any map that adds a line tomorrow): a ground haze the scene shader
+-- folds every surface into (see Voxel3D.fog), and VOLUMETRIC light let down
+-- through an INVISIBLE canopy hanging above the map's real trees, as if the
+-- carved hulls on screen were only the understorey of something taller.
+--
+-- The rays are not placed geometry. A fullscreen pass marches every
+-- pixel's eye ray through the air, stops at the frame's own depth buffer
+-- (the same detach-and-read Water runs), and asks two questions of every
+-- step of air on the way:
+--
+--   * the SUN'S question -- the shadow map. Air behind a tree hull is
+--     dark air; air in a real gap glows. A trunk stands in a column of
+--     its own shade, a character walks through the beams and blocks
+--     them, and every shaft on screen agrees with the light already on
+--     the floor, because it is read from the same map.
+--
+--   * the CANOPY'S question -- where this thread of sun pierced the
+--     invisible leaf layer. Every step of air on one sun ray shares that
+--     point, which is what makes a shaft a SHAFT, and the point samples
+--     a wind-blown noise field: the dapple drifts and shivers like
+--     leaves moving overhead, opening and closing the beams as it goes.
+--
+-- The shafts lean along the fixed noon shear, deliberately: a canopy
+-- map's rig is pinned to noon (see DayNight.CANOPY), so light that
+-- followed the sun's arc would part company with every shadow on the
+-- floor. What follows the clock is colour and strength -- gold spears of
+-- sun by day, silver moon rays after dark, dying back through the
+-- twilights -- plus the crew each shift brings: pollen adrift in the
+-- day's beams, fireflies once they cool. A forward-scattering phase term
+-- brightens the beams for a camera looking up into the light, which is
+-- most of what makes them read as light in air rather than paint on it.
+--
+-- Everything is deterministic: placement and the leaf field are dealt by
+-- a seeded xorshift (StadiumFx's generator), motion is a pure function
+-- of one `time` uniform, so a pinned ForestAtmos.time reproduces a frame
+-- exactly (see tests/forest_fog_shots). Every shader compiles lazily
+-- behind pcall -- nil untried, false unavailable -- and each refusal
+-- subtracts only itself: no march without readable depth, no beams
+-- without a shadow map, and the fog rides the scene shader whatever
+-- happens here.
+
+local V = ...
+
+local DayNight = V.require("DayNight")
+local ModSetting = V.require("ModSetting")
+
+local floor, sqrt, min, max = math.floor, math.sqrt, math.min, math.max
+
+local ForestAtmos = {}
+
+-- The viewport, as both shaders here take it (see Voxel3D.cull: the field
+-- is set for a headset's diorama frame and for an orbit rung's window box,
+-- and nil for every other, where kind 0 means "no cut"). Read through
+-- V.require rather than held as an upvalue because this file loads before
+-- Voxel3D on some paths.
+local function cullAt()
+  local c = V.require("Voxel3D").cull
+  return c and { c.x, c.y, c.z } or { 0, 0, 0 }
+end
+
+local function cullShape()
+  local c = V.require("Voxel3D").cull
+  return c and { c.r, c.invFade, c.kind } or { 0, 0, 0 }
+end
+
+local function cullRect()
+  local c = V.require("Voxel3D").cull
+  return c and { c.rx or c.r, c.rz or c.r } or { 0, 0 }
+end
+
+-- FULL is the point; LOW halves the march and drops the particles, for
+-- hardware that minds a per-pixel loop under 4X supersampling.
+--
+-- On ANDROID the ladder itself is shorter: LOW and OFF, with LOW the
+-- default. The march needs a depth texture it can READ, and no driver on
+-- the phones this runs on has granted one (see newDepth in Voxel3D) --
+-- so FULL would be a rung with nothing behind it, which reads as a
+-- broken mod rather than a missing feature. LOW there is the haze, the
+-- one part of the atmosphere that rides the scene shader and works
+-- everywhere. A desktop save opened on a phone stores FULL still;
+-- ModSetting's unknown-value fallback lands it on LOW, and putting the
+-- save back on the desktop restores the choice.
+local function onAndroid()
+  if not (love and love.system and love.system.getOS) then return false end
+  local ok, os = pcall(love.system.getOS)
+  return ok and os == "Android"
+end
+
+ForestAtmos.setting = onAndroid()
+  and ModSetting.new("atmos", "FOREST FX", { "low", "off" },
+                     { "LOW", "OFF" })
+  or ModSetting.new("atmos", "FOREST FX", { "full", "low", "off" },
+                    { "FULL", "LOW", "OFF" })
+
+-- the animation clock: ticked by main.lua's always-running update hook,
+-- pinnable (frozen = true) so a screenshot driver can hold a frame still
+ForestAtmos.time = 0
+ForestAtmos.frozen = false
+
+function ForestAtmos.update(dt)
+  if ForestAtmos.frozen then return end
+  ForestAtmos.time = ForestAtmos.time + (dt or 0)
+end
+
+-- ------- the authored table
+--
+-- Same shape as BattleArena's: the data file behind a pcall with a false
+-- sentinel, and an overrides table a tuning driver can stage a candidate
+-- through before anything is written down. `~= nil` on the override,
+-- because false is meaningful -- "this map has no atmosphere, whatever
+-- the file says".
+
+local authored = nil
+local overrides = {}
+
+local function configFor(mapId)
+  if not mapId then return nil end
+  local forced = overrides[mapId]
+  if forced ~= nil then return forced or nil end
+  if authored == nil then
+    local ok, list = pcall(V.data, "map_atmosphere")
+    authored = (ok and type(list) == "table") and list or false
+  end
+  if not authored then return nil end
+  return authored[mapId]
+end
+
+ForestAtmos.configFor = configFor
+
+-- ------- caches
+--
+-- Particle layouts and meshes go stale with the map (map.reloaded, and
+-- the pipeline's invalidate); called with no map id this also resets the
+-- shader and texture sentinels, which is what a lost GL context needs.
+
+local layoutCache = {}
+local meshCache = {}
+local shaders = {}            -- keyed by variant; nil untried, false refused
+local leafTex = nil           -- the tiling leaf-dapple field
+local rayMesh = nil           -- the fullscreen ray-fan quad, re-aimed per draw
+
+-- Every bail here is deliberate and silent on screen -- a missing piece
+-- subtracts itself, never the frame -- but "the beams are off" and "the
+-- beams are off BECAUSE ..." are different debugging days. Each reason
+-- is said once on the console, the way VR reports a missing runtime.
+local said = {}
+local function say(key, msg)
+  if said[key] then return end
+  said[key] = true
+  print("[DRAMATIC_SHAPE] atmos: " .. msg)
+end
+
+function ForestAtmos.invalidate(mapId)
+  if mapId then
+    layoutCache[mapId] = nil
+    meshCache[mapId] = nil
+  else
+    layoutCache, meshCache = {}, {}
+    shaders = {}
+    leafTex = nil
+    rayMesh = nil
+  end
+end
+
+function ForestAtmos.setOverride(mapId, entry)
+  overrides[mapId] = entry
+  ForestAtmos.invalidate(mapId)
+end
+
+-- ------- the hour's answer
+--
+-- One ramp, authored per phase and blended with DayNight's own weights,
+-- so the fog and the rays can never disagree about what hour it is. The
+-- two interact three ways: the fog colour leans toward the ray colour
+-- (noon warms the haze, midnight silvers it), the rays scale with the
+-- fog's density (a beam IS lit fog -- less medium, less beam), and the
+-- march accumulates through the same density the surfaces sink into.
+
+ForestAtmos.RAMP = {
+  day    = { fog = { 0.78, 0.86, 0.70 }, ray = { 1.00, 0.93, 0.70 },
+             alpha = 0.55, density = 1.00, motes = 1.0, flies = 0.0 },
+  golden = { fog = { 0.84, 0.76, 0.58 }, ray = { 1.00, 0.85, 0.55 },
+             alpha = 0.35, density = 1.00, motes = 0.6, flies = 0.0 },
+  dawn   = { fog = { 0.80, 0.70, 0.66 }, ray = { 1.00, 0.80, 0.62 },
+             alpha = 0.20, density = 1.05, motes = 0.3, flies = 0.25 },
+  dusk   = { fog = { 0.78, 0.66, 0.58 }, ray = { 1.00, 0.76, 0.55 },
+             alpha = 0.20, density = 1.05, motes = 0.2, flies = 0.5 },
+  violet = { fog = { 0.52, 0.50, 0.66 }, ray = { 0.82, 0.80, 1.00 },
+             alpha = 0.25, density = 1.10, motes = 0.0, flies = 1.0 },
+  night  = { fog = { 0.34, 0.40, 0.56 }, ray = { 0.72, 0.80, 1.00 },
+             alpha = 0.40, density = 1.15, motes = 0.0, flies = 1.0 },
+}
+
+-- The frame's atmosphere for `map` at clock `t` (defaulting to now), or
+-- nil -- no entry, or the row is OFF -- in which case nothing is drawn
+-- and Voxel3D.fog should be left nil.
+function ForestAtmos.frame(map, t)
+  if ForestAtmos.setting:get() == "off" then return nil end
+  local cfg = configFor(map and map.id)
+  if not cfg then return nil end
+  local mix = DayNight.mix(t or DayNight.time())
+  local fr, fg, fb, rr, rg, rb = 0, 0, 0, 0, 0, 0
+  local alpha, dens, motes, flies = 0, 0, 0, 0
+  for name, w in pairs(mix) do
+    local p = ForestAtmos.RAMP[name] or ForestAtmos.RAMP.day
+    fr, fg, fb = fr + p.fog[1] * w, fg + p.fog[2] * w, fb + p.fog[3] * w
+    rr, rg, rb = rr + p.ray[1] * w, rg + p.ray[2] * w, rb + p.ray[3] * w
+    alpha = alpha + p.alpha * w
+    dens = dens + p.density * w
+    motes = motes + p.motes * w
+    flies = flies + p.flies * w
+  end
+  -- the haze takes on a little of the light standing in it
+  local LEAN = 0.15
+  fr = fr + (rr - fr) * LEAN
+  fg = fg + (rg - fg) * LEAN
+  fb = fb + (rb - fb) * LEAN
+  local base = cfg.fog or {}
+  local rays = cfg.rays or {}
+  return {
+    -- in exactly the shape Voxel3D.fog takes, so callers assign it whole
+    fog = { color = { fr, fg, fb },
+            density = (base.density or 0) * dens,
+            start = base.start or 0,
+            heightK = base.heightK or 0 },
+    rayColor = { rr, rg, rb },
+    -- a beam is scattered fog: less medium, less beam
+    rayAlpha = alpha * (0.4 + 0.6 * min(dens, 1)),
+    rayStrength = rays.strength or 12,
+    rayReach = rays.reach or 380,
+    moteLevel = motes,
+    fireflyLevel = flies,
+    cfg = cfg,
+  }
+end
+
+-- ------- deterministic noise
+--
+-- The same written-out xorshift StadiumFx runs (see the note there on why
+-- not LuaJIT's `bit`): the particle deal and the leaf field must come out
+-- identical on every machine and every visit.
+
+local function bxor32(a, b)
+  local r, p = 0, 1
+  for _ = 1, 32 do
+    local x, y = a % 2, b % 2
+    if x ~= y then r = r + p end
+    a, b, p = floor(a / 2), floor(b / 2), p * 2
+  end
+  return r
+end
+
+local Rng = {}
+Rng.__index = Rng
+
+local function newRng(seed)
+  local s = seed % 0x100000000
+  if s == 0 then s = 0x9E3779B9 end
+  return setmetatable({ s = s }, Rng)
+end
+
+function Rng:next()
+  local x = self.s
+  x = bxor32(x, (x % 0x80000) * 0x2000)               -- x ^= (x << 13)
+  x = bxor32(x, floor(x / 0x20000))                   -- x ^= x >> 17
+  x = bxor32(x, (x % 0x8000000) * 0x20)               -- x ^= (x << 5)
+  self.s = x % 0x100000000
+  return self.s
+end
+
+function Rng:unit()
+  return self:next() / 0x100000000
+end
+
+-- bilinear value noise on a torus (StadiumFx's), so the leaf field tiles
+local function lattice(rng, w, h)
+  local g = {}
+  for y = 1, h do
+    local row = {}
+    for x = 1, w do row[x] = rng:unit() end
+    g[y] = row
+  end
+  return g
+end
+
+local function smoothstep01(t)
+  return t * t * (3 - 2 * t)
+end
+
+local function torus(grid, w, h, x, y)
+  local x0, y0 = floor(x), floor(y)
+  local fx, fy = smoothstep01(x - x0), smoothstep01(y - y0)
+  local x1, y1 = (x0 + 1) % w, (y0 + 1) % h
+  x0, y0 = x0 % w, y0 % h
+  local a = grid[y0 + 1][x0 + 1]
+  local b = grid[y0 + 1][x1 + 1]
+  local c = grid[y1 + 1][x0 + 1]
+  local d = grid[y1 + 1][x1 + 1]
+  return (a + (b - a) * fx) + ((c + (d - c) * fx) - (a + (b - a) * fx)) * fy
+end
+
+-- ------- the leaf field
+--
+-- One small tiling texture of three-octave value noise, generated once
+-- from a fixed seed: the pattern of the unseen foliage. The shader reads
+-- it at two drifting, differently-scaled offsets and thresholds the sum,
+-- so the pools of light between the leaves slide, open and close -- the
+-- movement is the WIND's, all in the sampling; the cloth itself never
+-- changes, which is what keeps a pinned frame reproducible.
+
+local function leafTexture()
+  if leafTex ~= nil then return leafTex or nil end
+  if not (love and love.image and love.image.newImageData
+          and love.graphics and love.graphics.newImage) then
+    leafTex = false
+    return nil
+  end
+  local ok, tex = pcall(function()
+    local N = 128
+    local rng = newRng(0x1EAF)
+    local g1 = lattice(rng, 8, 8)
+    local g2 = lattice(rng, 16, 16)
+    local g3 = lattice(rng, 32, 32)
+    local img = love.image.newImageData(N, N)
+    for y = 0, N - 1 do
+      local v = y / N
+      for x = 0, N - 1 do
+        local u = x / N
+        local n = torus(g1, 8, 8, u * 8, v * 8) * 0.5
+                + torus(g2, 16, 16, u * 16, v * 16) * 0.3
+                + torus(g3, 32, 32, u * 32, v * 32) * 0.2
+        img:setPixel(x, y, n, n, n, 1)
+      end
+    end
+    local t = love.graphics.newImage(img)
+    t:setWrap("repeat", "repeat")
+    t:setFilter("linear", "linear")
+    return t
+  end)
+  leafTex = (ok and tex) or false
+  return leafTex or nil
+end
+
+-- ------- placement (the particles; the light places itself)
+
+local MARGIN = 24     -- keep off the map's edge, world px
+
+function ForestAtmos.layout(cfg, w, h)
+  local rng = newRng((cfg.seed or 0x51D))
+  local canopy = cfg.canopyY or 56
+  local motes = {}
+  for _ = 1, (cfg.motes and cfg.motes.count) or 0 do
+    motes[#motes + 1] = {
+      x = MARGIN + rng:unit() * max(w - 2 * MARGIN, 1),
+      y = 3 + rng:unit() * max(canopy - 11, 8),
+      z = MARGIN + rng:unit() * max(h - 2 * MARGIN, 1),
+      phase = rng:unit() * 6.2832,
+      rate = 0.5 + rng:unit(),
+    }
+  end
+  local flies = {}
+  for _ = 1, (cfg.fireflies and cfg.fireflies.count) or 0 do
+    flies[#flies + 1] = {
+      x = MARGIN + rng:unit() * max(w - 2 * MARGIN, 1),
+      y = 3 + rng:unit() * 12,
+      z = MARGIN + rng:unit() * max(h - 2 * MARGIN, 1),
+      phase = rng:unit() * 6.2832,
+      rate = 0.5 + rng:unit(),
+    }
+  end
+  return { motes = motes, flies = flies }
+end
+
+-- A map is width x height BLOCKS of 4x4 tiles of 8 pixels -- times 32
+-- for world pixels (the same arithmetic Structures runs in tiles).
+local function layoutFor(map)
+  local hit = layoutCache[map.id]
+  if hit ~= nil then return hit or nil end
+  local cfg = configFor(map.id)
+  if not cfg then
+    layoutCache[map.id] = false
+    return nil
+  end
+  local def = map.def or {}
+  local L = ForestAtmos.layout(cfg, (def.width or 16) * 32,
+                               (def.height or 16) * 32)
+  layoutCache[map.id] = L
+  return L
+end
+
+ForestAtmos.layoutFor = layoutFor
+
+-- ------- the volumetric march
+--
+-- A fullscreen quad whose four corners carry the camera's own frustum
+-- rays; the varying interpolates them into a world ray per pixel. The
+-- pixel stage walks that ray to the depth buffer's surface, and every
+-- step of air on the way is lit or not by the shadow map and the leaf
+-- field, accumulated through the same haze the surfaces sink into.
+--
+-- Conventions copied from Water's march: the ray walks the FLAT world
+-- (the space it is straight in) and every depth compare bends the sample
+-- first, by the same displacement the vertex stage applies -- so the
+-- march reads the depth buffer it actually has. The shadow lookup stays
+-- flat, exactly like the scene shader's own vSun. STEPS is spliced into
+-- the source rather than sent (the LOW rung is a second compile), and
+-- there are no uniform arrays anywhere -- see the note in Sky about the
+-- Android driver that reads them as zero.
+
+local RAY_SHADER = [[
+  varying vec3 vRay;
+#ifdef VERTEX
+  attribute vec3 RayDir;
+  vec4 position(mat4 transform_projection, vec4 vertex_position) {
+    vRay = RayDir;
+    return transform_projection * vertex_position;
+  }
+#endif
+#ifdef PIXEL
+  uniform Image depthTex;    // the frame's own depth, detached to read
+  uniform Image sunMap;      // the sun's answer (see ShadowMap)
+  uniform Image leafTex;     // the unseen foliage, tiling
+  uniform mat4 vp;
+  uniform mat4 sunVP;
+  uniform float sunBias;
+  uniform vec3 eye;
+  uniform vec3 curve;        // xy = the focus in world XZ, z = k; 0 = off
+  uniform vec2 screen;       // canvas size, for the pixel's own uv
+  uniform vec4 fogW;         // density, heightK, canopyY, fadeTo
+  uniform vec3 shear;        // the noon shear kx, kz; z = reach
+  uniform vec3 rayColor;
+  uniform float strength;
+  uniform vec3 sunward;      // unit, toward the unseen sun
+  uniform vec2 wind;         // leaf-field drift, uv per second
+  uniform float time;
+  // the viewport, as the scene shader takes it (see Voxel3D): air outside
+  // the model is not air, so a sample out there contributes nothing and
+  // the beams end with the world they fall through
+  uniform vec3 cullAt;
+  uniform vec3 cullShape;
+  uniform vec2 cullRect;     // the box's half-extents in x and z
+
+  float dioramaCull(vec3 p) {
+    if (cullShape.z <= 0.5) return 1.0;
+    vec3 cd = p - cullAt;
+    float inside;
+    if (cullShape.z < 1.5) {                 // the box
+      inside = min(cullRect.x - abs(cd.x), cullRect.y - abs(cd.z));
+    } else if (cullShape.z < 2.5) {
+      inside = cullShape.x - length(cd);     // the ball
+    } else {
+      inside = cullShape.x - length(cd.xz);  // the fight's pillar
+    }
+    return clamp(inside * cullShape.y, 0.0, 1.0);
+  }
+
+  float sunDepth(vec2 uv) {
+    vec4 c = Texel(sunMap, uv);
+    return c.r + c.g * (1.0 / 255.0);
+  }
+
+  vec4 effect(vec4 color, Image tex, vec2 tc, vec2 sc) {
+    vec2 uv = sc / screen;
+    float sceneD = Texel(depthTex, uv).r;
+    vec3 dir = normalize(vRay);
+    // Spend every sample where a sample can glow. Above the canopy no
+    // beam exists, and below the floor there is no air at all -- so the
+    // march runs from where this ray first dips under the leaves to
+    // where it would pass the ground, however long or short that
+    // stretch is. From the orbit camera that is the last few dozen
+    // pixels of a mostly-vertical ray, and dividing the WHOLE reach by
+    // the step count there starved the beams to nothing.
+    float t0 = 0.0;
+    if (eye.y > fogW.z) {
+      if (dir.y >= -0.01) return vec4(0.0);
+      t0 = (eye.y - fogW.z) / -dir.y;
+    }
+    float tEnd = shear.z;
+    if (dir.y < -0.01) {
+      tEnd = min(tEnd, (eye.y + 8.0) / -dir.y);
+    }
+    if (tEnd <= t0) return vec4(0.0);
+    // interleaved gradient noise staggers neighbouring pixels' steps,
+    // which is what turns 20-odd samples into a smooth volume instead
+    // of an onion of banded slices
+    float jitter = fract(52.9829189
+                         * fract(dot(sc, vec2(0.06711056, 0.00583715))));
+    float dt = (tEnd - t0) / float(STEPS);
+    // HALF the fog's own extinction, on the way in and per step: the
+    // full rate is what the surfaces sink by, and beams that obeyed it
+    // too died before the orbit camera ever saw them. Half keeps the
+    // depth cue and leaves the light alive.
+    float trans = exp(-fogW.x * 0.5 * t0);
+    float acc = 0.0;
+    for (int i = 0; i < STEPS; i++) {
+      float t = t0 + (float(i) + jitter) * dt;
+      vec3 p = eye + dir * t;
+      // stop at the surface: bend the sample the way the geometry bent
+      vec2 cd = p.xz - curve.xy;
+      vec4 c = vp * vec4(p.x, p.y - dot(cd, cd) * curve.z, p.z, 1.0);
+      if (c.w <= 1e-6) break;
+      if (c.z / c.w * 0.5 + 0.5 > sceneD) break;
+      if (p.y < fogW.z) {
+        // the sun's question: is this air behind a tree? Outside the
+        // frustum nothing was recorded and the air counts as lit, eased
+        // at the rim exactly like the scene shader's shadows
+        float lit = 1.0;
+        vec3 su = (sunVP * vec4(p, 1.0)).xyz;
+        if (su.x > 0.0 && su.x < 1.0 && su.y > 0.0 && su.y < 1.0
+            && su.z < 1.0) {
+          vec2 e2 = min(su.xy, 1.0 - su.xy);
+          float edge = smoothstep(0.0, 0.06, min(e2.x, e2.y));
+          lit = mix(1.0, step(su.z - sunBias, sunDepth(su.xy)), edge);
+        }
+        // the canopy's question: where did this thread of light pierce
+        // the leaves? Every step of air on one sun ray shares the
+        // answer -- that shared point is what makes a shaft a shaft --
+        // and the two drifting reads of the field are the wind moving
+        // the foliage overhead, opening and closing the beams
+        float up = fogW.z - p.y;
+        vec2 gap = (p.xz - shear.xy * up) * (1.0 / 96.0);
+        float n = Texel(leafTex, gap + wind * time).r * 0.65
+                + Texel(leafTex, gap * 2.3 - wind * (time * 0.7)
+                        + vec2(0.37, 0.61)).r * 0.35;
+        float dapple = 0.08 + 0.92 * smoothstep(0.45, 0.85, n);
+        // the beam fades IN below the invisible canopy, thins with
+        // altitude like the haze it is made of, and kisses the floor
+        float y = max(p.y, 0.0);
+        float fadeIn = clamp(up / max(fogW.z - fogW.w, 1.0), 0.0, 1.0);
+        float foot = 0.55 + 0.45 * clamp(y / 16.0, 0.0, 1.0);
+        float dens = fogW.x * exp(-y * fogW.y);
+        acc += trans * lit * dapple * fadeIn * foot * dens * dt
+               * dioramaCull(p);
+      }
+      trans *= exp(-fogW.x * 0.5 * dt);
+    }
+    // forward scattering: beams bloom for a camera looking up into the
+    // light, which is most of what makes them read as light IN air
+    float phase = 0.35 + 0.65 * pow(max(dot(dir, sunward), 0.0), 6.0);
+    return vec4(rayColor * (acc * strength * phase), 1.0) * color;
+  }
+#endif
+]]
+
+local function rayShaderFor(steps)
+  local key = "ray" .. steps
+  local s = shaders[key]
+  if s ~= nil then return s or nil end
+  if not (love and love.graphics and love.graphics.newShader) then
+    shaders[key] = false
+    return nil
+  end
+  local src = "#define STEPS " .. steps .. "\n" .. RAY_SHADER
+  local ok, sh = pcall(love.graphics.newShader, src)
+  if not ok then
+    say(key, "ray shader refused -- beams off, fog stays: "
+        .. tostring(sh))
+  end
+  shaders[key] = (ok and sh) or false
+  return shaders[key] or nil
+end
+
+local RAY_FORMAT = {
+  { "VertexPosition", "float", 2 },
+  { "RayDir", "float", 3 },
+}
+
+-- The camera's frustum corners, from the same fields every pass sets:
+-- eye, focus, fovY, and the placed camera's up when there is one (VR
+-- eyes roll; the orbit never does). Interpolating a corner ray across
+-- the quad IS the standard reconstruction for a perspective camera, so
+-- this works identically for the orbit, first person and both eyes.
+local function rayQuad(Voxel3D, w, h)
+  local e, fo, fov = Voxel3D.eye, Voxel3D.focus, Voxel3D.fovY
+  if not (e and fo and fov) then return nil end
+  local fx, fy, fz = fo[1] - e[1], fo[2] - e[2], fo[3] - e[3]
+  local fl = sqrt(fx * fx + fy * fy + fz * fz)
+  if fl < 1e-6 then return nil end
+  fx, fy, fz = fx / fl, fy / fl, fz / fl
+  local cam = Voxel3D.camera
+  local up = (cam and cam.up) or { 0, 1, 0 }
+  -- right = forward x up, then a true up perpendicular to both
+  local rx = fy * up[3] - fz * up[2]
+  local ry = fz * up[1] - fx * up[3]
+  local rz = fx * up[2] - fy * up[1]
+  local rl = sqrt(rx * rx + ry * ry + rz * rz)
+  if rl < 1e-6 then return nil end
+  rx, ry, rz = rx / rl, ry / rl, rz / rl
+  local ux = ry * fz - rz * fy
+  local uy = rz * fx - rx * fz
+  local uz = rx * fy - ry * fx
+  local hh = math.tan(fov * 0.5)
+  local hw = hh * (w / h)
+  -- canvas row 0 is the TOP of the frame, which is the +up corner
+  local function corner(su, sv)
+    return fx + rx * hw * su + ux * hh * sv,
+           fy + ry * hw * su + uy * hh * sv,
+           fz + rz * hw * su + uz * hh * sv
+  end
+  local x0, y0, z0 = corner(-1, 1)
+  local x1, y1, z1 = corner(1, 1)
+  local x2, y2, z2 = corner(1, -1)
+  local x3, y3, z3 = corner(-1, -1)
+  local verts = {
+    { 0, 0, x0, y0, z0 },
+    { w, 0, x1, y1, z1 },
+    { w, h, x2, y2, z2 },
+    { 0, h, x3, y3, z3 },
+  }
+  if not rayMesh then
+    local ok, mesh = pcall(love.graphics.newMesh, RAY_FORMAT, verts,
+                           "fan", "stream")
+    rayMesh = ok and mesh or nil
+    return rayMesh
+  end
+  local ok = pcall(rayMesh.setVertices, rayMesh, verts)
+  return ok and rayMesh or nil
+end
+
+-- ------- the particles
+
+local PART_SHADER = [[
+  varying vec2 vCorner;
+  varying float vGlow;
+#ifdef VERTEX
+  uniform mat4 vp;
+  uniform vec3 curve;
+  uniform vec3 cullAt;     // the viewport (see Voxel3D.cull): a mote
+  uniform vec3 cullShape;  // outside the model is not in the air
+  uniform vec2 cullRect;   // the box's half-extents in x and z
+  uniform vec3 axisR;      // the camera's right, world space
+  uniform vec3 axisU;      // and its up: the billboard's own frame
+  uniform float time;
+  uniform float size;
+  uniform vec2 sway;       // wander amplitude: horizontal, vertical
+  uniform float blinky;    // 0 = steady motes, 1 = blinking fireflies
+  attribute vec4 AtmosData;    // corner x, corner y, phase, rate
+  vec4 position(mat4 transform_projection, vec4 vertex_position) {
+    float ph = AtmosData.z;
+    float rt = AtmosData.w;
+    float t = time * (0.5 + rt);
+    // bounded wander only -- three incommensurate sines, so nothing ever
+    // walks off the map or needs a CPU tick to bring it home
+    vec3 base = vertex_position.xyz + vec3(
+      sin(t * 0.23 + ph) * sway.x,
+      sin(t * 0.17 + ph * 2.7) * sway.y,
+      cos(t * 0.19 + ph * 1.3) * sway.x);
+    float s = 0.5 + 0.5 * sin(t * 1.6 + ph * 9.0);
+    vGlow = mix(1.0, smoothstep(0.35, 0.75, s), blinky);
+    // a whole mote at once: these are points, so the rim can dim them
+    // rather than having to cut one in half
+    if (cullShape.z > 0.5) {
+      vec3 cd = base - cullAt;
+      float inside;
+      if (cullShape.z < 1.5) {
+        inside = min(cullRect.x - abs(cd.x), cullRect.y - abs(cd.z));
+      } else if (cullShape.z < 2.5) {
+        inside = cullShape.x - length(cd);
+      } else {
+        inside = cullShape.x - length(cd.xz);
+      }
+      vGlow *= clamp(inside * cullShape.y, 0.0, 1.0);
+    }
+    vCorner = AtmosData.xy;
+    vec4 w = vec4(base + axisR * (AtmosData.x * size)
+                       + axisU * (AtmosData.y * size), 1.0);
+    if (curve.z > 0.0) {
+      vec2 cd = w.xz - curve.xy;
+      w.y -= dot(cd, cd) * curve.z;
+    }
+    return vp * w;
+  }
+#endif
+#ifdef PIXEL
+  uniform vec3 dotColor;
+  uniform float level;
+  vec4 effect(vec4 color, Image tex, vec2 tc, vec2 sc) {
+    float d = dot(vCorner, vCorner);
+    float glow = max(0.0, 1.0 - d);
+    glow *= glow;
+    return vec4(dotColor, glow * level * vGlow) * color;
+  }
+#endif
+]]
+
+local function partShader()
+  local s = shaders.part
+  if s ~= nil then return s or nil end
+  if not (love and love.graphics and love.graphics.newShader) then
+    shaders.part = false
+    return nil
+  end
+  local ok, sh = pcall(love.graphics.newShader, PART_SHADER)
+  shaders.part = (ok and sh) or false
+  return shaders.part or nil
+end
+
+local PART_FORMAT = {
+  { "VertexPosition", "float", 3 },
+  { "AtmosData", "float", 4 },
+}
+
+local CORNERS = { { -1, -1 }, { 1, -1 }, { 1, 1 }, { -1, 1 } }
+
+local function pushQuad(map, n)
+  local b = n * 4
+  map[#map + 1] = b + 1
+  map[#map + 1] = b + 2
+  map[#map + 1] = b + 3
+  map[#map + 1] = b + 1
+  map[#map + 1] = b + 3
+  map[#map + 1] = b + 4
+end
+
+local function buildPartMesh(points)
+  if #points == 0 then return nil end
+  local verts, indices = {}, {}
+  for i = 1, #points do
+    local p = points[i]
+    for c = 1, 4 do
+      verts[#verts + 1] = { p.x, p.y, p.z,
+                            CORNERS[c][1], CORNERS[c][2], p.phase, p.rate }
+    end
+    pushQuad(indices, i - 1)
+  end
+  local ok, mesh = pcall(love.graphics.newMesh, PART_FORMAT, verts,
+                         "triangles", "static")
+  if not ok then return nil end
+  pcall(mesh.setVertexMap, mesh, indices)
+  return mesh
+end
+
+local function meshesFor(map, L)
+  local hit = meshCache[map.id]
+  if hit then return hit end
+  local M = {
+    motes = buildPartMesh(L.motes),
+    flies = buildPartMesh(L.flies),
+  }
+  meshCache[map.id] = M
+  return M
+end
+
+local MOTE_COLOR = { 1.0, 0.96, 0.78 }
+local FLY_COLOR = { 0.72, 1.0, 0.45 }
+
+-- The billboard frame: the camera's own right and up, from the same
+-- fields every pass sets (per VR eye too -- drawScene runs per eye and
+-- reads the eye's camera). Degenerate looks answer nil and the
+-- particles sit this one out.
+local function billboardAxes(Voxel3D)
+  local e, fo = Voxel3D.eye, Voxel3D.focus
+  if not (e and fo) then return nil end
+  local lx, ly, lz = fo[1] - e[1], fo[2] - e[2], fo[3] - e[3]
+  local ll = sqrt(lx * lx + ly * ly + lz * lz)
+  if ll < 1e-6 then return nil end
+  lx, ly, lz = lx / ll, ly / ll, lz / ll
+  local rx, rz = -lz, lx
+  local rl = sqrt(rx * rx + rz * rz)
+  if rl < 1e-4 then return nil end
+  rx, rz = rx / rl, rz / rl
+  return { rx, 0, rz }, { -rz * ly, rz * lx - rx * lz, rx * ly }
+end
+
+-- ------- the draw
+--
+-- Inside the scene pass, in VoxelScene's prop slot. The march borrows
+-- the frame's depth through Voxel3D.beginWater -- the same detach Water
+-- runs -- and hand-tests every step against it, so the pass itself needs
+-- no depth attachment; the particles come after, depth-tested additive
+-- geometry like the Stadium flames. Anything missing -- no entry, OFF, a
+-- refused shader, no readable depth, no shadow map -- subtracts only
+-- itself.
+function ForestAtmos.draw(map)
+  local rung = ForestAtmos.setting:get()
+  if rung == "off" then return end
+  local f = ForestAtmos.frame(map)
+  if not f then return end
+  local Voxel3D = V.require("Voxel3D")
+  local ShadowMap = V.require("ShadowMap")
+
+  if f.rayAlpha > 0.01 then
+    if not Voxel3D.depthReadable() then
+      say("depth", "no readable depth this frame -- beams off, fog stays")
+      return
+    end
+    -- no beams without the sun's own pass: uvVP is only the world -> map
+    -- transform while a shadow map is actually standing
+    local sunTex = ShadowMap.active() and ShadowMap.texture()
+    if not sunTex then
+      say("sun", "no shadow map standing -- beams off, fog stays")
+    end
+    local leaf = leafTexture()
+    if not leaf then
+      say("leaf", "leaf field would not build -- beams off, fog stays")
+    end
+    local sh = rayShaderFor(rung == "low" and 12 or 24)
+    local w, h = Voxel3D.size()
+    local quad = (sh and sunTex and leaf and w) and rayQuad(Voxel3D, w, h)
+    if sh and sunTex and leaf and w and not quad then
+      say("quad", "no camera frame for the ray fan -- beams off")
+    end
+    if quad then
+      local _, depth = Voxel3D.beginWater(nil)
+      if depth then
+        say("on", "volumetric beams running")
+        local kx, kz = DayNight.shearAt(DayNight.T.day)
+        local kl = sqrt(kx * kx + kz * kz + 1)
+        love.graphics.setBlendMode("add", "alphamultiply")
+        love.graphics.setShader(sh)
+        pcall(sh.send, sh, "depthTex", depth)
+        pcall(sh.send, sh, "sunMap", sunTex)
+        pcall(sh.send, sh, "leafTex", leaf)
+        pcall(sh.send, sh, "vp", "row", Voxel3D.vp)
+        pcall(sh.send, sh, "sunVP", "row", ShadowMap.uvVP)
+        pcall(sh.send, sh, "sunBias", ShadowMap.bias)
+        pcall(sh.send, sh, "eye", Voxel3D.eye)
+        pcall(sh.send, sh, "curve",
+              { Voxel3D.curveX or 0, Voxel3D.curveZ or 0,
+                Voxel3D.curveK or 0 })
+        pcall(sh.send, sh, "cullAt", cullAt())
+        pcall(sh.send, sh, "cullShape", cullShape())
+        pcall(sh.send, sh, "cullRect", cullRect())
+        pcall(sh.send, sh, "screen", { w, h })
+        pcall(sh.send, sh, "fogW",
+              { f.fog.density, f.fog.heightK,
+                f.cfg.canopyY or 56, f.cfg.fadeTo or 28 })
+        pcall(sh.send, sh, "shear", { kx, kz, f.rayReach })
+        pcall(sh.send, sh, "rayColor", f.rayColor)
+        pcall(sh.send, sh, "strength", f.rayStrength * f.rayAlpha)
+        pcall(sh.send, sh, "sunward", { -kx / kl, 1 / kl, -kz / kl })
+        pcall(sh.send, sh, "wind", { 0.016, 0.009 })
+        pcall(sh.send, sh, "time", ForestAtmos.time)
+        pcall(love.graphics.draw, quad)
+        love.graphics.setShader()
+        love.graphics.setBlendMode("alpha")
+      end
+      Voxel3D.endWater()
+    end
+  end
+
+  if rung == "full" then
+    local L = layoutFor(map)
+    local M = L and meshesFor(map, L)
+    local psh = partShader()
+    local axisR, axisU = billboardAxes(Voxel3D)
+    if M and psh and axisR then
+      Voxel3D.blend("add")
+      if Voxel3D.beginEffect(psh) then
+        pcall(psh.send, psh, "vp", "row", Voxel3D.vp)
+        pcall(psh.send, psh, "curve",
+              { Voxel3D.curveX or 0, Voxel3D.curveZ or 0,
+                Voxel3D.curveK or 0 })
+        pcall(psh.send, psh, "cullAt", cullAt())
+        pcall(psh.send, psh, "cullShape", cullShape())
+        pcall(psh.send, psh, "cullRect", cullRect())
+        pcall(psh.send, psh, "axisR", axisR)
+        pcall(psh.send, psh, "axisU", axisU)
+        pcall(psh.send, psh, "time", ForestAtmos.time)
+        if M.motes and f.moteLevel > 0.02 then
+          pcall(psh.send, psh, "size", 1.4)
+          pcall(psh.send, psh, "sway", { 5, 2.5 })
+          pcall(psh.send, psh, "blinky", 0)
+          pcall(psh.send, psh, "dotColor", MOTE_COLOR)
+          pcall(psh.send, psh, "level", f.moteLevel * 0.5)
+          pcall(love.graphics.draw, M.motes)
+        end
+        if M.flies and f.fireflyLevel > 0.02 then
+          pcall(psh.send, psh, "size", 1.6)
+          pcall(psh.send, psh, "sway", { 10, 4 })
+          pcall(psh.send, psh, "blinky", 1)
+          pcall(psh.send, psh, "dotColor", FLY_COLOR)
+          pcall(psh.send, psh, "level", f.fireflyLevel * 0.85)
+          pcall(love.graphics.draw, M.flies)
+        end
+        Voxel3D.endEffect()
+      end
+      Voxel3D.blend(nil)
+    end
+  end
+end
+
+return ForestAtmos

lib/FreeMove.lua

@@ -0,0 +1,387 @@
+-- Voxel world mode: free movement for the free-roam rungs.
+--
+-- The engine walks a grid: sixteen frames per cell, four directions,
+-- input locked mid-step. Inside a camera that stands with the player that
+-- gait reads as riding a rail, so while 1ST or 3RD drives, this module
+-- replaces the WALK and nothing else: the player's position becomes
+-- continuous, steered by the camera's own yaw -- push forward and you go
+-- where you look, at any angle, sliding along whatever you graze.
+--
+-- Both rungs walk identically: the boom behind the shoulder (3RD) changes
+-- where the eye stands, not which way it points, and the walk was always
+-- rotated by the YAW. The one thing it does change is which way the body
+-- POINTS while it moves -- see bodyFacing in the tick.
+--
+-- THE GRID IS STILL THE GAME. Every fact the world cares about is a fact
+-- about cells -- what blocks, what warps, what rustles, what bites -- and
+-- this module keeps the player's logical cell synced to wherever the free
+-- walk stands, then reuses the engine's own machinery for every one of
+-- those questions:
+--
+--   passability      the same isWalkableCell / water-while-surfing /
+--                    tile-pair / entity-occupancy verdicts Collision
+--                    hands the grid walker, asked per cell the player's
+--                    body overlaps.
+--
+--   cell arrival     OverworldState:onStepComplete, the same landing
+--                    pipeline a grid step runs -- warps, spinners, gates,
+--                    forced currents, poison, repel, encounters, the
+--                    step counters -- fired once per cell crossed, which
+--                    is exactly the rate a grid walk fires it.
+--
+--   the special pushes   walking off the map edge, into a ledge, or into
+--                    a boulder hands the quantised direction straight to
+--                    checkEdgeExit / checkLedgeHop / checkBoulderPush,
+--                    the engine's own handlers, which validate and stage
+--                    everything themselves (connections, the hop arc,
+--                    the two-push arm). While any of those animates a
+--                    scripted grid move, this module stands aside and
+--                    adopts the result.
+--
+-- Nothing here writes save state, rolls encounters, or decides what a
+-- warp does -- it moves a point, keeps the cell honest, and lets the
+-- engine be the engine. Stepping off the rung snaps the point to its
+-- cell and hands the walk back to the grid, and with the rung off this
+-- module costs one gate check per frame.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local FirstPerson = V.require("FirstPerson")
+
+local FreeMove = {}
+
+-- The body: a circle in the ground plane. Small enough to walk every
+-- one-cell corridor the grid game has (half a cell is 8), big enough to
+-- keep the eye's near plane out of wall faces when sliding along them.
+FreeMove.RADIUS = 5.5
+
+-- World pixels per fixed 60Hz frame -- the grid walker's own speeds (16
+-- frames per 16px cell on foot, 8 on the bike), so distance covered per
+-- second is unchanged and the encounter rate per tile crossed stays the
+-- game's own.
+FreeMove.WALK = 1.0
+FreeMove.BIKE = 2.0
+
+local EPS = 0.01
+
+-- the free position (player centre, world px) and the px/py we last wrote
+-- -- if they differ from the player's, something else (a warp, a script)
+-- moved them, and the free walk adopts rather than fights
+local pos = nil
+local lastPx, lastPy = nil, nil
+
+local function adopt(p)
+  pos = { x = p.px + 8, z = p.py + 8 }
+  lastPx, lastPy = p.px, p.py
+end
+
+function FreeMove.drop()
+  pos = nil
+  -- and the body with it: while something else is walking the player --
+  -- a scripted move, a ledge hop, the grid walk off the rung -- the
+  -- engine's own four-direction facing is the whole truth about which way
+  -- they point, so the card must stop reading our finer one
+  FirstPerson.releaseBody()
+end
+
+-- named for the suite: the module's live position, nil while dropped
+function FreeMove._pos()
+  return pos
+end
+
+-- ------- the per-cell verdict
+--
+-- The same questions Collision.canMove asks for a grid step, asked of one
+-- cell from the player's current standing. The player's OWN cell never
+-- blocks -- the body must always be free to leave wherever it stands
+-- (a warp mat, the water it is surfing, a cell an NPC just stepped
+-- against).
+
+local function pairBlocked(map, surfing, sx, sy, tx, ty)
+  local Game = require("src.core.Game")
+  local tp = Game.data and Game.data.field and Game.data.field.tilePairs
+  if not tp then return false end
+  local list = surfing and tp.water or tp.land
+  if not list or #list == 0 then return false end
+  local tileset = map.def.tileset
+  local a = map:cellTile(sx, sy)
+  local b = map:cellTile(tx, ty)
+  for _, p in ipairs(list) do
+    if p.tileset == tileset
+       and ((p.a == a and p.b == b) or (p.a == b and p.b == a)) then
+      return true
+    end
+  end
+  return false
+end
+
+-- Why (cx, cy) refuses the player's body, or nil when it may enter:
+-- "bounds" | "tile" | "entity", the grid verdict's own names.
+local function blockedCell(state, p, cx, cy)
+  if cx == p.cellX and cy == p.cellY then return nil end
+  local map = state.map
+  if not map:inBounds(cx, cy) then return "bounds" end
+  if not map:isWalkableCell(cx, cy) then
+    if not (p.surfing and map:isWaterCell(cx, cy)) then return "tile" end
+  end
+  if pairBlocked(map, p.surfing, p.cellX, p.cellY, cx, cy) then
+    return "tile"
+  end
+  local Collision = require("src.world.Collision")
+  if Collision.occupied(state.entities, cx, cy, p) then return "entity" end
+  return nil
+end
+
+FreeMove._blockedCell = blockedCell   -- named for the suite
+
+-- ------- the slide
+--
+-- One axis at a time, clamped at the first refusing cell's face: the
+-- classic axis-separated walk, which is where wall-sliding comes from --
+-- the blocked axis stops and the free one keeps going. Returns the
+-- refusal ("bounds"/"tile"/"entity") when this axis was clamped.
+
+local function slideX(state, p, dx)
+  if dx == 0 then return nil end
+  local r = FreeMove.RADIUS
+  local nx = pos.x + dx
+  local z0 = math.floor((pos.z - r + EPS) / 16)
+  local z1 = math.floor((pos.z + r - EPS) / 16)
+  local hit = nil
+  local edge = dx > 0 and math.floor((nx + r) / 16)
+               or math.floor((nx - r) / 16)
+  for zc = z0, z1 do
+    hit = blockedCell(state, p, edge, zc)
+    if hit then break end
+  end
+  if hit then
+    if dx > 0 then nx = math.min(nx, edge * 16 - r - EPS)
+    else nx = math.max(nx, (edge + 1) * 16 + r + EPS) end
+  end
+  pos.x = nx
+  return hit
+end
+
+local function slideZ(state, p, dz)
+  if dz == 0 then return nil end
+  local r = FreeMove.RADIUS
+  local nz = pos.z + dz
+  local x0 = math.floor((pos.x - r + EPS) / 16)
+  local x1 = math.floor((pos.x + r - EPS) / 16)
+  local hit = nil
+  local edge = dz > 0 and math.floor((nz + r) / 16)
+               or math.floor((nz - r) / 16)
+  for xc = x0, x1 do
+    hit = blockedCell(state, p, xc, edge)
+    if hit then break end
+  end
+  if hit then
+    if dz > 0 then nz = math.min(nz, edge * 16 - r - EPS)
+    else nz = math.max(nz, (edge + 1) * 16 + r + EPS) end
+  end
+  pos.z = nz
+  return hit
+end
+
+-- ------- the blocked push
+--
+-- The grid game's blocked step is where half its verbs live: the map-edge
+-- crossing, the ledge hop, the boulder shove, and the route-gate warp
+-- fired by collision. Hand the engine the quantised direction and let its
+-- own handlers decide -- each one validates itself (checkLedgeHop matches
+-- the tile pair, checkEdgeExit checks the bounds), so calling them on
+-- every firm push is safe. Returns true when one of them took the frame
+-- over.
+--
+-- The one verb NOT restated here is the bonk. On the grid a blocked step
+-- is a discrete event -- you pressed a direction, the game refused, and
+-- the bump answers you once. A free walk has no such moment: the body
+-- SLIDES along whatever it grazes, so a player walking a fence line or
+-- rounding a doorframe is blocked on one axis continuously, and the same
+-- sound comes out as a rattle for as long as they keep walking. It is
+-- feedback for a refusal that is not happening. The grid walk keeps its
+-- own bump (the engine's, in OverworldController) untouched.
+local function pushSpecials(state, dir, why)
+  local p = state.player
+  p.facing = dir      -- the handlers read the push off the facing
+  if why == "bounds" and state:checkEdgeExit(dir) then return true end
+  if state:checkLedgeHop(dir) then return true end
+  if state:checkBoulderPush(dir) then return true end
+  if why ~= "entity" and state:canCollisionWarp() then
+    local Game = require("src.core.Game")
+    local Warp = require("src.world.Warp")
+    local w = Warp.onCollision(state.map, Game.data.field.warpCarpets,
+                               p.cellX, p.cellY, dir)
+    if w then
+      state:takeWarp(w.def)
+      return true
+    end
+  end
+  -- and NO bonk. The grid walk's collision sound marks a discrete event:
+  -- you pressed a direction, the step was refused, nothing happened. A
+  -- free walk has no such moment -- the body slides along every wall it
+  -- grazes, continuously, and a corridor taken at a slight angle is a
+  -- steady graze from end to end. Rate-limited or not, that came out as a
+  -- machine-gun of bonks for walking normally down a hallway. The wall
+  -- stopping you is the feedback; the sound only ever said so twice a
+  -- second whether or not anything had changed.
+  return false
+end
+
+-- ------- the tick
+--
+-- Runs in place of OverworldState:handleInput while first person drives
+-- (see install below), which means it inherits every gate the grid walk
+-- has: never during scripted moves, transitions, or with anything above
+-- the overworld on the stack.
+
+function FreeMove.tick(state)
+  local p = state.player
+
+  -- a grid move is animating -- a ledge hop, a spinner slide, a scripted
+  -- walk -- or a cutscene owns the player: stand aside, adopt the result
+  if p.moving or p.inputLocked then
+    FreeMove.drop()
+    return
+  end
+  if not pos or p.px ~= lastPx or p.py ~= lastPy then adopt(p) end
+
+  local Game = require("src.core.Game")
+  local input = Game.input
+
+  -- the head is the facing: what A talks to, what the sun's card shows,
+  -- which way a bonk points. (A body that is WALKING may turn along its
+  -- travel instead -- see below, once there is a travel to turn along; a
+  -- standing one always faces where the camera looks, which is what makes
+  -- A predictable.) pointBody rather than compassFacing, so the card also
+  -- gets the CONTINUOUS bearing behind that compass point.
+  p.facing = FirstPerson.pointBody(0, 0)
+
+  -- HORDE MODE takes both of these away for as long as it runs: there is
+  -- no pausing (START), and nobody stops to read a sign with the horde
+  -- coming (A, which is also the button the mode's own GAME OVER card
+  -- wants left unspent). Everything below -- the walk, the wall slide and
+  -- the blocked-push verbs, warps included -- keeps working, because the
+  -- crowd has to be able to follow the player through a door.
+  local suppressed = V.require("Horde").suppressWorldInput()
+
+  if not suppressed and input:wasPressed("a") then
+    state:interact()
+    return
+  end
+  if not suppressed and input:wasPressed("start") then
+    require("src.core.Sound").play(Game.data, "Start_Menu")
+    require("src.ui.Screens").push(Game, "StartMenu")
+    return
+  end
+
+  local mx, mz = FirstPerson.moveVector()
+  local wx, wz = FirstPerson.moveWorld(mx, mz)
+
+  -- Cycling Road's downhill pull, the free-walk restatement of the grid
+  -- path's simulated PAD_DOWN: south drift with nothing held, braked by
+  -- holding A or B exactly as the Route 17 sign promises
+  local moving = (mx ~= 0 or mz ~= 0)
+  if not moving and Game.save and Game.save.onBike then
+    local fm = Game.data.field.forcedMovement
+    local braking = input:isDown("a") or input:isDown("b")
+    if fm and not braking then
+      for _, m in ipairs(fm.slopeMaps or {}) do
+        if m == state.map.id then
+          wx, wz, moving = 0, 1, true
+          break
+        end
+      end
+    end
+  end
+
+  if not moving then return end
+
+  -- and once there IS a direction of travel, the body may point along it
+  -- rather than along the head: on the boom (3RD) you can see yourself, so
+  -- a strafe has to look like walking sideways. In the head it is the head
+  -- either way -- bodyBearing says so.
+  p.facing = FirstPerson.pointBody(wx, wz)
+
+  -- the engine's own bonk clock, kept draining while the free walk has the
+  -- wheel: nothing here rings it (see pushSpecials), but stepping back onto
+  -- the grid must not inherit a cooldown frozen at whatever it held when
+  -- the rung was picked
+  state.bumpCooldown = math.max(0, (state.bumpCooldown or 0) - 1)
+
+  local speed = (Game.save and Game.save.onBike) and FreeMove.BIKE
+                or FreeMove.WALK
+  local dx, dz = wx * speed, wz * speed
+
+  local hitX = slideX(state, p, dx)
+  local hitZ = slideZ(state, p, dz)
+
+  -- the walk cycle: the wall-bonk clock animates the legs of a player the
+  -- grid thinks is standing still, refreshed while the free walk covers
+  -- ground (Player:update ticks animClock off it; walkPhase reads it)
+  p.bumpFrames = 2
+
+  p.px, p.py = pos.x - 8, pos.z - 8
+  lastPx, lastPy = p.px, p.py
+
+  -- the cell the body stands in; crossing into a new one IS a step
+  local ncx = math.floor(pos.x / 16)
+  local ncy = math.floor(pos.z / 16)
+  if ncx ~= p.cellX or ncy ~= p.cellY then
+    p.cellX, p.cellY = ncx, ncy
+    state:onStepComplete()
+    -- a warp or a battle may have moved the world out from under the
+    -- walk; the adopt check on the next tick picks the pieces up
+    return
+  end
+
+  -- a firm push into something that refused: the engine's own blocked-step
+  -- verbs, aimed the way the push leans
+  local hit, dir
+  if hitX and (not hitZ or math.abs(dx) >= math.abs(dz)) then
+    hit, dir = hitX, (dx > 0 and "right" or "left")
+  elseif hitZ then
+    hit, dir = hitZ, (dz > 0 and "down" or "up")
+  end
+  if hit and math.max(math.abs(dx), math.abs(dz)) > 0.4 * speed then
+    if pushSpecials(state, dir, hit) then
+      FreeMove.drop()
+      return
+    end
+    -- the push handlers may have turned the facing; the walk still rules
+    p.facing = FirstPerson.pointBody(wx, wz)
+  end
+end
+
+-- ------- the seam
+--
+-- OverworldState:handleInput is the one choke point where the grid walk
+-- reads the pad -- the same seam the engine's own Cycling Road pull and
+-- collision warps live behind -- so replacing the walk means wrapping it
+-- and nothing else. Every gate ABOVE the call (scripted moves, trainer
+-- engagement, transitions, anything on the stack) still applies to the
+-- free walk, because the wrap sits below them all.
+function FreeMove.install()
+  local OverworldState = require("src.world.OverworldController")
+  if OverworldState.dramaticShapeFreeMoveHook then return end
+  local inner = OverworldState.handleInput
+
+  function OverworldState:handleInput()
+    if not FirstPerson.driving() then
+      if pos then
+        -- stepping off the rung: back onto the grid, on the cell the
+        -- free walk stood in
+        local p = self.player
+        p.px, p.py = p.cellX * 16, p.cellY * 16
+        FreeMove.drop()
+      end
+      return inner(self)
+    end
+    return FreeMove.tick(self)
+  end
+
+  OverworldState.dramaticShapeFreeMoveHook = true
+end
+
+return FreeMove

lib/GlassMask.lua

@@ -0,0 +1,174 @@
+-- Voxel world mode: the glass in the windows, found rather than listed.
+--
+-- Buildings and doors in the overworld art carry small panes -- six texels
+-- wide, framed in black, with a diagonal shine drawn in. This module finds
+-- them by SHAPE in the tileset image itself: a border row of six black
+-- texels, four or five rows of black-flanked non-black glass under it, and
+-- a closing border row. No tile ids are hardcoded, so a total conversion
+-- that draws its own windows in the same idiom gets glass for free, and art
+-- with no windows gets an empty mask and costs nothing.
+--
+-- The scan slides at PIXEL granularity because the art does: the building
+-- window sits a row down inside its tile, and the door's pane straddles a
+-- 2x2 tile block entirely -- a per-tile matcher finds neither.
+--
+-- What the scan yields is a MASK TEXTURE the same size as the tileset
+-- atlas: opaque white on glass texels, transparent everywhere else. Terrain
+-- meshes sample the atlas by normalized coordinates (ChunkMesher.uvRect),
+-- so the scene shader can sample this mask with the SAME coordinates and
+-- know, per fragment, whether it is drawing glass -- on any wall, at any
+-- angle, in free-roam or a staged battle, with no geometry work anywhere.
+-- The recoloured atlases (display modes, RED++) keep the tileset's layout,
+-- so the alignment holds under every palette.
+--
+-- What the shader does with the answer (Voxel3D): by day a thin glint
+-- sweeps across the panes -- a pseudo reflection, view-anchored, preserving
+-- the art under it -- and after dark the panes are LIT: the texel's own
+-- shine pattern, warmed and brightened, exempt from the sun, the shadow
+-- map and the hour's tint, as a window with a lamp behind it is.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Assets = require("src.render.Assets")
+
+local GlassMask = {}
+
+-- pane geometry the scan accepts: six glass texels across, and this many
+-- rows of them between the two border rows
+GlassMask.GLASS_W = 6
+GlassMask.ROWS = { 4, 5 }        -- door pane, building pane
+
+-- Whether a channel triple is the border black. The raw tileset art is the
+-- four DMG greys, so black is genuinely zero; the threshold forgives a
+-- rescaled asset without accepting the dark grey rung (85/255 = 0.33).
+local function isBlack(r, g, b)
+  return r < 0.12 and g < 0.12 and b < 0.12
+end
+
+GlassMask._isBlack = isBlack     -- named for the suite
+
+-- Find every pane in an image, through a pure reader so the geometry is
+-- testable headless: `getPixel(x, y)` returns r, g, b in 0..1 for 0-based
+-- coordinates. Returns { {x=, y=, w=, h=}, ... } rects of GLASS texels
+-- (the border is the detector's evidence, not part of the answer).
+function GlassMask.scan(getPixel, w, h)
+  local function black(x, y)
+    return isBlack(getPixel(x, y))
+  end
+  local function borderRow(x, y)
+    for c = 1, 6 do
+      if not black(x + c, y) then return false end
+    end
+    return true
+  end
+  local function glassRow(x, y)
+    if not (black(x, y) and black(x + 7, y)) then return false end
+    for c = 1, 6 do
+      if black(x + c, y) then return false end
+    end
+    return true
+  end
+  local want = {}
+  for _, n in ipairs(GlassMask.ROWS) do want[n] = true end
+
+  local rects = {}
+  for y = 0, h - 1 do
+    for x = 0, w - 8 do
+      if borderRow(x, y) then
+        local n = 0
+        while y + 1 + n < h and glassRow(x, y + 1 + n) do
+          n = n + 1
+        end
+        if want[n] and y + 1 + n < h and borderRow(x, y + 1 + n) then
+          rects[#rects + 1] = { x = x + 1, y = y + 1,
+                                w = GlassMask.GLASS_W, h = n }
+        end
+      end
+    end
+  end
+  return rects
+end
+
+-- ------- the runtime cache, one entry per tileset image
+
+local cache = {}       -- image path -> { rects, texture (or false) }
+
+local function entry(tileset)
+  local path = tileset and tileset.image
+  if not path then return nil end
+  local hit = cache[path]
+  if hit then return hit end
+  local ok, data = pcall(Assets.imageData, path)
+  if not (ok and data) then
+    -- unreadable art is a verdict for the session, not a retry loop
+    cache[path] = { rects = {}, texture = false }
+    return cache[path]
+  end
+  local w, h = data:getDimensions()
+  local rects = GlassMask.scan(function(x, y)
+    return data:getPixel(x, y)
+  end, w, h)
+  local texture = false
+  if #rects > 0 and love.image and love.image.newImageData
+     and love.graphics and love.graphics.newImage then
+    local built = pcall(function()
+      local mask = love.image.newImageData(w, h)
+      for _, r in ipairs(rects) do
+        for yy = r.y, r.y + r.h - 1 do
+          for xx = r.x, r.x + r.w - 1 do
+            mask:setPixel(xx, yy, 1, 1, 1, 1)
+          end
+        end
+      end
+      texture = love.graphics.newImage(mask)
+      texture:setFilter("nearest", "nearest")
+    end)
+    if not built then texture = false end
+  end
+  cache[path] = { rects = rects, texture = texture }
+  return cache[path]
+end
+
+-- The panes found in a tileset's art, as glass rects in atlas pixels.
+function GlassMask.rects(tileset)
+  local e = entry(tileset)
+  return e and e.rects or {}
+end
+
+-- The mask texture for a tileset, or nil when it has no panes (or the art
+-- is unreadable, or there is no GPU) -- callers bind the blank instead.
+function GlassMask.texture(tileset)
+  local e = entry(tileset)
+  return (e and e.texture) or nil
+end
+
+-- A 1x1 transparent stand-in, for the frames (and drivers) with no mask:
+-- the scene shader always declares the sampler, and an unbound sampler is
+-- a driver-dependent crash rather than a fallback.
+local blank = nil
+
+function GlassMask.blank()
+  if blank == nil then
+    local ok, img = pcall(function()
+      local data = love.image.newImageData(1, 1)
+      data:setPixel(0, 0, 0, 0, 0, 0)
+      return love.graphics.newImage(data)
+    end)
+    blank = (ok and img) or false
+  end
+  return blank or nil
+end
+
+-- Drop the GPU objects (window resize, hot reload). The rects survive --
+-- they are a fact about the art -- but textures are rebuilt on demand.
+function GlassMask.invalidate()
+  for _, e in pairs(cache) do
+    if e.texture and e.texture.release then pcall(e.texture.release, e.texture) end
+    e.texture = false
+  end
+  cache = {}
+  blank = nil
+end
+
+return GlassMask

lib/Horde.lua

@@ -0,0 +1,707 @@
+-- HORDE MODE: the code, the dark, and the way back.
+--
+-- Up Up Down Down Left Right Left Right B A, standing in the overworld,
+-- and Kanto turns on you: the sky goes to a starless violet night, the
+-- Lavender Town theme comes up, the camera locks into the player's own
+-- head, a handgun appears in their right hand, and waves of people walk
+-- out of the dark to kill them. Score goes up per kill; when the health
+-- runs out a GAME OVER screen offers a score and PRESS A, and pressing it
+-- puts everything back exactly as it was.
+--
+-- WHAT THIS FILE OWNS: the code detector, the state machine, the snapshot
+-- and its restore, and every hook that holds the world still while the
+-- mode runs. The gun is lib/HordeGun, the crowd is lib/HordeMobs, the
+-- readout is lib/HordeHud, the sounds are lib/HordeSfx and the ending is
+-- lib/HordeGameOver.
+--
+-- IT IS NOT A STACK STATE, and that is the load-bearing decision. Pushing
+-- a state over the overworld stops StateStack ticking the overworld,
+-- which stops OverworldState:handleInput, which stops FreeMove -- the
+-- player would be unable to walk. So horde mode is a MODE FLAG driven
+-- from the voxel pipeline's update hook, exactly as lib/OverworldBattle
+-- rides it: the one tick that keeps running through menus, transitions
+-- and battles. The GAME OVER screen IS a pushed state, because by then
+-- the walking is over and freezing the world under it is the point.
+--
+-- THE CODE IS READ OFF GAME BOY BUTTONS, not off keys. Every input device
+-- the engine has -- keyboard, gamepad, raw joystick, the touch overlay,
+-- and the VR controllers (lib/VR.driveControls feeds Input:overlayPressed
+-- and the stick path) -- lands in src/core/Input as one of eight buttons.
+-- One detector on that abstraction is therefore a detector on ALL of
+-- them, which is why the code works on a headset with no keyboard in the
+-- room. It reads Input.pressQueue from the `input.step` hook, the fixed
+-- step's own boundary, so it sees every edge exactly once whatever the
+-- frame rate did.
+--
+-- THE DARK is not a new renderer. DayNight is pinned to NIGHT and then
+-- its two public colour functions are WRAPPED and multiplied down toward
+-- violet -- so the sky bands, the world tint, the flat 2D world (DayTint
+-- paints the same multiply), the water's reflection and the shadow rig
+-- all darken together, because every one of them already reads those two
+-- functions. Wrapped rather than edited in place because both memoise
+-- into file-local caches this module cannot reach.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Voxel = V.require("VoxelState")
+local Voxel3D = V.require("Voxel3D")
+local DayNight = V.require("DayNight")
+local FirstPerson = V.require("FirstPerson")
+local HordeSfx = V.require("HordeSfx")
+
+local Horde = {}
+
+-- lib modules that require THIS one back (the mobs read the session, the
+-- gun reports kills). Loaded on first use rather than at the top, so the
+-- require cycle never closes.
+local Mobs, Gun, Hud
+local function parts()
+  Mobs = Mobs or V.require("HordeMobs")
+  Gun = Gun or V.require("HordeGun")
+  Hud = Hud or V.require("HordeHud")
+  return Mobs, Gun, Hud
+end
+
+-- ------- tuning
+--
+-- Every number the mode is balanced on, in one place.
+
+Horde.MAX_HP = 100
+Horde.CONTACT_DAMAGE = 9        -- one mob's touch
+Horde.INTRO_TIME = 3.6          -- the beat before the first wave
+Horde.DYING_TIME = 1.1          -- from the last hit to the GAME OVER card
+Horde.SONG = "Music_Lavender"
+
+-- how far down NIGHT is dragged. The sky's bands and the world tint are
+-- multiplied by these; the third is how much of the colour is pulled out
+-- on the way (1 keeps it, 0 is greyscale) -- a little desaturation is
+-- what turns "dark" into "grim".
+Horde.GLOOM_SKY = { 0.34, 0.30, 0.46 }
+Horde.GLOOM_WORLD = { 0.42, 0.38, 0.56 }
+Horde.GLOOM_INDOOR = { 0.55, 0.50, 0.68 }
+Horde.GLOOM_SAT = 0.72
+Horde.SHADOW_BOOST = 1.45       -- the moon presses harder than it should
+
+-- ------- state
+
+Horde.active = false            -- every hook in this file gates on it
+Horde.state = "idle"            -- idle | intro | active | dying | gameover
+Horde.session = nil
+
+-- Whether the combat is live: mobs move, the gun fires, damage lands.
+-- False during the intro beat, the death fade, the GAME OVER card -- and
+-- while ANYTHING is on the stack above the overworld, which is what
+-- stops the trigger from firing into a world the player has stopped
+-- looking at while the exit prompt asks them a question.
+function Horde.playing()
+  if not (Horde.active and Horde.state == "active") then return false end
+  local ok, live = pcall(function()
+    local G = require("src.core.Game")
+    local ow = G.overworld
+    return G.stack and ow and G.stack:top() == ow and not ow.transitioning
+  end)
+  return ok and live == true
+end
+
+-- Whether the mode owns the camera rung right now, which is the whole of
+-- what "locked to first person" means: main.lua's cycleVoxel refuses
+-- while this is true, and that one function is what the 3 key, the pad's
+-- SELECT and the VR stick click all call.
+function Horde.viewLocked()
+  return Horde.active
+end
+
+-- Whether the free walk should skip its A (talk) and START (menu)
+-- branches. Nobody stops to read a sign mid-firefight, and START has a
+-- different job here (see askExit).
+function Horde.suppressWorldInput()
+  return Horde.active
+end
+
+local function game()
+  local ok, G = pcall(require, "src.core.Game")
+  return ok and G or nil
+end
+
+local function overworld(G)
+  G = G or game()
+  return G and G.overworld or nil
+end
+
+-- The way out, on demand. START -- the pad's, the keyboard's ESCAPE, the
+-- touch overlay's -- and the VR left stick click all ask this, and it
+-- asks the player. Nothing here ends the mode; the prompt does that
+-- through Horde.finish if the answer is yes.
+--
+-- Refused while anything is already on top of the overworld, so the
+-- question cannot stack on itself or arrive over the GAME OVER card.
+--
+-- BELOW the two helpers above, deliberately: a Lua local is only in
+-- scope after its declaration, so a function written above them captures
+-- the GLOBAL of that name instead -- which is nil, and only says so when
+-- somebody presses the button.
+function Horde.askExit(G)
+  G = G or game()
+  if not (Horde.active and Horde.state ~= "gameover") then return false end
+  local ow = overworld(G)
+  if not (G and G.stack and ow and G.stack:top() == ow) then return false end
+  if ow.transitioning then return false end
+  local pushed = false
+  pcall(function()
+    require("src.ui.Screens").push(G, "HordeExitPrompt")
+    pushed = true
+  end)
+  return pushed
+end
+
+-- ------- the code
+--
+-- Advance on the expected button; on a wrong one, fall back to the
+-- longest run already entered that is still a valid start of the code,
+-- and try again from there. That fallback is why this is a table rather
+-- than a counter: the code STARTS with a repeat, so a player who presses
+-- Up three times has, on the third, still entered "Up Up" -- and a naive
+-- "wrong button, back to the beginning" rule would throw one of them
+-- away and refuse a code that was in fact typed correctly. (It is the
+-- prefix function from Knuth-Morris-Pratt, over ten buttons.)
+--
+-- The timeout is in fixed steps, 60 to the second: a code is a deliberate
+-- act, and a stray Up a minute ago should not be half of one.
+
+local SEQUENCE = { "up", "up", "down", "down",
+                   "left", "right", "left", "right", "b", "a" }
+local IDLE_STEPS = 150          -- two and a half seconds between buttons
+
+-- FALLBACK[n] = how much of the code is still entered after n matched
+-- buttons and then a wrong one
+local FALLBACK = { [0] = 0, [1] = 0 }
+do
+  local k = 0
+  for i = 2, #SEQUENCE do
+    while k > 0 and SEQUENCE[k + 1] ~= SEQUENCE[i] do k = FALLBACK[k] end
+    if SEQUENCE[k + 1] == SEQUENCE[i] then k = k + 1 end
+    FALLBACK[i] = k
+  end
+end
+
+local progress = 0
+local sinceLast = 0
+
+-- Named for the suite: how far into the code the detector has got.
+function Horde._progress()
+  return progress
+end
+
+local function resetCode()
+  progress, sinceLast = 0, 0
+end
+
+-- Can the mode start from where the player is standing? The overworld has
+-- to be the live state (not a menu, not a battle, not a transition wipe),
+-- the 3D pass has to exist to put a camera inside, and the world has to be
+-- free-roaming rather than mid-cutscene.
+--
+-- MID-STEP IS ALLOWED, and that is not an oversight. Six of the code's ten
+-- buttons are directions, so entering it on a d-pad walks the player four
+-- cells across the map -- and at the moment the closing A lands they are
+-- very often still animating the last of those steps. Refusing a code for
+-- being mid-step would refuse most of the codes anyone actually enters.
+-- The snapshot records the cell the step began from, which is where the
+-- restore puts them back.
+function Horde.canStart(G)
+  G = G or game()
+  if not G or Horde.active then return false end
+  local ow = overworld(G)
+  if not (ow and ow.map and ow.player) then return false end
+  if not (G.stack and G.stack:top() == ow) then return false end
+  if ow.transitioning or ow.scripted or ow.engaging then return false end
+  if ow.player.inputLocked then return false end
+  if not Voxel3D.available() then return false end
+  return true
+end
+
+-- One fixed step of the detector, over the edges about to be promoted.
+-- Separated from the hook so the suite can drive it with a plain list.
+function Horde.feed(queue)
+  if Horde.active then
+    resetCode()
+    return false
+  end
+  sinceLast = sinceLast + 1
+  if progress > 0 and sinceLast > IDLE_STEPS then resetCode() end
+  local fired = false
+  for _, btn in ipairs(queue or {}) do
+    sinceLast = 0
+    while progress > 0 and SEQUENCE[progress + 1] ~= btn do
+      progress = FALLBACK[progress]
+    end
+    if SEQUENCE[progress + 1] == btn then
+      progress = progress + 1
+      if progress >= #SEQUENCE then
+        resetCode()
+        fired = true
+      end
+    end
+  end
+  return fired
+end
+
+-- ------- the snapshot
+--
+-- Everything the mode changes, read back before it changes any of it.
+-- Presentational settings included: the rung, the two engine FX levels the
+-- rung clearing would zero, and the clock -- a player who was watching a
+-- CYCLE sunset gets their sunset back.
+
+local function snapshot(G)
+  local ow = overworld(G)
+  local p = ow.player
+  local Pipelines = require("src.render.Pipelines")
+  local opts = G.save and G.save.options or {}
+  local snap = {
+    mapId = ow.map.id,
+    cellX = p.cellX, cellY = p.cellY,
+    px = p.px, py = p.py,
+    facing = p.facing,
+    viewLevel = Pipelines.level("voxel"),
+    tilt = opts.tilt or 0,
+    gbcfx = opts.gbcfx or 0,
+    fpYaw = FirstPerson.yaw,
+    fpPitch = FirstPerson.pitch,
+    dayIndex = DayNight.setting:read(),
+    dayClock = DayNight.clock,
+  }
+  return snap
+end
+
+-- ------- the gloom
+--
+-- Installed once and inert while the mode is off: each wrapper calls
+-- through and returns the base answer untouched unless Horde.active.
+
+local gloomInstalled = false
+
+local function desaturate(r, g, b, keep)
+  local lum = 0.30 * r + 0.59 * g + 0.11 * b
+  return lum + (r - lum) * keep,
+         lum + (g - lum) * keep,
+         lum + (b - lum) * keep
+end
+
+local function installGloom()
+  if gloomInstalled then return end
+  gloomInstalled = true
+
+  -- The sky's bands. Sky.bands caches BY COLOUR VALUE, so darkening what
+  -- this returns rebuilds the band ramp on its own -- and puts it back the
+  -- same way when the mode ends.
+  do
+    local base = DayNight.palette
+    local cacheIn, cacheOut = nil, nil
+    DayNight.palette = function(t)
+      local pal = base(t)
+      if not Horde.active then return pal end
+      if cacheIn == pal then return cacheOut end
+      local k = Horde.GLOOM_SKY
+      local out = {}
+      for i, c in ipairs(pal) do
+        local r, g, b = c[1] * k[1], c[2] * k[2], c[3] * k[3]
+        r, g, b = desaturate(r, g, b, Horde.GLOOM_SAT)
+        out[i] = { math.floor(r), math.floor(g), math.floor(b) }
+      end
+      cacheIn, cacheOut = pal, out
+      return out
+    end
+  end
+
+  -- The world multiply -- the voxel shader's tint uniform AND, through
+  -- DayTint, the flat 2D world. Indoors normally returns neutral white;
+  -- under the horde it does not, because a Pokemon Centre with the horde
+  -- in it should not look like a Pokemon Centre.
+  do
+    local base = DayNight.tint
+    local cacheIn, cacheOut, cacheOutdoor = nil, nil, nil
+    DayNight.tint = function(outdoor, t)
+      local c = base(outdoor, t)
+      if not Horde.active then return c end
+      if cacheIn == c and cacheOutdoor == outdoor then return cacheOut end
+      local k = outdoor and Horde.GLOOM_WORLD or Horde.GLOOM_INDOOR
+      local r, g, b = c[1] * k[1], c[2] * k[2], c[3] * k[3]
+      r, g, b = desaturate(r, g, b, Horde.GLOOM_SAT)
+      cacheIn, cacheOutdoor, cacheOut = c, outdoor, { r, g, b }
+      return cacheOut
+    end
+  end
+
+  -- and the shadows press harder: applyRig writes SHADOW_ALPHA from the
+  -- hour, so the boost goes on after it has had its say
+  do
+    local base = DayNight.applyRig
+    DayNight.applyRig = function(outdoor)
+      local t = base(outdoor)
+      if Horde.active then
+        Voxel3D.SHADOW_ALPHA = math.min(0.75,
+          (Voxel3D.SHADOW_ALPHA or 0) * Horde.SHADOW_BOOST)
+      end
+      return t
+    end
+  end
+end
+
+-- ------- starting
+
+-- The banner over the world: text, and how long it holds before fading.
+function Horde.banner(text, hold)
+  local s = Horde.session
+  if not s then return end
+  s.bannerText = text
+  s.bannerT = 0
+  s.bannerHold = hold or 2.2
+end
+
+function Horde.begin(G)
+  G = G or game()
+  if not Horde.canStart(G) then return false end
+  local Pipelines = require("src.render.Pipelines")
+  local mobs, gun = parts()
+
+  local snap = snapshot(G)
+  Horde.session = {
+    hp = Horde.MAX_HP, maxHp = Horde.MAX_HP,
+    score = 0, wave = 0, kills = 0,
+    t = 0, introT = Horde.INTRO_TIME, dyingT = 0,
+    damageFlash = 0, hitMarker = 0, hurtCooldown = 0,
+    bannerText = nil, bannerT = 0, bannerHold = 0,
+    snapshot = snap,
+    spawned = {},          -- mapId -> { [objIndex] = true }, for the scrub
+    mobs = {},
+    waveRemaining = 0, waveGap = 0, spawnGap = 0, followQueue = 0,
+    startedAt = os and os.time and os.time() or 0,
+  }
+  Horde.active = true
+  Horde.state = "intro"
+
+  -- the rung, forced and then held: FP_LEVEL is the one rung with a camera
+  -- inside the world, and cycleVoxel refuses to leave it while active
+  Pipelines.setLevel("voxel", Voxel.FP_LEVEL)
+  Pipelines.syncOptions(G.save.options)
+  G.save.options.tilt, G.save.options.gbcfx = 0, 0
+  pcall(function() require("src.render.Tilt").setLevel(0) end)
+  pcall(function() require("src.render.GBCFX").setLevel(0) end)
+  pcall(G.writeOptions, G)
+
+  -- night, pinned; the gloom wrappers do the rest on top of it
+  local nightIndex = 3          -- DayNight.setting values: sync/day/NIGHT/...
+  for i, v in ipairs(DayNight.setting.values) do
+    if v == "night" then nightIndex = i end
+  end
+  DayNight.setting:setIndex(nightIndex, G)
+
+  pcall(function()
+    require("src.core.Music").play(G.data, Horde.SONG, true,
+                                   { reason = "horde" })
+  end)
+
+  gun.reset()
+  mobs.begin(G)
+  Horde.banner("A DARKNESS APPROACHES", 2.6)
+  return true
+end
+
+-- ------- damage and score
+
+function Horde.addScore(n)
+  local s = Horde.session
+  if not s then return end
+  s.score = s.score + (n or 0)
+end
+
+-- A mob reached the player. Returns true when the hit landed (it is on a
+-- cooldown, so a crowd of six does not delete the player in one frame).
+function Horde.damage(n)
+  local s = Horde.session
+  if not (s and Horde.playing()) then return false end
+  if s.hurtCooldown > 0 then return false end
+  s.hurtCooldown = 0.55
+  s.hp = math.max(0, s.hp - (n or Horde.CONTACT_DAMAGE))
+  s.damageFlash = 1
+  HordeSfx.play(HordeSfx.HURT)
+  if s.hp <= 0 then
+    Horde.state = "dying"
+    s.dyingT = Horde.DYING_TIME
+    pcall(function() require("src.core.Sound").stopLoop("Low_Health_Alarm") end)
+  end
+  return true
+end
+
+-- ------- the ending
+
+local function pushGameOver(G)
+  Horde.state = "gameover"
+  local s = Horde.session
+  local best = 0
+  pcall(function() best = V.mod.save:get("hordeBest", 0) or 0 end)
+  if s.score > best then
+    best = s.score
+    pcall(function() V.mod.save:set("hordeBest", best) end)
+  end
+  s.best = best
+  pcall(function() require("src.core.Music").stop() end)
+  pcall(function()
+    require("src.ui.Screens").push(G, "HordeGameOver")
+  end)
+end
+
+-- Put everything back. Called from the GAME OVER card's A press.
+--
+-- Order matters: active goes false FIRST, so the music hook, the gloom
+-- wrappers and the mob spawner have all stood down before anything is
+-- restored under them. The warp home is taken even when the player never
+-- left the map they started on -- setMap rebuilds the cast from the map
+-- record, which is what puts every NPC the horde ate back on its feet.
+function Horde.finish(G)
+  G = G or game()
+  local s = Horde.session
+  if not s then return false end
+  local mobs = parts()
+  local snap = s.snapshot or {}
+
+  Horde.active = false
+  Horde.state = "idle"
+  resetCode()
+
+  mobs.cleanup(G)
+  pcall(function() require("src.core.Sound").stopLoop("Low_Health_Alarm") end)
+
+  -- the clock, back to the hour and the setting the player kept
+  if snap.dayIndex then DayNight.setting:setIndex(snap.dayIndex, G) end
+  if snap.dayClock then DayNight.clock = snap.dayClock end
+
+  -- the rung and the two FX levels the rung clearing zeroed
+  pcall(function()
+    local Pipelines = require("src.render.Pipelines")
+    Pipelines.setLevel("voxel", snap.viewLevel or 0)
+    Pipelines.syncOptions(G.save.options)
+    G.save.options.tilt = snap.tilt or 0
+    G.save.options.gbcfx = snap.gbcfx or 0
+    require("src.render.Tilt").setLevel(snap.tilt or 0)
+    require("src.render.GBCFX").setLevel(snap.gbcfx or 0)
+    G:writeOptions()
+  end)
+
+  if snap.fpYaw then FirstPerson.yaw = snap.fpYaw end
+  if snap.fpPitch then FirstPerson.pitch = snap.fpPitch end
+
+  Horde.session = nil
+
+  -- home, through the engine's own warp: a fade, a setMap, and the map's
+  -- own music coming back up on the other side (the hook that was forcing
+  -- Lavender is inert now)
+  local ow = overworld(G)
+  if ow and snap.mapId then
+    pcall(function()
+      ow:startWarpTo(snap.mapId, snap.cellX, snap.cellY, snap.facing or "down",
+                     function()
+                       -- the pixel position and the facing, restated on
+                       -- the far side of the fade. setMap already placed
+                       -- both, but the free walk owns them while the rung
+                       -- is still easing out of the head, and the head was
+                       -- looking wherever the last shot was aimed
+                       local p = overworld(G) and overworld(G).player
+                       if not p then return end
+                       if snap.px then p.px, p.py = snap.px, snap.py end
+                       if snap.facing then p.facing = snap.facing end
+                     end,
+                     { via = "warp" })
+    end)
+  end
+  return true
+end
+
+-- ------- the tick
+--
+-- Rides the voxel pipeline's update hook, which Game:update calls every
+-- frame whatever the level and whatever is on the stack -- so the mode
+-- keeps thinking through a warp's transition wipe and under the GAME OVER
+-- card, which is exactly what a mode that owns the whole screen needs.
+
+function Horde.update(dt)
+  if not Horde.active then return end
+  local s = Horde.session
+  if not s then
+    Horde.active = false
+    return
+  end
+  dt = math.min(dt or 0, 0.1)         -- a hitch must not teleport the wave
+  local G = game()
+  local mobs, gun, hud = parts()
+
+  s.t = s.t + dt
+  s.damageFlash = math.max(0, s.damageFlash - dt * 2.2)
+  s.hitMarker = math.max(0, s.hitMarker - dt * 4)
+  s.hurtCooldown = math.max(0, s.hurtCooldown - dt)
+  if s.bannerText then
+    s.bannerT = s.bannerT + dt
+    if s.bannerT > s.bannerHold + 1.1 then s.bannerText = nil end
+  end
+  hud.update(dt)
+
+  if Horde.state == "intro" then
+    s.introT = s.introT - dt
+    if s.introT <= 0 then
+      Horde.state = "active"
+      mobs.nextWave(G)
+    end
+    return
+  end
+
+  if Horde.state == "dying" then
+    s.dyingT = s.dyingT - dt
+    mobs.update(dt, G)             -- the crowd keeps coming while you fall
+    if s.dyingT <= 0 then pushGameOver(G) end
+    return
+  end
+
+  if Horde.state ~= "active" then return end
+
+  -- the world only ticks while the overworld is actually the live state:
+  -- during a warp's wipe there is no map under the mobs to walk on
+  local ow = overworld(G)
+  local live = G and G.stack and ow and G.stack:top() == ow
+                 and not ow.transitioning
+  gun.update(dt, live)
+  if live then mobs.update(dt, G) end
+
+  -- the siren the game already owns, for the last third of the health bar
+  local low = s.hp <= s.maxHp * 0.3
+  if low ~= s.alarmOn then
+    s.alarmOn = low
+    pcall(function()
+      local Sound = require("src.core.Sound")
+      if low then Sound.startLoop(G.data, "Low_Health_Alarm")
+      else Sound.stopLoop("Low_Health_Alarm") end
+    end)
+  end
+end
+
+-- ------- the seams
+--
+-- Every engine and mod hook the mode needs, installed once. main.lua
+-- calls this AFTER FreeMove.install and the SELECT wrap, so the
+-- handleInput wrap this adds sits outside both of theirs.
+
+local installed = false
+
+function Horde.install()
+  if installed then return end
+  installed = true
+  local mod = V.mod
+
+  installGloom()
+
+  -- THE CODE. `input.step` runs once per fixed step, immediately before
+  -- Input:step promotes the queue into this step's edges -- so pressQueue
+  -- is exactly "the buttons that were pressed since last time", in order,
+  -- from every device at once. Read, never consumed: the game still gets
+  -- every one of them.
+  mod.hooks:wrap("input.step", function(next, G, dt)
+    local inp = G and G.input
+    if inp and inp.pressQueue and Horde.feed(inp.pressQueue) then
+      pcall(Horde.begin, G)
+    elseif Horde.playing() and inp and inp.pressQueue then
+      -- B is a trigger while the horde is up (the pad's B, the keyboard's,
+      -- the touch overlay's). Read here rather than in the frame tick
+      -- because THIS is the boundary that sees each press exactly once.
+      for _, btn in ipairs(inp.pressQueue) do
+        if btn == "b" then
+          local _, gun = parts()
+          gun.fire()
+        end
+      end
+    end
+    return next(G, dt)
+  end)
+
+  -- Lavender, and it stays Lavender. Every song choice in the engine goes
+  -- through this hook, so a door into a building cannot change the record.
+  mod.hooks:wrap("music.select", function(next, chosen, ctx)
+    if Horde.active and Horde.state ~= "gameover" then
+      return next(Horde.SONG, ctx)
+    end
+    return next(chosen, ctx)
+  end)
+
+  -- no wild encounters: returning nil from this hook suppresses the roll
+  -- outright, which is the documented way to do it
+  mod.hooks:wrap("encounter.roll", function(next, encDef, ctx)
+    if Horde.active then return nil end
+    return next(encDef, ctx)
+  end)
+
+  -- and no trainer walking up to talk. Wrapped rather than set through
+  -- self.engaging, which would also freeze the player's own input.
+  do
+    local OverworldState = require("src.world.OverworldController")
+    if not OverworldState.dramaticShapeHordeSight then
+      local inner = OverworldState.checkTrainerSight
+      function OverworldState:checkTrainerSight(...)
+        if Horde.active then return end
+        return inner(self, ...)
+      end
+      OverworldState.dramaticShapeHordeSight = true
+    end
+  end
+
+  -- THE BUTTONS THE WORLD MAY NOT HAVE. A, START, SELECT and B are the
+  -- mode's, and this wrap is where they are taken -- the OUTERMOST wrap on
+  -- handleInput, installed after FreeMove's and after the SELECT hook, so
+  -- the edges are gone before either of them looks.
+  --
+  -- It has to be here rather than inside the free walk, because the free
+  -- walk is not always the one reading: the rung is forced to 1ST at the
+  -- moment the code completes, but the camera takes a few frames to blend
+  -- into the head, and until it does the GRID walk still owns the frame.
+  -- That is not a corner case -- it is the very first frame of every run,
+  -- and the code's own closing A was landing in it and opening a dialogue
+  -- with whoever the player happened to be standing next to.
+  --
+  -- The EDGE is cleared, not the hold: pressed[] is rebuilt from scratch
+  -- every fixed step, so this reaches exactly this step's presses and
+  -- nothing downstream of it can revive one.
+  do
+    local OverworldState = require("src.world.OverworldController")
+    if not OverworldState.dramaticShapeHordeInput then
+      local inner = OverworldState.handleInput
+      function OverworldState:handleInput(...)
+        if Horde.active then
+          local G = game()
+          local inp = G and G.input
+          if inp and inp.pressed then
+            -- START is the way out, and it is asked rather than taken:
+            -- read here, BEFORE the edge is cleared, so the engine's own
+            -- START menu never sees it
+            if inp.pressed.start then Horde.askExit(G) end
+            inp.pressed.a = nil        -- no talking
+            inp.pressed.b = nil        -- the trigger, already read
+            inp.pressed.start = nil    -- and no start menu
+            inp.pressed.select = nil   -- no changing the view
+          end
+        end
+        return inner(self, ...)
+      end
+      OverworldState.dramaticShapeHordeInput = true
+    end
+  end
+
+  -- the crowd follows the player through the door: a warp lands a new map
+  -- with none of the old one's actors on it, so the roster is re-seeded on
+  -- the far side (lib/HordeMobs)
+  mod.events:on("map.entered", function(payload)
+    if not Horde.active then return end
+    local mobs = parts()
+    pcall(mobs.onMapEntered, payload)
+  end)
+end
+
+return Horde

lib/HordeExitPrompt.lua

@@ -0,0 +1,94 @@
+-- HORDE MODE: the way out.
+--
+-- START (the pad's, the keyboard's ESCAPE, the touch overlay's) and the
+-- VR left stick click all land here: a plain yes/no over the frozen
+-- world, asking whether to leave. YES hands over to Horde.finish, which
+-- is the same restore the GAME OVER card runs -- the map, the cell, the
+-- facing, the camera rung, the hour, the music and every NPC put back
+-- exactly as they were. NO drops the player straight back into the
+-- firefight.
+--
+-- Pushing a state is what pauses the mode, and it is the only thing that
+-- can: horde mode rides the pipeline's update hook rather than the state
+-- stack precisely so that nothing on the stack stops it, but the combat
+-- inside Horde.update is gated on the overworld actually being the live
+-- state, so this prompt freezes the crowd and the gun for as long as it
+-- is up. That is the correct behaviour for a confirmation and it is why
+-- "no pausing" does not extend to this one.
+--
+-- Drawn the way the game draws a yes/no: a white bordered box with black
+-- text and the filled arrow beside the row (see Theme.choiceBox, which
+-- is where the original's own YES_NO_MENU sits). Black on white because
+-- that is what the font IS -- the sheets are black glyphs on transparent
+-- and no colour can lighten one.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Horde = V.require("Horde")
+
+local HordeExitPrompt = {}
+HordeExitPrompt.__index = HordeExitPrompt
+
+-- the question's box, and the choice box under it, in 8px tiles
+local ASK = { tx = 1, ty = 6, tw = 18, th = 4 }
+local PICK = { tx = 13, ty = 10, tw = 6, th = 6 }
+
+function HordeExitPrompt.new(game)
+  local self = setmetatable({}, HordeExitPrompt)
+  self.game = game
+  -- NOT opaque: the horde is still standing out there behind this, which
+  -- is most of what makes the question feel like a decision
+  self.isOpaque = false
+  self.index = 2          -- NO, the way every dangerous prompt starts
+  self.done = false
+  return self
+end
+
+local function sfx(game, name)
+  pcall(function()
+    require("src.core.Sound").play(game.data, name)
+  end)
+end
+
+function HordeExitPrompt:update()
+  if self.done then return end
+  local input = self.game and self.game.input
+  if not input then return end
+
+  if input:wasPressed("up") or input:wasPressed("down") then
+    self.index = self.index == 1 and 2 or 1
+  elseif input:wasPressed("a") then
+    self.done = true
+    sfx(self.game, "Press_AB")
+    self.game.stack:pop()
+    if self.index == 1 then pcall(Horde.finish, self.game) end
+  elseif input:wasPressed("b") or input:wasPressed("start") then
+    -- B and START both mean "no": the button that opened this closes it,
+    -- which is the one thing a player who opened it by accident will try
+    self.done = true
+    sfx(self.game, "Press_AB")
+    self.game.stack:pop()
+  end
+end
+
+function HordeExitPrompt:draw()
+  local ok, Font = pcall(require, "src.render.Font")
+  if not ok then return end
+  local okT, Theme = pcall(require, "src.ui.Theme")
+
+  Font.drawBox(ASK.tx, ASK.ty, ASK.tw, ASK.th)
+  love.graphics.setColor(0, 0, 0, 1)
+  Font.draw("EXIT MINI GAME?", (ASK.tx + 2) * 8, (ASK.ty + 2) * 8)
+
+  Font.drawBox(PICK.tx, PICK.ty, PICK.tw, PICK.th)
+  love.graphics.setColor(0, 0, 0, 1)
+  Font.draw("YES", (PICK.tx + 2) * 8, (PICK.ty + 2) * 8)
+  Font.draw("NO", (PICK.tx + 2) * 8, (PICK.ty + 4) * 8)
+  local cursor = okT and Theme.cursor or 0xED
+  Font.drawCode(cursor, (PICK.tx + 1) * 8,
+                (PICK.ty + 2 + (self.index - 1) * 2) * 8)
+  love.graphics.setColor(1, 1, 1, 1)
+end
+
+return HordeExitPrompt

lib/HordeGameOver.lua

@@ -0,0 +1,107 @@
+-- HORDE MODE: the card at the end.
+--
+-- A stack state, unlike the mode itself -- and for the opposite reason.
+-- Horde mode cannot be a pushed state because pushing one stops the
+-- overworld ticking and the player could not walk; the GAME OVER card
+-- WANTS exactly that. Pushed, it freezes the world underneath, takes the
+-- buttons, and stands there until A.
+--
+-- It draws in the engine's own 160x144 UI canvas with the game's own
+-- font, which is what makes it work in VR for free: with a headset live
+-- and something other than the overworld on top of the stack, lib/VR
+-- already puts the flat screen on the floating panel (or on the Pokedex
+-- in the player's left hand). A card drawn the way the game draws cards
+-- arrives there with no VR code at all.
+--
+-- A pops it and hands over to Horde.finish, which is what puts the world
+-- back: the map, the cell, the facing, the camera rung, the hour, the
+-- music, and every NPC the horde had turned into a mob.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Horde = V.require("Horde")
+
+local W, H = 160, 144
+
+local HordeGameOver = {}
+HordeGameOver.__index = HordeGameOver
+
+function HordeGameOver.new(game)
+  local self = setmetatable({}, HordeGameOver)
+  self.game = game
+  self.isOpaque = true
+  self.t = 0
+  -- the session is read ONCE, here: Horde.finish clears it, and this card
+  -- outlives that by a frame or two while the warp home fades
+  local s = Horde.session or {}
+  self.score = math.floor(s.score or 0)
+  self.best = math.floor(s.best or 0)
+  self.wave = math.max(1, s.wave or 1)
+  self.kills = s.kills or 0
+  self.done = false
+  return self
+end
+
+function HordeGameOver:update(dt)
+  self.t = self.t + (dt or 0)
+  if self.done then return end
+  -- a beat of dead air before the prompt takes input, so the button that
+  -- was being mashed at the moment of death does not dismiss the card
+  if self.t < 0.6 then return end
+  local input = self.game and self.game.input
+  if input and input:wasPressed("a") then
+    self.done = true
+    pcall(function()
+      require("src.core.Sound").play(self.game.data, "Press_AB")
+    end)
+    self.game.stack:pop()
+    pcall(Horde.finish, self.game)
+  end
+end
+
+-- THE CARD IS DRAWN THE WAY THE GAME DRAWS CARDS: a bordered white box
+-- with black text in it (Font.drawBox then setColor(0,0,0)), exactly as
+-- HallOfFame and every menu do. That is not decoration -- the UI canvas
+-- is a FOUR-SHADE Game Boy screen, and an arbitrary colour drawn into it
+-- has nowhere to land. A first cut of this card painted a dark red on
+-- near-black and composited as a rectangle of pure black, with the score
+-- in it and invisible.
+local function centred(Font, str, y, scale)
+  scale = scale or 1
+  local w = Font.width(str) * scale
+  love.graphics.push()
+  love.graphics.translate(math.floor((W - w) / 2), y)
+  love.graphics.scale(scale, scale)
+  Font.draw(str, 0, 0)
+  love.graphics.pop()
+end
+
+function HordeGameOver:draw()
+  local ok, Font = pcall(require, "src.render.Font")
+  if not ok then return end
+
+  -- the whole screen as one box: isOpaque keeps the stack from drawing
+  -- the world under it, but the canvas still holds whatever was there
+  Font.drawBox(0, 0, 20, 18)
+
+  love.graphics.setColor(0, 0, 0, 1)
+  centred(Font, "GAME OVER", 3 * 8, 2)
+
+  centred(Font, ("SCORE  %d"):format(self.score), 8 * 8)
+  centred(Font, ("WAVE %d"):format(self.wave), 10 * 8)
+  centred(Font, ("KILLS %d"):format(self.kills), 11 * 8)
+
+  if self.best > 0 then
+    centred(Font, (self.score >= self.best) and "NEW BEST!"
+                  or ("BEST  %d"):format(self.best), 13 * 8)
+  end
+
+  -- the prompt blinks the way every "press a button" in this game blinks
+  if self.t > 0.6 and (self.t % 1.0) < 0.62 then
+    centred(Font, "PRESS A", 15 * 8)
+  end
+  love.graphics.setColor(1, 1, 1, 1)
+end
+
+return HordeGameOver

lib/HordeGun.lua

@@ -0,0 +1,511 @@
+-- HORDE MODE: the handgun.
+--
+-- A voxel model in the player's right hand, authored here in METRES the
+-- way lib/Pokedex authors the device in the left one -- because the VR
+-- mapping's scale is what turns metres into world pixels, a mesh built
+-- this way is the right size in the hand at every scale the mod has, and
+-- the same mesh serves the flat screen's view model.
+--
+-- IN VR the gun rides the tracked right hand through VRRig.propMatrix,
+-- pointed by the runtime's AIM pose where one exists (the pose a runtime
+-- defines as "where the user is pointing") and by the grip pose where it
+-- does not. You aim it by pointing it. The iron sights are real geometry,
+-- and lining them up is how you shoot accurately, because the shot is
+-- traced down the model's own barrel axis.
+--
+-- ON THE FLAT SCREEN there is no hand to track, so the gun is carried by
+-- the camera: a model matrix built from the first-person eye and its yaw
+-- and pitch, with the gun hanging at the hip until the player aims. AIM
+-- DOWN SIGHTS slides it to the centre of the screen with the sight line
+-- ON the eye axis -- the model is authored with its rear notch at the
+-- origin precisely so that offset is (0, 0, forward) -- and narrows the
+-- field of view, which is the whole of what aiming does here.
+--
+-- THE SHOT IS A RAY, traced the same way in both modes: march it in world
+-- pixels, let terrain height stop it (a wall is a tall cell, so a cell
+-- whose ground is above the ray's height is a wall the bullet hits), and
+-- test every live mob against it as a standing cylinder. Nearest wins,
+-- and a hit above the shoulder line counts double.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Mat4 = V.require("Mat4")
+local Voxel3D = V.require("Voxel3D")
+local VRRig = V.require("VRRig")
+local FirstPerson = V.require("FirstPerson")
+local Horde = V.require("Horde")
+local HordeSfx = V.require("HordeSfx")
+
+local HordeGun = {}
+
+-- ------- tuning
+
+HordeGun.MAG = 8
+HordeGun.RELOAD_TIME = 1.5
+HordeGun.FIRE_COOLDOWN = 0.17      -- semi-auto, and it fits the reload clicks
+HordeGun.RANGE = 220               -- world pixels: about fourteen cells
+HordeGun.HIT_RADIUS = 6            -- a person is about twelve pixels wide
+HordeGun.ADS_TIME = 0.13
+HordeGun.ADS_FOV = math.rad(40)
+
+-- Where the gun sits relative to the EYE, in metres, hip and aimed. The
+-- model's own origin is its rear sight notch, so the aimed offset is a
+-- pure push forward: nothing to line up, it is already lined up.
+HordeGun.HIP = { -0.115, -0.125, 0.30 }
+HordeGun.ADS = { 0, -0.002, 0.34 }
+
+-- Where it sits relative to the tracked hand, in METRES and in the POSE's
+-- own axes -- so with the barrel pointed away from the player (see below)
+-- -Z is forward, and this nudges the gun a little down and forward of the
+-- pose origin so the hand is behind it rather than inside it.
+HordeGun.HAND_OFFSET = { 0, -0.012, -0.02 }
+
+-- THE BARREL, AND WHICH WAY IS FORWARD.
+--
+-- OpenXR's AIM pose -- the one this rides where the runtime offers it --
+-- is defined with its **-Z axis pointing the way the user is aiming**.
+-- The model below is authored with its barrel along **+Z**, because that
+-- is what the flat screen's view model wants (Ry(yaw)*Rx(pitch) carries
+-- +Z onto the look direction). Half a turn about Y is what reconciles
+-- them, and it is the whole of the attachment.
+--
+-- Getting this wrong does not read as "slightly off": the first cut
+-- copied the Pokedex's quarter-turn about X, which lays a flat slab along
+-- the controller's body and is exactly right for a slab -- on a gun it
+-- pointed the muzzle at the player's own face.
+HordeGun.HAND_YAW = math.pi
+
+-- AND A PITCH, because a hand is not a tripod. A controller held the way
+-- you hold a pistol -- fist closed, wrist cocked -- has its own aim axis
+-- running up and forward out of the top of your fist, well above the line
+-- your hand FEELS like it is pointing along. A model laid flat on that
+-- axis reads as a gun held by somebody with a broken wrist.
+--
+-- So the gun tips its muzzle down 45 degrees off the pose, which puts the
+-- barrel back on the line the grip implies. The shot follows: the ray is
+-- read off the finished matrix's own +Z column (see place), so it comes
+-- out of the barrel as drawn rather than off the pose it was hung on --
+-- point the gun, hit the thing.
+HordeGun.HAND_PITCH = math.rad(45)
+
+-- ------- the model
+--
+-- One voxel is 8mm, so the pistol below comes out about 18cm long -- a
+-- compact service automatic. Authored around the REAR SIGHT NOTCH at the
+-- origin, barrel down +Z, up +Y. (+X is the viewer's LEFT: the world runs
+-- +X east and +Z south, so a body facing +Z has its right hand toward
+-- -X, which is why the hip offset's x is negative.)
+
+local VOX = 0.008
+
+local COLORS = {
+  { 60, 62, 72 },      -- 1 slide
+  { 30, 31, 38 },      -- 2 frame / shadowed
+  { 46, 40, 40 },      -- 3 grip
+  { 104, 108, 122 },   -- 4 highlight
+  { 248, 240, 176 },   -- 5 sight dot
+  { 18, 18, 22 },      -- 6 bore
+  { 132, 136, 148 },   -- 7 trigger
+  { 255, 246, 196 },   -- 8 flash core
+  { 255, 168, 56 },    -- 9 flash edge
+}
+
+local paletteTex, bodyMesh, flashMesh = nil, nil, nil
+
+local function palette()
+  if paletteTex then return paletteTex end
+  if not (love.image and love.image.newImageData
+          and love.graphics and love.graphics.newImage) then return nil end
+  local ok, data = pcall(love.image.newImageData, #COLORS, 1)
+  if not (ok and data) then return nil end
+  for i, c in ipairs(COLORS) do
+    pcall(data.setPixel, data, i - 1, 0,
+          c[1] / 255, c[2] / 255, c[3] / 255, 1)
+  end
+  local built, img = pcall(love.graphics.newImage, data)
+  if not built then return nil end
+  pcall(img.setFilter, img, "nearest", "nearest")
+  paletteTex = img
+  return img
+end
+
+-- one solid box, in voxels, straight into the shared vertex format
+local function box(verts, indices, x, y, z, w, h, d, color)
+  local u = (color - 0.5) / #COLORS
+  local ox, oy, oz = x * VOX, y * VOX, z * VOX
+  local sx, sy, sz = w * VOX, h * VOX, d * VOX
+  for face = 1, 6 do
+    local corners = Voxel3D.FACE_CORNERS[face]
+    local shade = Voxel3D.FACE_SHADE[face]
+    local n = #verts / 4
+    for _, c in ipairs(corners) do
+      verts[#verts + 1] = { ox + c[1] * sx, oy + c[2] * sy, oz + c[3] * sz,
+                            u, 0.5, shade }
+    end
+    Voxel3D.pushQuad(indices, n)
+  end
+end
+
+local function buildBody()
+  if bodyMesh then return bodyMesh end
+  local v, i = {}, {}
+  -- slide, and the bore's dark eye at the end of it
+  box(v, i, -2, -5, -1, 4, 4, 18, 1)
+  box(v, i, -2, -2, -1, 4, 0.6, 18, 4)        -- the light along the top edge
+  box(v, i, -1, -4, 16.6, 2, 2, 0.6, 6)
+  -- frame under the slide, and the dust cover forward of the guard
+  box(v, i, -1.8, -8, 0.5, 3.6, 3.2, 12, 2)
+  -- the grip, three blocks stepping back: a raked butt without a hull
+  box(v, i, -1.8, -11, -1.2, 3.6, 3.2, 5, 3)
+  box(v, i, -1.8, -14, -2.6, 3.6, 3.2, 5, 3)
+  box(v, i, -1.8, -16.8, -3.8, 3.6, 3, 5, 2)
+  -- trigger guard: the bar under, the post in front
+  box(v, i, -1.4, -11.4, 3.6, 2.8, 1, 4.4, 2)
+  box(v, i, -1.4, -11.4, 7.4, 2.8, 3.4, 1, 2)
+  box(v, i, -0.9, -10.8, 4.6, 1.8, 2, 1, 7)   -- the trigger itself
+  -- IRON SIGHTS. Two rear posts with a notch between them at the origin,
+  -- one front post at the muzzle: look through the gap, put the front
+  -- post's dot in it, and the barrel is pointing where you are looking.
+  box(v, i, -2, -1, -0.2, 0.9, 1.3, 1.4, 2)
+  box(v, i, 1.1, -1, -0.2, 0.9, 1.3, 1.4, 2)
+  box(v, i, -1.95, -0.2, 0.3, 0.5, 0.5, 0.5, 5)
+  box(v, i, 1.45, -0.2, 0.3, 0.5, 0.5, 0.5, 5)
+  box(v, i, -0.45, -1, 15.2, 0.9, 1.5, 1, 2)
+  box(v, i, -0.3, 0.1, 15.4, 0.6, 0.6, 0.6, 5)
+  bodyMesh = Voxel3D.newMesh(v, i)
+  return bodyMesh
+end
+
+-- the muzzle flash: a bright cross of boxes off the bore, drawn for two
+-- frames after a shot and never lit by anything
+local function buildFlash()
+  if flashMesh then return flashMesh end
+  local v, i = {}, {}
+  box(v, i, -1.6, -4.6, 17.4, 3.2, 3.2, 2.6, 8)
+  box(v, i, -3.4, -3.8, 17.6, 6.8, 1.6, 1.8, 9)
+  box(v, i, -0.9, -6.4, 17.6, 1.8, 6.4, 1.8, 9)
+  box(v, i, -1.1, -4.1, 19.6, 2.2, 2.2, 2.2, 9)
+  flashMesh = Voxel3D.newMesh(v, i)
+  return flashMesh
+end
+
+-- ------- state
+
+local gun = {
+  ammo = HordeGun.MAG,
+  reloading = false,
+  reloadT = 0,
+  reloadStage = 0,
+  cooldown = 0,
+  ads = false,
+  adsBlend = 0,
+  kick = 0,
+  flash = 0,
+  frame = nil,        -- the VR hand's model matrix for this frame
+  ray = nil,          -- the VR aim ray in world space, if there is one
+}
+
+HordeGun.state = gun
+
+function HordeGun.reset()
+  gun.ammo = HordeGun.MAG
+  gun.reloading, gun.reloadT, gun.reloadStage = false, 0, 0
+  gun.cooldown, gun.kick, gun.flash = 0, 0, 0
+  gun.ads, gun.adsBlend = false, 0
+  gun.frame, gun.ray = nil, nil
+end
+
+-- how far into the aim the sights are, 0..1 -- read by the HUD (the
+-- crosshair goes away) and by the camera (the field of view narrows)
+function HordeGun.adsBlend()
+  return gun.adsBlend
+end
+
+function HordeGun.ammo()
+  return gun.ammo, HordeGun.MAG, gun.reloading
+end
+
+function HordeGun.setAds(on)
+  gun.ads = on and true or false
+end
+
+-- ------- the shot
+
+-- The eye and the direction it is looking, in world pixels. In VR this is
+-- the gun's own barrel (set by the VR frame); on the flat screen it is
+-- the camera, because the gun follows the camera exactly.
+local function ray(G)
+  if gun.ray then return gun.ray end
+  local ow = G and G.overworld
+  if not (ow and ow.player and ow.map) then return nil end
+  local p = ow.player
+  local gh = 0
+  pcall(function()
+    gh = V.require("VoxelScene").groundAt(ow.map, p.cellX, p.cellY) or 0
+  end)
+  local cp = math.cos(FirstPerson.pitch)
+  return {
+    p.px + 8, gh + FirstPerson.EYE_HEIGHT, p.py + 8,
+    math.sin(FirstPerson.yaw) * cp,
+    -math.sin(FirstPerson.pitch),
+    math.cos(FirstPerson.yaw) * cp,
+  }
+end
+
+-- How far the ray travels before terrain stops it. A wall in this world
+-- is a cell whose ground stands taller than the ray does where it crosses
+-- it, which is the same test for a fence you can shoot over, a building
+-- you cannot, and a doorway you can shoot through.
+local function occlusion(map, r)
+  local VoxelScene = V.require("VoxelScene")
+  local step = 3
+  local t = step
+  while t <= HordeGun.RANGE do
+    local x = r[1] + r[4] * t
+    local y = r[2] + r[5] * t
+    local z = r[3] + r[6] * t
+    local cx, cy = math.floor(x / 16), math.floor(z / 16)
+    if not map:inBounds(cx, cy) then return t end
+    local gh = 0
+    local ok, got = pcall(VoxelScene.groundAt, map, cx, cy)
+    if ok and got then gh = got end
+    if y < gh - 0.5 then return t end
+    if y < 0 then return t end
+    t = t + step
+  end
+  return HordeGun.RANGE
+end
+
+-- The nearest mob the ray reaches, and whether it caught the head.
+local function pick(G, r, maxT)
+  local Mobs = V.require("HordeMobs")
+  local VoxelScene = V.require("VoxelScene")
+  local ow = G and G.overworld
+  if not (ow and ow.map) then return nil end
+  local flat = r[4] * r[4] + r[6] * r[6]
+  if flat < 1e-6 then return nil end
+  local best, bestT, bestHead = nil, maxT, false
+  for _, e in ipairs(Mobs.list()) do
+    local npc = e.npc
+    if npc and not e.dead and e.mapId == ow.map.id then
+      local mx, mz = npc.px + 8, npc.py + 8
+      local t = ((mx - r[1]) * r[4] + (mz - r[3]) * r[6]) / flat
+      if t > 0 and t < bestT then
+        local hx = r[1] + r[4] * t - mx
+        local hz = r[3] + r[6] * t - mz
+        if hx * hx + hz * hz <= HordeGun.HIT_RADIUS * HordeGun.HIT_RADIUS then
+          local gh = 0
+          local ok, got = pcall(VoxelScene.groundAt, ow.map,
+                                npc.cellX, npc.cellY)
+          if ok and got then gh = got end
+          local y = r[2] + r[5] * t
+          if y >= gh - 2 and y <= gh + 17 then
+            best, bestT, bestHead = e, t, y >= gh + 11
+          end
+        end
+      end
+    end
+  end
+  return best, bestHead
+end
+
+-- Pull the trigger. Every input device funnels here (see Horde.install,
+-- FirstPerson's mouse and touch wraps, and VR.driveControls), so the
+-- cooldown below is also what keeps two devices reporting the same press
+-- from spending two rounds.
+function HordeGun.fire()
+  if not Horde.playing() then return false end
+  if gun.cooldown > 0 or gun.reloading then return false end
+  if gun.ammo <= 0 then
+    gun.cooldown = 0.35
+    HordeSfx.play(HordeSfx.DRY)
+    HordeGun.reload()
+    return false
+  end
+  local G = require("src.core.Game")
+  gun.ammo = gun.ammo - 1
+  gun.cooldown = HordeGun.FIRE_COOLDOWN
+  gun.kick = 1
+  gun.flash = 0.05
+  HordeSfx.shot()
+
+  local r = ray(G)
+  if r then
+    local ow = G.overworld
+    local maxT = ow and ow.map and occlusion(ow.map, r) or HordeGun.RANGE
+    local hit, head = pick(G, r, maxT)
+    if hit then
+      local Mobs = V.require("HordeMobs")
+      local result = Mobs.hit(hit, head and 2 or 1)
+      local s = Horde.session
+      if s then
+        s.hitMarker = 1
+        if result == "kill" and head then Horde.addScore(50) end
+      end
+    end
+  end
+  if gun.ammo <= 0 then HordeGun.reload() end
+  return true
+end
+
+function HordeGun.reload()
+  if gun.reloading or gun.ammo >= HordeGun.MAG then return false end
+  gun.reloading = true
+  gun.reloadT = 0
+  gun.reloadStage = 0
+  return true
+end
+
+-- ------- the frame
+
+function HordeGun.update(dt, live)
+  if not Horde.active then
+    FirstPerson.fovScale = 1        -- give the lens back on the way out
+    return
+  end
+  gun.cooldown = math.max(0, gun.cooldown - dt)
+  gun.kick = math.max(0, gun.kick - dt * 7)
+  gun.flash = math.max(0, gun.flash - dt)
+
+  local target = (gun.ads and live) and 1 or 0
+  local astep = dt / HordeGun.ADS_TIME
+  if gun.adsBlend < target then
+    gun.adsBlend = math.min(target, gun.adsBlend + astep)
+  else
+    gun.adsBlend = math.max(target, gun.adsBlend - astep)
+  end
+  -- the lens narrows with the sights. Half of what aiming does here is
+  -- the model coming to the centre of the screen; the other half is this
+  local e = gun.adsBlend * gun.adsBlend * (3 - 2 * gun.adsBlend)
+  FirstPerson.fovScale = 1 - (1 - HordeGun.ADS_FOV / FirstPerson.FOV) * e
+
+  if gun.reloading then
+    local was = gun.reloadT
+    gun.reloadT = gun.reloadT + dt
+    -- three clicks on their own clock: the magazine out, the fresh one
+    -- in, the slide home. Staged by time rather than animated frames so
+    -- the sound and the dip below stay in step at any frame rate.
+    local marks = { { 0.10, HordeSfx.MAG_OUT }, { 0.62, HordeSfx.MAG_IN },
+                    { 1.15, HordeSfx.RACK } }
+    for _, m in ipairs(marks) do
+      if was < m[1] and gun.reloadT >= m[1] then HordeSfx.play(m[2]) end
+    end
+    if gun.reloadT >= HordeGun.RELOAD_TIME then
+      gun.reloading = false
+      gun.reloadT = 0
+      gun.ammo = HordeGun.MAG
+    end
+  end
+end
+
+-- ------- VR placement
+--
+-- Called from the VR frame with the same mapping the eyes got. `pose` is
+-- the tracked right hand -- the runtime's aim pose where it has one.
+
+function HordeGun.place(pose, pivot, anchor, scale, yaw)
+  if not (Horde.active and pose) then
+    HordeGun.clear()
+    return
+  end
+  local m = VRRig.propMatrix(pose, pivot, anchor, scale, yaw)
+  m = Mat4.mul(m, Mat4.translate(HordeGun.HAND_OFFSET[1],
+                                 HordeGun.HAND_OFFSET[2],
+                                 HordeGun.HAND_OFFSET[3]))
+  m = Mat4.mul(m, Mat4.rotateY(HordeGun.HAND_YAW))
+  m = Mat4.mul(m, Mat4.rotateX(HordeGun.HAND_PITCH))
+  -- the recoil, up and back along the gun's own axes
+  local k = gun.kick
+  if k > 0 then
+    m = Mat4.mul(m, Mat4.translate(0, 0, -0.05 * k))
+    m = Mat4.mul(m, Mat4.rotateX(-0.30 * k))
+  end
+  gun.frame = m
+
+  -- the barrel, in world pixels: the shot goes where the gun points, so
+  -- lining the sights up with an eye is what aims it
+  local o = { m[4], m[8], m[12] }
+  local dx, dy, dz = m[3], m[7], m[11]        -- the model's +Z column
+  local len = math.sqrt(dx * dx + dy * dy + dz * dz)
+  if len > 1e-6 then
+    gun.ray = { o[1], o[2], o[3], dx / len, dy / len, dz / len }
+  else
+    gun.ray = nil
+  end
+end
+
+function HordeGun.clear()
+  gun.frame, gun.ray = nil, nil
+end
+
+-- ------- drawing
+--
+-- Runs inside VoxelScene's drawScene, once per eye in VR and once per
+-- frame flat, after the world -- so the gun composites with real depth
+-- and leaning it into a wall occludes honestly.
+
+-- Should the gun be drawn at all this frame? Keyed on the first-person
+-- rig's own IDENTITY rather than on the rung's number, because a staged
+-- VR battle places a camera through the same seam and the gun has no
+-- business in it.
+function HordeGun.visible()
+  if not Horde.active then return false end
+  if gun.frame then return true end
+  return FirstPerson.cardBlend() > 0.35
+end
+
+-- The flat screen's view model matrix: carried by the camera, offset to
+-- the hip or the sight line, with the recoil on top.
+local function flatModel()
+  local cam = Voxel3D.camera
+  local eye = cam and cam.eye
+  if not eye then return nil end
+  local a = gun.adsBlend
+  a = a * a * (3 - 2 * a)
+  local hip, ads = HordeGun.HIP, HordeGun.ADS
+  local ox = hip[1] + (ads[1] - hip[1]) * a
+  local oy = hip[2] + (ads[2] - hip[2]) * a
+  local oz = hip[3] + (ads[3] - hip[3]) * a
+  -- the reload dip: the gun swings down and out of the shot while the
+  -- hands are busy, easing back as the slide comes home
+  if gun.reloading then
+    local t = math.min(1, gun.reloadT / HordeGun.RELOAD_TIME)
+    local dip = math.sin(math.min(1, t * 1.15) * math.pi)
+    oy = oy - 0.09 * dip
+    ox = ox - 0.03 * dip
+  end
+  local k = gun.kick
+  oz = oz - 0.045 * k
+
+  local m = Mat4.translate(eye[1], eye[2], eye[3])
+  m = Mat4.mul(m, Mat4.rotateY(FirstPerson.yaw))
+  m = Mat4.mul(m, Mat4.rotateX(FirstPerson.pitch - 0.34 * k))
+  m = Mat4.mul(m, Mat4.scale(VRRig.FP_SCALE, VRRig.FP_SCALE, VRRig.FP_SCALE))
+  m = Mat4.mul(m, Mat4.translate(ox, oy, oz))
+  if gun.reloading then
+    local t = math.min(1, gun.reloadT / HordeGun.RELOAD_TIME)
+    m = Mat4.mul(m, Mat4.rotateX(-0.55 * math.sin(math.min(1, t * 1.15)
+                                                  * math.pi)))
+  end
+  return m
+end
+
+function HordeGun.draw()
+  if not HordeGun.visible() then return end
+  local model = gun.frame or flatModel()
+  if not model then return end
+  local body, pal = buildBody(), palette()
+  if not (body and pal) then return end
+  Voxel3D.draw(body, pal, model)
+  if gun.flash > 0 then
+    local flash = buildFlash()
+    if flash then Voxel3D.draw(flash, pal, model) end
+  end
+end
+
+function HordeGun.invalidate()
+  paletteTex, bodyMesh, flashMesh = nil, nil, nil
+end
+
+return HordeGun

lib/HordeHud.lua

@@ -0,0 +1,484 @@
+-- HORDE MODE: the readout.
+--
+-- Health, ammunition, score, wave, the crosshair, the hit marker, the red
+-- that closes in when something reaches you, and the banners -- "A
+-- DARKNESS APPROACHES", then "WAVE 1" and every wave after it.
+--
+-- IT IS DRAWN TWICE, INTO TWO DIFFERENT PLACES, and that is not
+-- duplication for its own sake. The flat screen's HUD goes into the SCENE
+-- canvas through Voxel3D.beginOverlay -- the same seam the overworld's FX
+-- bubbles use -- because that canvas is what the window composites. A
+-- headset never sees that canvas: with VR live the window's world pass
+-- short-circuits to the mirror, and the eyes are rendered on their own in
+-- lib/VR. So the eye canvases get their own pass, at the same instant the
+-- VR frame paints its fade over them, in the same 2D idiom.
+--
+-- Both call the same draw with a different scale and a different safe
+-- area: a headset wants everything well inside the lens rather than
+-- pinned to the corners, because the corners of a VR frame are off the
+-- edge of the visible world.
+--
+-- EVERY WORD IS ON A WHITE PLATE, and that is not a style choice -- it is
+-- what the font is. The Game Boy font sheets are BLACK glyphs on
+-- transparent, so setColor cannot make a letter pale: multiplying black
+-- by white is still black. That is why every box in the game is drawn
+-- white first and its text black on top (Font.drawBox, then
+-- setColor(0,0,0)), and it is why a first cut of this HUD -- pale text,
+-- straight onto the night -- composited as black letters on a black
+-- street and could not be read at all. Plates also happen to be the right
+-- answer aesthetically: the game already talks to the player in white
+-- boxes, and a horde mode that shouts in the same voice belongs to it.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Horde = V.require("Horde")
+
+local HordeHud = {}
+
+local Font = nil
+local function font()
+  if Font then return Font end
+  local ok, F = pcall(require, "src.render.Font")
+  if ok then Font = F end
+  return Font
+end
+
+-- the pulse under the low-health plate and the banner's own breathing
+local blink = 0
+
+function HordeHud.update(dt)
+  blink = (blink + (dt or 0)) % 1.0
+end
+
+-- named for the suite: the banner's line breaking, which is the part with
+-- an answer worth pinning
+HordeHud._layout = nil        -- assigned below, once `layout` exists
+
+-- ------- pieces
+--
+-- Every helper takes a scale `s` and draws in GB pixels multiplied by it,
+-- so one layout serves a 4x window and a headset's eye buffer alike.
+
+local PAD = 3           -- plate padding, in GB pixels
+
+-- A white plate with a dark edge: the surface a black glyph can be read
+-- on. Returns the interior origin, so a caller lays text out from there.
+local function plate(x, y, w, h, s, alpha)
+  love.graphics.setColor(0.06, 0.05, 0.09, (alpha or 1) * 0.92)
+  love.graphics.rectangle("fill", x - s, y - s, w + 2 * s, h + 2 * s)
+  love.graphics.setColor(0.93, 0.94, 0.90, alpha or 1)
+  love.graphics.rectangle("fill", x, y, w, h)
+  return x + PAD * s, y + PAD * s
+end
+
+local function textWidth(str, s)
+  local F = font()
+  if not F then return 0 end
+  return F.width(str) * s
+end
+
+-- Black glyphs at `s` times their size. Black because that is the only
+-- colour the font has (see the header).
+local function text(str, x, y, s)
+  local F = font()
+  if not F then return 0 end
+  love.graphics.setColor(0, 0, 0, 1)
+  love.graphics.push()
+  love.graphics.translate(math.floor(x), math.floor(y))
+  love.graphics.scale(s, s)
+  F.draw(str, 0, 0)
+  love.graphics.pop()
+end
+
+-- One line of text on its own plate, anchored left or right.
+local function label(str, x, y, s, align)
+  local tw = textWidth(str, s)
+  local pw, ph = tw + PAD * 2 * s, 8 * s + PAD * 2 * s
+  local px = (align == "right") and (x - pw) or x
+  local ix, iy = plate(px, y, pw, ph, s)
+  text(str, ix, iy, s)
+  return pw, ph
+end
+
+-- The health bar: a plate with a red bar inside it, so the red reads
+-- against white rather than against a night street.
+local function healthBar(x, y, w, h, s, fill, flash)
+  local ix, iy = plate(x, y, w, h, s)
+  local iw, ih = w - PAD * 2 * s, h - PAD * 2 * s
+  love.graphics.setColor(0.80, 0.80, 0.78, 1)
+  love.graphics.rectangle("fill", ix, iy, iw, ih)
+  local r, g, b = 0.78, 0.12, 0.16
+  if flash then r, g, b = 1, 0.45, 0.35 end
+  love.graphics.setColor(r, g, b, 1)
+  love.graphics.rectangle("fill", ix, iy, math.max(0, iw * fill), ih)
+end
+
+-- The crosshair: four ticks around a gap that opens as the gun kicks, and
+-- gone entirely down the sights, where the iron sights ARE the crosshair.
+-- Drawn as a dark pair under a light pair so it survives both a white
+-- wall and a black doorway.
+local function crosshair(cx, cy, s, spread, alpha)
+  local gap = (3 + spread * 4) * s
+  local len = 4 * s
+  local t = math.max(1, s)
+  local function ticks(o, thick, r, g, b, a)
+    love.graphics.setColor(r, g, b, a)
+    love.graphics.rectangle("fill", cx - gap - len - o, cy - thick / 2 - o,
+                            len + 2 * o, thick + 2 * o)
+    love.graphics.rectangle("fill", cx + gap - o, cy - thick / 2 - o,
+                            len + 2 * o, thick + 2 * o)
+    love.graphics.rectangle("fill", cx - thick / 2 - o, cy - gap - len - o,
+                            thick + 2 * o, len + 2 * o)
+    love.graphics.rectangle("fill", cx - thick / 2 - o, cy + gap - o,
+                            thick + 2 * o, len + 2 * o)
+  end
+  ticks(math.max(1, s * 0.5), t, 0, 0, 0, alpha * 0.85)
+  ticks(0, t, 0.98, 0.98, 1, alpha)
+end
+
+local function hitMarker(cx, cy, s, amount)
+  if amount <= 0 then return end
+  love.graphics.setColor(1, 0.30, 0.26, amount)
+  local o = 5 * s
+  local len = 5 * s
+  local t = math.max(1, s)
+  for _, d in ipairs({ { -1, -1 }, { 1, -1 }, { -1, 1 }, { 1, 1 } }) do
+    love.graphics.push()
+    love.graphics.translate(cx + d[1] * o, cy + d[2] * o)
+    love.graphics.rotate(math.pi / 4 * (d[1] * d[2] > 0 and 1 or -1))
+    love.graphics.rectangle("fill", -t / 2, -len / 2, t, len)
+    love.graphics.pop()
+  end
+end
+
+-- How wide a run of glyphs comes out at `bs` pixels per font pixel, with
+-- `track` of air after each one.
+local function runWidth(F, codes, bs, track)
+  local total = 0
+  for _, code in ipairs(codes) do
+    total = total + F.advanceOf(code) * bs + track
+  end
+  return total - track
+end
+
+-- The banner's lines, and the size to draw them at.
+--
+-- THE SCALE IS NEGOTIATED, not assumed. The caller's scale comes from the
+-- window's own zoom, so a player zoomed well in gets a large `s` -- and
+-- "A DARKNESS APPROACHES" at twice a large scale is wider than the
+-- screen, which is how the words ran off both edges. So: shrink until the
+-- longest single WORD fits, then wrap the words into as many lines as
+-- that leaves. Wrapping first and shrinking only when a word alone cannot
+-- fit keeps the announcement as big as the frame can carry it.
+local function layout(F, str, scale, maxW)
+  local words = {}
+  for word in tostring(str):gmatch("%S+") do words[#words + 1] = word end
+  if #words == 0 then return nil end
+
+  local bs = math.max(1, scale * 2)
+  local function track(size) return math.max(1, math.floor(size / 2)) end
+  while bs > 1 do
+    local widest = 0
+    for _, word in ipairs(words) do
+      local ww = runWidth(F, F.encode(word), bs, track(bs))
+      if ww > widest then widest = ww end
+    end
+    if widest <= maxW then break end
+    bs = bs - 1
+  end
+
+  local tr = track(bs)
+  local spaceW = runWidth(F, F.encode(" "), bs, tr) + tr
+  local lines, line, lineW = {}, nil, 0
+  for _, word in ipairs(words) do
+    local ww = runWidth(F, F.encode(word), bs, tr)
+    if not line then
+      line, lineW = word, ww
+    elseif lineW + spaceW + ww <= maxW then
+      line, lineW = line .. " " .. word, lineW + spaceW + ww
+    else
+      lines[#lines + 1] = { text = line, width = lineW }
+      line, lineW = word, ww
+    end
+  end
+  lines[#lines + 1] = { text = line, width = lineW }
+  return lines, bs, tr
+end
+
+HordeHud._layout = layout
+
+-- The banner: a plate across the middle of the frame with the words on
+-- it, as big as the frame can carry. It fades in and out rather than
+-- cutting -- an announcement, not a notification -- and the plate fades
+-- with it.
+local function banner(w, h, scale)
+  local sess = Horde.session
+  if not (sess and sess.bannerText) then return end
+  local t, hold = sess.bannerT, sess.bannerHold
+  local alpha
+  if t < 0.4 then alpha = t / 0.4
+  elseif t < hold then alpha = 1
+  else alpha = math.max(0, 1 - (t - hold) / 1.1) end
+  if alpha <= 0 then return end
+
+  local F = font()
+  if not F then return end
+  local margin = 6 * scale
+  local lines, bs, tr = layout(F, sess.bannerText, scale, w - margin * 2)
+  if not lines then return end
+
+  local lineH = 8 * bs
+  local gap = math.max(1, math.floor(bs * 0.4))
+  local pad = PAD * 2 * scale
+  local ph = #lines * lineH + (#lines - 1) * gap + pad * 2
+  local y = math.floor(h * 0.30 - ph / 2)
+  -- the plate runs the full width: a band across the world, which reads
+  -- as the game interrupting itself rather than as a label on it
+  plate(0, y, w, ph, scale, alpha)
+  local iy = y + pad
+
+  love.graphics.setColor(0, 0, 0, alpha)
+  for i, line in ipairs(lines) do
+    local pen = math.floor((w - line.width) / 2)
+    local ly = iy + (i - 1) * (lineH + gap)
+    for _, code in ipairs(F.encode(line.text)) do
+      love.graphics.push()
+      love.graphics.translate(pen, ly)
+      love.graphics.scale(bs, bs)
+      F.drawCode(code, 0, 0)
+      love.graphics.pop()
+      pen = pen + F.advanceOf(code) * bs + tr
+    end
+  end
+end
+
+-- ------- the whole thing
+--
+-- `inset` is how far off the edges the corners sit, which is the one real
+-- difference between a window and a headset.
+
+local function draw(w, h, s, inset)
+  local sess = Horde.session
+  if not sess then return end
+  local Gun = V.require("HordeGun")
+  local ammo, mag, reloading = Gun.ammo()
+  local ads = Gun.adsBlend()
+
+  love.graphics.push("all")
+  love.graphics.setBlendMode("alpha")
+
+  -- The red. A VIGNETTE rather than a wash over everything: a full-screen
+  -- fill strong enough to register at a glance also hides the thing that
+  -- just hit you, which in a mode about being surrounded is the one thing
+  -- it must not do. Bands closing in from the edges instead, so the
+  -- middle of the frame stays readable and the alarm arrives in the
+  -- corner of the eye.
+  local hurt = sess.damageFlash
+  local low = 1 - math.min(1, sess.hp / (sess.maxHp * 0.35))
+  local wash = math.max(hurt * 0.9, low * 0.6
+                        * (0.7 + 0.3 * math.sin(blink * math.pi * 2)))
+  if wash > 0 then
+    local band = math.min(w, h) * 0.38
+    local steps = 8
+    for i = 1, steps do
+      local t = i / steps
+      local d = band * t
+      love.graphics.setColor(0.60, 0.02, 0.06, wash * 0.13)
+      love.graphics.rectangle("fill", 0, 0, w, d)
+      love.graphics.rectangle("fill", 0, h - d, w, d)
+      love.graphics.rectangle("fill", 0, 0, d, h)
+      love.graphics.rectangle("fill", w - d, 0, d, h)
+    end
+  end
+
+  -- health, top left
+  local barW, barH = 60 * s, 8 * s + PAD * 2 * s
+  healthBar(inset, inset, barW, barH, s, sess.hp / sess.maxHp, hurt > 0.3)
+  label(("%d"):format(math.ceil(sess.hp)), inset, inset + barH + 3 * s, s)
+
+  -- score and wave, top right
+  label(("SCORE %d"):format(math.floor(sess.score)), w - inset, inset, s,
+        "right")
+  label(("WAVE %d"):format(math.max(1, sess.wave)),
+        w - inset, inset + (8 * s + PAD * 2 * s) + 3 * s, s, "right")
+
+  -- ammunition, bottom right: the rounds as pips over the count, which
+  -- reads at a glance in a firefight where a number does not
+  local ammoStr = reloading and "RELOADING" or ("%d / %d"):format(ammo, mag)
+  local _, ah = label(ammoStr, w - inset, h - inset - (8 * s + PAD * 2 * s), s,
+                      "right")
+  local pipW, pipH, pipGap = 3 * s, 7 * s, 2 * s
+  local pipsW = mag * (pipW + pipGap) - pipGap
+  local px = w - inset - pipsW
+  local py = h - inset - ah - pipH - 5 * s
+  love.graphics.setColor(0.06, 0.05, 0.09, 0.85)
+  love.graphics.rectangle("fill", px - 2 * s, py - 2 * s,
+                          pipsW + 4 * s, pipH + 4 * s)
+  for i = 1, mag do
+    if i <= ammo and not reloading then
+      love.graphics.setColor(0.98, 0.86, 0.36, 1)
+    else
+      love.graphics.setColor(0.32, 0.30, 0.36, 1)
+    end
+    love.graphics.rectangle("fill", px + (i - 1) * (pipW + pipGap), py,
+                            pipW, pipH)
+  end
+  if reloading then
+    local t = math.min(1, Gun.state.reloadT / Gun.RELOAD_TIME)
+    love.graphics.setColor(0.55, 0.78, 0.98, 1)
+    love.graphics.rectangle("fill", px, py + pipH + 1 * s, pipsW * t, 2 * s)
+  end
+
+  -- the sight picture
+  local cx, cy = w / 2, h / 2
+  if ads < 0.6 then
+    crosshair(cx, cy, s, Gun.state.kick, (1 - ads / 0.6) * 0.9)
+  end
+  hitMarker(cx, cy, s, sess.hitMarker)
+
+  banner(w, h, s)
+
+  love.graphics.pop()
+  love.graphics.setColor(1, 1, 1, 1)
+end
+
+-- ------- the two callers
+
+-- The flat window. Called from the voxel pipeline's overlay block, into
+-- the scene canvas -- which is at the window's PIXEL size and may be
+-- supersampled on top of that, so the caller's scale carries both.
+--
+-- The caller's scale is CAPPED against the canvas rather than taken as
+-- given, because that scale is the world's zoom: zoom in far enough and
+-- the health bar was a metre wide and half of it off the top of the
+-- screen. A readout is not part of the world and should not zoom with
+-- it -- so it sizes off the frame it is drawn in, which keeps its
+-- apparent size the same at every zoom and grows it honestly on a bigger
+-- display (and with supersampling, which is in both numbers).
+function HordeHud.drawFlat(w, h, scale)
+  if not Horde.active then return end
+  local cap = math.max(1, math.floor(h / 260))
+  local s = math.max(1, math.min(math.floor((scale or 1) + 0.5), cap))
+  draw(w, h, s, 8 * s)
+end
+
+-- ------- and the headset's, which is not a screen overlay at all
+--
+-- A VR eye gets NO 2D overlay. An earlier cut drew this same HUD into
+-- both eye canvases and it came out torn down the middle: the eye frusta
+-- are ASYMMETRIC, so the same canvas pixel is a different ANGLE in each
+-- eye, and the two images never fuse. Nor is there a crosshair to draw --
+-- the gun is a real object with real sights and the shot goes down its
+-- barrel, so a dot painted at the centre of the frame would be pointing
+-- at something else entirely.
+--
+-- What the headset gets instead is this: the readout as a TEXTURE, which
+-- lib/VR puts on the POKEDEX in the player's left hand -- already
+-- tracked, already lit, and already the surface this mod shows
+-- information on. Geometry in the world, so both eyes see it from their
+-- own position and the stereo is correct by construction. (It rode the
+-- gun for one revision and that was worse: a screen on the slide sits
+-- exactly where the iron sights have to be looked through.)
+--
+-- Sized to the device's own screen, which is the GB frame's 10:9.
+
+local panelCanvas = nil
+local PANEL_W, PANEL_H = 160, 144
+
+function HordeHud.panelTexture()
+  if not Horde.active then return nil end
+  if not (love.graphics and love.graphics.newCanvas) then return nil end
+  local sess = Horde.session
+  if not sess then return nil end
+  local F = font()
+  if not F then return nil end
+
+  if not panelCanvas then
+    local ok, c = pcall(love.graphics.newCanvas, PANEL_W, PANEL_H)
+    if not ok then return nil end
+    panelCanvas = c
+    pcall(panelCanvas.setFilter, panelCanvas, "nearest", "nearest")
+  end
+
+  local Gun = V.require("HordeGun")
+  local ammo, mag, reloading = Gun.ammo()
+
+  local ok = pcall(function()
+    love.graphics.push("all")
+    love.graphics.setCanvas(panelCanvas)
+    love.graphics.setBlendMode("alpha")
+    love.graphics.clear(0.93, 0.94, 0.90, 1)
+
+    -- the health bar, framed, across the top
+    love.graphics.setColor(0, 0, 0, 1)
+    love.graphics.rectangle("fill", 8, 8, PANEL_W - 16, 20)
+    love.graphics.setColor(0.80, 0.80, 0.78, 1)
+    love.graphics.rectangle("fill", 11, 11, PANEL_W - 22, 14)
+    love.graphics.setColor(0.78, 0.12, 0.16, 1)
+    love.graphics.rectangle("fill", 11, 11,
+                            (PANEL_W - 22) * math.max(0, sess.hp / sess.maxHp),
+                            14)
+
+    love.graphics.setColor(0, 0, 0, 1)
+    F.draw(("HP %d"):format(math.ceil(sess.hp)), 8, 34)
+    F.draw(reloading and "RELOADING" or ("AMMO %d/%d"):format(ammo, mag),
+           8, 50)
+
+    -- the round pips, so ammunition reads without counting digits
+    local pipW, gap = 9, 5
+    for i = 1, mag do
+      if i <= ammo and not reloading then
+        love.graphics.setColor(0.85, 0.65, 0.10, 1)
+      else
+        love.graphics.setColor(0.72, 0.73, 0.70, 1)
+      end
+      love.graphics.rectangle("fill", 8 + (i - 1) * (pipW + gap), 66, pipW, 12)
+    end
+
+    love.graphics.setColor(0, 0, 0, 1)
+    F.draw(("WAVE %d"):format(math.max(1, sess.wave)), 8, 86)
+    F.draw(("%d"):format(math.floor(sess.score)), 8, 102)
+
+    -- and the banner, wrapped to the panel rather than to the frame.
+    -- BLACK on the panel's own white, like everything else here: the font
+    -- sheets are black glyphs on transparent, so a pale letter is not a
+    -- thing that can be drawn (see the header).
+    if sess.bannerText then
+      local lines, bs, tr = layout(F, sess.bannerText, 1, PANEL_W - 8)
+      if lines then
+        local top = PANEL_H - 8 * bs * #lines - 5
+        love.graphics.setColor(0, 0, 0, 1)
+        love.graphics.rectangle("fill", 0, top - 2, PANEL_W, 1)
+        for i, line in ipairs(lines) do
+          local pen = math.floor((PANEL_W - line.width) / 2)
+          local ly = PANEL_H - 8 * bs * (#lines - i + 1) - 3
+          for _, code in ipairs(F.encode(line.text)) do
+            love.graphics.push()
+            love.graphics.translate(pen, ly)
+            love.graphics.scale(bs, bs)
+            F.drawCode(code, 0, 0)
+            love.graphics.pop()
+            pen = pen + F.advanceOf(code) * bs + tr
+          end
+        end
+      end
+    end
+
+    love.graphics.setCanvas()
+    love.graphics.pop()
+  end)
+  pcall(love.graphics.setCanvas)
+  if not ok then return nil end
+  return panelCanvas
+end
+
+-- window resize / hot reload
+function HordeHud.invalidate()
+  if panelCanvas and panelCanvas.release then
+    pcall(panelCanvas.release, panelCanvas)
+  end
+  panelCanvas = nil
+end
+
+return HordeHud

lib/HordeMobs.lua

@@ -0,0 +1,553 @@
+-- HORDE MODE: the crowd.
+--
+-- Waves of people who want to touch you, walking the same grid the game
+-- walks, wearing the overworld's own character sheets. Every mob IS a
+-- real engine NPC (OverworldState:addRuntimeObject), which is what buys
+-- the whole feature for nothing: the engine interpolates their steps,
+-- the collision system lets them jostle, the voxel pass billboards them
+-- with the right frame for the angle you see them from, and the flat 2D
+-- path draws them too. Nothing here draws a character.
+--
+-- THEY ARE DRIVEN, NOT SCRIPTED. OverworldState:scriptMove would be the
+-- obvious way to walk one, and it is a trap: a queued script move sets
+-- `scripted` on the state, which blocks the PLAYER's input for as long as
+-- it runs. So mobs are spawned with movement = "STAY" (which leaves
+-- NPC:update's wander branch inert) and this file writes facing / target /
+-- moving / progress directly, once per step. NPC:update then does the
+-- pixel interpolation and the cell commit exactly as it does for a
+-- wandering shopkeeper.
+--
+-- PATHING IS A FLOW FIELD, not A* per mob. One breadth-first sweep out
+-- from the player's cell, over the map's walkable cells, gives EVERY mob
+-- its next step at once -- and gives it correctly through doorways and
+-- around buildings, which is what "gang up on the player" actually
+-- requires. Rebuilt a few times a second rather than per frame; between
+-- rebuilds a mob just walks downhill on the numbers. It also answers two
+-- other questions for free: how far a cell is from the player (so a spawn
+-- point can be picked at a fair distance and be guaranteed REACHABLE),
+-- and whether a mob is adjacent enough to swing.
+--
+-- The sweep ignores entity occupancy on purpose. Mobs are solid to each
+-- other, so a pack funnelling down a corridor will jam -- and the fix for
+-- that is not a cleverer path, it is that a mob whose downhill step is
+-- occupied tries its second choice and otherwise waits. That is what
+-- makes them pool around the player instead of forming a queue.
+--
+-- FOLLOWING THROUGH DOORS. A warp tears down every NPC on the old map, so
+-- the roster cannot survive one. What survives is the COUNT: the number
+-- still alive when the player ran, re-spawned on the far side over the
+-- next few seconds, from the cells nearest the door they came in by. From
+-- the player's chair that is the horde coming through the door after them.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Horde = V.require("Horde")
+local HordeSfx = V.require("HordeSfx")
+
+local HordeMobs = {}
+
+-- ------- tuning
+
+-- Wave n throws this many at you, and no more than CAP stand at once.
+local function waveSize(n) return 4 + 3 * n end
+local CAP = 14
+local SPAWN_INTERVAL = 0.75      -- seconds between arrivals inside a wave
+local WAVE_GAP = 4.0             -- the breather, and the banner's window
+local FOLLOW_INTERVAL = 0.55     -- how fast they pour through a door
+
+-- Frames per cell. The engine's own walk is 16; the horde is quicker than
+-- a shopkeeper and gets quicker as the waves stack, floored so it never
+-- outruns the player's own free walk.
+local function stepFrames(n)
+  return math.max(9, 15 - math.floor(n / 2))
+end
+
+local function mobHp(n) return math.min(4, 1 + math.floor(n / 3)) end
+local function killScore(n) return 100 + 25 * (n - 1) end
+local function waveBonus(n) return 250 * n end
+
+-- How close a mob comes before it stops walking and starts swinging, in
+-- CELLS, and how close it has to be to land the hit, in world pixels.
+--
+-- The standoff is the difference between a horde and a wall. Nothing
+-- stops a mob taking the cell next to the player -- and when it does, a
+-- sixteen-pixel figure a cell away fills a sixty-five-degree lens edge to
+-- edge, so being surrounded looks like a texture rather than like people.
+-- Two cells back they read as figures closing in, the ring holds a dozen
+-- of them, and the player can still see what they are shooting at.
+local STANDOFF = 2
+local REACH = 40
+
+-- The cast. Overworld sprite sheets that read as a threat coming out of
+-- the dark; anything missing from the loaded game is dropped at spawn.
+local CAST = {
+  "SPRITE_ROCKET", "SPRITE_CHANNELER", "SPRITE_SCIENTIST", "SPRITE_BIKER",
+  "SPRITE_GUARD", "SPRITE_SUPER_NERD", "SPRITE_HIKER", "SPRITE_SWIMMER",
+  "SPRITE_GYM_GUIDE", "SPRITE_BLACK_HAIR_BOY_1", "SPRITE_GIRL",
+  "SPRITE_MIDDLE_AGED_MAN", "SPRITE_FISHER", "SPRITE_GAMBLER",
+}
+
+local OWNER = "DRAMATIC_SHAPE"
+
+-- ------- the flow field
+--
+-- dist[cy * w + cx] = steps from the player, over walkable cells only.
+-- Nil where the sweep never reached, which is the same answer as "no way
+-- there from here" -- an island across water, a room behind a locked door.
+
+local field = { mapId = nil, w = 0, h = 0, dist = nil, at = nil, age = 0 }
+
+local REBUILD_EVERY = 0.28
+
+local function passable(map, cx, cy)
+  if not map:inBounds(cx, cy) then return false end
+  if not map:isWalkableCell(cx, cy) then return false end
+  -- a warp cell is walkable but standing on one takes the warp; mobs may
+  -- cross them (that IS the door they follow you through) so they stay in
+  return true
+end
+
+-- fixed order, so a tie between two equally good steps always breaks the
+-- same way -- a mob that dithers between two cells reads as broken, and a
+-- pairs() walk over a hash would give a different answer every run
+local DIRS = { "right", "left", "down", "up" }
+local DX = { right = 1, left = -1, down = 0, up = 0 }
+local DY = { right = 0, left = 0, down = 1, up = -1 }
+
+local function rebuildField(map, px, py)
+  local w, h = map.widthCells, map.heightCells
+  local dist = {}
+  -- a plain array queue: BFS on a grid never revisits a cell, so no heap
+  -- and no priority is needed and the whole sweep is one pass
+  local qx, qy = { px }, { py }
+  local head = 1
+  dist[py * w + px] = 0
+  while head <= #qx do
+    local cx, cy = qx[head], qy[head]
+    head = head + 1
+    local d = dist[cy * w + cx] + 1
+    for i = 1, 4 do
+      local dir = DIRS[i]
+      local nx, ny = cx + DX[dir], cy + DY[dir]
+      local key = ny * w + nx
+      if dist[key] == nil and passable(map, nx, ny) then
+        dist[key] = d
+        qx[#qx + 1], qy[#qy + 1] = nx, ny
+      end
+    end
+  end
+  field.mapId, field.w, field.h, field.dist = map.id, w, h, dist
+  field.at = { px, py }
+  field.age = 0
+end
+
+local function distAt(cx, cy)
+  if not field.dist then return nil end
+  if cx < 0 or cy < 0 or cx >= field.w or cy >= field.h then return nil end
+  return field.dist[cy * field.w + cx]
+end
+
+-- named for the suite: the sweep, and the distance it wrote to a cell
+HordeMobs._dist = distAt
+HordeMobs._rebuild = rebuildField
+
+-- ------- spawning
+
+local function liveSprites(G)
+  local out = {}
+  local sprites = G and G.data and G.data.sprites
+  for _, key in ipairs(CAST) do
+    if sprites and sprites[key] then out[#out + 1] = key end
+  end
+  if #out == 0 and sprites then
+    -- a total conversion with none of the vanilla sheets: take whatever
+    -- walker it does have rather than spawning nothing at all
+    local keys = {}
+    for key, def in pairs(sprites) do
+      if def and def.walker then keys[#keys + 1] = key end
+    end
+    table.sort(keys)
+    for i = 1, math.min(6, #keys) do out[i] = keys[i] end
+  end
+  return out
+end
+
+-- Cells at a fair distance from the player that the flow field says are
+-- actually reachable, preferring the far end of the band so the horde
+-- arrives from off in the dark rather than on top of you.
+local function spawnCells(map, near, far, want)
+  local out = {}
+  if not field.dist then return out end
+  for key, d in pairs(field.dist) do
+    if d >= near and d <= far then
+      local cy = math.floor(key / field.w)
+      local cx = key - cy * field.w
+      out[#out + 1] = { cx, cy, d }
+    end
+  end
+  -- shuffle, then bias toward distance: sorting outright would file every
+  -- mob in from the same corner
+  for i = #out, 2, -1 do
+    local j = love.math.random(i)
+    out[i], out[j] = out[j], out[i]
+  end
+  table.sort(out, function(a, b) return a[3] > b[3] end)
+  while #out > (want or 16) do table.remove(out) end
+  return out
+end
+
+local function occupiedCell(state, cx, cy)
+  local Collision = require("src.world.Collision")
+  return Collision.occupied(state.entities, cx, cy, nil) ~= nil
+end
+
+-- One mob, on a cell, on the live map. Returns the roster entry or nil.
+local function spawnAt(G, state, cx, cy, wave)
+  local s = Horde.session
+  if not s then return nil end
+  local sprites = liveSprites(G)
+  if #sprites == 0 then return nil end
+  local def = {
+    x = cx, y = cy,
+    sprite = sprites[love.math.random(#sprites)],
+    movement = "STAY",
+    range = "DOWN",
+    name = "HORDE",
+    hordeMob = true,
+  }
+  local mapId = state.map.id
+  local okAdd, npcId = pcall(state.addRuntimeObject, state, mapId, def, OWNER)
+  if not (okAdd and npcId) then return nil end
+  s.spawned[mapId] = s.spawned[mapId] or {}
+  s.spawned[mapId][def.index] = true
+
+  local npc = nil
+  for _, e in ipairs(state.npcs) do
+    if e.id == npcId then npc = e break end
+  end
+  if not npc then return nil end
+  npc.wanders = false
+  npc.stepFrames = stepFrames(wave)
+  local entry = {
+    npc = npc, id = npcId, mapId = mapId,
+    hp = mobHp(wave), attackT = 0,
+  }
+  s.mobs[#s.mobs + 1] = entry
+  return entry
+end
+
+-- ------- removal
+--
+-- Targeted, because the engine's own removeRuntimeObject walks every map
+-- in the game to find one object and a firefight calls this several times
+-- a second.
+
+local function dropNpc(state, npcId)
+  for _, list in ipairs({ state.npcs or {}, state.entities or {} }) do
+    for i = #list, 1, -1 do
+      if list[i].id == npcId then table.remove(list, i) end
+    end
+  end
+  if state.npcPool then state.npcPool[npcId] = nil end
+end
+
+-- Take this mode's objects back out of a map record. Runtime objects live
+-- in Game.data.maps[id].objects until removed, and setMap respawns from
+-- that list -- so a def left behind is a mob waiting on the far side of a
+-- door long after the mode ended.
+local function scrubMap(G, mapId, indices)
+  local def = G and G.data and G.data.maps and G.data.maps[mapId]
+  if not def or not def.objects then return end
+  for i = #def.objects, 1, -1 do
+    local obj = def.objects[i]
+    if obj and obj.hordeMob and (not indices or indices[obj.index]) then
+      table.remove(def.objects, i)
+    end
+  end
+end
+
+-- ------- the roster's own step
+
+local function faceToward(npc, cx, cy)
+  local dx, dy = cx - npc.cellX, cy - npc.cellY
+  if math.abs(dx) > math.abs(dy) then
+    return dx > 0 and "right" or "left"
+  end
+  return dy > 0 and "down" or "up"
+end
+
+-- Walk one mob downhill on the flow field. The best neighbour is the one
+-- with the lowest distance; when it is taken, the second best is tried,
+-- and when both are taken the mob waits a beat -- which is what makes a
+-- pack pool around the player instead of queueing behind one another.
+local function stepMob(state, entry)
+  local npc = entry.npc
+  if npc.moving then return end
+  local here = distAt(npc.cellX, npc.cellY)
+  -- close enough: stand and swing rather than crowding into the lens
+  if here and here <= STANDOFF then
+    local p = state.player
+    npc.facing = faceToward(npc, p.cellX, p.cellY)
+    return
+  end
+  local best, bestD, second, secondD = nil, nil, nil, nil
+  for i = 1, 4 do
+    local dir = DIRS[i]
+    local tx, ty = npc.cellX + DX[dir], npc.cellY + DY[dir]
+    local d = distAt(tx, ty)
+    -- the standoff is enforced on the cell being ENTERED, not the one
+    -- being stood on: a mob that checked only where it was would still
+    -- finish the step it was already taking and end up in the lens
+    if d and d < STANDOFF then d = nil end
+    if d and (not here or d < here) then
+      if not bestD or d < bestD then
+        second, secondD = best, bestD
+        best, bestD = { dir, tx, ty }, d
+      elseif not secondD or d < secondD then
+        second, secondD = { dir, tx, ty }, d
+      end
+    end
+  end
+  for _, pick in ipairs({ best, second }) do
+    if pick then
+      local dir, tx, ty = pick[1], pick[2], pick[3]
+      if not occupiedCell(state, tx, ty) then
+        npc.facing = dir
+        npc.targetX, npc.targetY = tx, ty
+        npc.moving = true
+        npc.progress = 0
+        return
+      end
+    end
+  end
+  -- boxed in: keep facing the player so the pack still reads as a threat
+  local p = state.player
+  npc.facing = faceToward(npc, p.cellX, p.cellY)
+end
+
+-- ------- the public surface
+
+function HordeMobs.begin(G)
+  local s = Horde.session
+  if not s then return end
+  local state = G and G.overworld
+  if not (state and state.map) then return end
+  field.mapId = nil
+  s.wave, s.waveRemaining, s.waveGap, s.spawnGap = 0, 0, 0, 0
+  HordeMobs.convertLocals(state)
+end
+
+-- Everyone already standing on the map joins in. Their sprite, their
+-- position, their business -- now walking at the player. Nothing is
+-- stored to undo it, because the restore warps through setMap, which
+-- rebuilds every one of them from the map record (see Horde.finish).
+function HordeMobs.convertLocals(state)
+  local s = Horde.session
+  if not (s and state and state.npcs) then return end
+  local known = {}
+  for _, e in ipairs(s.mobs) do known[e.npc] = true end
+  for _, npc in ipairs(state.npcs) do
+    if not known[npc] and not npc.passable then
+      npc.wanders = false
+      npc.frozen = false
+      npc.stepFrames = stepFrames(math.max(1, s.wave))
+      s.mobs[#s.mobs + 1] = {
+        npc = npc, id = npc.id, mapId = state.map.id,
+        hp = mobHp(math.max(1, s.wave)), attackT = 0, local_ = true,
+      }
+    end
+  end
+end
+
+function HordeMobs.nextWave(G)
+  local s = Horde.session
+  if not s then return end
+  s.wave = s.wave + 1
+  s.waveRemaining = waveSize(s.wave)
+  s.spawnGap = 0
+  Horde.banner(("WAVE %d"):format(s.wave), 1.6)
+  HordeSfx.play(HordeSfx.WAVE)
+  for _, e in ipairs(s.mobs) do
+    e.npc.stepFrames = stepFrames(s.wave)
+  end
+end
+
+-- A mob took a bullet. Returns "kill", "hit", or nil.
+function HordeMobs.hit(entry, damage)
+  local s = Horde.session
+  if not (s and entry) then return nil end
+  entry.hp = entry.hp - (damage or 1)
+  if entry.hp > 0 then
+    HordeSfx.play(HordeSfx.HIT)
+    return "hit"
+  end
+  entry.dead = true
+  s.kills = s.kills + 1
+  Horde.addScore(killScore(math.max(1, s.wave)))
+  HordeSfx.randomCry()
+  return "kill"
+end
+
+-- Every live mob, for the gun's ray to test against.
+function HordeMobs.list()
+  local s = Horde.session
+  return s and s.mobs or {}
+end
+
+function HordeMobs.update(dt, G)
+  local s = Horde.session
+  if not s then return end
+  local state = G and G.overworld
+  if not (state and state.map and state.player) then return end
+  local p = state.player
+
+  -- the flow field, rebuilt on a clock and whenever the player changes
+  -- cell far enough that the old numbers point at where they used to be
+  field.age = field.age + dt
+  local moved = field.at
+    and (math.abs(field.at[1] - p.cellX) + math.abs(field.at[2] - p.cellY)) or 99
+  if field.mapId ~= state.map.id or field.age >= REBUILD_EVERY or moved >= 2 then
+    rebuildField(state.map, p.cellX, p.cellY)
+  end
+
+  -- the dead, collected before anything walks
+  for i = #s.mobs, 1, -1 do
+    local e = s.mobs[i]
+    if e.dead or not e.npc then
+      if e.npc then dropNpc(state, e.id) end
+      table.remove(s.mobs, i)
+    end
+  end
+
+  -- the living
+  local pcx, pcy = p.px + 8, p.py + 8
+  for _, e in ipairs(s.mobs) do
+    local npc = e.npc
+    e.attackT = math.max(0, e.attackT - dt)
+    stepMob(state, e)
+    local dx, dz = (npc.px + 8) - pcx, (npc.py + 8) - pcy
+    if dx * dx + dz * dz <= REACH * REACH then
+      if e.attackT <= 0 then
+        e.attackT = 0.8
+        npc.facing = faceToward(npc, p.cellX, p.cellY)
+        Horde.damage()
+      end
+    end
+  end
+
+  if not Horde.playing() then return end
+
+  -- the crowd that followed the player through a door, arriving
+  if s.followQueue > 0 then
+    s.spawnGap = s.spawnGap - dt
+    if s.spawnGap <= 0 and #s.mobs < CAP then
+      s.spawnGap = FOLLOW_INTERVAL
+      local cells = spawnCells(state.map, 2, 9, 8)
+      local cell = cells[1]
+      if cell and spawnAt(G, state, cell[1], cell[2], s.wave) then
+        s.followQueue = s.followQueue - 1
+      else
+        s.followQueue = s.followQueue - 1   -- nowhere to put them; let it go
+      end
+    end
+    return
+  end
+
+  -- the wave itself
+  if s.waveRemaining > 0 then
+    s.spawnGap = s.spawnGap - dt
+    if s.spawnGap <= 0 and #s.mobs < CAP then
+      s.spawnGap = SPAWN_INTERVAL
+      local cells = spawnCells(state.map, 7, 18, 10)
+      if #cells == 0 then cells = spawnCells(state.map, 3, 30, 10) end
+      local cell = cells[1]
+      if cell and spawnAt(G, state, cell[1], cell[2], s.wave) then
+        s.waveRemaining = s.waveRemaining - 1
+      else
+        s.spawnGap = 1.5     -- no room right now; try again shortly
+      end
+    end
+  elseif #s.mobs == 0 then
+    s.waveGap = s.waveGap + dt
+    if s.waveGap == dt then
+      Horde.addScore(waveBonus(s.wave))
+      Horde.banner(("WAVE %d CLEAR"):format(s.wave), 1.8)
+    end
+    if s.waveGap >= WAVE_GAP then
+      s.waveGap = 0
+      HordeMobs.nextWave(G)
+    end
+  end
+end
+
+-- ------- the door
+--
+-- map.entered fires after setMap has rebuilt the world, which means every
+-- mob instance from the old map is already gone. What is left to do is
+-- take our defs off the old map (or they respawn if the player ever comes
+-- back), remember how many were chasing, and let update() walk them in.
+
+function HordeMobs.onMapEntered(payload)
+  local s = Horde.session
+  if not s then return end
+  local G = require("src.core.Game")
+  local state = G.overworld
+  if not (state and state.map) then return end
+  local newId = state.map.id
+
+  local following = 0
+  for _, e in ipairs(s.mobs) do
+    if e.mapId ~= newId and not e.local_ then following = following + 1 end
+  end
+  -- the old map's records, and any instance the pool kept
+  for mapId, indices in pairs(s.spawned) do
+    if mapId ~= newId then
+      scrubMap(G, mapId, indices)
+      s.spawned[mapId] = nil
+    end
+  end
+  for i = #s.mobs, 1, -1 do
+    if s.mobs[i].mapId ~= newId then table.remove(s.mobs, i) end
+  end
+
+  field.mapId = nil
+  s.followQueue = math.max(s.followQueue, following)
+  s.spawnGap = math.min(s.spawnGap, 0.4)
+  HordeMobs.convertLocals(state)
+end
+
+-- ------- the end
+--
+-- Every def this mode wrote, off every map it wrote one to. The live
+-- instances go too, though the restore's own warp would have taken them:
+-- cleanup has to leave a consistent world even when it is called from a
+-- path that never warps.
+
+function HordeMobs.cleanup(G)
+  G = G or require("src.core.Game")
+  local s = Horde.session
+  local state = G.overworld
+  if s then
+    for _, e in ipairs(s.mobs) do
+      if state and not e.local_ then dropNpc(state, e.id) end
+    end
+    for mapId, indices in pairs(s.spawned) do
+      scrubMap(G, mapId, indices)
+    end
+    s.mobs, s.spawned = {}, {}
+    s.followQueue, s.waveRemaining = 0, 0
+  else
+    -- a session that vanished under us (a reload mid-mode): sweep every
+    -- map for this mode's marker rather than leaving actors behind
+    for mapId in pairs((G.data and G.data.maps) or {}) do
+      scrubMap(G, mapId, nil)
+    end
+  end
+  field.mapId, field.dist, field.at = nil, nil, nil
+end
+
+-- named for the suite, down here because the walk is defined above it
+HordeMobs._stepMob = stepMob
+
+return HordeMobs

lib/HordeSfx.lua

@@ -0,0 +1,262 @@
+-- HORDE MODE: the gun, in Game Boy hardware.
+--
+-- Every sound this mode makes is SYNTHESIZED on the same emulated APU the
+-- rest of the game speaks through -- no sample files ship with the mod.
+-- That is a deliberate aesthetic choice as much as a legal one: Lavender
+-- Town is playing, the cries are the real cries, and a 44kHz foley
+-- gunshot dropped on top would read as a different program running in the
+-- same window. Authored here with ChipAsm (src/audio/ChipAsm.lua), which
+-- assembles note tables into the channel bytecode ChipAudio interprets.
+--
+-- WHAT A GUNSHOT IS, on this hardware. Channel 4 is a noise generator
+-- whose `parameter` byte is NR43: the high nibble is the shift clock (LOW
+-- values are BRIGHT, high values are low rumble), bit 3 picks the short
+-- 7-bit LFSR (metallic and pitched) over the long 15-bit one (white
+-- hiss), and the low three bits divide. A real gunshot is a bright crack
+-- collapsing into a body and then a room tail, so each sound here is a
+-- STAGED program: three or four noise notes marching down the parameter
+-- byte, each shorter-lived than the last. `len` is in frames of 1/60s,
+-- `volume` is 0-15, and `fade` is the envelope period -- 1 decays fastest,
+-- 7 slowest, 0 holds for the note's whole length.
+--
+-- The shot also gets two frames of channel 1 underneath it: a square note
+-- swept hard downward, which is the only way to put a low thump on this
+-- chip. It costs the music its lead channel for 1/30s per shot, which is
+-- inaudible as interference and is most of what makes the shot feel like
+-- it has weight.
+--
+-- THREE SHOT VARIANTS, round-robined. Sound.play caches ONE Source per
+-- registered name and restarts it (stop then play), so firing twice on
+-- one name cuts the first shot's tail off. Three names means three
+-- Sources, so a fast trigger finger overlaps its own echoes the way a
+-- real one does -- and the variants differ slightly in their tails, which
+-- takes the machine-gun sameness off a repeated sound.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local HordeSfx = {}
+
+-- the registered names, in the shape the rest of the mode asks for them
+HordeSfx.SHOTS = { "DS_HORDE_SHOT_1", "DS_HORDE_SHOT_2", "DS_HORDE_SHOT_3" }
+HordeSfx.DRY = "DS_HORDE_DRY"
+HordeSfx.MAG_OUT = "DS_HORDE_MAG_OUT"
+HordeSfx.MAG_IN = "DS_HORDE_MAG_IN"
+HordeSfx.RACK = "DS_HORDE_RACK"
+HordeSfx.HIT = "DS_HORDE_HIT"
+HordeSfx.HURT = "DS_HORDE_HURT"
+HordeSfx.WAVE = "DS_HORDE_WAVE"
+
+-- ------- the programs
+
+-- The shot's noise stage list: bright crack, body, tail, room. `tail`
+-- lets the three variants differ in how the last stage rings out without
+-- restating the whole program.
+local function shotNoise(tail)
+  return {
+    -- the crack: one frame, full volume, brightest parameter the chip has
+    { noiseNote = { len = 1, volume = 15, fade = 1, parameter = 0x00 } },
+    -- the body: the shift clock drops, the 7-bit LFSR gives it a metallic
+    -- edge -- this is the part that reads as "a mechanism did that"
+    { noiseNote = { len = 2, volume = 13, fade = 2, parameter = 0x2C } },
+    -- the tail: lower, softer, longer
+    { noiseNote = { len = 3, volume = 8, fade = 3, parameter = tail[1] } },
+    -- the room: a low breath of noise fading under everything
+    { noiseNote = { len = tail[2], volume = 4, fade = 4, parameter = tail[3] } },
+  }
+end
+
+-- The thump under the crack: channel 1's frequency register swept down
+-- hard. 0x600 is around 250Hz; the sweep drags it into the floor over the
+-- two frames it lives, which is a kick drum by another name.
+local THUMP = {
+  { pitchSweep = { pace = 2, subtract = true, shift = 3 } },
+  { squareNote = { len = 2, volume = 12, fade = 2, frequency = 0x600 } },
+}
+
+local function shot(tail)
+  return {
+    channels = {
+      { hw = 1, program = THUMP },
+      { hw = 4, program = shotNoise(tail) },
+    },
+  }
+end
+
+-- The reload, in three separate sounds the gun fires on its own clock:
+-- the magazine dropping out, the fresh one seating, and the slide coming
+-- back and going home. Noise only -- these are mechanical clicks, and
+-- keeping them off the tone channels leaves the music alone.
+local PROGRAMS = {
+  [HordeSfx.SHOTS[1]] = shot({ 0x55, 5, 0x76 }),
+  [HordeSfx.SHOTS[2]] = shot({ 0x54, 6, 0x77 }),
+  [HordeSfx.SHOTS[3]] = shot({ 0x65, 4, 0x86 }),
+
+  -- the hammer falling on nothing: one dull tick, no tail
+  [HordeSfx.DRY] = {
+    channels = {
+      { hw = 4, program = {
+        { noiseNote = { len = 1, volume = 7, fade = 1, parameter = 0x38 } },
+        { noiseNote = { len = 1, volume = 3, fade = 1, parameter = 0x54 } },
+      } },
+    },
+  },
+
+  -- the magazine leaving: a click and a soft drop away from it
+  [HordeSfx.MAG_OUT] = {
+    channels = {
+      { hw = 4, program = {
+        { noiseNote = { len = 1, volume = 10, fade = 1, parameter = 0x1A } },
+        { noiseNote = { len = 2, volume = 5, fade = 2, parameter = 0x58 } },
+      } },
+    },
+  },
+
+  -- the fresh magazine seating: a firmer, lower clack with a bit of body
+  [HordeSfx.MAG_IN] = {
+    channels = {
+      { hw = 4, program = {
+        { noiseNote = { len = 1, volume = 13, fade = 1, parameter = 0x18 } },
+        { noiseNote = { len = 2, volume = 8, fade = 2, parameter = 0x46 } },
+        { noiseNote = { len = 2, volume = 3, fade = 3, parameter = 0x67 } },
+      } },
+    },
+  },
+
+  -- the slide: back (bright scrape), a frame of nothing, then home (hard)
+  [HordeSfx.RACK] = {
+    channels = {
+      { hw = 4, program = {
+        { noiseNote = { len = 2, volume = 9, fade = 2, parameter = 0x25 } },
+        { rest = 1 },
+        { noiseNote = { len = 1, volume = 14, fade = 1, parameter = 0x11 } },
+        { noiseNote = { len = 2, volume = 6, fade = 2, parameter = 0x44 } },
+      } },
+    },
+  },
+
+  -- a bullet arriving: short, bright, gone -- the hit marker's own sound
+  [HordeSfx.HIT] = {
+    channels = {
+      { hw = 4, program = {
+        { noiseNote = { len = 1, volume = 11, fade = 1, parameter = 0x14 } },
+        { noiseNote = { len = 1, volume = 5, fade = 2, parameter = 0x42 } },
+      } },
+    },
+  },
+
+  -- being hit: a low ugly thud on the noise channel with a square groan
+  -- under it, sweeping DOWN -- the sound of losing something
+  [HordeSfx.HURT] = {
+    channels = {
+      { hw = 1, program = {
+        { pitchSweep = { pace = 3, subtract = true, shift = 4 } },
+        { squareNote = { len = 6, volume = 11, fade = 3, frequency = 0x480 } },
+      } },
+      { hw = 4, program = {
+        { noiseNote = { len = 2, volume = 12, fade = 2, parameter = 0x66 } },
+        { noiseNote = { len = 4, volume = 6, fade = 3, parameter = 0x78 } },
+      } },
+    },
+  },
+
+  -- a wave arriving: two rising square stabs, deliberately not a fanfare
+  [HordeSfx.WAVE] = {
+    channels = {
+      { hw = 1, program = {
+        { squareNote = { len = 3, volume = 10, fade = 2, frequency = 0x5C0 } },
+        { rest = 1 },
+        { squareNote = { len = 6, volume = 12, fade = 3, frequency = 0x680 } },
+      } },
+    },
+  },
+}
+
+-- ------- registration
+
+-- Assemble every program and put it in the sfx registry. Called once from
+-- main.lua at load. A malformed note table raises inside ChipAsm; each is
+-- assembled under pcall so one bad program is one missing sound rather
+-- than a mod that fails to load.
+function HordeSfx.register(mod)
+  local ok, ChipAsm = pcall(require, "src.audio.ChipAsm")
+  if not (ok and ChipAsm) then return false end
+  local n = 0
+  for name, spec in pairs(PROGRAMS) do
+    local built, out = pcall(ChipAsm.sfx, spec)
+    if built and out and out.chip then
+      local reg = pcall(function()
+        mod.content.sfx:register(name, { chip = out.chip })
+      end)
+      if reg then n = n + 1 end
+    elseif mod.log then
+      mod.log:error("horde: sfx %s did not assemble: %s", name, tostring(out))
+    end
+  end
+  return n > 0
+end
+
+-- ------- playback
+--
+-- One indirection so callers never touch Sound directly and a headless
+-- run (no love.audio) costs a pcall rather than an error.
+
+local function play(name)
+  pcall(function()
+    local Game = require("src.core.Game")
+    require("src.core.Sound").play(Game.data, name)
+  end)
+end
+
+HordeSfx.play = play
+
+local shotIndex = 0
+
+-- The next shot in the round-robin, so consecutive rounds overlap rather
+-- than cutting each other off (see the header).
+function HordeSfx.shot()
+  shotIndex = shotIndex % #HordeSfx.SHOTS + 1
+  play(HordeSfx.SHOTS[shotIndex])
+end
+
+-- ------- the cries
+--
+-- Every mob that dies screams as something from the national dex. The
+-- list is built once from the live cry registry -- whatever the game and
+-- whatever mods are loaded have between them -- so this needs no data of
+-- its own and picks up a total conversion's roster for free.
+
+local cryList = nil
+
+local function cries()
+  if cryList then return cryList end
+  local out = {}
+  pcall(function()
+    local Game = require("src.core.Game")
+    local table_ = Game.data and Game.data.audio and Game.data.audio.cries
+    for species in pairs(table_ or {}) do out[#out + 1] = species end
+  end)
+  table.sort(out)   -- love.math.random over a stable order, not hash order
+  cryList = out
+  return out
+end
+
+-- A random cry, at a random-ish pitch. Nothing is more Pokemon than the
+-- wrong animal noise coming out of a man in a suit.
+function HordeSfx.randomCry()
+  local list = cries()
+  if #list == 0 then return nil end
+  local species = list[love.math.random(#list)]
+  pcall(function()
+    local Game = require("src.core.Game")
+    require("src.core.Sound").playCry(Game.data, species)
+  end)
+  return species
+end
+
+-- a fresh boot (or a hot reload) rebuilds the species list
+function HordeSfx.invalidate()
+  cryList = nil
+end
+
+return HordeSfx

lib/ImageCache.lua

@@ -0,0 +1,65 @@
+-- Voxel world mode: decoded pixels, kept.
+--
+-- Assets.imageData is deliberately uncached upstream -- "pixel-level reads
+-- resolve the same way but stay uncached: the caller keeps the derived
+-- product" (src/render/Assets.lua) -- which is the right contract for the
+-- flat renderer, whose one caller decodes a strip once and keeps the strip.
+--
+-- This mod is not that caller. It reads the same handful of images over and
+-- over, from several places that do not know about each other:
+--
+--   * the tileset atlas, decoded by Structures (its own cache), by
+--     TerrainAtlas twice (the SGB bake and the RED++ rebake), by
+--     TerrainAtlas again to learn a tile's shades, and by GlassMask;
+--   * the FLOWER FRAME files, decoded inside patch() -- which runs every
+--     time the animation step turns over, about three times a second, for
+--     as long as the map is on screen. That one is not a load cost at all,
+--     it is a recurring per-second cost on the render thread, and it was
+--     the single clearest waste the first profile turned up.
+--
+-- So: one table, keyed by the path as the CALLER gave it, holding the
+-- decoded ImageData. Registered with Assets.invalidate so a hot reload
+-- drops it alongside every other downstream cache.
+--
+-- The entries are never evicted by size. That is deliberate and bounded:
+-- what lands here is tileset art and animation frames -- a few dozen small
+-- images for a whole session, tens of kilobytes each -- not per-map bakes,
+-- which have their own eviction in TerrainAtlas.setLive.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Assets = require("src.render.Assets")
+local Perf = V.require("Perf")
+
+local ImageCache = {}
+
+local cache = {}
+
+-- The decoded pixels for `path`, or nil when it cannot be read.
+--
+-- `false` is cached for an unreadable path, so a missing or corrupt asset
+-- costs one failed decode for the session rather than one per frame -- the
+-- same sticky-failure shape the rest of this mod uses for GPU objects.
+function ImageCache.get(path)
+  if not path then return nil end
+  local hit = cache[path]
+  if hit ~= nil then
+    Perf.count("imageCache.hit")
+    return hit or nil
+  end
+  local t0 = Perf.now()
+  local ok, data = pcall(Assets.imageData, path)
+  Perf.add("ImageCache.decode", t0)
+  Perf.count("imageCache.miss")
+  cache[path] = (ok and data) or false
+  return cache[path] or nil
+end
+
+function ImageCache.invalidate()
+  cache = {}
+end
+
+Assets.register(ImageCache.invalidate)
+
+return ImageCache

lib/Mat4.lua

@@ -6,9 +6,11 @@
 -- here -- translation in the fourth column, m[4]/m[8]/m[12].
 --
 -- Only what the renderer actually needs: a perspective projection (the
--- camera), an orthographic one (the sun's shadow pass), a look-based view,
--- and the translate/rotateY/scale a model matrix is built from. No general
--- inverse, no quaternions.
+-- camera), an orthographic one (the sun's shadow pass), an asymmetric one
+-- (a headset's per-eye frustum), a look-based view, a quaternion rotation
+-- (a headset's pose), and the translate/rotateY/scale a model matrix is
+-- built from. No general inverse -- the VR view inverts its rigid pieces
+-- one at a time.
 
 local Mat4 = {}
 
@@ -62,6 +64,45 @@ function Mat4.rotateX(a)
            0, 0, 0, 1 }
 end
 
+-- The rotation a unit quaternion describes, row-major. The VR rig is what
+-- needs it: an OpenXR eye pose arrives as position + orientation
+-- quaternion, and both the eye's transform and its inverse (the view) are
+-- built from this.
+function Mat4.fromQuat(x, y, z, w)
+  local xx, yy, zz = x * x, y * y, z * z
+  local xy, xz, yz = x * y, x * z, y * z
+  local wx, wy, wz = w * x, w * y, w * z
+  return { 1 - 2 * (yy + zz), 2 * (xy - wz), 2 * (xz + wy), 0,
+           2 * (xy + wz), 1 - 2 * (xx + zz), 2 * (yz - wx), 0,
+           2 * (xz - wy), 2 * (yz + wx), 1 - 2 * (xx + yy), 0,
+           0, 0, 0, 1 }
+end
+
+-- Transpose. For a pure rotation this IS the inverse, which is how the VR
+-- view matrix is assembled without a general 4x4 inverse.
+function Mat4.transpose(m)
+  return { m[1], m[5], m[9], m[13],
+           m[2], m[6], m[10], m[14],
+           m[3], m[7], m[11], m[15],
+           m[4], m[8], m[12], m[16] }
+end
+
+-- Right-handed perspective from an OpenXR-style asymmetric field of view:
+-- four signed HALF-ANGLES off the view axis (left and down negative), onto
+-- GL clip space (z in [-1, 1]). A headset's per-eye frustum is off-centre
+-- -- the nose side is narrower than the temple side -- so the symmetric
+-- perspective() above cannot express it.
+function Mat4.fovProjection(angleLeft, angleRight, angleUp, angleDown,
+                            near, far)
+  local l, r = math.tan(angleLeft), math.tan(angleRight)
+  local u, d = math.tan(angleUp), math.tan(angleDown)
+  local w, h, dz = r - l, u - d, near - far
+  return { 2 / w, 0, (r + l) / w, 0,
+           0, 2 / h, (u + d) / h, 0,
+           0, 0, (far + near) / dz, (2 * far * near) / dz,
+           0, 0, -1, 0 }
+end
+
 -- Right-handed perspective onto GL clip space (z in [-1, 1]).
 function Mat4.perspective(fovY, aspect, near, far)
   local f = 1 / math.tan(fovY / 2)

lib/ModSetting.lua

@@ -47,6 +47,42 @@ local function indexOf(self, value)
   return 1
 end
 
+-- ------- rungs that are not always there
+--
+-- A ladder may carry a rung that cannot be selected right now -- STADIUM
+-- needs models built out of a ROM the player supplies, and until that has
+-- happened there is nothing behind the option. `gate` is asked per rung and
+-- decides whether it exists at all this frame.
+--
+-- Skipped rather than shown-and-refused, deliberately. A row that can be
+-- cycled onto and then does nothing is indistinguishable from a broken mod;
+-- a row that simply has fewer stops reads as the mod not offering something,
+-- which is the truth. What the player is missing, and how to get it, is said
+-- once in the row's help text instead of implied by a dead setting.
+--
+-- values[1] is never gated: it is the default and the fallback, so there is
+-- always at least one rung to land on.
+function ModSetting:setGate(gate)
+  self.gate = gate
+  return self
+end
+
+function ModSetting:allows(i)
+  if i == 1 or not self.gate then return true end
+  local ok, allowed = pcall(self.gate, self.values[i], i)
+  return (not ok) or allowed and true or false
+end
+
+-- How many rungs are live, for a caller that wants to know whether a row is
+-- worth showing at all.
+function ModSetting:rungs()
+  local n = 0
+  for i = 1, #self.values do
+    if self:allows(i) then n = n + 1 end
+  end
+  return n
+end
+
 -- What the player left it at last session. Read lazily rather than at load
 -- time: the loader fills modOptions before a mod runs, but reading through
 -- the API keeps this honest about where the value lives.
@@ -63,7 +99,13 @@ function ModSetting:read()
 end
 
 function ModSetting:get()
-  return self.values[self:read()]
+  local i = self:read()
+  -- a rung that was live when it was stored and is not now -- the player
+  -- moved the ROM, or opened the same save on another machine -- reads as
+  -- the default rather than as a mode with nothing behind it. The stored
+  -- value is left alone, so putting the ROM back restores their choice.
+  if not self:allows(i) then return self.values[1] end
+  return self.values[i]
 end
 
 function ModSetting:level()
@@ -91,8 +133,32 @@ function ModSetting:setIndex(i, game)
   return value
 end
 
+-- Set by the STORED VALUE rather than by its place on the ladder, for a
+-- caller that knows which setting it wants and not where it sits -- a
+-- preset, or an assertion. An unrecognised value lands on values[1], the
+-- same default indexOf answers everywhere else, so this can never leave a
+-- setting holding something the row cannot display.
+--
+-- Worth having as its own entry point because a ladder's ORDER is not a
+-- promise: 3D-BTL grew a third rung in the middle of itself (see
+-- OverworldBattle), and every caller that had counted to two would have
+-- silently meant something else afterwards.
+function ModSetting:setValue(value, game)
+  return self:setIndex(indexOf(self, value), game)
+end
+
+-- Step to the next rung that is actually live, in `dir`. Bounded by the
+-- ladder's length so a gate that refuses everything still terminates on
+-- values[1], which allows() never gates.
 function ModSetting:cycle(game, dir)
-  return self:setIndex(self:read() + (dir or 1), game)
+  dir = dir or 1
+  local n = #self.values
+  local i = self:read()
+  for _ = 1, n do
+    i = ((i + dir - 1) % n + n) % n + 1
+    if self:allows(i) then break end
+  end
+  return self:setIndex(i, game)
 end
 
 -- Adopt a value set from somewhere else (the mod manager's settings page,
@@ -109,7 +175,12 @@ function ModSetting:row()
   return {
     id = "DRAMATIC_SHAPE:" .. self.key,
     label = self.label,
-    value = function() return self_.labels[self_:read()] end,
+    -- the label of the rung actually in force, which is not the stored one
+    -- when that rung has been gated away (see get)
+    value = function()
+      local i = self_:read()
+      return self_.labels[self_:allows(i) and i or 1]
+    end,
     step = function(game, dir)
       self_:cycle(game, dir)
       return true
@@ -120,7 +191,11 @@ end
 -- The row the mod manager's own settings page builds for this mod.
 function ModSetting:schema(help)
   local choices = {}
-  for i, v in ipairs(self.values) do choices[i] = { self.labels[i], v } end
+  -- gated rungs are left off the manager's page too, so the two rows agree
+  -- about what can be chosen
+  for i, v in ipairs(self.values) do
+    if self:allows(i) then choices[#choices + 1] = { self.labels[i], v } end
+  end
   if #self.values == 2 and self.values[1] == false then
     return { key = self.key, type = "toggle", label = self.label,
              default = self.values[1], help = help }

lib/Perf.lua

@@ -0,0 +1,353 @@
+-- Voxel world mode: the instrumentation core.
+--
+-- Ships DARK. Every entry point is one boolean test away from doing
+-- nothing, and the boolean is false unless a run explicitly asks for
+-- measurement (DS_PERF in the environment, or a ds_perf.flag file in the
+-- save directory for a device that has no environment to set). A mod that
+-- measures itself in every player's session is a mod that costs every
+-- player the measurement, so the default has to be off and the off path
+-- has to be free.
+--
+-- What it measures, and why those three things:
+--
+--   * LABELS -- named spans (a bake, a mesh build, a shader compile),
+--     accumulated as {n, total, max}. `max` is the one that matters: a
+--     bake that costs 40ms ONCE is a visible hitch, and an average hides
+--     it completely.
+--   * FRAMES -- a ring of the last N whole-frame times, stamped once per
+--     rendered frame. Frame time is the only number the player actually
+--     experiences; every label total is a hypothesis about which frames.
+--   * COUNTERS -- plain integers a caller bumps (sun-pass redraws, atlas
+--     rebakes). Cheaper than a span when the question is "how often",
+--     not "how long".
+--
+-- Spans are wall time, and on a GPU that means submission time, not
+-- completion time -- the driver is free to finish the work later. So a
+-- GPU-side saving shows up in the FRAME numbers rather than in the label
+-- for the pass that caused it, and both are reported.
+
+local Perf = {}
+
+local clock = (love and love.timer and love.timer.getTime) or os.clock
+
+-- Read through pcall: the loader's sandbox does not hand a mod `os`, and
+-- instrumentation must never be the reason the mod fails to load. Same
+-- shape as OverworldBattle's DS_BATTLE_DEBUG probe.
+local function envFlag(name)
+  local ok, value = pcall(function() return os.getenv(name) end)
+  if not ok then return nil end
+  if value == nil or value == "" or value == "0" then return nil end
+  return value
+end
+
+local function flagFile()
+  if not (love and love.filesystem and love.filesystem.getInfo) then
+    return false
+  end
+  local ok, info = pcall(love.filesystem.getInfo, "ds_perf.flag")
+  return ok and info ~= nil
+end
+
+Perf.enabled = (envFlag("DS_PERF") ~= nil) or flagFile()
+
+Perf.labels = {}      -- label -> { n, total, max }
+Perf.order = {}       -- insertion order, so a report reads chronologically
+Perf.counters = {}    -- name -> integer
+Perf.frames = {}      -- ring of frame times, seconds
+Perf.frameCount = 0
+Perf.RING = 4096
+
+-- The segment a frame belongs to ("map:ROUTE_1:first"). A benchmark
+-- names the phase it is driving; every frame and every label span
+-- recorded while that name is set is attributed to it, which is what
+-- turns "the walk was slow" into "the walk was slow ONLY on the frames
+-- right after ROUTE_1 came into view".
+Perf.segment = nil
+Perf.segments = {}    -- name -> { frames = {}, labels = {}, order = {} }
+
+local function segmentEntry()
+  local name = Perf.segment
+  if not name then return nil end
+  local s = Perf.segments[name]
+  if not s then
+    s = { name = name, frames = {}, labels = {}, order = {} }
+    Perf.segments[name] = s
+    Perf.segments[#Perf.segments + 1] = s   -- array half preserves order
+  end
+  return s
+end
+
+function Perf.setSegment(name)
+  Perf.segment = name
+  if name then segmentEntry() end
+end
+
+-- ---------------------------------------------------------------- spans
+--
+-- Call shape at the measured site:
+--
+--   local t0 = Perf.now()
+--   ... the work ...
+--   Perf.add("TerrainAtlas.staticAtlas", t0)
+--
+-- When disabled, now() returns nil and add() returns on the nil -- two
+-- function calls and a branch, no table touched, no string built. Sites
+-- that would run thousands of times a frame (per draw call, per vertex)
+-- are still too hot for that and are deliberately NOT instrumented; the
+-- frame ring covers them in aggregate.
+
+function Perf.now()
+  if not Perf.enabled then return nil end
+  return clock()
+end
+
+local function bump(store, order, label, dt)
+  local s = store[label]
+  if not s then
+    s = { n = 0, total = 0, max = 0 }
+    store[label] = s
+    order[#order + 1] = label
+  end
+  s.n = s.n + 1
+  s.total = s.total + dt
+  if dt > s.max then s.max = dt end
+end
+
+function Perf.add(label, t0)
+  if t0 == nil then return end
+  local dt = clock() - t0
+  bump(Perf.labels, Perf.order, label, dt)
+  local seg = segmentEntry()
+  if seg then bump(seg.labels, seg.order, label, dt) end
+end
+
+-- Wrap a function in a table, in place. Used by drivers to instrument
+-- module internals they do not own; the mod's own code calls now()/add()
+-- directly so the label is visible at the site.
+function Perf.wrap(tbl, name, label)
+  local orig = tbl and tbl[name]
+  if not orig then return false end
+  tbl[name] = function(...)
+    if not Perf.enabled then return orig(...) end
+    local t0 = clock()
+    local a, b, c, d = orig(...)
+    Perf.add(label or name, t0)
+    return a, b, c, d
+  end
+  return true
+end
+
+-- ------------------------------------------------------------- counters
+
+function Perf.count(name, by)
+  if not Perf.enabled then return end
+  Perf.counters[name] = (Perf.counters[name] or 0) + (by or 1)
+end
+
+-- --------------------------------------------------------------- frames
+--
+-- Called once per RENDERED frame (the endFrame seam), not once per
+-- logic update: a scripted run can step the game many times per render,
+-- and a frame the player never saw cannot have hitched for them.
+
+local lastFrame = nil
+
+function Perf.frame()
+  if not Perf.enabled then return end
+  local t = clock()
+  if lastFrame then
+    local dt = t - lastFrame
+    local n = Perf.frameCount + 1
+    Perf.frameCount = n
+    Perf.frames[(n - 1) % Perf.RING + 1] = dt
+    local seg = segmentEntry()
+    if seg then seg.frames[#seg.frames + 1] = dt end
+  end
+  lastFrame = t
+end
+
+-- Discard the pending frame stamp: after a long blocking operation the
+-- next frame delta would include it and libel the renderer.
+function Perf.resync()
+  lastFrame = Perf.enabled and clock() or nil
+end
+
+-- ------------------------------------------------------------ reporting
+
+local function percentile(sorted, p)
+  local n = #sorted
+  if n == 0 then return 0 end
+  local i = math.ceil(p * n)
+  if i < 1 then i = 1 end
+  if i > n then i = n end
+  return sorted[i]
+end
+
+-- Frame statistics in MILLISECONDS. p95/p99 rather than the average
+-- because smoothness is a tail property: a run that averages 9ms and
+-- spikes to 60ms four times reads as stuttering, and its average reads
+-- as fine.
+function Perf.frameStats(list)
+  local src = list or Perf.frames
+  local sorted = {}
+  for i = 1, #src do sorted[i] = src[i] * 1000 end
+  table.sort(sorted)
+  local n = #sorted
+  local total = 0
+  for i = 1, n do total = total + sorted[i] end
+  local over16, over33 = 0, 0
+  for i = 1, n do
+    if sorted[i] > 16.7 then over16 = over16 + 1 end
+    if sorted[i] > 33.3 then over33 = over33 + 1 end
+  end
+  return {
+    n = n,
+    avg = n > 0 and total / n or 0,
+    p50 = percentile(sorted, 0.50),
+    p95 = percentile(sorted, 0.95),
+    p99 = percentile(sorted, 0.99),
+    worst = n > 0 and sorted[n] or 0,
+    over16 = over16,
+    over33 = over33,
+  }
+end
+
+function Perf.reset()
+  Perf.labels, Perf.order = {}, {}
+  Perf.counters = {}
+  Perf.frames, Perf.frameCount = {}, 0
+  Perf.segments = {}
+  Perf.segment = nil
+  lastFrame = nil
+end
+
+local function sortedLabels(store, order)
+  local out = {}
+  for _, lbl in ipairs(order) do out[#out + 1] = lbl end
+  table.sort(out, function(a, b) return store[a].total > store[b].total end)
+  return out
+end
+
+function Perf.printReport(title)
+  print(("[perf] ==== %s ===="):format(tostring(title or "report")))
+  local f = Perf.frameStats()
+  print(("[perf] frames n=%d avg=%.2fms p50=%.2f p95=%.2f p99=%.2f worst=%.2f  >16.7ms=%d  >33.3ms=%d")
+    :format(f.n, f.avg, f.p50, f.p95, f.p99, f.worst, f.over16, f.over33))
+  for _, seg in ipairs(Perf.segments) do
+    local s = Perf.frameStats(seg.frames)
+    print(("[perf] seg %-28s n=%4d avg=%6.2f p95=%6.2f p99=%6.2f worst=%7.2f >16.7=%3d >33.3=%3d")
+      :format(seg.name, s.n, s.avg, s.p95, s.p99, s.worst, s.over16, s.over33))
+  end
+  print("[perf] ---- labels (ms, sorted by total) ----")
+  for _, lbl in ipairs(sortedLabels(Perf.labels, Perf.order)) do
+    local s = Perf.labels[lbl]
+    print(("[perf] %-46s n=%6d total=%9.1f max=%8.2f")
+      :format(lbl, s.n, s.total * 1000, s.max * 1000))
+  end
+  local names = {}
+  for k in pairs(Perf.counters) do names[#names + 1] = k end
+  table.sort(names)
+  if #names > 0 then print("[perf] ---- counters ----") end
+  for _, k in ipairs(names) do
+    print(("[perf] %-46s %d"):format(k, Perf.counters[k]))
+  end
+end
+
+-- ------------------------------------------------------------------ json
+--
+-- Hand-rolled rather than pulled from the engine: the report has to be
+-- readable by a diff tool between two runs, and that means stable key
+-- ORDER, which a generic serializer does not promise.
+
+local function q(s)
+  return '"' .. tostring(s):gsub('[%c"\\]', function(c)
+    if c == '"' then return '\\"' end
+    if c == "\\" then return "\\\\" end
+    return ("\\u%04x"):format(c:byte())
+  end) .. '"'
+end
+
+local function num(x)
+  return ("%.4f"):format(x)
+end
+
+local function statsJson(f)
+  return ("{\"n\":%d,\"avg\":%s,\"p50\":%s,\"p95\":%s,\"p99\":%s,\"worst\":%s,\"over16\":%d,\"over33\":%d}")
+    :format(f.n, num(f.avg), num(f.p50), num(f.p95), num(f.p99),
+            num(f.worst), f.over16, f.over33)
+end
+
+local function labelsJson(store, order)
+  local parts = {}
+  for _, lbl in ipairs(sortedLabels(store, order)) do
+    local s = store[lbl]
+    parts[#parts + 1] = ("%s:{\"n\":%d,\"total\":%s,\"max\":%s}")
+      :format(q(lbl), s.n, num(s.total * 1000), num(s.max * 1000))
+  end
+  return "{" .. table.concat(parts, ",") .. "}"
+end
+
+function Perf.toJson(meta)
+  local parts = {}
+  parts[#parts + 1] = "{"
+  parts[#parts + 1] = "\"meta\":{"
+  local m = {}
+  for k, v in pairs(meta or {}) do
+    m[#m + 1] = q(k) .. ":" .. (type(v) == "number" and num(v) or q(v))
+  end
+  table.sort(m)
+  parts[#parts + 1] = table.concat(m, ",") .. "},"
+  parts[#parts + 1] = "\"frames\":" .. statsJson(Perf.frameStats()) .. ","
+  parts[#parts + 1] = "\"segments\":{"
+  local segs = {}
+  for _, seg in ipairs(Perf.segments) do
+    segs[#segs + 1] = q(seg.name) .. ":{\"frames\":"
+      .. statsJson(Perf.frameStats(seg.frames))
+      .. ",\"labels\":" .. labelsJson(seg.labels, seg.order) .. "}"
+  end
+  parts[#parts + 1] = table.concat(segs, ",") .. "},"
+  parts[#parts + 1] = "\"labels\":" .. labelsJson(Perf.labels, Perf.order) .. ","
+  local cs = {}
+  for k, v in pairs(Perf.counters) do cs[#cs + 1] = q(k) .. ":" .. v end
+  table.sort(cs)
+  parts[#parts + 1] = "\"counters\":{" .. table.concat(cs, ",") .. "}"
+  parts[#parts + 1] = "}"
+  return table.concat(parts, "")
+end
+
+-- Written through love.filesystem (the save directory) rather than io:
+-- a driver run and an Android session both have one, and neither is
+-- guaranteed a writable working directory.
+function Perf.write(name, meta)
+  local body = Perf.toJson(meta)
+  if love and love.filesystem then
+    pcall(love.filesystem.createDirectory, "ds_bench")
+    local ok = pcall(love.filesystem.write, "ds_bench/" .. name .. ".json", body)
+    if ok then
+      print("[perf] wrote " .. tostring(love.filesystem.getSaveDirectory())
+            .. "/ds_bench/" .. name .. ".json")
+      return true
+    end
+  end
+  print("[perf] JSON " .. name .. ": " .. body)
+  return false
+end
+
+-- ----------------------------------------------------------- draw stats
+--
+-- love.graphics.getStats() resets per frame, so it is only meaningful
+-- read at the END of a frame -- which is where Perf.frame() runs.
+
+function Perf.drawStats()
+  if not (love and love.graphics and love.graphics.getStats) then return end
+  local s = love.graphics.getStats()
+  Perf.count("stat.drawcalls", s.drawcalls or 0)
+  Perf.count("stat.canvasswitches", s.canvasswitches or 0)
+  Perf.count("stat.shaderswitches", s.shaderswitches or 0)
+  Perf.count("stat.frames", 1)
+  Perf.texturememory = s.texturememory
+  Perf.canvases = s.canvases
+  Perf.images = s.images
+end
+
+return Perf

lib/PixelCanvas.lua

@@ -0,0 +1,9 @@
+local V = ...
+
+local PixelCanvas = {}
+
+function PixelCanvas.new(w, h)
+  return pcall(love.graphics.newCanvas, w, h, { dpiscale = 1 })
+end
+
+return PixelCanvas

lib/Pokedex.lua

@@ -0,0 +1,223 @@
+-- VR: the POKEDEX in the player's left hand -- a voxel model of the
+-- series' own field guide, strapped to the tracked grip pose, whose
+-- screen is a real texture the mod can put a picture on.
+--
+-- Why it exists: a staged VR battle needs the 2D battle screen SOMEWHERE
+-- -- the text, the menus, the HP bars are the game -- but a flat panel
+-- floating square in front of the fight hides the fight. A trainer in
+-- the world already has the right prop for "a handheld device with a
+-- screen": look down at the Pokedex in your hand to read the battle,
+-- look up to watch it happen on the map.
+--
+-- THE MODEL is authored here in voxels, in METRES (VOX metres a voxel),
+-- around its own centre, front face +Z -- a red slab with the lens, the
+-- LEDs, the hinge and a d-pad, and a dark bezel the screen sits proud
+-- of. It rides VRRig.propMatrix, the same XR-to-world mapping the eyes
+-- use, so it sits exactly where the hand is and keeps its real size in
+-- every mode: a hand-sized device over the diorama, the same hand-sized
+-- device at life scale in first person and in battle.
+--
+-- THE SCREEN is a separate one-quad mesh drawn with its own texture --
+-- whatever canvas the caller hands `Pokedex.screen` (the VR frame hands
+-- it the front buffer during a battle, cropped by UV to the battle's own
+-- letterbox). No texture leaves the screen dark: a device that is off.
+--
+-- Everything here is passive state plus a draw call; VR.lua decides when
+-- the frame exists (hand tracked, session live) and VoxelScene's eye
+-- pass draws it after the world, so it composites with real depth
+-- against everything else.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Mat4 = V.require("Mat4")
+local Voxel3D = V.require("Voxel3D")
+local VRRig = V.require("VRRig")
+
+local Pokedex = {}
+
+-- one voxel, in metres: a centimetre-ish grid gives the classic chunky
+-- read at a device you can read a battle off (the body below comes out
+-- about 12 x 19 x 3 cm -- a quarter up from the first, believable size,
+-- because the screen carries every menu and was squint-small in hand)
+Pokedex.VOX = 0.011 * 1.25
+
+-- Where the device sits relative to the GRIP pose, in metres, and how it
+-- is tipped. A full quarter turn forward lays the slab exactly along the
+-- controller's own body -- verified in the headset -- so holding the
+-- controller IS holding the device: raise your fist and the screen faces
+-- you. These two are the whole of the attachment.
+Pokedex.OFFSET = { 0, 0.04, -0.02 }
+Pokedex.TILT = -math.pi / 2      -- radians about X: 90 degrees forward,
+                                 -- flush with the controller
+
+-- body proportions, in voxels
+local W, H, D = 9, 14, 2
+
+-- the palette the body's faces point their UVs at, one texel per colour
+local COLORS = {
+  { 200, 40, 48 },    -- 1 body red
+  { 140, 24, 32 },    -- 2 hinge / shaded red
+  { 64, 132, 244 },   -- 3 the lens blue
+  { 208, 228, 255 },  -- 4 lens glint
+  { 232, 60, 48 },    -- 5 LED red
+  { 248, 216, 64 },   -- 6 LED yellow
+  { 72, 200, 96 },    -- 7 LED green
+  { 46, 46, 54 },     -- 8 bezel / d-pad dark
+  { 24, 24, 30 },     -- 9 the dark screen (the "off" state's face)
+}
+
+local paletteTex = nil          -- one texel per COLORS entry
+local bodyMesh = nil
+local screenMesh = nil
+local screenKey = nil           -- the UV rect screenMesh was built for
+
+local function palette()
+  if paletteTex then return paletteTex end
+  if not (love.image and love.image.newImageData
+          and love.graphics and love.graphics.newImage) then return nil end
+  local ok, data = pcall(love.image.newImageData, #COLORS, 1)
+  if not (ok and data) then return nil end
+  for i, c in ipairs(COLORS) do
+    pcall(data.setPixel, data, i - 1, 0,
+          c[1] / 255, c[2] / 255, c[3] / 255, 1)
+  end
+  local built, img = pcall(love.graphics.newImage, data)
+  if not built then return nil end
+  pcall(img.setFilter, img, "nearest", "nearest")
+  paletteTex = img
+  return img
+end
+
+-- Append one solid box's six faces to `verts`/`indices`: position in
+-- voxels (relative to the device centre), size in voxels, colour by
+-- palette index. Faces carry the mod's own directional shade, so the
+-- slab reads as a solid the way every extruded block here does.
+local function box(verts, indices, x, y, z, w, h, d, color)
+  local u = (color - 0.5) / #COLORS
+  local vox = Pokedex.VOX
+  local ox, oy, oz = (x - W / 2) * vox, (y - H / 2) * vox, (z - D / 2) * vox
+  local sx, sy, sz = w * vox, h * vox, d * vox
+  for face = 1, 6 do
+    local corners = Voxel3D.FACE_CORNERS[face]
+    local shade = Voxel3D.FACE_SHADE[face]
+    local n = #verts / 4
+    for _, c in ipairs(corners) do
+      verts[#verts + 1] = { ox + c[1] * sx, oy + c[2] * sy, oz + c[3] * sz,
+                            u, 0.5, shade }
+    end
+    Voxel3D.pushQuad(indices, n)
+  end
+end
+
+-- the screen's face on the front, in voxels (10:9, the GB frame's shape),
+-- shared by the dark "off" face in the body and the live quad
+local SCREEN = { x = 1.2, y = 4.6, w = 6.6, h = 5.94 }
+
+local function buildBody()
+  if bodyMesh then return bodyMesh end
+  local verts, indices = {}, {}
+  -- the slab, the hinge along the right edge, the lens, the LEDs, the
+  -- d-pad and two chunky buttons -- the classic cover furniture, one box
+  -- each on the front face (z = D..)
+  box(verts, indices, 0, 0, 0, W, H, D, 1)                       -- body
+  box(verts, indices, W - 0.7, 0, 0, 0.7, H, D + 0.15, 2)        -- hinge
+  box(verts, indices, 0.6, H - 2.6, D, 2, 2, 0.5, 3)             -- lens
+  box(verts, indices, 0.9, H - 1.3, D + 0.5, 0.6, 0.5, 0.12, 4)  -- glint
+  box(verts, indices, 3.2, H - 1.6, D, 0.8, 0.8, 0.35, 5)        -- LEDs
+  box(verts, indices, 4.5, H - 1.6, D, 0.8, 0.8, 0.35, 6)
+  box(verts, indices, 5.8, H - 1.6, D, 0.8, 0.8, 0.35, 7)
+  -- the bezel plate the screen sits in, and the dark screen face itself
+  -- (what shows when nothing is on: a device that is off, not a hole)
+  box(verts, indices, SCREEN.x - 0.4, SCREEN.y - 0.4, D,
+      SCREEN.w + 0.8, SCREEN.h + 0.8, 0.4, 8)
+  box(verts, indices, SCREEN.x, SCREEN.y, D + 0.4,
+      SCREEN.w, SCREEN.h, 0.1, 9)
+  -- d-pad below the screen, two crossed bars, and the A/B buttons
+  box(verts, indices, 5.6, 1.1, D, 2.1, 0.7, 0.45, 8)
+  box(verts, indices, 6.3, 0.4, D, 0.7, 2.1, 0.45, 8)
+  box(verts, indices, 1.2, 0.8, D, 1.1, 1.1, 0.45, 5)
+  box(verts, indices, 2.9, 0.8, D, 1.1, 1.1, 0.45, 8)
+  bodyMesh = Voxel3D.newMesh(verts, indices)
+  return bodyMesh
+end
+
+-- The live screen: one quad a hair proud of the dark face, UV-mapped to
+-- `uv` = { u0, v0, u1, v1 } of whatever texture is on it. Rebuilt only
+-- when the UV rect moves (a window resize moving the battle letterbox).
+local function buildScreen(uv)
+  local key = table.concat({ uv[1], uv[2], uv[3], uv[4] }, ":")
+  if screenMesh and screenKey == key then return screenMesh end
+  local vox = Pokedex.VOX
+  local x0 = (SCREEN.x - W / 2) * vox
+  local y0 = (SCREEN.y - H / 2) * vox
+  local x1 = x0 + SCREEN.w * vox
+  local y1 = y0 + SCREEN.h * vox
+  local z = (D / 2 + 0.55) * vox
+  local u0, v0, u1, v1 = uv[1], uv[2], uv[3], uv[4]
+  local verts = {
+    { x0, y0, z, u0, v1, 1 }, { x1, y0, z, u1, v1, 1 },
+    { x1, y1, z, u1, v0, 1 }, { x0, y1, z, u0, v0, 1 },
+  }
+  local indices = {}
+  Voxel3D.pushQuad(indices, 0)
+  local mesh = Voxel3D.newMesh(verts, indices)
+  if mesh then
+    screenMesh, screenKey = mesh, key
+  end
+  return mesh
+end
+
+-- ------- the frame's state, set by VR.lua
+--
+-- nil = no pokedex this frame (no session, no tracked left hand).
+Pokedex.frame = nil
+
+-- Stand the device on a tracked LEFT-HAND pose under the current
+-- XR-to-world mapping (the same pivot/anchor/scale/yaw the eyes got).
+function Pokedex.place(pose, pivot, anchor, scale, yaw)
+  local m = VRRig.propMatrix(pose, pivot, anchor, scale, yaw)
+  m = Mat4.mul(m, Mat4.translate(Pokedex.OFFSET[1], Pokedex.OFFSET[2],
+                                 Pokedex.OFFSET[3]))
+  m = Mat4.mul(m, Mat4.rotateX(Pokedex.TILT))
+  Pokedex.frame = { model = m }
+end
+
+-- What the screen shows: a texture and the UV rect of it to fill the
+-- screen with. nil for a dark screen. Only meaningful after place().
+function Pokedex.screen(tex, u0, v0, u1, v1)
+  if Pokedex.frame and tex then
+    Pokedex.frame.tex = tex
+    Pokedex.frame.uv = { u0 or 0, v0 or 0, u1 or 1, v1 or 1 }
+  end
+end
+
+function Pokedex.clear()
+  Pokedex.frame = nil
+end
+
+-- Draw the device with the scene's own pass (model matrix in world px).
+-- Runs inside VoxelScene's drawScene, per eye; no shadow-caster half --
+-- a UI prop should receive the world's light, not throw shade on it.
+function Pokedex.draw()
+  local f = Pokedex.frame
+  if not f then return end
+  local body = buildBody()
+  local pal = palette()
+  if body and pal then
+    Voxel3D.draw(body, pal, f.model)
+  end
+  if f.tex and f.uv then
+    local screen = buildScreen(f.uv)
+    if screen then
+      Voxel3D.draw(screen, f.tex, f.model)
+    end
+  end
+end
+
+-- window resize / hot reload: every GPU object here is derived and cheap
+function Pokedex.invalidate()
+  paletteTex, bodyMesh, screenMesh, screenKey = nil, nil, nil, nil
+end
+
+return Pokedex

lib/ShadowMap.lua

@@ -77,7 +77,44 @@ ShadowMap.HEIGHT = 160
 -- surface shadows itself in a moire of acne; too much and a shadow detaches
 -- from the foot of what casts it. The frustum is ~400 world pixels deep and
 -- the packed depth resolves under 0.01 of one, so there is room.
-ShadowMap.BIAS = 1.0
+--
+-- It cannot be ONE number, because what the comparison has to forgive is
+-- not fixed: the map stores one depth for a whole texel, so a lit surface
+-- reads its own depth wrong by however far it RAMPS across that texel --
+-- the texel's world size times the surface's slope in the light's frame.
+-- The texel swings from a third of a world pixel at the closest zoom to
+-- well over one at a maximised window on the widest, so a constant bias is
+-- generous at one end of the ladder and short at the other. Short shows up
+-- as diagonal bands of acne across big lit surfaces -- diagonal because
+-- the moire runs along neither the world grid nor the screen's, but along
+-- the depth ramp in the sun's own frame, and the sun sits southeast.
+--
+-- So: a floor for what does not scale (the packed depth's quantisation,
+-- and the two passes reaching the same world point by different matrices),
+-- plus a term in texels for what does.
+ShadowMap.BIAS = 0.5
+
+-- World pixels of slack per world pixel of texel, for the steepest LIT
+-- surface here: a roof pitched 45 degrees and turned away from the sun,
+-- whose depth ramps about 3.1 world pixels per texel crossed on EITHER of
+-- the light frame's two axes (a vertical wall, by comparison, manages 1.7,
+-- flat ground 0.7, and anything steeper than that roof has its back to the
+-- sun and never reads the map at all). The 2x2 filter's taps sit half a
+-- texel out on both axes at once, so the worst a tap can disagree by is
+-- half the ramp along each -- which is where the halving that turns 6.2
+-- into 3.1 comes from, and why it is the SUM of the two components rather
+-- than their magnitude.
+--
+-- Measured against the artefact rather than trusted: the probe
+-- (tests/voxel_acne_probe.lua) counts isolated shadowed pixels on lit
+-- surfaces, and the banding stops at slack ~2.4 world px on the widest
+-- rung -- where this lands 3.1 * 0.83 + 0.5.
+ShadowMap.SLOPE = 3.1
+
+-- The slack `fit` last worked out, in world pixels -- BIAS + SLOPE*texel.
+-- Read by probes; `ShadowMap.bias` is the same number as the [0,1] depth
+-- the map actually stores.
+ShadowMap.slack = ShadowMap.BIAS
 
 local SHADER = [[
   varying float vDepth;
@@ -93,17 +130,23 @@ local SHADER = [[
   }
 #endif
 #ifdef PIXEL
+  uniform float sprite;   // 1 while the CAST is being drawn; see ShadowMap.sprites
   vec4 effect(vec4 color, Image tex, vec2 tc, vec2 sc) {
     // the same alpha discard the main pass uses: a sprite card casts its
     // silhouette, not its 16x16 bounding box
     if (Texel(tex, tc).a < 0.5) discard;
-    // pack into two channels: the high byte in red, the low in green
+    // pack into two channels: the high byte in red, the low in green.
+    // Blue says WHAT cast this, which costs a channel that was zero anyway
+    // and lets a surface decline one kind of caster -- water does, for the
+    // people (see Water's sunLit).
     float d = clamp(vDepth, 0.0, 1.0) * 255.0;
-    return vec4(floor(d) / 255.0, fract(d), 0.0, 1.0);
+    return vec4(floor(d) / 255.0, fract(d), sprite, 1.0);
   }
 #endif
 ]]
 
+ShadowMap._source = function() return SHADER end   -- named for the suite
+
 local shader = nil            -- nil = untried, false = unavailable
 local canvas = nil            -- nil = untried, false = unavailable
 local canvasRes = 0           -- the edge `canvas` was made at
@@ -143,7 +186,7 @@ end
 local function getCanvas(res)
   if canvas == false then return nil end
   if canvas and canvasRes == res then return canvas end
-  local ok, c = pcall(love.graphics.newCanvas, res, res)
+  local ok, c = V.require("PixelCanvas").new(res, res)
   if not (ok and c) then
     canvas = false
     return nil
@@ -178,6 +221,9 @@ end
 -- where the canvas cannot be made -- VoxelScene then keeps the flat decal
 -- shadows, which need nothing but a quad.
 function ShadowMap.available()
+  if love.system and love.system.getOS and love.system.getOS() == "iOS" then
+    return false
+  end
   if not (love.graphics and love.graphics.newCanvas
           and love.graphics.setDepthMode) then
     return false
@@ -316,9 +362,58 @@ local function fit(cx, cy, vw, vh)
   -- what the frustum ended up covering, for probes: the lateral extent in
   -- world pixels divided by RES is how fine a shadow edge can land
   ShadowMap.extent = { r - l, t - b, far - near }
+  -- the slack the comparison needs, against the coarser of the two texel
+  -- axes (the box is asymmetric, and one number has to cover both)
+  ShadowMap.slack = ShadowMap.BIAS
+                    + ShadowMap.SLOPE * math.max(w, h) / res
   -- the stored depth spans the frustum, so a world-pixel bias is that
   -- fraction of it
-  ShadowMap.bias = ShadowMap.BIAS / math.max(1, far - near)
+  ShadowMap.bias = ShadowMap.slack / math.max(1, far - near)
+end
+
+-- How much of the compare's forgiveness a snugged caster takes back, 0..1.
+-- Short of 1 on purpose: at exactly 1 the card's own fragments compare
+-- against their own stored depth on a float-equality knife edge and can
+-- speckle. The tenth left over is dozens of times the packed depth's
+-- quantization -- ample for that -- and leaves the contact gap around a
+-- quarter of a world pixel at any sun, which no zoom resolves.
+ShadowMap.SNUG = 0.9
+
+-- A CASTER snugged up the sun ray -- moved TOWARD the light -- before it is
+-- drawn into the map.
+--
+-- The depth compare forgives `slack` world pixels (BIAS + the SLOPE term)
+-- so lit surfaces do not acne against their own texels -- but that same
+-- forgiveness is what lets the ground right next to a standing figure read
+-- as lit: a receiver within `slack` of its blocker along the ray passes the
+-- test, so the first stretch of every shadow is forgiven away and on screen
+-- it starts that far from the feet, further the lower the sun. The classic
+-- peter-panning; unseen while the sun hung at a fixed 45 degrees, plain at
+-- a day/night golden hour or under the moon.
+--
+-- Moving the card ALONG ITS OWN RAY changes nothing about where its shadow
+-- falls -- every point stays on the same light ray -- but moving it toward
+-- the sun stores it SHALLOWER, so a ground point right at the foot is
+-- already `slack` deeper than the stored blocker and fails the lit test:
+-- the root lands back under the feet. Nothing else is touched -- no
+-- terrain moved, so the acne margin the slack exists for is intact where
+-- it matters. For sprite cards and other thin stand-ins only.
+--
+-- ONE OBLIGATION comes with it: the caster's LIT draw must hand this same
+-- snugged transform to its shadow lookup (Voxel3D.draw's `sunModel`).
+-- Stored and lookup then agree exactly, as they did before snugging, and
+-- the compare keeps its full acne margin. A caster stored snugged but read
+-- un-snugged is 0.9 of the margin short, and the loss shows up as diagonal
+-- moire bands crawling across the card.
+--
+-- Valid between begin() and the next begin(): `slack` and the sun hold
+-- still between redraws of the map, so a lit frame that reuses last
+-- frame's map computes the same displacement it was stored with.
+function ShadowMap.snug(model)
+  local f = sunDir()
+  local s = -ShadowMap.slack * ShadowMap.SNUG
+  return Mat4.mul(Mat4.translate(f[1] * s, f[2] * s, f[3] * s),
+                  model or IDENTITY)
 end
 
 -- Whether the map has to be redrawn for `sig` -- a caller-built stamp of
@@ -354,6 +449,9 @@ function ShadowMap.begin(cx, cy, vw, vh)
   love.graphics.setShader(sh)
   love.graphics.setColor(1, 1, 1, 1)
   pcall(sh.send, sh, "lightVP", "row", ShadowMap.clipVP)
+  -- the world until a cast pass says otherwise, reset per pass so one that
+  -- forgot to put it back cannot leak into the next map's terrain
+  pcall(sh.send, sh, "sprite", 0)
   drawing = true
   ready = false
   return true
@@ -362,6 +460,25 @@ end
 -- Draw one caster. Same signature as Voxel3D.draw minus the camera-ward
 -- pull, which is a trick for the VIEW's depth buffer and would drag a
 -- shadow off whatever throws it.
+-- Whether what is drawn next is one of the CAST -- a walker, an authored
+-- figure, a battle's Pokemon -- rather than part of the world. false for the
+-- length of such a pass, true to put it back.
+--
+-- The map records it per texel (the shader's blue channel) so a surface can
+-- decline that kind of caster, and exactly one does: water. A character
+-- standing at a lake's edge threw a hard cut-out of its own sprite across
+-- the surface, which on something showing the sky and the shoreline reads as
+-- a sticker rather than as a shadow in the water. Everything else -- ground,
+-- roofs, ledges, the characters themselves -- still takes them.
+--
+-- Sent rather than branched, so a caller that forgets to put it back only
+-- mislabels casters rather than losing them; begin() resets it per pass.
+function ShadowMap.sprites(on)
+  if not drawing then return end
+  local sh = getShader()
+  if sh then pcall(sh.send, sh, "sprite", on and 1 or 0) end
+end
+
 function ShadowMap.draw(mesh, texture, model)
   if not (drawing and mesh) then return end
   local sh = getShader()

lib/Sky.lua

@@ -0,0 +1,747 @@
+-- The sky, generated rather than shipped.
+--
+-- The overworld's, on every VOXEL rung. Wherever the diorama is drawn the void
+-- behind it is sky rather than a black plate: at 75 degrees the horizon is
+-- genuinely in frame and the bands run down to meet it, and at the steeper rungs
+-- the void that shows is the ground running out past the map edge, which gets
+-- the same sky above the same haze. A battle's placed camera keeps the flat fill
+-- it has always had -- its horizon is above the frame and its look is not this
+-- rung's to change.
+--
+-- THE RECIPE is the 8-bit skybox one: a short palette of blues painted as flat
+-- horizontal bands, deepest overhead, with a CHECKERBOARD of the next band
+-- dithered into the bottom of each one. Alternating two colours on a pixel grid
+-- is how a machine with four colours to a palette got a fifth, sixth and seventh
+-- out of them, and it is what keeps four bands reading as a gradient rather than
+-- as four stripes. No clouds, nothing moving.
+--
+-- NOTHING IS RESAMPLED, which is the whole of why it is drawn this way. There is
+-- no baked 160x144 picture scaled up to the window and no downsized buffer blown
+-- back up: one full-region rectangle through a shader that answers every pixel
+-- from its own canvas coordinate. A pixel of sky is computed at the size it is
+-- displayed at, so there is nothing for a filter to soften and nothing to go
+-- stale when the window or the zoom changes. The shader does bind one texture,
+-- but it is a palette rather than an image -- the bands, one texel each, sampled
+-- nearest (see rampFor, and why it is not a uniform array).
+--
+-- THE PIXEL GRID follows the zoom for the same reason. Bands and dither cells
+-- are measured in DIORAMA pixels -- the pass's own pixels-per-world-pixel, handed
+-- in fresh every frame -- so a chunky sky at 4x is a chunky sky at 12x, band
+-- edges land on the same grid the world's own texels do, and a ZOOM keypress is
+-- reflected in the frame that follows it rather than whenever something else
+-- happened to rebuild.
+--
+-- PALETTE ORDER, which is easy to get wrong. Stored LIGHTEST FIRST, because that
+-- is shade order: a display mode transforms a four-colour palette by replacing it
+-- outright (PaletteFX.effectiveColors hands back GRAYS or CLASSIC), and those are
+-- written light to dark. So the sky reads the list backwards -- deepest shade
+-- overhead, shade 1 at the horizon -- and GRAY gets greys the right way up for
+-- nothing.
+--
+-- WHAT TIME IT IS decides the colours. The palette itself lives in DayNight
+-- (four phase palettes, blended along the clock and re-quantised to the
+-- lattice), and this file paints whatever the clock says: blue at noon, gold
+-- and violet through the twilights -- warmed further around the low sun by a
+-- dithered GLOW -- and deep navy under the moon. The sun and moon themselves
+-- hang here too: cell-art discs on the same grid as the dither, scissored to
+-- the sky's own region so a setting body slips below the horizon point and is
+-- gone, never wandering under the map.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local DayNight = V.require("DayNight")
+local PaletteFX = require("src.render.PaletteFX")
+
+local Sky = {}
+
+-- The most bands a phase palette may paint with. Eight leaves headroom over
+-- DayNight's six-band ones without paying for more; the ramp the shader reads
+-- them from is built at the width actually used, so the cap costs nothing.
+Sky.MAX_BANDS = 8
+
+-- The checkerboard between bands. DITHER_START is how far down a band it begins,
+-- as a fraction of that band: lower is a wider blend, and 1 switches it off. 0.6
+-- leaves the top of each band flat -- a band dithered all the way through reads
+-- as one averaged colour instead of as a step with a soft bottom edge.
+Sky.DITHER = true
+Sky.DITHER_START = 0.6
+
+-- How much of the frame the bands cover when the horizon is NOT in it, as a
+-- fraction of the canvas height.
+--
+-- At the steeper rungs the camera looks down far enough that the ground plane's
+-- vanishing line is above the top edge -- there is no horizon to hang the pale
+-- end on, but there is still void up there where the map runs out, and it should
+-- read as sky. So the bands take the same slice of the frame the top rung's own
+-- horizon gives them, which keeps the sky looking like one sky across the whole
+-- ladder instead of changing character rung by rung.
+Sky.SPAN = 0.23
+
+-- How much ELEVATION the gradient spans above the horizon, in radians, for
+-- a caller that anchors the sky IN SPACE rather than to the frame (the VR
+-- eyes -- see Voxel3D.beginScene). On the flat screen the bands run from
+-- the top edge of the frame down to the horizon, which is right for a
+-- camera whose pitch is the rung's: the frame IS the window on the sky.
+-- A headset's frame is wherever the head points, so glueing the zenith
+-- band to its top edge drags the whole gradient around with the head. An
+-- anchored caller instead hangs the gradient over a fixed slice of sky --
+-- horizon to ELEV_SPAN up -- and hands paint() the canvas row that span's
+-- top lands on this frame (the `top` argument), so tilting the head slides
+-- the frame across a sky that stays put.
+Sky.ELEV_SPAN = math.rad(55)
+
+-- ------- the bands
+--
+-- Top first, each a { r, g, b } in 0..1, as the display mode has them.
+--
+-- Memoised, because this runs once a frame and the answer only moves when the
+-- mode does.
+local cache = { bands = nil, key = {}, ramp = nil }
+
+function Sky.bands()
+  local pal = DayNight.palette()
+  local shades = PaletteFX.effectiveColors(pal) or pal
+  local n = math.min(#shades, #pal, Sky.MAX_BANDS)
+  local key, k = cache.key, 0
+  local same = cache.bands ~= nil and #cache.bands == n
+  for i = 1, n do
+    local c = shades[i]
+    for ch = 1, 3 do
+      k = k + 1
+      if key[k] ~= c[ch] then same = false end
+      key[k] = c[ch]
+    end
+  end
+  if same then return cache.bands end
+
+  -- the ramp is these bands as a texture (see rampFor); a new list is a new
+  -- ramp, and the old one is nothing's to keep
+  if cache.ramp and cache.ramp.release then pcall(cache.ramp.release, cache.ramp) end
+  cache.ramp, cache.rampFor = nil, nil
+
+  local bands = {}
+  for i = 1, n do
+    -- backwards: the palette's darkest rung is the top band
+    local c = shades[n - i + 1]
+    bands[i] = { c[1] / 255, c[2] / 255, c[3] / 255 }
+  end
+  cache.bands = bands
+  return bands
+end
+
+-- The hour's haze -- the palest band, in 0..1 -- which is both the sky's
+-- bottom edge and the right flat fill for any outdoor void that wants to
+-- match the clock without painting bands (the battle arena's backdrop).
+function Sky.haze()
+  local bands = Sky.bands()
+  return bands and bands[#bands] or nil
+end
+
+-- Put the sky onto a flat descriptor: the bands to paint, plus the flat fill
+-- replaced by the palest of them. That fill is what the caller CLEARS to, so
+-- making it the bottom band's own colour means the haze below the sky and the
+-- bottom of the sky are one colour -- the join has no seam, and a frame that
+-- cannot paint the bands is a hazy sky rather than a wrong one.
+--
+-- Mutates the descriptor, which is a fresh table per frame from its caller.
+function Sky.dress(sky)
+  local bands = Sky.bands()
+  local haze = bands and bands[#bands]
+  if not (sky and haze) then return sky end
+  sky[1], sky[2], sky[3] = haze[1], haze[2], haze[3]
+  sky.bands = bands
+  return sky
+end
+
+-- Where the sky's bottom edge goes, in canvas pixels: the camera's own horizon
+-- when that is in frame, and SPAN of the frame when it is not (see SPAN). nil
+-- when there is no room for any of it.
+function Sky.region(h, horizonY)
+  if not (h and h > 0) then return nil end
+  local edge = horizonY
+  if not (edge and edge > 0) then edge = h * Sky.SPAN end
+  edge = math.min(edge, h)
+  if edge < 1 then return nil end
+  return edge
+end
+
+-- ------- the pass
+--
+-- One rectangle, one shader. Every pixel answers for itself from its canvas
+-- coordinate, so the sky is drawn at exactly the resolution it is displayed at
+-- -- there is no image being scaled and so nothing to be soft. The one texture
+-- bound is the band ramp, which is a PALETTE and not a picture: n texels wide,
+-- sampled nearest, one lookup per pixel (see rampFor).
+--
+-- `cell` quantises BOTH the band edges and the dither: the y a pixel is judged
+-- by is the top of its own cell row, so a whole cell row is one colour and every
+-- edge in the sky lands on the diorama's pixel grid.
+local SHADER_SRC = [[
+uniform Image ramp;     // the bands, one texel each, top of the sky first
+uniform float count;    // how many texels wide that ramp is
+uniform float edge;     // the sky's bottom, in canvas pixels
+uniform float top;      // where the deepest band begins, in canvas pixels --
+                        // 0 glues the gradient to the frame (the flat
+                        // screen); an anchored caller passes the row its
+                        // fixed elevation span starts on, often negative
+uniform float cell;     // the diorama's pixel size, in canvas pixels
+uniform float start;    // where the checker begins inside a band
+uniform float axisX;    // the "toward the ground" direction on the canvas:
+uniform float axisY;    // (0,1) for a level camera; a rolled VR eye tips
+                        // it, and edge/top are distances along it
+uniform vec3 rayBase;   // the eye's ray fan (VRRig eyeCamera.skyRay): a
+uniform vec3 rayDu;     // canvas point at fractions (u, v) looks along
+uniform vec3 rayDv;     // base + u*du + v*dv, world axes -- so each pixel
+                        // knows its TRUE elevation and the gradient is a
+                        // real skybox, untouched by any head motion
+uniform float raySpan;  // radians of elevation the gradient covers
+uniform vec2 invSize;   // 1/w, 1/h: canvas pixels to fractions
+uniform float useRay;   // 0 = the flat screen's frame-linear gradient
+uniform float cellAng;  // one checker cell in RADIANS (ray path): the
+                        // dither's own grid, laid on azimuth/elevation so
+                        // the pattern is glued to the SKY -- a screen-cell
+                        // parity flips under every head motion and the
+                        // whole gradient shimmers
+uniform float alpha;
+uniform float glowAmt;  // twilight warmth around the low sun; 0 = none
+uniform vec2 glowPos;   // the sun disc, in canvas pixels (flat path)
+uniform float glowInvR; // 1 / the glow's reach in pixels (flat path)
+uniform vec3 glowDir;   // the sun's world direction (ray path)
+uniform float glowInvA; // 1 / the glow's reach in radians (ray path)
+uniform vec3 glowColor;
+
+// Band `i`, read from its own texel centre. The index is clamped rather than
+// trusted: `pos` below can land exactly on `count` when the arithmetic is
+// carried at mediump -- which is the fragment default on GLSL ES -- and a
+// sample past the last band must be the last band, not whatever is off the
+// end of the image.
+vec3 bandAt(float i) {
+  return Texel(ramp, vec2((clamp(i, 0.0, count - 1.0) + 0.5) / count, 0.5)).rgb;
+}
+
+vec4 effect(vec4 color, Image tex, vec2 tc, vec2 sc) {
+  float tn;
+  float parity;
+  float glowD = 2.0;                                  // past the reach
+  if (useRay > 0.5) {
+    // A SKYBOX, computed instead of stored: the pixel's own ray lands in
+    // a cell of the sky's angular grid (azimuth columns and elevation
+    // rows, cellAng square), and EVERYTHING -- the band, the checker's
+    // parity, the glow -- is answered from that cell's centre. The
+    // screen grid quantises nothing here; that is the point. A screen
+    // quantisation of similar pitch laid under the sky grid beats
+    // against it (moire), and every subpixel head motion re-snaps the
+    // beat -- the fizz. Sampled per pixel, the picture is exactly a
+    // nearest-filtered texture on a dome: its cells slide smoothly with
+    // the world and no motion of the head recomputes the pattern. The
+    // one seam, where azimuth wraps behind the camera, is a single cell
+    // column of a dither pattern.
+    vec3 dir = rayBase + rayDu * (sc.x * invSize.x)
+                       + rayDv * (sc.y * invSize.y);
+    float elev = atan(dir.y, length(dir.xz));
+    float ei = floor(elev / cellAng);                 // elevation row
+    if (ei < 0.0) { discard; }                        // below the horizon
+    float ai = floor(atan(dir.x, dir.z) / cellAng);   // azimuth column
+    float elc = (ei + 0.5) * cellAng;                 // the row's centre
+    tn = 1.0 - clamp(elc / max(raySpan, 0.001), 0.0, 1.0);
+    parity = mod(ai + ei, 2.0);
+    if (glowAmt > 0.0) {
+      // the glow by the angle between the CELL's centre direction and
+      // the sun's own, so its rings are pinned to the same sky grid
+      float azc = (ai + 0.5) * cellAng;
+      vec3 cd = vec3(cos(elc) * sin(azc), sin(elc), cos(elc) * cos(azc));
+      glowD = acos(clamp(dot(cd, glowDir), -1.0, 1.0)) * glowInvA;
+    }
+  } else {
+    vec2 cc0 = floor(sc / cell) * cell;               // top of this cell
+    float row = cc0.x * axisX + cc0.y * axisY;        // along the axis
+    if (row > edge) { discard; }                      // below the horizon
+    tn = clamp((row - top) / max(edge - top, 1.0), 0.0, 1.0);
+    parity = mod(floor(sc.x / cell) + floor(sc.y / cell), 2.0);
+    if (glowAmt > 0.0) {
+      vec2 cc = (floor(sc / cell) + 0.5) * cell;
+      glowD = length(cc - glowPos) * glowInvR;
+    }
+  }
+  float pos = tn * count;
+  float base = min(floor(pos), count - 1.0);
+  vec3 c = bandAt(base);
+  if (base < count - 1.0 && (pos - base) > start) {
+    if (parity < 0.5) { c = bandAt(base + 1.0); }
+  }
+  // The sunset's warmth, radiating from the disc: posterised to a few rungs
+  // and checker-dithered between them -- the same 8-bit move as the bands,
+  // so the glow reads as painted light rather than as a smooth airbrush --
+  // measured cell-to-cell on the flat frame and angle-to-angle on the
+  // skybox, so its rings ride whichever grid the checker itself is on.
+  if (glowAmt > 0.0) {
+    float g = glowAmt * pow(clamp(1.0 - glowD, 0.0, 1.0), 2.0);
+    float lvl = floor(g * 4.0);
+    if (g * 4.0 - lvl > 0.5 && parity < 0.5) { lvl += 1.0; }
+    c = mix(c, glowColor, min(lvl / 3.0, 1.0) * 0.65);
+  }
+  return vec4(c, alpha);
+}
+]]
+
+-- ------- the ramp
+--
+-- The bands as a one-texel-per-band TEXTURE rather than as a uniform array,
+-- which is what they used to be: `uniform vec3 bands[8]`, filled from Lua and
+-- read through a loop counter. On desktop GL that is as portable as it looks.
+-- On Android it was not. The sky's lower bands came back BLACK -- a hard-edged
+-- strip running from partway down the gradient to the horizon point, with the
+-- moon still drawn correctly over it, and with the haze BELOW the sky (the
+-- palest band again, but delivered by love.graphics.clear instead of by the
+-- array) landing in exactly the right colour. Same colour, two routes, one of
+-- them black: the fault was the array, not the palette.
+--
+-- Which of the ES failure modes it was hardly matters -- a driver that
+-- truncates a partially-filled array, a fragment uniform budget the guaranteed
+-- floor of which is sixteen vectors (eight bands plus the glow plus LOVE's own
+-- built-ins is over it), a reflection that finds bands[0] and nothing after --
+-- because they all have the same shape: slots past the first few read as zero,
+-- and zero is black.
+--
+-- A sampler has none of them. One texture unit replaces eight uniform vectors,
+-- there is no array to index and no budget to overrun, and a texel that does
+-- not exist cannot read as black because the image is built at exactly the
+-- width the shader divides by. Nearest and clamped, so a sample lands on one
+-- band's own colour and an out-of-range one lands on the end band rather than
+-- on nothing.
+--
+-- Rebuilt only when the bands move, which is when the clock or the display
+-- mode does; Sky.bands drops it as it rebuilds the list it is made from.
+local function rampFor(bands)
+  if cache.ramp and cache.rampFor == bands then return cache.ramp end
+  if not (love.image and love.image.newImageData
+          and love.graphics and love.graphics.newImage) then return nil end
+  local n = #bands
+  if n < 1 then return nil end
+  local ok, data = pcall(love.image.newImageData, n, 1)
+  if not (ok and data) then return nil end
+  for i = 1, n do
+    local c = bands[i]
+    pcall(data.setPixel, data, i - 1, 0, c[1], c[2], c[3], 1)
+  end
+  local built, img = pcall(love.graphics.newImage, data)
+  if not (built and img) then return nil end
+  -- nearest: a band is a flat colour, not something to interpolate between.
+  -- clamp: the shader clamps its index too, so this is the second of two
+  -- guards against ever sampling off the end -- and it returns the edge band.
+  pcall(img.setFilter, img, "nearest", "nearest")
+  pcall(img.setWrap, img, "clamp", "clamp")
+  cache.ramp, cache.rampFor = img, bands
+  return img
+end
+
+Sky._rampFor = rampFor            -- named for the suite
+
+-- The band ramp for the CURRENT bands, plus how many texels wide it is --
+-- for a pass that wants to read the same sky this one paints. The water's
+-- reflection is the one caller: it looks the reflected direction up on this
+-- very ramp, so the sky on the lake and the sky over it are one palette,
+-- through one display-mode transform, off one clock.
+--
+-- nil where the ramp could not be built, which is exactly when Sky.paint
+-- falls back to flat bands -- so a driver that loses the gradient loses the
+-- reflected gradient with it rather than showing two different skies.
+function Sky.ramp()
+  local bands = Sky.bands()
+  if not (bands and bands[1]) then return nil end
+  local img = rampFor(bands)
+  if not img then return nil end
+  return img, #bands, bands
+end
+
+-- How far the twilight glow reaches around the disc, in canvas pixels, for
+-- a `w`-wide frame. The same number Sky.paint sends as `glowInvR`.
+Sky.GLOW_REACH = 0.55
+
+local shader = nil            -- nil = untried, false = unavailable
+
+local function getShader()
+  if shader == nil then
+    shader = false
+    if love.graphics and love.graphics.newShader then
+      local ok, sh = pcall(love.graphics.newShader, SHADER_SRC)
+      if ok and sh then
+        shader = sh
+      elseif V and V.mod and V.mod.log then
+        -- once, and only where it can be read: the fallback below is a sky
+        -- without its dither, which is easy to look at and impossible to
+        -- diagnose without this line
+        V.mod.log:warn("sky shader did not compile: %s -- the bands draw flat, "
+                       .. "with no dither between them", tostring(sh))
+      end
+    end
+  end
+  return shader or nil
+end
+
+Sky._getShader = getShader        -- named for the suite
+
+-- The flat fallback: the same bands as solid rectangles, no checker, on the same
+-- quantised edges. For a driver that could not compile the shader -- which is
+-- also every headless run.
+local function paintFlat(w, h, bands, edge, alpha, cell, top)
+  local g = love.graphics
+  local n = #bands
+  local span = edge - (top or 0)
+  local prev = 0
+  for i = 1, n do
+    local cut = (i == n) and math.min(h, math.ceil(edge))
+                or math.floor(((top or 0) + i / n * span) / cell + 0.5) * cell
+    cut = math.max(prev, math.min(cut, math.min(h, math.ceil(edge))))
+    if cut > prev then
+      local c = bands[i]
+      g.setColor(c[1], c[2], c[3], alpha)
+      g.rectangle("fill", 0, prev, w, cut - prev)
+    end
+    prev = cut
+  end
+end
+
+-- ------- the discs
+--
+-- The sun and moon, as cell art: a circle of whole diorama cells with a
+-- lighter core, a dithered rim, and -- for the moon -- a few fixed crater
+-- cells. Drawn as plain rectangles on the same grid as the sky's own dither,
+-- through the same display-mode transform as every palette here, and
+-- SCISSORED to the sky's region: the horizon point is where a setting body
+-- disappears, so it can never hang under the map at a high pitch.
+--
+-- SIZED BY THE FRAME, not by the world: a celestial body's apparent size is
+-- an angle, so zooming the ground in and out must not swell and shrink the
+-- sun with it. The radius is a fraction of the frame height, converted to
+-- whole cells so the disc still sits on the diorama's grid -- chunky cells
+-- up close, fine ones at survey zoom, the same size body either way.
+Sky.DISC_FRAC = 0.030     -- disc radius, as a fraction of the frame height
+Sky.DISC_MIN = 3          -- but never fewer cells than this across a radius
+
+-- crater centres as fractions of the radius, so they ride any disc size.
+-- Public because the water's reflection draws the same moon (see Water):
+-- one list, so the disc on the lake cannot drift from the one in the sky.
+Sky.MOON_CRATERS = { { -0.4, -0.2 }, { 0.2, 0.45 }, { 0.5, -0.4 },
+                     { -0.15, 0.7 }, { 0.05, 0.05 } }
+
+-- a crater's radius, as a fraction of the disc's -- the r/5 paintDisc uses
+Sky.CRATER_FRAC = 0.2
+
+local MOON_CRATERS = Sky.MOON_CRATERS
+
+-- The disc's four shades as the display mode has them, lightest first.
+-- Shared with the reflection pass, so the sun on the water is the same sun
+-- that is in the sky, in the same mode's palette.
+function Sky.discShades(moon)
+  local src = moon and DayNight.MOON_COLORS or DayNight.SUN_COLORS
+  return PaletteFX.effectiveColors(src) or src
+end
+
+-- Whether this body is the LOOMING low sun -- the sunset exaggeration.
+local function looming(body)
+  return (body.glowAmt or 0) > 0.25 and not body.moon
+end
+
+-- The disc's radius for a `h`-tall frame on a `cell`-pixel grid: in CANVAS
+-- PIXELS, and in whole cells. Sized by the FRAME rather than by the world
+-- (see DISC_FRAC), so a zoom does not swell the sun.
+--
+-- Read by paintDisc below and by the reflection, which needs the same
+-- number in radians -- a disc drawn one size and mirrored another would
+-- read as two different suns.
+function Sky.discRadius(h, cell, body)
+  cell = math.max(1, cell or 1)
+  local r = math.max(Sky.DISC_MIN,
+                     math.floor(h * Sky.DISC_FRAC / cell + 0.5))
+  if body and looming(body) then r = r + math.max(1, math.floor(r * 0.4)) end
+  return r * cell, r
+end
+
+-- One disc's worth of cell art -- shared verbatim by the screen-space
+-- painter below (the flat screen) and by the BAKE the VR eyes texture
+-- their world-anchored quad with (Sky.discImage). `plot(dx, dy, c)` gets
+-- every kept cell in disc-local cell coordinates and its 0..255 colour.
+local function discCells(r, moon, shades, twilight, plot)
+  local core = shades[1]
+  local main = shades[twilight and 3 or 2]
+  local craterR = math.max(1, math.floor(r / 5))
+  for dy = -r, r do
+    for dx = -r, r do
+      local d = math.sqrt(dx * dx + dy * dy)
+      if d <= r + 0.1 then
+        local c = d <= r * 0.5 and core or main
+        -- dithered rim: the outer ring keeps only one parity of its cells
+        local keep = d <= r - 0.9 or (dx + dy) % 2 == 0
+        if moon then
+          for _, cr in ipairs(MOON_CRATERS) do
+            local cdx = dx - math.floor(cr[1] * r + 0.5)
+            local cdy = dy - math.floor(cr[2] * r + 0.5)
+            if cdx * cdx + cdy * cdy <= craterR * craterR then
+              c = shades[3]
+            end
+          end
+        end
+        if keep then plot(dx, dy, c) end
+      end
+    end
+  end
+end
+
+local function paintDisc(body, edge, cell, w, h)
+  local g = love.graphics
+  if not (body and body.y and g.setScissor) then return end
+  local shades = Sky.discShades(body.moon)
+  local twilight = looming(body)
+  local _, r = Sky.discRadius(h, cell, body)
+  -- snap the centre to the cell grid, like everything else in this sky
+  local bx = math.floor(body.x / cell) * cell + cell / 2
+  local by = math.floor(body.y / cell) * cell + cell / 2
+  if by - r * cell > edge then return end     -- wholly below the horizon point
+  local sx, sy, sw, sh = g.getScissor()
+  g.setScissor(0, 0, math.ceil(w), math.floor(edge))
+  discCells(r, body.moon, shades, twilight, function(dx, dy, c)
+    g.setColor(c[1] / 255, c[2] / 255, c[3] / 255, 1)
+    g.rectangle("fill", bx + dx * cell - cell / 2,
+                by + dy * cell - cell / 2, cell, cell)
+  end)
+  if sx then g.setScissor(sx, sy, sw, sh) else g.setScissor() end
+  g.setColor(1, 1, 1, 1)
+end
+
+-- ------- the disc as a TEXTURE, for the VR eyes
+--
+-- A VR eye must not paint the disc in screen space at all: a canvas-grid
+-- painting re-snaps to different cells every head movement (jitter) and
+-- holds its pattern square to the CANVAS (a rolled or pitched head
+-- watches the sun's face turn). So the same cell art is baked once into
+-- a texture, and Voxel3D hangs it on a quad ANCHORED IN THE WORLD --
+-- projected through the eye's own matrix like any geometry, stable under
+-- every head motion. Rebaked only when the palette or the twilight state
+-- moves the colours.
+local discBake = { key = nil, img = nil }
+
+Sky.DISC_BAKE_R = 9          -- bake radius, in cells
+Sky.DISC_BAKE_PX = 8         -- texture pixels per cell
+
+function Sky.discImage(moon, twilight)
+  if not (love.graphics and love.graphics.newCanvas) then return nil end
+  local shades = Sky.discShades(moon)
+  local key = (moon and "m" or "s") .. (twilight and "t" or "-")
+  for i = 1, math.min(3, #shades) do
+    local c = shades[i]
+    key = key .. ":" .. c[1] .. "," .. c[2] .. "," .. c[3]
+  end
+  if discBake.key == key and discBake.img then return discBake.img end
+  local r, px = Sky.DISC_BAKE_R, Sky.DISC_BAKE_PX
+  local size = (2 * r + 1) * px
+  local ok, canvas = pcall(love.graphics.newCanvas, size, size)
+  if not (ok and canvas) then return nil end
+  pcall(canvas.setFilter, canvas, "nearest", "nearest")
+  local g = love.graphics
+  local done = pcall(function()
+    g.push("all")
+    g.origin()
+    g.setCanvas(canvas)
+    g.clear(0, 0, 0, 0)
+    g.setBlendMode("alpha")
+    discCells(r, moon, shades, twilight, function(dx, dy, c)
+      g.setColor(c[1] / 255, c[2] / 255, c[3] / 255, 1)
+      g.rectangle("fill", (dx + r) * px, (dy + r) * px, px, px)
+    end)
+    g.pop()
+  end)
+  if not done then return nil end
+  discBake.key, discBake.img = key, canvas
+  return canvas
+end
+
+-- Whether this body is the looming low sun, for callers sizing the baked
+-- disc (the same exaggeration paintDisc applies through discRadius).
+function Sky.discLooming(glowAmt, moon)
+  return (glowAmt or 0) > 0.25 and not moon
+end
+
+-- Paint the sky into the bound canvas, filling it from the top edge down to
+-- `horizonY` (or to SPAN of the frame when the horizon is out of it).
+--
+-- `cell` is the diorama's pixel size in canvas pixels -- the pass's own
+-- pixels-per-world-pixel, handed in every frame so a zoom lands immediately.
+--
+-- `body` is the sun or moon to hang, already projected to canvas pixels by
+-- the caller's own camera (Voxel3D.skyBody), with the twilight glow riding
+-- along; nil hangs nothing and warms nothing.
+--
+-- `top` anchors the gradient in space rather than to the frame: the canvas
+-- row band 1 starts on (often negative -- above the frame), from a caller
+-- that mapped a fixed elevation span to its own camera (see ELEV_SPAN).
+-- nil or 0 is the flat screen's behaviour: zenith band at the top edge.
+--
+-- `axis` tips the whole painting to a rolled camera's true horizon: a unit
+-- {ax, ay} pointing "toward the ground" on the canvas (Voxel3D.horizonLine),
+-- with `horizonY` and `top` then read as distances ALONG it rather than as
+-- rows. nil is the level default. Only the shader path can tilt; the flat
+-- fallback paints level, which only a headless run ever sees. Under an
+-- axis the DISC is not painted here at all -- the VR caller hangs the
+-- baked disc (Sky.discImage) in the world instead; `body` still carries
+-- the twilight glow into the bands.
+--
+-- `ray` makes the gradient a SKYBOX: the eye's own ray fan (the camera
+-- record's skyRay, from VRRig.eyeCamera), letting every pixel take its
+-- band from its TRUE elevation -- so no motion of the head, on any axis,
+-- moves a band; only the clock does. nil keeps the linear frame gradient
+-- the flat screen has always painted.
+--
+-- Returns false when there is nothing to paint, in which case the caller's flat
+-- fill is the whole sky. That fill is the palest band, so a frame that declines
+-- this looks like a hazy day rather than like a bug.
+function Sky.paint(w, h, sky, horizonY, cell, body, top, axis, ray)
+  local bands = sky and sky.bands
+  if not (bands and bands[1]) then return false end
+  if not (w and h and w > 0 and h > 0) then return false end
+  local g = love.graphics
+  if not (g and g.rectangle) then return false end
+  -- with a ray fan the shader's own per-pixel elevation test is the only
+  -- boundary and the whole frame goes through it; along an axis the
+  -- caller's edge is already the signed distance and has no row to be
+  -- clamped to; level callers keep the SPAN fallback
+  local edge
+  if ray then
+    edge = h
+  elseif axis then
+    edge = horizonY
+  else
+    edge = Sky.region(h, horizonY)
+  end
+  if not edge then return false end
+  local alpha = sky[4] or 1
+  cell = math.max(1, math.floor((cell or 1) + 0.5))
+
+  -- State to put aside. The scene's shader is one, and the blend mode another --
+  -- a pass that left "replace" behind would make the fade-in strength meaningless
+  -- -- but the DEPTH MODE is the one that would break the frame: a rectangle
+  -- drawn under the pass's own ("lequal", true) stamps itself across the depth
+  -- buffer at the near plane and hides the entire world behind the sky.
+  local prevShader = g.getShader and g.getShader() or nil
+  local cmp, write
+  if g.getDepthMode then cmp, write = g.getDepthMode() end
+  if g.setDepthMode then g.setDepthMode("always", false) end
+  local blend, blendAlpha
+  if g.getBlendMode then blend, blendAlpha = g.getBlendMode() end
+  if g.setBlendMode then g.setBlendMode("alpha") end
+
+  local glowAmt = body and not body.moon and (body.glowAmt or 0) or 0
+  -- the skybox glow needs the sun's world DIRECTION (skyBody carries it);
+  -- a body without one has nothing to measure angles against, so no glow
+  if ray and glowAmt > 0 and not (body and body.dx) then glowAmt = 0 end
+  -- the world direction a canvas fraction (u, v) looks along, normalised
+  -- -- for sizing the angular checker and the glow's angular reach below
+  local function rayDirAt(u, v)
+    local b, du, dv = ray.base, ray.du, ray.dv
+    local x = b[1] + du[1] * u + dv[1] * v
+    local y = b[2] + du[2] * u + dv[2] * v
+    local z = b[3] + du[3] * u + dv[3] * v
+    local l = math.sqrt(x * x + y * y + z * z)
+    if l < 1e-9 then return 0, 0, -1 end
+    return x / l, y / l, z / l
+  end
+  local function rayAngle(u0, v0, u1, v1)
+    local ax, ay, az = rayDirAt(u0, v0)
+    local bx, by, bz = rayDirAt(u1, v1)
+    local d = ax * bx + ay * by + az * bz
+    return math.acos(math.max(-1, math.min(1, d)))
+  end
+  local sh = getShader()
+  local ramp = sh and rampFor(bands)
+  if not ramp then sh = nil end       -- no ramp, no gradient: paint it flat
+  if sh then
+    local sent = pcall(function()
+      -- the bands arrive as a texture, one texel each, and `count` is that
+      -- texture's width -- see rampFor for why they are not a uniform array
+      sh:send("ramp", ramp)
+      sh:send("count", #bands)
+      sh:send("edge", edge)
+      sh:send("top", math.min(top or 0, edge - 1))
+      sh:send("axisX", axis and axis[1] or 0)
+      sh:send("axisY", axis and axis[2] or 1)
+      sh:send("useRay", ray and 1 or 0)
+      if ray then
+        sh:send("rayBase", ray.base)
+        sh:send("rayDu", ray.du)
+        sh:send("rayDv", ray.dv)
+        sh:send("raySpan", Sky.ELEV_SPAN)
+        sh:send("invSize", { 1 / w, 1 / h })
+        -- the angular checker's cell: the angle one dither cell spans at
+        -- the frame's centre, so the sky-glued grid comes out the same
+        -- size on screen as the diorama's own pixel grid
+        sh:send("cellAng",
+                math.max(1e-4, rayAngle(0.5, 0, 0.5, 1) * cell / h))
+      end
+      sh:send("cell", cell)
+      sh:send("start", Sky.DITHER and Sky.DITHER_START or 2)
+      sh:send("alpha", alpha)
+      sh:send("glowAmt", glowAmt)
+      if glowAmt > 0 then
+        local gc = body.glowColor or { 248, 224, 168 }
+        if ray then
+          -- the glow in ANGLES: its direction is the sun's own, and its
+          -- reach is the same fraction of the view the pixel reach was
+          -- of the frame, so the two paths agree on how wide it looks
+          local dx, dy, dz = body.dx, body.dy, body.dz
+          local l = math.sqrt(dx * dx + dy * dy + dz * dz)
+          sh:send("glowDir", { dx / l, dy / l, dz / l })
+          sh:send("glowInvA", 1 / math.max(
+            1e-3, rayAngle(0, 0.5, 1, 0.5) * Sky.GLOW_REACH))
+        else
+          sh:send("glowPos", { body.x, body.y })
+          sh:send("glowInvR", 1 / math.max(1, w * Sky.GLOW_REACH))
+        end
+        sh:send("glowColor", { gc[1] / 255, gc[2] / 255, gc[3] / 255 })
+      end
+    end)
+    if sent then
+      g.setShader(sh)
+      g.setColor(1, 1, 1, 1)
+      -- tilted or rayed, the sky's reach is not a row: the full frame
+      -- goes through the shader and the discard is the boundary
+      local rectH = (axis or ray) and h or math.min(h, math.ceil(edge))
+      g.rectangle("fill", 0, 0, w, rectH)
+      g.setShader()
+    else
+      sh = nil
+    end
+  end
+  if not sh then
+    paintFlat(w, h, bands, (axis or ray) and math.min(h, edge) or edge,
+              alpha, cell, math.min(top or 0, edge - 1))
+  end
+  -- the disc goes over the glow, under nothing: plain rectangles, so it is
+  -- there whether or not the shader built. NOT under an axis or a ray fan:
+  -- those cameras hang the baked disc in the world instead (drawWorldDisc,
+  -- with Sky.discImage)
+  if not (axis or ray) then
+    paintDisc(body, math.min(h, edge), cell, w, h)
+  end
+  g.setColor(1, 1, 1, 1)
+
+  if g.setBlendMode and blend then g.setBlendMode(blend, blendAlpha) end
+  if g.setDepthMode then g.setDepthMode(cmp or "always", write or false) end
+  if prevShader and g.setShader then g.setShader(prevShader) end
+  return true
+end
+
+-- Drop the compiled shader (window resize, hot reload), so a re-created graphics
+-- context builds a new one instead of drawing with a handle from the old. The
+-- ramp is a GPU object on the same context and goes with it.
+function Sky.invalidate()
+  shader = nil
+  if cache.ramp and cache.ramp.release then pcall(cache.ramp.release, cache.ramp) end
+  cache.ramp, cache.rampFor = nil, nil
+  if discBake.img and discBake.img.release then
+    pcall(discBake.img.release, discBake.img)
+  end
+  discBake.key, discBake.img = nil, nil
+end
+
+return Sky

lib/Stadium.lua

@@ -0,0 +1,730 @@
+-- STADIUM battles: the two Pokemon as real 3D models.
+--
+-- The 3D-BTL row's two STADIUM rungs. OFF is the engine's own white battle
+-- field; the 2D-3D rungs stand the GB's own pics up as quads
+-- (BattleBillboard); STADIUM replaces those quads with the Pokemon Stadium
+-- battle models -- skinned, animated, and playing the animation the move
+-- being used actually calls for. A or B decides whether that happens on the
+-- map or on two discs, and is the same choice on either pair of rungs.
+--
+-- The models come out of the Stadium ROM through model_extract, and are
+-- packed into assets/stadium/NNN.dsm by tools/stadium_pack.py. Nothing here
+-- knows about the ROM; the pack is the interface.
+--
+-- ------- what this file is, and is not
+--
+-- It is the MODE: which species is out on each side, which animation the
+-- fight is asking each of them for, whether the model or the flat pic is
+-- standing in this frame, and the two draw calls. The arithmetic is
+-- StadiumRig's, the file format is StadiumPack's, and one side's own state
+-- is StadiumMon's.
+--
+-- It is not a rewrite of the staged battle. The arena is picked the same
+-- way, the camera is solved the same way, the HUDs and the text box and the
+-- move animations and the depth of field are all exactly what 2D-3D draws
+-- -- because all of those are hung off the arena's CELLS, not off the
+-- pics. Swapping what stands on a cell changes nothing about where the cell
+-- projects to. That is why this is an option on the mode rather than a
+-- second mode.
+--
+-- ------- declining, per Pokemon
+--
+-- Every gate here is per SIDE and per FRAME, not per battle:
+--
+--   no pack for that species, or its meshes would not build -> that side
+--   falls back to its flat pic, and the other side keeps its model
+--
+--   the side is showing a TRAINER (the foe's class before the send-out,
+--   the player's own back before "Go!") -> that is not a Pokemon and there
+--   is no model for it; the pic stands, exactly as in 2D-3D
+--
+--   a SUBSTITUTE is up -> the engine replaces the pic with the mini doll,
+--   which is the thing the player is being told is there. A model of the
+--   Pokemon behind the doll would be a lie about the battle state.
+--
+-- So `covers` is asked per side per frame, and OverworldBattle renders a
+-- billboard texture for exactly the sides it answers false for.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Voxel3D = V.require("Voxel3D")
+local StadiumPack = V.require("StadiumPack")
+local StadiumMon = V.require("StadiumMon")
+
+local Stadium = {}
+
+-- The stored values of the two 3D-BTL rungs that select this mode. Strings
+-- rather than further booleans so an older save's `true` still means the
+-- 2D-3D it was written for (see OverworldBattle.setting).
+--
+--   A  the models on the MAP -- real ground, the map's own light and sky
+--   B  the models on two DISCS against the sky, with no map at all
+--
+-- Everything below is shared: which species is out, which animation the
+-- fight is asking for, the skinning, the draw. The difference is entirely
+-- in what the camera is pointed at, which is BattleScene's business and
+-- StadiumStage's.
+Stadium.VALUE = "stadium"
+Stadium.VALUE_B = "stadiumB"
+
+-- ------- the live pair
+
+local session = nil     -- nil when no staged fight is running
+
+local function game()
+  return require("src.core.Game")
+end
+
+-- Whether the row is on this rung. Deliberately NOT gated on whether the
+-- packs are installed: a mod folder without assets/stadium still cycles the
+-- row, and each Pokemon declines on its own when its pack does not load --
+-- which is one message on the console rather than a row that silently
+-- refuses to move.
+function Stadium.selected()
+  return Stadium.mode() ~= nil
+end
+
+-- "A", "B", or nil when the row is on neither stadium rung.
+function Stadium.mode()
+  local OverworldBattle = V.require("OverworldBattle")
+  local value = OverworldBattle.setting:get()
+  if value == Stadium.VALUE then return "A" end
+  if value == Stadium.VALUE_B then return "B" end
+  return nil
+end
+
+-- Whether the fight is staged on the DISCS rather than on the map.
+--
+-- Not this file's question any more: the flat 2D-3D B rung stands the game's
+-- own pics on the same two discs with no model anywhere in the frame, so the
+-- stage and the actors are chosen separately (see OverworldBattle's ladder).
+-- Kept as a forwarder because "are we on discs" is a fair thing to ask the
+-- module named after the mode, and because the shot drivers ask it here.
+function Stadium.discs()
+  return V.require("OverworldBattle").discs()
+end
+
+function Stadium.enabled()
+  if not Stadium.selected() then return false end
+  return Voxel3D.available()
+end
+
+-- A staged fight has begun on `arena`. Called from OverworldBattle.begin,
+-- which is the one place that knows a fight is being staged at all.
+function Stadium.begin(arena)
+  Stadium.finish()
+  if not Stadium.enabled() then return false end
+  -- a new fight gets its own first complaint: `reported` is a one-shot so the
+  -- console is not filled sixty times a second, but latched for the whole
+  -- process it would swallow every failure after the first one ever
+  Stadium.reported = false
+  session = {
+    arena = arena,
+    groundY = 0,
+    player = StadiumMon.new("player"),
+    enemy = StadiumMon.new("enemy"),
+    -- what each side has been TRANSFORMED into, if anything (see install)
+    transform = {},
+    -- sides that are going to collapse, but whose HP bar has not finished
+    -- emptying yet (see faintReady)
+    faintPending = {},
+    -- who was standing in each slot last frame, so a replacement is noticed
+    -- even when it is the same species (see update)
+    at = {},
+  }
+  return true
+end
+
+function Stadium.finish()
+  if not session then return end
+  session.player:release()
+  session.enemy:release()
+  session = nil
+end
+
+function Stadium.active()
+  return session ~= nil
+end
+
+-- ------- which species each side is showing
+
+-- The National Dex number for a battler, which is the number the Stadium
+-- packs are keyed by. The engine's species are string keys ("PIKACHU") and
+-- carry their dex number on the definition, so this is one lookup rather
+-- than a table of its own.
+local function dexOf(species)
+  if not species then return nil end
+  local data = game() and game().data
+  local def = data and data.pokemon and data.pokemon[species]
+  return def and def.dex or nil
+end
+
+-- Whether this side is showing a TRAINER rather than a Pokemon.
+local function showingTrainer(battle, side)
+  if side == "enemy" then
+    return (battle.showEnemyTrainer and battle.trainerPic) and true or false
+  end
+  return (battle.showPlayerBack and battle.playerBackPic) and true or false
+end
+
+-- Whether this side has anything on the field at all this frame.
+--
+-- Mirrors BattleState's own guards, the same way OverworldBattle.sideVisible
+-- mirrors them for the flat cards: there is no seam that reports "the foe is
+-- off screen right now", and a model left standing through a send-out or a
+-- damage blink would be the one thing in the frame that ignored the battle.
+-- ------- and the collapse gets to finish
+--
+-- A fainted Pokemon leaves the field when its pic does, which is the end of
+-- the engine's slide -- SlideDownFaintedMonPic, seven rows two frames apart,
+-- FOURTEEN frames of a 60 Hz clock. Under a quarter of a second.
+--
+-- The Stadium faint animations are nothing like that short. The briefest in
+-- the set is 49 frames of a 30 Hz clock -- a second and two thirds -- the
+-- median is 110 and the longest 230, which is nearly eight seconds. Held to
+-- the pic's window every one of them was cut off inside its first fifth: the
+-- Pokemon began to fall and vanished mid-fall, which is worse than not
+-- animating at all, because the eye has been told something is happening and
+-- then had it taken away.
+--
+-- So a model that is COLLAPSING stays until it has finished collapsing, and
+-- the two timings stop being tied to each other. That is the whole of the
+-- divergence: the slide is how long a flat pic takes to slide off the bottom
+-- of a 160x144 frame, and it has nothing to say about how long it takes a
+-- Gyarados to fall over.
+--
+-- Bounded at both ends rather than open-ended. It ends when the animation
+-- does (StadiumMon.finished), not when the battle moves on -- so nothing is
+-- left lying on the field for the rest of the fight -- and the side is reset
+-- outright the moment a different battler stands in that slot (see update),
+-- which is what stops the next Pokemon out of the ball arriving face down.
+local function onField(battle, side, mon)
+  local battler = side == "player" and battle.player or battle.enemy
+  if not (battler and battler.sprite) then return false end
+  -- A model that is GROWING out of its ball is on the field by definition --
+  -- that is what the grow is -- even though the engine still calls the side
+  -- "sending out", because the flat pic it wrote that flag for does not
+  -- appear until the ball has finished opening and this one comes out with
+  -- it (see StadiumMon.GROW_TIME).
+  local growing = (mon and mon.grow) and true or false
+  if side == "enemy" then
+    if battle.enemyHidden then return false end
+    if battle.enemySendingOut and not growing then return false end
+  else
+    if battle.safari or battle.demo then return false end
+    if battle.sendingOut and not growing then return false end
+    -- ------- and not before the battle has even opened
+    --
+    -- The player's Pokemon is not out during the INTRO. Every other guard
+    -- here is a field the engine sets once the battle is running, and during
+    -- the opening none of them is set yet: `showPlayerBack` is still nil
+    -- (BattleState assigns it further in, when the back pic is built),
+    -- `playerBackPic` is nil with it, and `sendingOut` does not go true until
+    -- the ball is actually thrown. So the whole opening read as "this
+    -- Pokemon is standing on the field" and the model was drawn through it --
+    -- two and a half seconds of it, on its tile, playing its standby loop,
+    -- before the trainer sprite it is supposed to be hiding behind had even
+    -- appeared. It then vanished when that sprite arrived and came back with
+    -- its entrance when the ball opened, so the first Pokemon of a battle
+    -- appeared, left and arrived again.
+    --
+    -- A SWITCH has no intro, which is why a switch always looked right and
+    -- was the thing worth comparing against.
+    --
+    -- Gated on the PHASE rather than on a flag latched at the send-out: a
+    -- latch that never fires (a link battle, a script pushing a battle
+    -- straight to the menu) would hide the Pokemon for good, and being wrong
+    -- in that direction is far worse than the two seconds this fixes.
+    if battle.phase == "intro" then return false end
+  end
+  local ok, hidden = pcall(battle.fxHidden, battle, battler)
+  if ok and hidden then return false end
+  -- ------- FLY and DIG: the Pokemon that is not there
+  --
+  -- `fxHidden` above is the damage BLINK and nothing else. The other way a
+  -- Pokemon leaves the screen -- the important one -- is the engine's
+  -- per-battler pic program, `picFx`, and that is where the two-turn moves
+  -- live: FLY runs SE_SLIDE_MON_OFF and DIG SE_SLIDE_MON_DOWN on the charge
+  -- turn, each a 19-24 frame slide that ENDS by setting `hidden`, and the
+  -- release turn puts the pic back through SE_SLIDE_MON_UP /
+  -- SE_SHOW_MON_PIC. Every other vanishing act is the same field: the user
+  -- of Explosion, a Pokemon that has been Teleported away.
+  --
+  -- Without this the model simply stood on its tile while the game said it
+  -- was underground -- and said it in the strongest way it has, by making
+  -- every attack aimed at it miss. That is the one thing in the frame
+  -- contradicting the battle it is part of.
+  --
+  -- Read as the engine's own answer rather than as a list of moves: this
+  -- mode's whole method is to let the battle decide and follow it, and a
+  -- table of move ids here would be a second place for the same facts to
+  -- live and would go stale against a mod that adds a third one.
+  --
+  -- The engine's slide is 19-24 frames, so the model plays the opening of
+  -- its own FLY or DIG animation while the pic slides and is gone when the
+  -- pic is. It is NOT held to the end of that animation the way a collapse
+  -- is (see below), and the difference is not an oversight: the Stadium
+  -- animations are authored as the WHOLE move -- Charizard's DIG is 3.83
+  -- seconds of burrow, emerge and hit -- because Stadium plays it in one
+  -- turn. Gen 1 splits it across two, so cutting at the engine's own hide
+  -- shows the burrowing and holds the strike back for the turn it lands on,
+  -- which is the right half of the animation for the turn being played.
+  local pf = battle.picFx and battle.picFx[battler]
+  if pf and pf.hidden then return false end
+  if battler.fainted then
+    local okF, sliding = pcall(battle.fxFaintActive, battle, battler)
+    if okF and sliding then return true end
+    -- the pic has finished sliding away; the model has not finished falling
+    return (mon and mon.state == "faint" and not mon:finished()) and true
+           or false
+  end
+  return true
+end
+
+Stadium._onField = onField
+
+-- Whether the 3D model is standing in for this side's pic this frame. The
+-- one question OverworldBattle asks, and the answer that decides whether a
+-- billboard texture gets rendered for that side at all.
+function Stadium.covers(battle, side)
+  if not (session and battle) then return false end
+  local mon = session[side]
+  if not (mon and mon.rig) then return false end
+  if showingTrainer(battle, side) then return false end
+  local battler = side == "player" and battle.player or battle.enemy
+  -- the substitute doll is what the player is being shown is out there
+  if battler and battler.substituteHP then return false end
+  return true
+end
+
+-- ------- the collapse waits for the bar
+--
+-- `onFaint` runs the instant HP reaches zero, which is NOT when a Pokemon
+-- falls over. The engine queues the collapse -- the slide, the cry, the
+-- "fainted!" line -- to run after the move animation and the HP-bar drain
+-- (BattleState.onFaint's own comment), and the drain takes real frames: a
+-- 150 HP mon's bar walks down over some four seconds.
+--
+-- So asking for the faint animation at `onFaint` played it against a bar
+-- that was still emptying: the Pokemon lay down, and then its health went on
+-- draining above the corpse. What the player reads as the moment of death is
+-- the bar hitting zero, and that is what this waits for.
+--
+-- `shownHP` is the engine's own bar position (BattleState.stepHPDrain walks
+-- it toward mon.hp a point at a time), so this is not a guess at the timing
+-- -- it is the same number the bar is drawn from.
+local function faintReady(battler)
+  if not battler then return false end
+  -- nothing is animating the bar for this battler: there is nothing to wait
+  -- for, and waiting forever would mean never collapsing at all
+  if battler.shownHP == nil then return true end
+  return battler.shownHP <= 0
+end
+
+-- Whether a pending collapse is still owed. A switch, a revive or a battler
+-- that was replaced under us drops it rather than firing late at whoever is
+-- standing there now.
+local function faintStillDue(battler)
+  return (battler and battler.faintQueued
+          and battler.mon and (battler.mon.hp or 0) <= 0) and true or false
+end
+
+-- named for the suite: these timing rules are the whole of what decides when
+-- a Pokemon falls and when it goes, and they are testable without a graphics
+-- context where the mode itself is not
+Stadium._faintReady = faintReady
+Stadium._faintStillDue = faintStillDue
+
+-- ------- per frame
+--
+-- Runs from OverworldBattle.update, before the pics are rendered and before
+-- the scene is drawn: what this decides is exactly which sides need a pic.
+function Stadium.update(dt, battle, groundY)
+  if not session then return end
+  session.groundY = groundY or session.groundY or 0
+  if not battle then return end
+
+  local arena = session.arena
+  for _, side in ipairs({ "enemy", "player" }) do
+    local mon = session[side]
+    local battler = side == "player" and battle.player or battle.enemy
+    local dex = nil
+    if battler and not showingTrainer(battle, side) then
+      dex = session.transform[side] or dexOf(battler.mon and battler.mon.species)
+    end
+
+    -- A DIFFERENT POKEMON IS IN THIS SLOT. Normally that shows up as a
+    -- change of species and setSpecies rebuilds everything -- but a trainer
+    -- who leads with two Rattata sends the second one out onto the first
+    -- one's dex number, so nothing downstream would notice. What it would
+    -- inherit is the state, and the state after a faint is `faint`, which
+    -- refuses every request there is (see StadiumMon.request -- a faint is
+    -- meant to be final). The new Pokemon would arrive lying on the ground.
+    --
+    -- The battler TABLE is the identity here rather than the species or the
+    -- mon: it is the slot's occupant, and the engine replaces it on a switch,
+    -- a send-out and a new battle alike.
+    if session.at[side] ~= battler then
+      session.at[side] = battler
+      -- a fresh arrival: this Pokemon has not grown out of its ball yet
+      if mon then mon.grow, mon.grewOwn = nil, nil end
+      if mon and mon.rig and mon.state == "faint" then mon:play("idle") end
+    end
+    -- the collapse this side is owed, once its bar has finished emptying
+    if session.faintPending and session.faintPending[side] then
+      if not faintStillDue(battler) then
+        session.faintPending[side] = nil
+      elseif faintReady(battler) then
+        session.faintPending[side] = nil
+        if mon and mon.rig then mon:request("faint") end
+      end
+    end
+
+    mon:setSpecies(dex)
+    -- and tell the pack cache this one is standing there, every frame. Its
+    -- eviction order is keyed on LOADS, and a side only loads when its
+    -- species changes -- so without this a Pokemon that has been out for a
+    -- few turns is the least recently loaded thing in the cache and gets its
+    -- textures released out from under it the moment a fifth species enters
+    -- the battle (see StadiumPack.keep).
+    if mon.species then StadiumPack.keep(mon.species) end
+    mon.visible = (mon.rig ~= nil) and onField(battle, side, mon)
+                  and not (battler and battler.substituteHP)
+    -- cleared up front, so a side that has just lost its rig cannot leave
+    -- last frame's matrix behind it
+    mon.model_matrix = nil
+
+    if mon.rig then
+      -- ------- the ball is opening: start growing out of it
+      --
+      -- The POOF is the ball coming apart, and it is where a Pokemon should
+      -- begin to exist -- not 27 frames later when the engine starts scaling
+      -- up the flat pic it was written for. Only for a side the battle says
+      -- is actually sending out, so the same animation played at a thrown
+      -- Poke Ball (a capture attempt, which aims it at the FOE) cannot start
+      -- the wrong Pokemon growing.
+      local poof = (battle.animPlaying
+                    and battle.animName == "POOF_ANIM") and true or false
+      local sending = (side == "player") and battle.sendingOut
+                      or battle.enemySendingOut
+      if poof and sending and mon:beginGrow() then
+        -- and the arrival animation with it, so the whole thing is one
+        -- performance rather than a grow followed by a flourish
+        mon:request("entrance")
+      end
+
+      -- how big it is drawn. Its own ramp while it is growing (see
+      -- StadiumMon.growScale); the engine's three-step one otherwise, which
+      -- still covers a send-out that never showed a poof.
+      if mon.grow then
+        mon.scale = mon:growScale()
+      elseif mon.grewOwn then
+        mon.scale = 1
+      else
+        local okG, grow = pcall(battle.growInScale, battle, battler)
+        mon.scale = (okG and grow) or 1
+      end
+      mon:update(dt or 0)
+      if mon.visible and arena then
+        local cell = arena[side]
+        local other = arena[side == "player" and "enemy" or "player"]
+        if cell and other then
+          -- posed and skinned inside the same guard the draws use: this is
+          -- where a bad track or a released texture is first touched, and a
+          -- throw here would take the OTHER side's update with it (the
+          -- caller wraps this whole function in one pcall)
+          Stadium.guard(side, mon, "build", function()
+            mon.model_matrix = mon:matrix(cell[1], session.groundY, cell[2],
+                                          other[1] - cell[1],
+                                          other[2] - cell[2])
+            mon:build()
+          end)
+        else
+          mon.model_matrix = nil
+        end
+      else
+        mon.model_matrix = nil
+      end
+    end
+  end
+  Stadium.debug(dt)
+end
+
+-- ------- the draws
+--
+-- Both take the pass as they find it: this is called from inside
+-- BattleScene's own beginScene/endScene window (and, in a headset, from
+-- VoxelScene's), so the camera, the shadow map, the hour's tint and the hit
+-- flash are all already set. StadiumRig turns the wireframe and the glass
+-- mask off around its own draws and puts them back.
+
+-- ------- one model going wrong is not both
+--
+-- These two draws used to be a bare loop inside the caller's single pcall,
+-- which had two consequences and both were bad. A throw on the FIRST side
+-- skipped the second, so one broken Pokemon took its opponent off the screen
+-- with it. And nothing recorded that it had happened, so the same throw came
+-- back every frame for the rest of the fight -- the mode's own fallback (that
+-- side draws its flat pic instead) was sitting right there and never reached,
+-- because falling back needs somebody to decide the model is not working.
+--
+-- So each side is drawn inside its own pcall, and a side that throws is
+-- RETIRED: its rig is released, which is exactly the state a species with no
+-- pack is in, and OverworldBattle renders a billboard for it from the next
+-- frame on. The fight carries on with a flat Pokemon instead of a missing
+-- one, which is the difference the player actually sees.
+-- On the TABLE rather than a local, because Stadium.update calls it and sits
+-- above this line: a local would still be nil there.
+function Stadium.guard(side, mon, what, fn)
+  local ok, err = pcall(fn)
+  if ok then return true end
+  Stadium.report(err)
+  -- release rather than merely hide: the rig holds meshes and texture
+  -- references, and whatever went wrong with them is not going to be better
+  -- next frame. setSpecies rebuilds from scratch if this Pokemon is sent out
+  -- again later.
+  if mon.rig then pcall(mon.release, mon) end
+  mon.rig, mon.visible, mon.model_matrix = nil, false, nil
+  if session then session.broken = session.broken or {} end
+  if session then session.broken[side] = what end
+  return false
+end
+
+function Stadium.draw(pull)
+  if not session then return end
+  for _, side in ipairs({ "enemy", "player" }) do
+    local mon = session[side]
+    if mon.rig and mon.visible and mon.model_matrix then
+      Stadium.guard(side, mon, "draw", function()
+        mon.rig:draw(mon.model_matrix, pull)
+      end)
+    end
+  end
+end
+
+-- The same models as the SUN sees them, so a Pokemon throws the shadow of
+-- the pose it is actually in -- an outstretched wing puts an outstretched
+-- wing on the ground.
+function Stadium.cast(shadowMap)
+  if not session then return end
+  for _, side in ipairs({ "enemy", "player" }) do
+    local mon = session[side]
+    if mon.rig and mon.visible and mon.model_matrix then
+      Stadium.guard(side, mon, "cast", function()
+        mon.rig:caster(shadowMap, mon.model_matrix)
+      end)
+    end
+  end
+end
+
+-- Which state a side's model is playing, or nil. Named for the shot drivers:
+-- checking that an animation starts on the right FRAME is an ordering
+-- question, and a screenshot cannot answer one.
+function Stadium.animOf(side)
+  if not session then return nil end
+  local mon = session[side]
+  return mon and mon.state or nil
+end
+
+-- Whether this side's model is actually being drawn this frame. Named for
+-- the shot drivers alongside animOf: "how long does it stay" is a span, and
+-- a screenshot taken at one moment has no span in it.
+function Stadium.showing(side)
+  if not session then return false end
+  local mon = session[side]
+  return (mon and mon.visible) and true or false
+end
+
+-- How big this side's model is being drawn this frame, 0..1 -- the send-out
+-- grow. Named for the shot drivers: a ramp is a curve over time and a
+-- screenshot has one point of it.
+function Stadium.scaleOf(side)
+  if not session then return nil end
+  local mon = session[side]
+  return mon and mon.scale or nil
+end
+
+-- How wide the Pokemon on `side` stands, in world pixels, or nil when there
+-- is not one. What STADIUM B sizes that side's platform to (StadiumStage).
+function Stadium.footprint(side)
+  if not session then return nil end
+  local mon = session[side]
+  if not (mon and mon.model) then return nil end
+  local r = mon:worldRadius()
+  return (r > 0) and r or nil
+end
+
+-- Whether anything at all is standing this frame -- what the shadow
+-- signature keys on alongside the pics' own token.
+function Stadium.standing()
+  if not session then return false end
+  return (session.player.visible or session.enemy.visible) and true or false
+end
+
+-- ------- what the fight asks for
+--
+-- The animation state machine is driven from four points in the engine's
+-- own battle, and each is a wrap rather than a rewrite: the inner function
+-- runs exactly as it always did and this reads what went past.
+
+local function sideOf(battle, battler)
+  if not (session and battler) then return nil end
+  if battler == battle.player then return "player" end
+  if battler == battle.enemy then return "enemy" end
+  return nil
+end
+
+local function ask(battle, battler, state, animIndex, auxIndex)
+  local side = sideOf(battle, battler)
+  if not side then return end
+  local mon = session[side]
+  if mon and mon.rig then mon:request(state, animIndex, auxIndex) end
+end
+
+function Stadium.install()
+  local BattleState = require("src.battle.BattleState")
+  if BattleState.dramaticShapeStadiumHook then return end
+  BattleState.dramaticShapeStadiumHook = true
+
+  -- THE ATTACK. performMove is the one place a move is actually used, and
+  -- the move's own `index` is the Gen 1 move id the Stadium tables are
+  -- keyed by -- so the species' own animation for that move comes straight
+  -- out of the pack, with no name mapping and no per-move code.
+  local innerMove = BattleState.performMove
+  function BattleState:performMove(user, target, moveInst, isCalled)
+    if session then
+      local side = sideOf(self, user)
+      local mon = side and session[side]
+      if mon and mon.rig then
+        local okDef, def = pcall(self.moveDef, self, moveInst)
+        local index = okDef and def and def.index or nil
+        if not (index and mon:attack(index)) then
+          -- a move the table has nothing for still swings: the generic
+          -- attack is what the species' own reaction slot resolves to
+          mon:request("attack")
+        end
+      end
+    end
+    return innerMove(self, user, target, moveInst, isCalled)
+  end
+
+  -- THE HIT is deliberately NOT hooked. There is no damage reaction in this
+  -- set to play -- what looked like one is the species' default attack (see
+  -- StadiumMon's STATES), which is why being hit used to look like swinging.
+  -- The engine's own flash, pic blink and bar drain are what say "that hurt",
+  -- and they are already in the frame.
+
+  -- THE FAINT. Held on its last frame rather than looped (see StadiumMon's
+  -- STATES), because a Pokemon that collapses and then stands back up
+  -- while the message is still on screen is worse than no animation.
+  --
+  -- RECORDED HERE, PLAYED LATER. This runs the moment HP reaches zero, which
+  -- is several seconds before the Pokemon is supposed to fall over -- the
+  -- engine queues the collapse behind the move animation and the HP-bar
+  -- drain. Marking the side and letting Stadium.update fire it when the bar
+  -- empties is what keeps the two together (see faintReady).
+  local innerFaint = BattleState.onFaint
+  function BattleState:onFaint(battler)
+    if session and not (battler and battler.faintQueued) then
+      local side = sideOf(self, battler)
+      if side and session.faintPending then
+        session.faintPending[side] = true
+      end
+    end
+    return innerFaint(self, battler)
+  end
+
+  -- THE ENTRANCE. startGrowIn is the send-out: the ball opens, the pic
+  -- scales up over twelve frames, and the model plays the animation the
+  -- battle system's own entrance slot names.
+  local innerGrow = BattleState.startGrowIn
+  function BattleState:startGrowIn(battler)
+    if session then
+      -- unless the model is already on its way out of the ball, in which
+      -- case the entrance started with the POOF (see update) and asking
+      -- again here would restart it a third of a second in
+      local side = sideOf(self, battler)
+      local mon = side and session[side]
+      if not (mon and mon.grow) then ask(self, battler, "entrance") end
+    end
+    return innerGrow(self, battler)
+  end
+
+  -- TRANSFORM. The engine records a transform by swapping the battler's
+  -- sprite and nothing else, so this is the only seam that reports one --
+  -- and it reports the side, which is all that is needed to point that
+  -- side's model at the copied species. Cleared when a side's own species
+  -- changes under it (a switch, or the next battle).
+  local innerSpecies = BattleState.speciesSprite
+  function BattleState:speciesSprite(species, isPlayerSide)
+    if session then
+      session.transform[isPlayerSide and "player" or "enemy"] = dexOf(species)
+    end
+    return innerSpecies(self, species, isPlayerSide)
+  end
+
+  -- and a switch or a send-out ends any transform on that side
+  local innerSwitch = BattleState.resolveSwitch
+  function BattleState:resolveSwitch(newMon)
+    if session then session.transform.player = nil end
+    return innerSwitch(self, newMon)
+  end
+end
+
+-- ------- when a draw goes wrong
+--
+-- The draw and the shadow cast are both called through a pcall, because a
+-- throw inside the scene pass would hand the whole voxel mode to Pipelines'
+-- guard and retire it for the session. Swallowed silently, though, a broken
+-- model is indistinguishable from an invisible one -- so the first failure
+-- of a battle says so, once, and the rest of the fight carries on without
+-- it.
+Stadium.reported = false
+
+function Stadium.report(err)
+  if Stadium.reported then return end
+  Stadium.reported = true
+  V.mod.log:warn("stadium: a model failed and was retired for this battle: "
+                 .. "%s -- that Pokemon falls back to its flat battle pic, "
+                 .. "and its opponent is unaffected", tostring(err))
+end
+
+-- DS_STADIUM_DEBUG=1 prints what each side resolved to once a second, which
+-- is how "nothing is on screen" gets told apart from "nothing was asked
+-- for". Read through pcall: the loader's sandbox does not hand a mod `os`,
+-- and a diagnostic must never be why the mod fails to load.
+local DEBUG = select(2, pcall(function() return os.getenv("DS_STADIUM_DEBUG") end))
+if DEBUG == nil or DEBUG == false then DEBUG = nil end
+
+local debugAt = 0
+
+function Stadium.debug(dt)
+  if not (DEBUG and session) then return end
+  debugAt = debugAt + (dt or 0)
+  if debugAt < 1 then return end
+  debugAt = 0
+  for _, side in ipairs({ "enemy", "player" }) do
+    local mon = session[side]
+    local m = mon.model_matrix
+    V.mod.log:info("stadium %s: dex=%s rig=%s visible=%s anim=%s t=%.2f "
+                   .. "height=%.1f at=%s",
+                   side, tostring(mon.species), tostring(mon.rig ~= nil),
+                   tostring(mon.visible), tostring(mon.anim), mon.time or 0,
+                   mon.model and mon:worldHeight() or 0,
+                   m and ("%.0f,%.0f,%.0f"):format(m[4], m[8], m[12]) or "-")
+  end
+end
+
+function Stadium.invalidate()
+  if session then
+    session.player:release()
+    session.enemy:release()
+  end
+  StadiumPack.invalidate()
+  -- the discs are a mesh and a texture like anything else, and a graphics
+  -- context that went away took them with it
+  pcall(function() V.require("StadiumStage").invalidate() end)
+end
+
+return Stadium

lib/StadiumBuild.lua

@@ -0,0 +1,711 @@
+-- STADIUM battles: turning the ROM into assets/stadium/NNN.dsm.
+--
+-- The Lua half of tools/stadium_pack.py: measure the bind pose, decide
+-- whether a species' standby loop can be trusted, and write the packed file.
+-- Together with StadiumRom, StadiumFragment and StadiumFx this is everything
+-- between `baserom.z64` and a Pokemon standing on a battle tile.
+--
+-- The Python remains the ORACLE. tests/stadium_extract_test.lua runs this
+-- over the same ROM and requires all 151 files to come out byte for byte
+-- identical to what the packer writes. That is a strong test in a way a unit
+-- test of any one function here would not be: every rounding mode, every
+-- iteration order, every off-by-one in an index shows up as a differing byte,
+-- and there are thirty-four megabytes of them.
+--
+-- ------- stepped, not blocking
+--
+-- `StadiumBuild.job()` returns a coroutine-backed job that does one species
+-- per `step()`, so the caller can draw a progress bar between them
+-- (StadiumInstall). A species is a few tens of milliseconds; the whole set is
+-- around half a minute, which is far too long to spend inside one frame and
+-- perfectly fine spread across a loading screen.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local StadiumRom = V.require("StadiumRom")
+local StadiumFragment = V.require("StadiumFragment")
+local StadiumFx = V.require("StadiumFx")
+
+local StadiumBuild = {}
+
+local floor = math.floor
+local sin, cos = math.sin, math.cos
+local pi = math.pi
+local char = string.char
+local concat = table.concat
+local frexp = math.frexp
+local roundHalfEven = StadiumFragment.roundHalfEven
+
+-- The battle system's fixed context slots, in slot order from 165. The mod
+-- indexes this list by POSITION, so the ORDER is the format's contract and
+-- has to stay identical to StadiumPack.CONTEXT and to the packer's CONTEXTS.
+StadiumBuild.CONTEXTS = {
+  "idle", "attack_default", "faint", "entrance", "reaction_169", "reaction_170",
+  "reaction_171", "reaction_172", "reaction_173", "reaction_174",
+  "struggle", "idle_alt", "faint_alt", "flinch", "reaction_179",
+  "reaction_180", "reaction_181", "reaction_182", "entrance_alt",
+  "idle_return",
+}
+
+-- Which context name wins when several claim the same animation.
+local NAME_PREF = { "idle", "attack_default", "faint", "entrance",
+                    "struggle", "flinch" }
+
+local N_MOVES = StadiumRom.N_MOVES
+local CTX_BASE = 165
+local NONE16 = 0xFFFF
+
+-- ------- the bind pose
+
+-- The game's rotation as a 3x3, rows first (src/F420.c func_8000F730):
+-- Rx*Ry*Rz in row-vector form.
+local function quatBasis(r)
+  local sx, cx = sin(r[1] / 32768 * pi), cos(r[1] / 32768 * pi)
+  local sy, cy = sin(r[2] / 32768 * pi), cos(r[2] / 32768 * pi)
+  local sz, cz = sin(r[3] / 32768 * pi), cos(r[3] / 32768 * pi)
+  return { cy * cz, sx * sy * cz - cx * sz, cx * sy * cz + sx * sz },
+         { cy * sz, sx * sy * sz + cx * cz, cx * sy * sz - sx * cz },
+         { -sy, sx * cy, cx * cy }
+end
+
+-- 3x4 (three rotation rows plus a translation column) times the same.
+local function matMul(a, b)
+  local out = {}
+  for r = 1, 3 do
+    local ar = a[r]
+    out[r] = {
+      ar[1] * b[1][1] + ar[2] * b[2][1] + ar[3] * b[3][1],
+      ar[1] * b[1][2] + ar[2] * b[2][2] + ar[3] * b[3][2],
+      ar[1] * b[1][3] + ar[2] * b[2][3] + ar[3] * b[3][3],
+      ar[1] * b[1][4] + ar[2] * b[2][4] + ar[3] * b[3][4] + ar[4],
+    }
+  end
+  return out
+end
+
+-- One component of one bone's t/r/s at a frame. The extractor's own shape: a
+-- bare number when the component holds still for the whole animation, one
+-- number a frame when it does not.
+local function component(comps, i, frame, fallback)
+  if comps == nil then return fallback end
+  local c = comps[i]
+  if type(c) == "table" then
+    local n = #c
+    if n == 0 then return fallback end
+    return c[frame % n + 1]
+  end
+  return c
+end
+
+-- The bone TRS an animation holds at `frame`, rest where it is silent.
+local function animSample(bones, anim, frame)
+  local tracks = anim.tracks
+  return function(i)
+    local b = bones[i]
+    local tr = tracks[i]
+    if not tr then return b.t, b.r, b.s end
+    return { component(tr.t, 1, frame, b.t[1]),
+             component(tr.t, 2, frame, b.t[2]),
+             component(tr.t, 3, frame, b.t[3]) },
+           { component(tr.r, 1, frame, b.r[1]),
+             component(tr.r, 2, frame, b.r[2]),
+             component(tr.r, 3, frame, b.r[3]) },
+           { component(tr.s, 1, frame, b.s[1]),
+             component(tr.s, 2, frame, b.s[2]),
+             component(tr.s, 3, frame, b.s[3]) }
+  end
+end
+
+local function restSample(bones)
+  return function(i)
+    local b = bones[i]
+    return b.t, b.r, b.s
+  end
+end
+
+-- Every bone's draw matrix at one instant, as 3x4 rows.
+--
+-- The game keeps bone scale OUT of the matrix chain: it accumulates in its own
+-- stack, a bone's local translation is pre-multiplied by the PARENT's
+-- accumulated scale, and the bone's own accumulated scale is applied to the
+-- finished matrix at draw time.
+--
+-- Two chains, and the distinction is the whole point: `pivot` is the
+-- rotation/translation a CHILD inherits, and the draw matrix is that with the
+-- bone's own accumulated scale applied on the right. Folding the scale into
+-- the chain instead applies every ancestor's scale twice -- which is exactly
+-- the multiplicative propagation glTF has and the game does not.
+local function bindMatrices(bones, sample)
+  sample = sample or restSample(bones)
+  local pivot, draw, acc = {}, {}, {}
+  local IDENT = { { 1, 0, 0, 0 }, { 0, 1, 0, 0 }, { 0, 0, 1, 0 } }
+  for i = 1, #bones do
+    local bt, br, bs = sample(i)
+    local p = bones[i].parent
+    local pa = (p >= 0) and acc[p + 1] or { 1.0, 1.0, 1.0 }
+    local pm = (p >= 0) and pivot[p + 1] or IDENT
+    local r1, r2, r3 = quatBasis(br)
+    local m = matMul(pm, {
+      { r1[1], r1[2], r1[3], bt[1] * pa[1] },
+      { r2[1], r2[2], r2[3], bt[2] * pa[2] },
+      { r3[1], r3[2], r3[3], bt[3] * pa[3] },
+    })
+    local a = { pa[1] * bs[1], pa[2] * bs[2], pa[3] * bs[3] }
+    acc[i] = a
+    pivot[i] = m
+    -- scale on the right: the bone's own space, so it cannot reach children
+    draw[i] = {
+      { m[1][1] * a[1], m[1][2] * a[2], m[1][3] * a[3], m[1][4] },
+      { m[2][1] * a[1], m[2][2] * a[2], m[2][3] * a[3], m[2][4] },
+      { m[3][1] * a[1], m[3][2] * a[2], m[3][3] * a[3], m[3][4] },
+    }
+  end
+  return draw
+end
+
+StadiumBuild.bindMatrices = bindMatrices
+StadiumBuild.animSample = animSample
+
+-- The axis-aligned box the whole model occupies under `mats`, in game units
+-- after the model_root scale.
+local function poseBox(data, mats)
+  local root = data.rootScale[1]
+  local lo1, lo2, lo3 = 1e30, 1e30, 1e30
+  local hi1, hi2, hi3 = -1e30, -1e30, -1e30
+  for _, prim in ipairs(data.prims) do
+    local pos, skin = prim.pos, prim.skin
+    for i = 1, prim.nverts do
+      local m = mats[skin[i] + 1]
+      if m then
+        local x, y, z = pos[i * 3 - 2], pos[i * 3 - 1], pos[i * 3]
+        local a = (m[1][1] * x + m[1][2] * y + m[1][3] * z + m[1][4]) * root
+        local b = (m[2][1] * x + m[2][2] * y + m[2][3] * z + m[2][4]) * root
+        local c = (m[3][1] * x + m[3][2] * y + m[3][3] * z + m[3][4]) * root
+        if a < lo1 then lo1 = a end
+        if b < lo2 then lo2 = b end
+        if c < lo3 then lo3 = c end
+        if a > hi1 then hi1 = a end
+        if b > hi2 then hi2 = b end
+        if c > hi3 then hi3 = c end
+      end
+    end
+  end
+  return lo1, lo2, lo3, hi1, hi2, hi3
+end
+
+-- (height, floor, radius): how tall the mon is, where its lowest point sits
+-- relative to the model's own origin, and how wide it is -- all in game units
+-- after the model_root scale.
+--
+-- Measured on the BIND POSE, which is the one pose in the set that can be
+-- trusted for this. It reproduces the verified glTF export exactly on all 151
+-- species, and it is immune to the animation quirks a handful of them carry
+-- (see idleIsBroken) -- quirks that would otherwise decide how big every OTHER
+-- frame of those species is drawn.
+--
+-- The floor is the interesting number, and it reads cleanly: 119 of the 151
+-- sit within 5% of zero, which says the model origin IS where the game stands
+-- a Pokemon on its field. Every species that does not is one that hovers.
+local function stance(data)
+  local lo1, lo2, lo3, hi1, hi2, hi3 = poseBox(data, bindMatrices(data.bones))
+  if lo1 > hi1 then return 0.0, 0.0, 0.0 end
+  local w, d = hi1 - lo1, hi3 - lo3
+  return hi2 - lo2, lo2, (w > d and w or d) / 2
+end
+
+StadiumBuild.stance = stance
+
+-- Whether this species' standby loop is corrupt as extracted.
+--
+-- No species trips this today. Exeggutor, Tangela and Magmar used to, when
+-- the flags byte was misread and their hermite-keyframe animations were
+-- decoded as packed streams, throwing bones hundreds of units off the body.
+-- It stays as the guard against the next extraction bug: played, a broken
+-- idle looks like a Pokemon coming apart, and the mod would rather show
+-- the sprite fallback (see StadiumMon).
+--
+-- The test is deliberately narrow, because "differs from the bind pose" is NOT
+-- brokenness. It is asked only of the STANDBY loop -- the one animation that
+-- is supposed to stay where it is, since a faint is meant to end far from the
+-- standing pose and an attack is meant to lunge -- and it wants both a large
+-- size blow-up and real drift, or an enormous amount of one. Dewgong is what
+-- calibrates it: its idle is 2.4x its own bind pose because the BIND is the
+-- collapsed one, and it drifts barely at all, so it must not be caught.
+local function idleIsBroken(data, idle)
+  if idle == nil then return false end
+  local bones = data.bones
+  local _, lo2, _, _, hi2 = poseBox(data, bindMatrices(bones))
+  local span = hi2 - lo2
+  if span <= 0 then return false end
+  local worstH, worstDrift = 1.0, 0.0
+  local frame = 0
+  while frame < idle.frames do
+    local _, flo2, _, _, fhi2 = poseBox(data,
+      bindMatrices(bones, animSample(bones, idle, frame)))
+    local h = (fhi2 - flo2) / span
+    if h > worstH then worstH = h end
+    local d1 = (flo2 - lo2) / span
+    local d2 = (fhi2 - hi2) / span
+    if d1 < 0 then d1 = -d1 end
+    if d2 < 0 then d2 = -d2 end
+    if d1 > worstDrift then worstDrift = d1 end
+    if d2 > worstDrift then worstDrift = d2 end
+    frame = frame + 3
+  end
+  return (worstH > 2.5 and worstDrift > 1.5)
+         or worstDrift > 2.0 or worstH > 3.4
+end
+
+-- ------- writing
+
+local function clamp(v, lo, hi)
+  if v < lo then return lo end
+  if v > hi then return hi end
+  return v
+end
+
+-- Toward zero, which is what Python's int() does to a float and NOT what
+-- floor() does to a negative one.
+--
+-- It matters in exactly one place, and it is easy to miss: almost everything
+-- reaching the integer writers below has already been rounded, so truncation
+-- is a no-op on it. The exception is the generated effects' crossed quads
+-- (StadiumFx), whose vertices are raw floats and straddle the origin -- so
+-- the ones at negative x, and only those, come out a unit adrift if this
+-- floors.
+local function trunc(v)
+  if v >= 0 then return floor(v) end
+  return -floor(-v)
+end
+
+-- 16.16, which holds every bone scale in the set (-31 .. 100) with more
+-- precision than anything can see.
+local function fixed(v)
+  return clamp(roundHalfEven(v * 65536), -2147483648, 2147483647)
+end
+
+-- IEEE 754 single, little-endian, rounded to nearest with ties to even -- the
+-- same rounding Python's struct.pack('<f') does, so the four floats in the
+-- header come out bit for bit the same as the packer's.
+local function f32(x)
+  local sign = 0
+  if x < 0 or (x == 0 and 1 / x < 0) then
+    sign = 128
+    x = -x
+  end
+  if x ~= x then return char(0, 0, 192, 127 + sign) end        -- NaN
+  if x == math.huge then return char(0, 0, 128, 127 + sign) end
+  if x == 0 then return char(0, 0, 0, sign) end
+  local m, e = frexp(x)                       -- x = m * 2^e, 0.5 <= m < 1
+  local E = e - 1 + 127
+  local mant
+  if E >= 255 then
+    return char(0, 0, 128, 127 + sign)                          -- overflow
+  elseif E <= 0 then
+    -- subnormal: no exponent left, so the mantissa carries the whole value
+    mant = roundHalfEven(x / 2 ^ -149)
+    if mant >= 8388608 then
+      mant, E = mant - 8388608, 1
+    else
+      E = 0
+    end
+  else
+    mant = roundHalfEven((m * 2 - 1) * 8388608)
+    if mant == 8388608 then                   -- rounded up into the next
+      mant, E = 0, E + 1
+      if E >= 255 then return char(0, 0, 128, 127 + sign) end
+    end
+  end
+  local b4 = sign + floor(E / 2)
+  local b3 = (E % 2) * 128 + floor(mant / 65536)
+  local b2 = floor(mant / 256) % 256
+  local b1 = mant % 256
+  return char(b1, b2, b3, b4)
+end
+
+StadiumBuild.f32 = f32
+
+local Writer = {}
+Writer.__index = Writer
+
+local function newWriter()
+  return setmetatable({ parts = {}, n = 0 }, Writer)
+end
+
+function Writer:raw(s)
+  self.n = self.n + 1
+  self.parts[self.n] = s
+end
+
+function Writer:u8(v)
+  self:raw(char(v % 256))
+end
+
+function Writer:i8(v)
+  v = clamp(trunc(v), -128, 127)
+  self:raw(char(v % 256))
+end
+
+function Writer:u16(v)
+  v = v % 65536
+  self:raw(char(v % 256, floor(v / 256)))
+end
+
+function Writer:i16(v)
+  v = clamp(trunc(v), -32768, 32767) % 65536
+  self:raw(char(v % 256, floor(v / 256)))
+end
+
+function Writer:u32(v)
+  v = v % 4294967296
+  self:raw(char(v % 256, floor(v / 256) % 256, floor(v / 65536) % 256,
+                floor(v / 16777216) % 256))
+end
+
+function Writer:i32(v)
+  v = clamp(trunc(v), -2147483648, 2147483647) % 4294967296
+  self:raw(char(v % 256, floor(v / 256) % 256, floor(v / 65536) % 256,
+                floor(v / 16777216) % 256))
+end
+
+function Writer:f32(v)
+  self:raw(f32(v))
+end
+
+function Writer:bytes()
+  return concat(self.parts)
+end
+
+-- One component of one bone's t/r/s in one animation. `values` is the
+-- extractor's own shape: a bare number when the component holds still for the
+-- whole animation, or one number a frame when it does not. That fold is where
+-- most of the size saving is -- a bone that only rotates costs two bytes for
+-- each of its six other components.
+local function writeTrackComponent(w, values, kind)
+  local isArray = type(values) == "table"
+  w:u8(isArray and 1 or 0)
+  if kind == "s" then
+    if isArray then
+      for i = 1, #values do w:i32(fixed(values[i])) end
+    else
+      w:i32(fixed(values))
+    end
+  else
+    if isArray then
+      for i = 1, #values do w:i16(roundHalfEven(values[i])) end
+    else
+      w:i16(roundHalfEven(values))
+    end
+  end
+end
+
+-- Which animation each fixed battle context slot resolves to: entries 165
+-- upward of the species' own battle table, in slot order. An entry naming an
+-- animation the species does not have is written as "none" rather than
+-- clamped -- the mod would rather fall back than play the wrong clip.
+function StadiumBuild.contextTable(rows, nAnims)
+  local ctx = {}
+  for i = 1, #StadiumBuild.CONTEXTS do
+    local row = rows[CTX_BASE + i - 1]
+    local ai = row and row[1] or nil
+    ctx[i] = (ai ~= nil and ai < nAnims) and ai or NONE16
+  end
+  return ctx
+end
+
+-- ------- naming the animations
+--
+-- build.py's label_animations. The names are not read at runtime -- the mod
+-- addresses animations by index through the move and context tables -- but
+-- they are in the format, so they have to be produced the same way for the
+-- oracle diff to mean anything. They also make a packed file readable in a
+-- hex dump, which is worth the byte apiece.
+
+local function labelAnimations(data, rows, nAux)
+  local anims = data.anims
+  local n = #anims
+  local uses, moveUses = {}, {}
+  local auxOrder, auxCount = {}, {}
+  for i = 1, n do
+    uses[i], moveUses[i] = {}, 0
+    auxOrder[i], auxCount[i] = {}, {}
+  end
+  for e = 0, rows.n - 1 do
+    local ai = rows[e][1]
+    if ai < n then
+      if e < N_MOVES then
+        moveUses[ai + 1] = moveUses[ai + 1] + 1
+      elseif e >= CTX_BASE and e < CTX_BASE + #StadiumBuild.CONTEXTS then
+        local list = uses[ai + 1]
+        list[#list + 1] = StadiumBuild.CONTEXTS[e - CTX_BASE + 1]
+      end
+      local ax = rows[e][2]
+      if ax >= 0 and ax < nAux then
+        local counts, order = auxCount[ai + 1], auxOrder[ai + 1]
+        if counts[ax] == nil then
+          counts[ax] = 0
+          order[#order + 1] = ax
+        end
+        counts[ax] = counts[ax] + 1
+      end
+    end
+  end
+
+  for i = 1, n do
+    -- sorted(set(uses)) -- the alphabetically first context is the fallback
+    -- name, so the ordering is part of the answer
+    local seen, ctx = {}, {}
+    for _, name in ipairs(uses[i]) do
+      if not seen[name] then
+        seen[name] = true
+        ctx[#ctx + 1] = name
+      end
+    end
+    table.sort(ctx)
+    local name = nil
+    for _, pref in ipairs(NAME_PREF) do
+      if seen[pref] then
+        name = pref
+        break
+      end
+    end
+    if not name then
+      if moveUses[i] > 0 then
+        name = "attack"
+      elseif ctx[1] then
+        name = ctx[1]
+      else
+        name = "anim" .. (i - 1)
+      end
+    end
+    anims[i].name = name
+    -- Counter.most_common(1): the highest count, and on a tie the one that
+    -- was inserted first
+    local best, bestN = -1, -1
+    local order, counts = auxOrder[i], auxCount[i]
+    for _, ax in ipairs(order) do
+      if counts[ax] > bestN then
+        best, bestN = ax, counts[ax]
+      end
+    end
+    anims[i].aux = best
+  end
+
+  local seenName = {}
+  for i = 1, n do
+    local base = anims[i].name
+    local k = seenName[base] or 0
+    seenName[base] = k + 1
+    if k > 0 then anims[i].name = base .. "_" .. (k + 1) end
+  end
+end
+
+-- ------- the pack
+
+function StadiumBuild.pack(data, species, moveRows, ctx)
+  local w = newWriter()
+  local bones, prims = data.bones, data.prims
+  local textures, anims, aux = data.textures, data.anims, data.auxAnims
+
+  local height, floorY, radius = stance(data)
+
+  local idleIndex = ctx[1]                    -- CONTEXTS[1] is "idle"
+  local idle = (idleIndex ~= NONE16) and anims[idleIndex + 1] or nil
+  local static = idleIsBroken(data, idle)
+
+  w:raw("DSM3")
+  w:u16(species)
+  w:u16(#bones)
+  w:u16(#prims)
+  w:u16(#textures)
+  w:u16(#anims)
+  w:u16(#aux)
+  w:f32(data.rootScale[1])
+  -- 1 = hold the bind pose, never play an animation
+  w:u8(static and 1 or 0)
+  w:f32(height)
+  w:f32(floorY)
+  w:f32(radius)
+
+  for m = 1, N_MOVES do
+    local row = moveRows[m]
+    w:u16((row and row[1] < #anims) and row[1] or NONE16)
+  end
+  for m = 1, N_MOVES do
+    local row = moveRows[m]
+    w:i16((row and row[2] >= 0 and row[2] < #aux) and row[2] or -1)
+  end
+  for i = 1, #ctx do w:u16(ctx[i]) end
+
+  for i = 1, #bones do
+    local b = bones[i]
+    w:i16(b.parent)
+    for k = 1, 3 do w:i16(roundHalfEven(b.t[k])) end
+    for k = 1, 3 do w:i16(b.r[k]) end
+    for k = 1, 3 do w:i32(fixed(b.s[k])) end
+  end
+
+  for i = 1, #prims do
+    local p = prims[i]
+    w:u16(p.tex)
+    -- the display list's own cull mode: 1024 is G_CULL_BACK
+    w:u8((p.cull and p.cull ~= 0) and 1 or 0)
+    w:u8((p.blend == "add") and 1 or 0)
+    w:i16(p.texAnim or -1)
+    -- sorted by the stream's own byte, which is what the reader keys on
+    local keys = {}
+    if p.texMap then
+      for k in pairs(p.texMap) do keys[#keys + 1] = k end
+      table.sort(keys)
+    end
+    w:u8(#keys)
+    for _, k in ipairs(keys) do
+      w:u8(k)
+      w:u16(p.texMap[k])
+    end
+    local frames = p.fxFrames
+    w:u16(frames and #frames or 0)
+    if frames then
+      for k = 1, #frames do w:u16(frames[k]) end
+    end
+    local pos, uv, nrm, skin = p.pos, p.uv, p.nrm, p.skin
+    w:u16(p.nverts)
+    w:u16(p.nidx)
+    for k = 1, p.nverts do
+      w:i16(pos[k * 3 - 2])
+      w:i16(pos[k * 3 - 1])
+      w:i16(pos[k * 3])
+      -- 1/512, which puts a texel of the largest texture in the set well
+      -- inside a step and still reaches the +-32 the wrapped coordinates of
+      -- some display lists run to
+      w:i16(roundHalfEven(uv[k * 2 - 1] * 512))
+      w:i16(roundHalfEven(uv[k * 2] * 512))
+      w:i8(roundHalfEven(nrm[k * 3 - 2] * 127))
+      w:i8(roundHalfEven(nrm[k * 3 - 1] * 127))
+      w:i8(roundHalfEven(nrm[k * 3] * 127))
+      w:u8(skin[k])
+    end
+    for k = 1, p.nidx do w:u16(p.idx[k]) end
+  end
+
+  for i = 1, #textures do
+    local t = textures[i]
+    w:u16(t.w)
+    w:u16(t.h)
+    w:u32(#t.rgba)
+    w:raw(t.rgba)
+  end
+
+  local REST = { t = { 0, 0, 0 }, r = { 0, 0, 0 }, s = { 1.0, 1.0, 1.0 } }
+  for i = 1, #anims do
+    local a = anims[i]
+    local name = a.name or ""
+    if #name > 255 then name = name:sub(1, 255) end
+    w:u8(#name)
+    w:raw(name)
+    w:u16(a.frames)
+    w:u16(a.loopStart or 0)
+    w:i16(a.aux or -1)
+    for bi = 1, #bones do
+      local tr = a.tracks[bi]
+      if not tr then
+        w:u8(0)
+      else
+        w:u8(1)
+        for _, key in ipairs({ "t", "r", "s" }) do
+          local comps = tr[key]
+          if comps == nil then
+            -- a bone the animation leaves at its rest value for this path:
+            -- written as three constants so the reader never has to branch on
+            -- a missing path
+            comps = bones[bi][key] or REST[key]
+          end
+          for c = 1, 3 do writeTrackComponent(w, comps[c], key) end
+        end
+      end
+    end
+  end
+
+  for i = 1, #aux do
+    local a = aux[i]
+    w:u16(a.frames)
+    w:u16(a.loopStart or 0)
+    w:u16(#a.channels)
+    for _, ch in ipairs(a.channels) do
+      w:u16(ch.n)
+      for k = 1, ch.n do w:u16(ch[k]) end
+    end
+  end
+
+  return w:bytes(), height, floorY, radius
+end
+
+-- ------- one species, end to end
+
+-- The same three steps build.py takes: parse the fragment, label the
+-- animations off the species' battle table, then hang the generated fire/gas
+-- stand-ins on the bones the game's own effect callbacks hang off.
+function StadiumBuild.species(rom, fileno)
+  local blob = rom:model(fileno)
+  if not blob then return nil, ("file %d is not in the archive"):format(fileno) end
+  local data, err = StadiumFragment.extract(blob, ("%d.bin"):format(fileno))
+  if not data then return nil, err end
+  local species = data.species
+  local rows = rom:battleRows(species)
+  labelAnimations(data, rows, #data.auxAnims)
+  StadiumFx.attach(data, species)
+
+  local moveRows = {}
+  for m = 1, N_MOVES do moveRows[m] = rows[m - 1] end
+  local ctx = StadiumBuild.contextTable(rows, #data.anims)
+  local bytes, height, floorY, radius =
+    StadiumBuild.pack(data, species, moveRows, ctx)
+  return { species = species, bytes = bytes, height = height,
+           floor = floorY, radius = radius, bones = #data.bones,
+           prims = #data.prims, anims = #data.anims,
+           warnings = data.warnings }
+end
+
+-- ------- the stepped job
+--
+-- `write(species, bytes)` is called for each finished pack and must answer
+-- truthy; anything else stops the job with an error. Returning a job rather
+-- than taking a callback for progress keeps the caller in charge of when work
+-- happens, which is what lets a loading screen stay responsive.
+function StadiumBuild.job(rom, write, count)
+  local total = count or StadiumRom.N_POKEMON
+  local n = rom:modelCount()
+  if total > n then total = n end
+  local job = { total = total, done = 0, bytes = 0, failed = {}, species = nil }
+
+  function job:step()
+    if self.done >= self.total then return false end
+    local fileno = self.done
+    local ok, res, err = pcall(StadiumBuild.species, rom, fileno)
+    if ok and res then
+      local wrote, wErr = write(res.species, res.bytes)
+      if not wrote then
+        self.error = wErr or ("could not write species " .. res.species)
+        self.done = self.total
+        return false
+      end
+      self.bytes = self.bytes + #res.bytes
+      self.species = res.species
+    else
+      self.failed[#self.failed + 1] = fileno
+      self.lastError = ok and err or res
+    end
+    self.done = self.done + 1
+    return self.done < self.total
+  end
+
+  function job:progress()
+    if self.total <= 0 then return 1 end
+    return self.done / self.total
+  end
+
+  return job
+end
+
+return StadiumBuild

lib/StadiumFx.lua

@@ -0,0 +1,436 @@
+-- STADIUM battles: the generated fire and gas stand-ins.
+--
+-- A port of model_extract/pipeline/effects.py, plus the bind-pose measurement
+-- build.py sizes them against.
+--
+-- IMPORTANT: nothing here is extracted game data. The real tail flame, mane
+-- fire and gas are drawn by procedural callbacks that live in a different
+-- fragment -- geo command 0x08 records an attachment point and
+-- func_80014A60 calls node->unk_10, and the model file supplies only two
+-- empty display lists plus zeroed scratch buffers for it to fill. Those
+-- callbacks have not been ported, so the models genuinely contain no flame
+-- mesh and no flame texture: Charmander's texture set is eyes, claws, teeth
+-- and skin.
+--
+-- What follows is an ORIGINAL, procedurally generated replacement -- looping
+-- flipbook noise on a pair of crossed quads, anchored to the exact bone the
+-- callback hangs off so it sits where the real effect would and follows the
+-- animation. Seeds derive from the species number, so a given Pokemon always
+-- generates the same flame.
+--
+-- Which species get one is the game's own grouping: every species sharing a
+-- callback shares an effect.
+--
+--   0x810000D8  Charmander, Charmeleon, Charizard, Magmar, Moltres   tail flame
+--   0x81000108  Ponyta, Rapidash, Moltres's wings                    small flame
+--   0x810000E0  Gastly (only)                                        gas cloud
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local StadiumFx = {}
+
+local floor = math.floor
+local sqrt = math.sqrt
+local sin, cos = math.sin, math.cos
+local char = string.char
+local concat = table.concat
+local pi = math.pi
+
+local FIRE_TAIL  = 0x810000D8
+local FIRE_SMALL = 0x81000108
+local AURA       = 0x810000E0
+
+-- Desired size as a fraction of the model's world-space height: length, width.
+StadiumFx.SIZES = {
+  fire_tail  = { 0.40, 0.22 },
+  fire_small = { 0.075, 0.042 },
+  gas        = { 1.05, 1.05 },
+}
+
+-- ------- 32-bit exclusive-or, in arithmetic
+--
+-- The generator below is an xorshift, so it needs a real 32-bit xor and a
+-- real 32-bit wrap. Written out rather than taken from LuaJIT's `bit`, which
+-- works in SIGNED 32-bit and would need converting back on every step -- see
+-- the same note in StadiumFragment.
+
+local function bxor32(a, b)
+  local r, p = 0, 1
+  for _ = 1, 32 do
+    local x, y = a % 2, b % 2
+    if x ~= y then r = r + p end
+    a, b, p = floor(a / 2), floor(b / 2), p * 2
+  end
+  return r
+end
+
+-- ------- deterministic noise
+
+local Rng = {}
+Rng.__index = Rng
+
+local function newRng(seed)
+  local s = seed % 0x100000000
+  if s == 0 then s = 0x9E3779B9 end
+  return setmetatable({ s = s }, Rng)
+end
+
+function Rng:next()
+  local x = self.s
+  x = bxor32(x, (x % 0x80000) * 0x2000)               -- x ^= (x << 13)
+  x = bxor32(x, floor(x / 0x20000))                   -- x ^= x >> 17
+  x = bxor32(x, (x % 0x8000000) * 0x20)               -- x ^= (x << 5)
+  self.s = x % 0x100000000
+  return self.s
+end
+
+function Rng:unit()
+  return self:next() / 0x100000000
+end
+
+-- A w-by-h lattice of unit noise, consumed row by row so the sequence -- and
+-- therefore the texture -- is reproducible.
+local function lattice(rng, w, h)
+  local g = {}
+  for y = 1, h do
+    local row = {}
+    for x = 1, w do row[x] = rng:unit() end
+    g[y] = row
+  end
+  return g
+end
+
+local function smooth(t)
+  return t * t * (3 - 2 * t)
+end
+
+-- Bilinear value noise on a torus, so the field tiles in both axes.
+local function sample(grid, x, y)
+  local h = #grid
+  local w = #grid[1]
+  local fx0, fy0 = floor(x), floor(y)
+  local x0, y0 = fx0 % w, fy0 % h
+  local x1, y1 = (x0 + 1) % w, (y0 + 1) % h
+  local fx, fy = smooth(x - fx0), smooth(y - fy0)
+  local r0, r1 = grid[y0 + 1], grid[y1 + 1]
+  local a = r0[x0 + 1] + (r0[x1 + 1] - r0[x0 + 1]) * fx
+  local b = r1[x0 + 1] + (r1[x1 + 1] - r1[x0 + 1]) * fx
+  return a + (b - a) * fy
+end
+
+-- Sum octaves of tileable noise.
+local function fbm(grids, x, y, scale)
+  local total, amp, norm = 0.0, 1.0, 0.0
+  for i = 1, #grids do
+    local f = scale * 2 ^ (i - 1)
+    total = total + sample(grids[i], x * f, y * f) * amp
+    norm = norm + amp
+    amp = amp * 0.5
+  end
+  return total / norm
+end
+
+-- Intensity -> RGBA, through a piecewise ramp.
+local function ramp(stops, t)
+  if t < 0.0 then t = 0.0 elseif t > 1.0 then t = 1.0 end
+  for i = 1, #stops - 1 do
+    local a, b = stops[i], stops[i + 1]
+    if t <= b[1] then
+      local k = 0.0
+      if b[1] ~= a[1] then k = (t - a[1]) / (b[1] - a[1]) end
+      return floor(a[2] + (b[2] - a[2]) * k), floor(a[3] + (b[3] - a[3]) * k),
+             floor(a[4] + (b[4] - a[4]) * k), floor(a[5] + (b[5] - a[5]) * k)
+    end
+  end
+  local last = stops[#stops]
+  return last[2], last[3], last[4], last[5]
+end
+
+local FIRE_RAMP = {
+  { 0.00, 0, 0, 0, 0 },
+  { 0.30, 120, 24, 8, 90 },
+  { 0.52, 226, 78, 16, 205 },
+  { 0.74, 252, 176, 44, 245 },
+  { 1.00, 255, 246, 214, 255 },
+}
+
+local GAS_RAMP = {
+  { 0.00, 0, 0, 0, 0 },
+  { 0.34, 52, 26, 78, 70 },
+  { 0.60, 96, 52, 140, 140 },
+  { 0.82, 148, 96, 196, 190 },
+  { 1.00, 208, 176, 236, 215 },
+}
+
+local TRANSPARENT = char(0, 0, 0, 0)
+
+-- An upward-advected noise plume. Scrolling by an exact multiple of the
+-- lattice over the frame count is what makes the loop seamless.
+local function fireFrames(seed, w, h, frames, wisp)
+  wisp = wisp or 1.0
+  local rng = newRng(seed)
+  local grids = { lattice(rng, 8, 8), lattice(rng, 16, 16),
+                  lattice(rng, 32, 32) }
+  local out = {}
+  for f = 0, frames - 1 do
+    local t = f / frames
+    local buf = {}
+    for i = 1, w * h do buf[i] = TRANSPARENT end
+    for y = 0, h - 1 do
+      local v = y / (h - 1)                 -- 0 at the base, 1 at the tip
+      -- plume envelope: wide and hot at the base, pinched at the tip
+      local taper = 1.0 - v
+      if taper < 0.0 then taper = 0.0 end
+      taper = taper ^ 0.42
+      for x = 0, w - 1 do
+        local u = (x / (w - 1)) * 2 - 1     -- -1 .. 1 across the flame
+        local denom = taper * 0.95
+        if denom < 0.10 then denom = 0.10 end
+        local radial = 1.0 - (u < 0 and -u or u) / denom
+        if radial > 0 then
+          radial = radial ^ 0.7
+          local n = fbm(grids, x / w, (y / h) - t, 3.0)
+          local lick = 0.55 + 0.75 * (n - 0.5) * wisp
+          local inten = radial * (0.55 + 0.8 * taper) * lick
+          inten = inten - 0.16 * v           -- cool towards the tip
+          if inten > 0.02 then
+            local r, g, b, a = ramp(FIRE_RAMP, inten)
+            -- +Y in texture space is up
+            buf[(h - 1 - y) * w + x + 1] = char(r, g, b, a)
+          end
+        end
+      end
+    end
+    out[f + 1] = concat(buf)
+  end
+  return w, h, out
+end
+
+-- Slow swirling haze that fades out towards the rim.
+local function gasFrames(seed, w, h, frames)
+  local rng = newRng(seed)
+  local grids = { lattice(rng, 8, 8), lattice(rng, 16, 16),
+                  lattice(rng, 32, 32) }
+  local out = {}
+  for f = 0, frames - 1 do
+    local t = f / frames
+    local buf = {}
+    for i = 1, w * h do buf[i] = TRANSPARENT end
+    local ang = t * 2 * pi
+    local ca, sa = cos(ang), sin(ang)
+    for y = 0, h - 1 do
+      for x = 0, w - 1 do
+        local dx = (x / (w - 1)) * 2 - 1
+        local dy = (y / (h - 1)) * 2 - 1
+        local d = sqrt(dx * dx + dy * dy)
+        if d < 1.0 then
+          local falloff = (1.0 - d) ^ 0.85
+          -- rotate the sample point so the haze churns without popping
+          local sx = dx * ca - dy * sa
+          local sy = dx * sa + dy * ca
+          local n = fbm(grids, sx * 0.5 + 0.5, sy * 0.5 + 0.5 - t, 2.5)
+          local inten = falloff * (0.78 + 1.30 * (n - 0.44))
+          if inten > 0.03 then
+            local r, g, b, a = ramp(GAS_RAMP, inten)
+            buf[y * w + x + 1] = char(r, g, b, a)
+          end
+        end
+      end
+    end
+    out[f + 1] = concat(buf)
+  end
+  return w, h, out
+end
+
+-- Two quads at right angles, so the effect reads from any angle. `axis` picks
+-- which bone-local direction the quad grows along: bone-local +X runs down the
+-- limb, so a flame laid out along X comes out lying sideways, and 'y' is that
+-- same quad turned a quarter left about Z, which stands it up. `centred`
+-- straddles the origin instead of growing from it.
+local function crossedQuads(bone, length, width, axis, centred)
+  local pos, uv, nrm, skin, idx = {}, {}, {}, {}, {}
+  local ST = { { 0, 0 }, { 1, 0 }, { 1, 1 }, { 0, 1 } }
+  local nv, ni = 0, 0
+  for q = 0, 1 do
+    local base = nv
+    for k = 1, 4 do
+      local s, t = ST[k][1], ST[k][2]
+      local a = (s - 0.5) * width
+      local b = centred and (t - 0.5) * length or t * length
+      local px, py, pz
+      if axis == "x" then
+        if q == 0 then px, py, pz = b, a, 0.0 else px, py, pz = b, 0.0, a end
+      else                                       -- (x, y) -> (-y, x)
+        if q == 0 then px, py, pz = -a, b, 0.0 else px, py, pz = 0.0, b, a end
+      end
+      pos[nv * 3 + 1], pos[nv * 3 + 2], pos[nv * 3 + 3] = px, py, pz
+      uv[nv * 2 + 1], uv[nv * 2 + 2] = s, 1.0 - t
+      if q == 0 then
+        nrm[nv * 3 + 1], nrm[nv * 3 + 2], nrm[nv * 3 + 3] = 0.0, 0.0, 1.0
+      else
+        nrm[nv * 3 + 1], nrm[nv * 3 + 2], nrm[nv * 3 + 3] = 1.0, 0.0, 0.0
+      end
+      skin[nv + 1] = bone
+      nv = nv + 1
+    end
+    idx[ni + 1], idx[ni + 2], idx[ni + 3] = base, base + 1, base + 2
+    idx[ni + 4], idx[ni + 5], idx[ni + 6] = base, base + 2, base + 3
+    ni = ni + 6
+  end
+  return { pos = pos, uv = uv, nrm = nrm, skin = skin, nverts = nv,
+           idx = idx, nidx = ni }
+end
+
+-- ------- the bind pose these are sized against
+--
+-- build.py's bind_extent, kept in its own 4x4 column-major convention rather
+-- than folded into StadiumBuild's 3x4 walk. The two agree -- they are the
+-- same skeleton -- but the effect sizes come out of THIS one's per-bone scale
+-- measurement, and rewriting it into the other convention is exactly the kind
+-- of change that moves a byte without anyone noticing.
+
+local function trs(t, r, s)
+  local function S(v) return sin(v / 32768 * pi) end
+  local function C(v) return cos(v / 32768 * pi) end
+  local sx, cx = S(r[1]), C(r[1])
+  local sy, cy = S(r[2]), C(r[2])
+  local sz, cz = S(r[3]), C(r[3])
+  return { cy * cz * s[1], cy * sz * s[1], -sy * s[1], 0,
+           (sx * sy * cz - cx * sz) * s[2], (sx * sy * sz + cx * cz) * s[2],
+           sx * cy * s[2], 0,
+           (cx * sy * cz + sx * sz) * s[3], (cx * sy * sz - sx * cz) * s[3],
+           cx * cy * s[3], 0,
+           t[1], t[2], t[3], 1 }
+end
+
+local function mul(a, b)
+  local r = {}
+  for c = 0, 3 do
+    for i = 1, 4 do
+      r[c * 4 + i] = a[i] * b[c * 4 + 1] + a[4 + i] * b[c * 4 + 2]
+                     + a[8 + i] * b[c * 4 + 3] + a[12 + i] * b[c * 4 + 4]
+    end
+  end
+  return r
+end
+
+-- (height of the bind pose, per-bone local scale). Height rather than the
+-- largest dimension: sizing off the max would scale Moltres's flames to its
+-- wingspan.
+function StadiumFx.bindExtent(data)
+  local root = trs({ 0, 0, 0 }, { 0, 0, 0 }, data.rootScale)
+  local acc, uns, mats = {}, {}, {}
+  for i = 1, #data.bones do
+    local b = data.bones[i]
+    local p = b.parent
+    local pa = (p >= 0) and acc[p + 1] or { 1.0, 1.0, 1.0 }
+    local pu = (p >= 0) and uns[p + 1] or root
+    local u = mul(pu, trs({ b.t[1] * pa[1], b.t[2] * pa[2], b.t[3] * pa[3] },
+                          b.r, { 1, 1, 1 }))
+    local a = { pa[1] * b.s[1], pa[2] * b.s[2], pa[3] * b.s[3] }
+    local m = {}
+    for k = 1, 16 do m[k] = u[k] end
+    for k = 1, 4 do
+      m[k] = m[k] * a[1]
+      m[4 + k] = m[4 + k] * a[2]
+      m[8 + k] = m[8 + k] * a[3]
+    end
+    acc[i], uns[i], mats[i] = a, u, m
+  end
+
+  local lo = { 1e9, 1e9, 1e9 }
+  local hi = { -1e9, -1e9, -1e9 }
+  for _, prim in ipairs(data.prims) do
+    local pos, skin = prim.pos, prim.skin
+    for i = 1, prim.nverts do
+      local m = mats[skin[i] + 1]
+      if m then
+        local x, y, z = pos[i * 3 - 2], pos[i * 3 - 1], pos[i * 3]
+        local wx = m[1] * x + m[5] * y + m[9] * z + m[13]
+        local wy = m[2] * x + m[6] * y + m[10] * z + m[14]
+        local wz = m[3] * x + m[7] * y + m[11] * z + m[15]
+        if wx < lo[1] then lo[1] = wx end
+        if wy < lo[2] then lo[2] = wy end
+        if wz < lo[3] then lo[3] = wz end
+        if wx > hi[1] then hi[1] = wx end
+        if wy > hi[2] then hi[2] = wy end
+        if wz > hi[3] then hi[3] = wz end
+      end
+    end
+  end
+  local extent = (lo[1] <= hi[1]) and (hi[2] - lo[2]) or 1.0
+
+  -- how much each bone scales its own local space, so an effect can divide it
+  -- back out and come out the size it asked for wherever it hangs
+  local scales = {}
+  for i = 1, #mats do
+    local m = mats[i]
+    scales[i] = sqrt(m[1] * m[1] + m[2] * m[2] + m[3] * m[3])
+  end
+  return extent, scales
+end
+
+-- ------- what a species gets
+
+-- Returns a list of { kind, bone, geo, w, h, frames }, or an empty list.
+function StadiumFx.buildFor(species, fx, extent, boneScale)
+  local out = {}
+  for _, node in ipairs(fx) do
+    local cb, bone = node.callback, node.bone
+    if bone >= 0 and bone < #boneScale then
+      local k = boneScale[bone + 1]
+      if k == 0 then k = 1.0 end
+      if cb == FIRE_TAIL then
+        local fl, fw = StadiumFx.SIZES.fire_tail[1], StadiumFx.SIZES.fire_tail[2]
+        local w, h, fr = fireFrames(species * 7919 + 1, 32, 64, 8)
+        out[#out + 1] = { kind = "fire", bone = bone, w = w, h = h, frames = fr,
+                          geo = crossedQuads(bone, extent * fl / k,
+                                             extent * fw / k, "y", false) }
+      elseif cb == FIRE_SMALL then
+        local fl, fw = StadiumFx.SIZES.fire_small[1],
+                       StadiumFx.SIZES.fire_small[2]
+        local w, h, fr = fireFrames(species * 6271 + bone, 24, 40, 8, 1.25)
+        out[#out + 1] = { kind = "fire", bone = bone, w = w, h = h, frames = fr,
+                          geo = crossedQuads(bone, extent * fl / k,
+                                             extent * fw / k, "y", false) }
+      elseif cb == AURA and species == 92 then        -- Gastly only
+        local fl, fw = StadiumFx.SIZES.gas[1], StadiumFx.SIZES.gas[2]
+        local w, h, fr = gasFrames(species * 5237 + 3, 48, 48, 10)
+        out[#out + 1] = { kind = "gas", bone = bone, w = w, h = h, frames = fr,
+                          geo = crossedQuads(bone, extent * fl / k,
+                                             extent * fw / k, "y", true) }
+      end
+    end
+  end
+  return out
+end
+
+-- Append the generated prims and their flipbook textures to a model, exactly
+-- as build.py's attach_effects does. Returns how many were made.
+function StadiumFx.attach(data, species)
+  if not (data.fx and #data.fx > 0) then return 0 end
+  local extent, boneScale = StadiumFx.bindExtent(data)
+  local made = StadiumFx.buildFor(species, data.fx, extent, boneScale)
+  for _, e in ipairs(made) do
+    local first = #data.textures                      -- 0-based, as the file
+    for i = 1, #e.frames do
+      data.textures[first + i] = { index = -1, w = e.w, h = e.h,
+                                   generated = true, rgba = e.frames[i] }
+    end
+    local g = e.geo
+    local fxFrames = {}
+    for i = 1, #e.frames do fxFrames[i] = first + i - 1 end
+    data.prims[#data.prims + 1] = {
+      tex = first, cull = 0, texAnim = -1, texMap = nil,
+      generated = true, effect = e.kind,
+      blend = (e.kind == "fire") and "add" or "alpha",
+      fxFrames = fxFrames,
+      pos = g.pos, uv = g.uv, nrm = g.nrm, skin = g.skin, nverts = g.nverts,
+      idx = g.idx, nidx = g.nidx,
+    }
+  end
+  return #made
+end
+
+return StadiumFx

lib/StadiumInstall.lua

@@ -0,0 +1,361 @@
+-- STADIUM battles: finding the ROM, and building the models out of it once.
+--
+-- The mod does not ship the Pokemon Stadium models and cannot: they are that
+-- game's data. What it ships is the READER -- StadiumRom, StadiumFragment,
+-- StadiumFx and StadiumBuild -- and the player supplies the cartridge, which
+-- is exactly the arrangement this engine already has for the Game Boy ROM it
+-- is a recompilation of (src/import/RomImporter.lua).
+--
+-- So: supply a Pokemon Stadium (US) 1.0 ROM -- the OPTIONS row opens a file
+-- picker for one, or drop it in `baseroms/` -- and the first time the
+-- game runs with the mod on, the models are built. Once, on a loading screen,
+-- in about ten seconds. After that the packs sit in the save directory and
+-- the mod reads them like any other asset.
+--
+-- ------- where "baseroms/" is
+--
+-- One relative path, and it deliberately covers two different places at once,
+-- because PhysFS searches the save directory AND the game folder under the
+-- same names:
+--
+--   * a folder install, or a checkout -- `baseroms/` next to main.lua
+--   * a packaged or fused build, where the game folder is inside an archive
+--     and cannot be written to -- `baseroms/` in the save directory, whose
+--     absolute path this reports on screen so it can be found
+--
+-- The file goes STRAIGHT IN THERE, with no revision subfolder under it. The
+-- decompilation's own `make init` uses `baseroms/us/`, and the offline
+-- pipeline under model_extract/ still reads from there because it shares that
+-- tree -- but the instruction given to a player is "drop the file in this
+-- folder", and one folder is the whole of it.
+--
+-- Any of `.z64`, `.n64` and `.v64` is accepted; StadiumRom normalises the
+-- byte order on load.
+--
+-- ------- what "installed" means
+--
+-- A marker file next to the packs, holding the format magic, how many species
+-- were written and the md5 of the ROM they came from. All three matter. The
+-- magic catches a format change (the packs are rebuilt rather than read as
+-- garbage), the count catches a build that was interrupted half way, and the
+-- md5 catches the player swapping the ROM for a different revision.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local StadiumPack = V.require("StadiumPack")
+
+local StadiumInstall = {}
+
+-- Where a ROM is looked for, and where the built packs are kept.
+StadiumInstall.ROM_DIR = "baseroms"
+StadiumInstall.DIR = StadiumPack.CACHE_DIR
+StadiumInstall.MARKER = StadiumInstall.DIR .. "/pack.info"
+
+-- Bumped whenever the .dsm format changes, so an old cache is rebuilt rather
+-- than misread. Must track StadiumPack's magic.
+StadiumInstall.FORMAT = "DSM3"
+
+-- Bumped when the packs' CONTENT changes without the byte layout moving, so
+-- a cache built by an older extractor is rebuilt rather than trusted. Rev 2
+-- is the hermite-animation decode fix: the five keyframe species (Pidgeot,
+-- Dodrio, Exeggutor, Tangela, Magmar) come out garbled or bind-posed from
+-- any rev-1 build.
+StadiumInstall.REV = 2
+
+StadiumInstall.COUNT = 151
+
+-- Named ROM files, then any ROM at all sitting in the folder.
+--
+-- Flat in `baseroms/`, with no revision subfolder: the offline pipeline under
+-- model_extract/ keeps the decompilation's own `baseroms/us/` convention
+-- because it shares that tree, but what is being asked of a PLAYER here is
+-- "drop the file in this folder", and one folder is the whole of that
+-- instruction. A path they have to build out of two parts is a path half of
+-- them will get wrong, and the failure is silent -- the rungs are simply not
+-- on the row.
+local NAMED = {
+  StadiumInstall.ROM_DIR .. "/baserom.z64",
+  StadiumInstall.ROM_DIR .. "/baserom.n64",
+  StadiumInstall.ROM_DIR .. "/baserom.v64",
+}
+
+local function fs()
+  return love and love.filesystem
+end
+
+local function isFile(path)
+  local f = fs()
+  if not (f and f.getInfo) then return false end
+  local ok, info = pcall(f.getInfo, path, "file")
+  return (ok and info) and true or false
+end
+
+-- The ROM's path on the PhysFS read path, or nil.
+function StadiumInstall.romPath()
+  local f = fs()
+  if not f then return nil end
+  for _, path in ipairs(NAMED) do
+    if isFile(path) then return path end
+  end
+  local ok, items = pcall(f.getDirectoryItems, StadiumInstall.ROM_DIR)
+  if ok and items then
+    table.sort(items)
+    for _, name in ipairs(items) do
+      if name:lower():match("%.[nvz]64$") then
+        local path = StadiumInstall.ROM_DIR .. "/" .. name
+        if isFile(path) then return path end
+      end
+    end
+  end
+  return nil
+end
+
+function StadiumInstall.romPresent()
+  return StadiumInstall.romPath() ~= nil
+end
+
+-- Where to tell the player to put it. The save directory is the answer that
+-- is always writable, and it is the one a packaged build needs.
+function StadiumInstall.romHint()
+  local f = fs()
+  local base = (f and f.getSaveDirectory and select(2, pcall(f.getSaveDirectory)))
+  if type(base) ~= "string" then base = "the game folder" end
+  return base .. "/" .. StadiumInstall.ROM_DIR
+end
+
+-- The same thing with a FILENAME on the end, which is what a player actually
+-- needs: a folder alone leaves them guessing what to call the file, and the
+-- guess is not obviously "baserom.z64".
+--
+-- Taken from the head of NAMED rather than retyped, so the name shown is by
+-- construction the first name looked for. It is not the ONLY one that works
+-- -- `.n64` and `.v64` are accepted, and so is any other name carrying one
+-- of those extensions -- but an instruction that names one file is one a
+-- player can follow, and an instruction that lists every possibility is one
+-- they have to interpret.
+function StadiumInstall.romHintFile()
+  return StadiumInstall.romHint() .. "/" .. (NAMED[1]:match("[^/]+$") or "")
+end
+
+-- ------- the marker
+
+local function readMarker()
+  local f = fs()
+  if not (f and isFile(StadiumInstall.MARKER)) then return nil end
+  local ok, text = pcall(f.read, StadiumInstall.MARKER)
+  if not (ok and type(text) == "string") then return nil end
+  local format, count, md5, rev = text:match("^(%S+)%s+(%d+)%s*(%S*)%s*(%S*)")
+  if not format then return nil end
+  return { format = format, count = tonumber(count), md5 = md5,
+           rev = tonumber(rev) }
+end
+
+-- Whether a complete, current set of packs is on disk.
+local readyCache = nil
+
+function StadiumInstall.ready()
+  if readyCache ~= nil then return readyCache end
+  local m = readMarker()
+  readyCache = (m ~= nil and m.format == StadiumInstall.FORMAT
+                and m.count == StadiumInstall.COUNT
+                and m.rev == StadiumInstall.REV) and true or false
+  return readyCache
+end
+
+-- Whether a complete set came WITH the mod folder -- a developer checkout
+-- that has run tools/stadium_pack.py. Never true of a released build, which
+-- carries no models at all.
+--
+-- Sampled at both ends of the dex rather than counted. The question being
+-- asked is "did somebody run the packer here", not "is every one of the 151
+-- present"; a genuinely half-written folder is a case for the marker file,
+-- which is what catches an interrupted RUNTIME build.
+local function shipped()
+  local mod = V.mod
+  if not (mod and mod.read) then return false end
+  for _, dex in ipairs({ 1, 151 }) do
+    local ok, bytes = pcall(mod.read, mod,
+                            ("%s/%03d.dsm"):format(StadiumPack.DIR, dex))
+    if not (ok and type(bytes) == "string" and #bytes > 4) then return false end
+  end
+  return true
+end
+
+-- Whether the STADIUM rungs can be offered at all: either the packs have been
+-- built from the player's ROM, or the mod folder already carries a set.
+function StadiumInstall.available()
+  if StadiumInstall.ready() then return true end
+  return shipped()
+end
+
+-- Whether there is work to do: something to build from, and nothing usable
+-- yet.
+--
+-- A checkout that already carries a set is NOT pending. Building anyway would
+-- be correct and would also mean a ten-second loading screen on the first run
+-- of every checkout, to arrive at the files that were already sitting there.
+function StadiumInstall.pending()
+  if StadiumInstall.available() then return false end
+  return StadiumInstall.romPresent()
+end
+
+function StadiumInstall.forget()
+  readyCache = nil
+end
+
+-- ------- building
+
+local job = nil
+local status = { state = "idle", done = 0, total = StadiumInstall.COUNT }
+
+StadiumInstall.status = status
+
+local function writePack(species, bytes)
+  local f = fs()
+  if not f then return false, "no filesystem" end
+  local ok, err = f.write(("%s/%03d.dsm"):format(StadiumInstall.DIR, species),
+                          bytes)
+  if not ok then return false, tostring(err) end
+  return true
+end
+
+-- Open the ROM found in `baseroms/` and start a stepped build. Returns false
+-- plus a reason when there is nothing to build from.
+function StadiumInstall.begin()
+  local f = fs()
+  if not f then return false, "no filesystem" end
+  local path = StadiumInstall.romPath()
+  if not path then return false, "no ROM in " .. StadiumInstall.ROM_DIR end
+
+  local okRead, bytes = pcall(f.read, path)
+  if not (okRead and type(bytes) == "string") then
+    return false, "could not read " .. path
+  end
+  return StadiumInstall.beginFrom(bytes, path)
+end
+
+-- The same, from bytes somebody else has already got hold of -- which is the
+-- IMPORTED path (StadiumRomPick), where the file is at an absolute location
+-- love.filesystem cannot see and was read with io.open.
+--
+-- The two entry points share everything from here down on purpose: an
+-- imported cartridge and a dropped one produce the same 151 files, the same
+-- marker and the same md5, so there is exactly one build in this mod and no
+-- second one to keep in step.
+--
+-- `label` is only ever used to say WHICH file a complaint is about.
+function StadiumInstall.beginFrom(bytes, label)
+  local f = fs()
+  if not f then return false, "no filesystem" end
+  if type(bytes) ~= "string" or #bytes == 0 then return false, "empty file" end
+
+  local StadiumRom = V.require("StadiumRom")
+  local StadiumBuild = V.require("StadiumBuild")
+  local rom, err = StadiumRom.open(bytes)
+  if not rom then return false, tostring(err) end
+  status.wrongVersion = false
+  if not rom:isExpectedUS() then
+    -- Built anyway rather than refused: a dump can differ from the reference
+    -- for reasons that do not move a single model offset (a byte-order
+    -- variant already normalised on load, a trimmed overdump). But every
+    -- offset in this reader was measured against US 1.0 and nothing else is
+    -- promised, so it is said loudly, with the md5 that IS expected so the
+    -- player can check their own file against it.
+    status.wrongVersion = true
+    V.mod.log:warn("stadium: %s is md5 %s -- the model offsets are keyed to "
+                   .. "Pokemon Stadium (US) 1.0, which is md5 %s. Building "
+                   .. "anyway, but the models may be wrong or fail to build.",
+                   tostring(label or "the ROM"), tostring(rom:md5()),
+                   tostring(StadiumRom.US_MD5))
+  end
+
+  -- ------- refuse a ROM with no models in it, BEFORE anything is written
+  --
+  -- A file picker invites the wrong file -- most obviously the Game Boy
+  -- cartridge the player already imported once -- and the reader's answer to
+  -- one is a model count of zero. That has to be caught HERE rather than
+  -- allowed to become an empty build, because an empty build is
+  -- indistinguishable from a finished one further down: `job.total` is
+  -- clamped to the count, `step` completes on the first call with nothing
+  -- attempted and therefore nothing FAILED, and the marker gets written
+  -- saying `DSM3 0`.
+  --
+  -- On a fresh machine that is merely a lie on the loading screen -- READY,
+  -- with no models. On one that already HAD them it is worse: the marker is
+  -- the only thing that makes 151 files on disk count as installed, so
+  -- overwriting it with a zero uninstalls a good set and the STADIUM rungs
+  -- vanish off the row. Nothing below this line runs for a file that cannot
+  -- possibly produce a build.
+  local models = rom:modelCount()
+  if not (models and models >= StadiumInstall.COUNT) then
+    return false, "needs Pokemon Stadium US 1.0"
+  end
+
+  pcall(f.createDirectory, StadiumInstall.DIR)
+  job = StadiumBuild.job(rom, writePack, StadiumInstall.COUNT)
+  job.md5 = rom:md5()
+  status.state = "building"
+  status.done = 0
+  status.total = job.total
+  status.error = nil
+  return true
+end
+
+-- One species. Returns true while there is more to do.
+function StadiumInstall.step()
+  if not job then return false end
+  local more = job:step()
+  status.done = job.done
+  status.species = job.species
+  if job.error then
+    status.state = "failed"
+    status.error = job.error
+    job = nil
+    return false
+  end
+  if not more then
+    local f = fs()
+    -- `job.total > 0` as well as "nothing failed", because a job with nothing
+    -- IN it satisfies the second on its own -- and the marker this writes is
+    -- what makes a set count as installed, so it must never be written for a
+    -- build that did not happen. beginFrom refuses such a ROM outright; this
+    -- is the same rule stated where the consequence is.
+    local wrote = #job.failed == 0 and job.total > 0
+    if wrote and f then
+      pcall(f.write, StadiumInstall.MARKER,
+            ("%s %d %s %d\n"):format(StadiumInstall.FORMAT, job.total,
+                                     tostring(job.md5 or ""),
+                                     StadiumInstall.REV))
+      readyCache = nil
+      StadiumPack.forget()
+    end
+    if not wrote then
+      status.state = "failed"
+      -- EVERY species failing is not a bad build, it is the wrong file: the
+      -- offsets the reader walks are Pokemon Stadium's, so a different game
+      -- -- or the Game Boy cartridge the player already imported once, which
+      -- is the mistake a file picker invites -- misses on all 151 rather than
+      -- on a few. Worth telling apart, because "0 of 151 models were built"
+      -- reads as a broken mod and this reads as a wrong click.
+      if #job.failed >= job.total then
+        status.error = "needs Pokemon Stadium US 1.0"
+      else
+        status.error = ("%d of %d models could not be built")
+                       :format(#job.failed, job.total)
+      end
+    else
+      status.state = "done"
+    end
+    job = nil
+    return false
+  end
+  return true
+end
+
+function StadiumInstall.cancel()
+  job = nil
+  status.state = "idle"
+end
+
+return StadiumInstall

lib/StadiumMon.lua

@@ -0,0 +1,480 @@
+-- STADIUM battles: one Pokemon, standing on its tile.
+--
+-- The side's live state -- which species is out, the rig posing it, which
+-- animation the fight has asked for and how far through it is, and the
+-- matrix that puts it on its cell at the right size facing the right way.
+-- Stadium owns the pair of these; StadiumRig owns the arithmetic.
+--
+-- ------- how big a Pokemon is
+--
+-- The one genuinely invented number in this mode, and it is worth saying
+-- why it is invented rather than measured.
+--
+-- The flat 2D-3D mode has an exact answer: a full-size 56-pixel pic covers
+-- one 16-pixel overworld square, so a canvas pixel is a fixed number of
+-- world pixels and every species comes out at whatever its own artwork's
+-- size implies (see BattleBillboard.FULL_W). The camera is then SOLVED to
+-- make one square that big on screen (BattleCam).
+--
+-- The Stadium models have no such anchor. Their units are the N64's, they
+-- run from Caterpie at 9 units to Gyarados at 147 -- a sixteenfold spread,
+-- where the Gen 1 pics span barely one and a half -- and the game they come
+-- from framed each one with its own camera, which a fight staged on the
+-- overworld cannot do because the two mons share a shot.
+--
+-- Taken literally, that spread puts Caterpie at a couple of pixels on a
+-- 144-pixel screen while Gyarados leaves the frame. So the range is
+-- COMPRESSED rather than either honoured or discarded: a species is drawn
+-- at REF_HEIGHT world pixels scaled by its own height over the set's
+-- median, raised to SQUASH. At 1 that would be the raw sixteenfold spread;
+-- at 0 every Pokemon would be the same size; at 0.55 the order and the
+-- feel of the differences survive -- Onix and Gyarados tower, Diglett and
+-- Caterpie are small enough to have to look for -- inside a range a shared
+-- frame can hold.
+--
+-- ------- and where its feet are
+--
+-- The pack measures each model's lowest point against its own origin
+-- (tools/stadium_pack.py's `stance`), and the answer splits the set in
+-- three. 119 species sit within 5% of zero: the origin IS the floor, and
+-- the game stood them on its field with it. A handful sit ABOVE it --
+-- Zubat, Magnemite, Geodude -- which is a hover the model is authored with.
+-- The rest hang BELOW it -- Tentacruel, Gastly, Haunter, Weezing, Zapdos --
+-- which is a model centred on its origin rather than standing on it.
+--
+-- So a model is stood on its own lowest point, and then given back as much
+-- of its authored hover as the shot can hold -- HOVER_CAP of its own height,
+-- no more. The middle group is unaffected either way, which is the check
+-- that the rule is reading the data rather than correcting it.
+--
+-- The cap is not tidiness. Stadium framed one Pokemon per camera and could
+-- afford to hang Zubat three body-heights off the floor; this shot has the
+-- foe's feet on GB row 56 of 144, so the same hover puts Zubat off the top
+-- of the frame entirely -- which is exactly what it did before the cap. The
+-- flat 2D-3D mode has the same constraint and answers it by bottom-aligning
+-- every pic, hovering species included; this keeps the hover but spends
+-- only the room there is.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Mat4 = V.require("Mat4")
+local StadiumPack = V.require("StadiumPack")
+local StadiumRig = V.require("StadiumRig")
+
+local StadiumMon = {}
+StadiumMon.__index = StadiumMon
+
+-- How tall a median Pokemon stands, in world pixels.
+--
+-- Not picked by eye: it is what the FLAT mode already puts on those cells.
+-- A full-size Gen 1 pic is 56 pixels for the foe and 64 for the player's
+-- own, drawn with its feet on GB rows 56 and 96 of a 144-row frame -- so a
+-- full-size mon covers 39% of the frame at the far cell and 44% at the near
+-- one. Against the lens BattleCam solves (about 38 world pixels of frame at
+-- the far cell, 30 at the near one, because the near one is closer) both of
+-- those work out at roughly fourteen world pixels.
+--
+-- So this is the number that makes a median Stadium model exactly as big as
+-- the artwork it replaces, which is what keeps the composition the camera
+-- was solved for.
+StadiumMon.REF_HEIGHT = 14
+
+-- The set's own median bind height, in game units (tools/stadium_pack.py
+-- --report prints it). Only ever a reference point for the ratio above, so
+-- a re-extraction that moved it slightly changes nothing but the middle of
+-- the ladder.
+StadiumMon.MEDIAN = 52.25
+
+-- How much of the raw size spread survives. See the header.
+StadiumMon.SQUASH = 0.5
+
+-- And hard stops either end, because a compression is not a guarantee. The
+-- ceiling is what keeps Onix and Gyarados inside a frame whose top edge is
+-- only 56 GB rows above the foe's own feet: past about this they stop being
+-- imposing and start being cropped.
+StadiumMon.MIN_HEIGHT = 5
+StadiumMon.MAX_HEIGHT = 18
+
+-- How much of an authored hover survives, as a fraction of the Pokemon's
+-- own height. See the header: Stadium could hang a flier three body-heights
+-- up because it framed one Pokemon at a time.
+StadiumMon.HOVER_CAP = 0.5
+
+-- The animation clock. Every animation in the set is authored at 30 fps
+-- (model_extract/README.md), and the eyes run on their own counter at the
+-- same rate.
+StadiumMon.FPS = StadiumPack.FPS
+
+-- ------- coming out of the ball
+--
+-- The engine grows its flat pic in the Game Boy's own three steps -- 0, then
+-- 3/7, then 5/7, then full -- across the twelve frames after the ball opens
+-- (BattleState.growInScale). Two things about that do not carry to a model.
+--
+-- It is three steps, which on a 56-pixel sprite is a chunky pop and on a
+-- smooth 3D model is just a pop. And it starts AFTER the ball: measured, the
+-- poof animation runs for 27 frames and `startGrowIn` fires on the frame
+-- after it ends, so the Pokemon does not begin to exist until the ball has
+-- finished opening -- which reads as the ball opening and then a Pokemon
+-- being switched on beside it.
+--
+-- So the model runs its own ramp, started when the POOF begins rather than
+-- when it ends, and continuous rather than stepped: it grows out of nothing
+-- while the ball is opening and reaches full size as the engine's own grow
+-- finishes. GROW_TIME is measured off that -- 27 frames of poof plus the
+-- engine's 12 of grow is 39, which is this.
+StadiumMon.GROW_TIME = 0.65
+
+-- How far an animation may carry the Pokemon off its tile, in the Pokemon's
+-- own body-heights, before the excess is taken back out (StadiumRig.anchor).
+--
+-- Measured against the frame rather than chosen by eye. A mon is drawn
+-- REF_HEIGHT world pixels tall and the GB frame holds about 38 world pixels
+-- at the far cell, with the foe's feet on row 56 of 144 -- so there is
+-- roughly one body-height of room above it and about one and a half either
+-- side. Three quarters of a height keeps every part of a travelling Pokemon
+-- inside that with a margin, and leaves the 83 species that never reach it
+-- untouched.
+StadiumMon.TRAVEL = 0.75
+
+-- ------- the animation the fight is asking for
+--
+-- Each entry says which context slot to look up, whether it loops, and
+-- what it falls back to when the species has no animation in that slot.
+-- ------- there is no hit reaction, and there never was
+--
+-- This used to carry `hit` and `flinch` states, played when damage landed,
+-- resolving through context slots 166 and 178. Both were wrong, and the data
+-- says so plainly once the move table is read alongside them:
+--
+--   Bulbasaur's slot 166 is a 95-frame animation that 66 of its moves play.
+--   Pidgey's is 138 frames -- four and a half seconds -- and 111 of its moves
+--   play it. Slot 178, and 173, 179, 180 and 181, all point at the same one.
+--
+-- A four-and-a-half-second animation that most of the move table uses is the
+-- species' DEFAULT ATTACK, not a flinch, which is why being hit looked like
+-- swinging: it literally was the swing.
+--
+-- Nor is the reaction hiding elsewhere. Exactly one animation per species is
+-- claimed by no slot and no move, and it is the same length as the idle for
+-- essentially every one of them -- 48/48, 56/56, 60/60, 84/84 -- so it is a
+-- second standby loop, not a recoil. The set has no damage reaction in it.
+--
+-- So damage plays nothing, and the Pokemon carries on with what it was doing.
+-- That is not a gap: the engine flashes the screen, blinks the pic and drains
+-- the bar, which is how Gen 1 says "that hurt" and is already in the frame.
+local STATES = {
+  idle = { slot = "idle", loop = true },
+  entrance = { slot = "entrance", loop = false, next = "idle" },
+  faint = { slot = "faint", loop = false, hold = true },
+  -- A move names its own animation out of the move table. `attack_default`
+  -- is the fallback for one the table has nothing for -- which is what slot
+  -- 166 actually is, so the generic swing is now a real swing rather than
+  -- the standby loop it used to resolve to.
+  attack = { slot = "attack_default", loop = false, next = "idle" },
+}
+
+function StadiumMon.new(side)
+  return setmetatable({
+    side = side,               -- "player" or "enemy"
+    species = nil,             -- the dex number currently modelled
+    model = nil,
+    rig = nil,
+    state = "idle",
+    anim = nil,                -- index into model.anims
+    time = 0,                  -- seconds into it
+    loop = true,
+    hold = false,
+    aux = nil,                 -- the texture animation running alongside
+    visible = false,
+    scale = 1,                 -- the send-out grow, 1 the rest of the time
+  }, StadiumMon)
+end
+
+function StadiumMon:release()
+  if self.rig then self.rig:release() end
+  self.rig, self.model, self.species = nil, nil, nil
+end
+
+-- ------- which species this side is showing
+--
+-- Returns true when the model is ready to draw. A species with no pack, one
+-- whose meshes would not build, or one whose animation data is corrupt at
+-- source answers false -- and Stadium then leaves that side to the flat
+-- card, which is a per-POKEMON decline rather than a per-battle one: a fight
+-- can perfectly well have a model on one side and a pic on the other.
+--
+-- ------- staticPose: the corrupt-idle escape hatch
+--
+-- StadiumBuild.idleIsBroken measures whether a species' standby loop throws
+-- bones off the body, and the pack carries the verdict as `staticPose`. A
+-- species so marked DECLINES here -- the Game Boy's own battle sprite
+-- stands on the tile instead, drawn by the same 2D-3D path every species
+-- uses when its model is unavailable -- because a bind pose held for a
+-- whole fight reads as broken, not as "this one does not animate".
+--
+-- No species is marked today. Exeggutor, Tangela and Magmar used to be:
+-- their animations are hermite keyframes (flags & 8), the extractor misread
+-- the flags byte and decoded them as packed streams, and the exploding
+-- result tripped the detector (Pidgeot and Dodrio were garbled by the same
+-- bug, just not hard enough to trip it). The detector stays, keyed on the
+-- DATA rather than a list of dex numbers, so a future extraction bug that
+-- corrupts a species' idle falls back to the sprite instead of coming
+-- apart on the field -- and nothing here has to be edited when it does.
+function StadiumMon:setSpecies(dex)
+  if dex == self.species then return self.rig ~= nil end
+  if self.rig then self.rig:release() end
+  self.rig, self.model, self.species = nil, nil, dex
+  self.grow, self.grewOwn = nil, nil
+  if not dex then return false end
+  local model = StadiumPack.load(dex)
+  if not model then return false end
+  if model.staticPose then return false end
+  local rig = StadiumRig.new(model)
+  if not rig then return false end
+  self.model, self.rig = model, rig
+  -- a new Pokemon on the field opens on its standby loop; whoever sent it
+  -- out asks for the entrance a moment later
+  self.state, self.anim, self.time = nil, nil, 0
+  self:play("idle")
+  return true
+end
+
+-- ------- the state machine
+
+-- Which animation a context slot resolves to for this species, or nil.
+function StadiumMon:slotAnim(name)
+  local model = self.model
+  local slot = model and StadiumPack.SLOT[name]
+  if not slot then return nil end
+  local index = model.ctx[slot]
+  if not index or index == StadiumPack.NONE then return nil end
+  return index + 1
+end
+
+-- Start a state. `animIndex` overrides the state's own slot lookup, which
+-- is what an attack uses.
+function StadiumMon:play(state, animIndex, auxIndex)
+  local model = self.model
+  if not model then return false end
+  local def = STATES[state] or STATES.idle
+  local index = animIndex
+  if not index and def.slot then index = self:slotAnim(def.slot) end
+  if not index and def.fallback then index = self:slotAnim(def.fallback) end
+  if not index then
+    -- the species has nothing for this; the standby loop is always there
+    if state == "idle" then index = 1 else return self:play("idle") end
+  end
+  local anim = model.anims[index]
+  if not anim then return false end
+
+  self.state, self.anim, self.time = state, index, 0
+  self.done = false
+  -- (a species whose animations are corrupt at source never gets this far:
+  -- setSpecies declines it outright and its flat pic stands instead)
+  self.loop = def.loop and true or false
+  self.hold = def.hold and true or false
+  -- The eyes that go with it. Every skeletal animation carries the texture
+  -- animation the battle table most often set alongside it (the pack's own
+  -- `aux`), and a move may name a different one -- a hit that leaves the
+  -- Pokemon confused swaps the open eye for the dizzy swirl.
+  self.aux = auxIndex or anim.aux
+  return true
+end
+
+-- Ask for a state, but never interrupt one that outranks it. A faint is
+-- final, and an entrance cannot be cut short by the standby loop it hands
+-- on to.
+local RANK = { idle = 0, entrance = 1, attack = 2, faint = 3 }
+
+function StadiumMon:request(state, animIndex, auxIndex)
+  if not self.model then return false end
+  local now = RANK[self.state] or 0
+  local want = RANK[state] or 0
+  if self.state == "faint" then return false end
+  -- an equal-ranked request RESTARTS: the second move of a two-hit turn
+  -- should swing again rather than be swallowed by the first
+  if want < now then return false end
+  return self:play(state, animIndex, auxIndex)
+end
+
+-- The animation a move plays for this species, from the battle system's own
+-- per-species table (model_extract's moves.json, packed into the .dsm).
+-- `moveIndex` is the Gen 1 move id, which the engine's move defs carry as
+-- `index` -- the same numbering, so no name mapping is needed.
+function StadiumMon:attack(moveIndex)
+  local model = self.model
+  if not (model and moveIndex and moveIndex >= 1
+          and moveIndex <= StadiumPack.N_MOVES) then
+    return false
+  end
+  local index = model.moveAnim[moveIndex]
+  if not index or index == StadiumPack.NONE then return false end
+  local aux = model.moveAux[moveIndex]
+  return self:request("attack", index + 1,
+                      (aux and aux >= 0) and (aux + 1) or nil)
+end
+
+-- ------- per frame
+
+function StadiumMon:update(dt)
+  -- kept for build(), which runs later in the same frame and needs it to
+  -- advance the anchor's filter (StadiumRig.anchor). Stashed before the
+  -- early-outs below, so a species with nothing to play still has one.
+  self.dt = dt or 0
+  -- the ball-to-full-size ramp, which runs whether or not there is an
+  -- animation to play alongside it
+  if self.grow then
+    self.grow = self.grow + (dt or 0) / StadiumMon.GROW_TIME
+    if self.grow >= 1 then self.grow = nil end
+  end
+  local model = self.model
+  if not (model and self.anim) then return end
+  local anim = model.anims[self.anim]
+  if not anim then return end
+  self.time = self.time + (dt or 0)
+  if self.time >= anim.seconds and not self.loop then
+    if self.hold then
+      -- a faint stays down: hold the last frame rather than snapping back
+      -- to a standing pose the moment the animation runs out
+      self.time = math.max(0, anim.seconds - 1 / StadiumMon.FPS)
+      -- and SAY so, once. The clamp above means the clock can no longer be
+      -- asked whether the animation is over -- it stops a frame short of the
+      -- end and stays there forever -- and something has to know, because a
+      -- collapse that has finished is the moment the Pokemon may leave the
+      -- field (see Stadium's onField).
+      self.done = true
+    else
+      local nextState = (STATES[self.state] or {}).next or "idle"
+      self:play(nextState)
+    end
+  end
+end
+
+-- ------- the grow
+--
+-- Begin coming out of the ball. Answers whether it actually started, so the
+-- caller can play the entrance alongside it and the engine's own send-out
+-- seam a moment later does not restart what is already running.
+function StadiumMon:beginGrow()
+  if self.grow or not self.model then return false end
+  self.grow = 0
+  -- and remember that THIS arrival was ours to size, so the engine's own
+  -- three-step ramp is not consulted again for it. Ours starts earlier and
+  -- finishes a few frames sooner, and in that gap the engine's ramp still
+  -- reads 5/7 -- so falling back to it shrank the Pokemon from 0.96 back to
+  -- 0.71 and then snapped it to full, a visible hitch at the end of an
+  -- animation that exists to not have one.
+  self.grewOwn = true
+  return true
+end
+
+-- How big this Pokemon is drawn this frame, as a fraction of its real size.
+--
+-- Smoothstep rather than a straight ramp or an ease-out: the ball is opening
+-- for the first half of this, so a curve that is already near full size by
+-- then would have the Pokemon standing there while the ball is still coming
+-- apart. Slow, then quick through the middle, then settling exactly as the
+-- engine's own grow ends.
+function StadiumMon:growScale()
+  local t = self.grow
+  if not t then return 1 end
+  if t <= 0 then return 0 end
+  if t >= 1 then return 1 end
+  return t * t * (3 - 2 * t)
+end
+
+-- Whether a HELD animation -- which in practice means a faint -- has played
+-- all the way through and is now sitting on its last frame. Always false for
+-- a looping one, which never finishes, and for one that hands on to another
+-- state, which has already stopped being itself by the time anyone can ask.
+function StadiumMon:finished()
+  return self.done and true or false
+end
+
+-- How tall this species stands on the map, in world pixels.
+function StadiumMon:worldHeight()
+  local model = self.model
+  local h = model and model.height or 0
+  if not (h > 0) then return StadiumMon.REF_HEIGHT end
+  local k = (h / StadiumMon.MEDIAN) ^ StadiumMon.SQUASH
+  local out = StadiumMon.REF_HEIGHT * k
+  if out < StadiumMon.MIN_HEIGHT then out = StadiumMon.MIN_HEIGHT end
+  if out > StadiumMon.MAX_HEIGHT then out = StadiumMon.MAX_HEIGHT end
+  return out
+end
+
+-- How wide this Pokemon stands, in world pixels -- the same scale
+-- worldHeight is in, so a caller can size something to its footprint.
+--
+-- Only STADIUM B asks: it needs to know how big a platform to put under a
+-- mon, and "as tall as it is" is the wrong answer for a Snorlax, which is
+-- half as tall as an Onix and three times as wide.
+--
+-- The send-out grow is deliberately NOT folded in. A Pokemon scaling up out
+-- of its ball should arrive on a platform that was already there, not one
+-- that inflates under its feet.
+function StadiumMon:worldRadius()
+  local model = self.model
+  if not model then return 0 end
+  local h = model.height or 0
+  if not (h > 0) then return 0 end
+  return (model.radius or 0) * self:worldHeight() / h
+end
+
+-- The model matrix: stand this Pokemon on world (x, groundY, z) facing
+-- (faceX, faceZ), at whatever the send-out grow has done to its size.
+--
+-- The vertices the rig writes are in the model's RAW units -- before the
+-- model_root scale the game applies -- so the scale here carries that too,
+-- and the floor offset is measured in the same raw units on the way in.
+function StadiumMon:matrix(x, groundY, z, faceX, faceZ)
+  local model = self.model
+  if not model then return nil end
+  local root = model.rootScale
+  if not (root and root > 0) then root = 1 end
+  local k = root * self:worldHeight() / math.max(model.height, 1e-6)
+  k = k * (self.scale or 1)
+  -- stand it on its own lowest point, then give back as much of the
+  -- authored hover as the shot can hold (see the header)
+  local floor = model.floor or 0
+  local hover = math.min(math.max(floor, 0),
+                         StadiumMon.HOVER_CAP * math.max(model.height, 0))
+  local lift = (floor - hover) / root
+  local yaw = 0
+  if faceX and faceZ and (faceX ~= 0 or faceZ ~= 0) then
+    -- the card and the model share this convention: an unrotated model
+    -- faces +Z, which is map SOUTH, which is what "facing down" is in the
+    -- flat game (see Voxel3D's axis note)
+    yaw = math.atan2(faceX, faceZ)
+  end
+  self.yaw = yaw
+  return Mat4.mul(
+    Mat4.mul(Mat4.mul(Mat4.translate(x, groundY, z), Mat4.rotateY(yaw)),
+             Mat4.scale(k, k, k)),
+    Mat4.translate(0, -lift, 0))
+end
+
+-- Pose and skin for this frame. Separate from the draw because both the
+-- SUN and the camera -- and, in a headset, both eyes -- want the same
+-- skinned mesh, and skinning it once is the whole reason this is worth
+-- doing on the CPU.
+function StadiumMon:build()
+  if not (self.rig and self.model) then return false end
+  -- self.anim is nil while a species has nothing to play, and pose() reads
+  -- that as "the bind pose", which is exactly what is wanted
+  self.rig:pose(self.anim, self.time * StadiumMon.FPS, self.loop)
+  -- and then back onto the tile, because these animations were authored for
+  -- a camera that followed the Pokemon and this one does not move (see
+  -- StadiumRig.anchor)
+  self.rig:anchor(StadiumMon.TRAVEL, self.dt)
+  self.rig:skin(self.yaw or 0)
+  -- no clock of its own: the texture animation rides the frame pose() just
+  -- resolved, which is what keeps a blink inside its standby loop and a
+  -- fainted Pokemon's eyes shut once it has stopped moving
+  self.rig:textures(self.aux)
+  return true
+end
+
+return StadiumMon

lib/StadiumPack.lua

@@ -0,0 +1,595 @@
+-- STADIUM battles: reading one species' model off disk.
+--
+-- `NNN.dsm` holds one Pokemon Stadium battle model. It is written by
+-- StadiumBuild, out of the player's own copy of that ROM, the first time the
+-- mod runs (see StadiumInstall) -- and by tools/stadium_pack.py, which is the
+-- oracle that Lua path is tested against. This file is the other half of that
+-- format and nothing else: bytes in, tables out. What the tables MEAN is
+-- StadiumRig's business (posing a skeleton) and StadiumMon's (which animation
+-- a fight is asking for).
+--
+-- Three things shape it.
+--
+-- BINARY, NOT LUA. A species is a couple of hundred kilobytes of numbers,
+-- most of it animation, and a Lua source file of that is a parse the loader
+-- would pay for on every boot whether a battle happened or not. A byte
+-- string is read once, on the frame a fight starts, and only for the two
+-- species actually fighting.
+--
+-- LAZY ANIMATIONS. Geometry, bones and textures are decoded on load --
+-- they are small, and every one of them is needed the moment the mon
+-- appears. The animations are not: a fight uses idle, an entrance and
+-- whichever handful of attacks come up, out of the seven to twenty-one a
+-- species carries. So the load pass SCANS the animation block, recording
+-- where each one starts and skipping the rest, and a track is decoded the
+-- first time something plays it. That turns a 200 KB decode into a 20 KB
+-- one plus a few milliseconds spread over the fight.
+--
+-- AN LRU OF FOUR. A model is shared by everything that draws that species
+-- -- both sides of a mirror match, both VR eyes -- and kept for a few
+-- battles after, because the next fight on the same route is very often
+-- the same Pokemon. Four is enough for a wild fight (two) plus the
+-- trainer's next two, and it bounds what the mode can hold to a few
+-- megabytes.
+--
+-- Everything is pcall-guarded and every failure answers nil: a missing
+-- pack, a truncated file or a driver that will not make an image all end
+-- at the same place, which is the flat 2D-3D card this mode falls back to
+-- (see Stadium).
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local StadiumPack = {}
+
+local byte = string.byte
+local floor = math.floor
+
+-- ------- where a pack comes from
+--
+-- Two places, asked in this order.
+--
+-- CACHE_DIR is in the save directory and is what actually ships: the mod
+-- carries no models (they are Pokemon Stadium's data), so StadiumInstall
+-- builds them out of the player's own ROM on first run and writes them here.
+--
+-- DIR is inside the mod, and exists for a developer checkout that has run
+-- tools/stadium_pack.py -- which is also how the oracle the Lua extractor is
+-- tested against gets built. It is second because a locally built CURRENT
+-- cache should win over whatever a checkout happens to have lying around --
+-- current as judged by StadiumInstall's marker, so a cache an old extractor
+-- built does not shadow a fresh set (see readPack).
+StadiumPack.CACHE_DIR = "dramatic_shape/stadium"
+StadiumPack.DIR = "assets/stadium"
+
+local function readPack(species)
+  -- The cache only counts when StadiumInstall's marker says it is a
+  -- complete, CURRENT build -- an old cache (a rev the extractor has since
+  -- fixed, a format that moved) must not shadow a fresh shipped set, and a
+  -- half-written folder must not be read at all. Required lazily: Install
+  -- requires this module at load, so the reverse edge cannot be taken then.
+  local rel = ("%s/%03d.dsm"):format(StadiumPack.CACHE_DIR, species)
+  if love and love.filesystem and love.filesystem.getInfo
+     and V.require("StadiumInstall").ready() then
+    local okInfo, info = pcall(love.filesystem.getInfo, rel, "file")
+    if okInfo and info then
+      local ok, bytes = pcall(love.filesystem.read, rel)
+      if ok and type(bytes) == "string" and #bytes > 4 then return bytes end
+    end
+  end
+  local mod = V.mod
+  if not (mod and mod.read) then return nil end
+  local ok, bytes = pcall(mod.read, mod,
+                          ("%s/%03d.dsm"):format(StadiumPack.DIR, species))
+  if ok and type(bytes) == "string" and #bytes > 4 then return bytes end
+  return nil
+end
+
+-- The battle system's context slots, in the order tools/stadium_pack.py
+-- writes them -- slot 165 upward (see model_extract/manifest.json's
+-- animationSlots). Indexed by POSITION, so this list is the format's
+-- contract and the packer's CONTEXTS must stay identical to it.
+-- Position 2 was called "hit" until the move table was read against it: it
+-- is the animation most of a species' MOVES play, which makes it the default
+-- attack and not a damage reaction (see StadiumMon's STATES). The slot TABLE
+-- is indexed by position, but the name also reaches the packed files: the
+-- packers bake it into the animation NAME strings, so it has to match
+-- tools/stadium_pack.py's CONTEXTS *and* pipeline/battle.py's CONTEXT_SLOTS,
+-- or the oracle diff reports every species.
+StadiumPack.CONTEXT = {
+  "idle", "attack_default", "faint", "entrance", "reaction_169", "reaction_170",
+  "reaction_171", "reaction_172", "reaction_173", "reaction_174",
+  "struggle", "idle_alt", "faint_alt", "flinch", "reaction_179",
+  "reaction_180", "reaction_181", "reaction_182", "entrance_alt",
+  "idle_return",
+}
+
+-- name -> slot position, for callers that ask by name
+StadiumPack.SLOT = {}
+for i, name in ipairs(StadiumPack.CONTEXT) do StadiumPack.SLOT[name] = i end
+
+StadiumPack.N_MOVES = 165
+StadiumPack.NONE = 0xFFFF
+
+-- The frame rate every animation in the set is authored at
+-- (model_extract/README.md: keyframe times are frame / 30).
+StadiumPack.FPS = 30
+
+-- ------- readers
+--
+-- One cursor threaded through by hand rather than an object: this runs over
+-- a couple of hundred thousand values on the frame a battle starts, and a
+-- method call per value is the difference between a hitch and no hitch.
+
+local function u8(s, p) return byte(s, p), p + 1 end
+
+local function u16(s, p)
+  local a, b = byte(s, p, p + 1)
+  return a + b * 256, p + 2
+end
+
+local function i16(s, p)
+  local a, b = byte(s, p, p + 1)
+  local v = a + b * 256
+  if v >= 32768 then v = v - 65536 end
+  return v, p + 2
+end
+
+local function u32(s, p)
+  local a, b, c, d = byte(s, p, p + 3)
+  return a + b * 256 + c * 65536 + d * 16777216, p + 4
+end
+
+local function i32(s, p)
+  local v
+  v, p = u32(s, p)
+  if v >= 2147483648 then v = v - 4294967296 end
+  return v, p
+end
+
+-- IEEE 754 single, by hand. LOVE has love.data.unpack, but this file reads
+-- exactly four floats per model (the header's extents) and a hand decode
+-- costs nothing while removing a version floor from the mod's whole
+-- STADIUM path.
+local function f32(s, p)
+  local b1, b2, b3, b4 = byte(s, p, p + 3)
+  local sign = 1
+  if b4 >= 128 then sign, b4 = -1, b4 - 128 end
+  local expo = b4 * 2 + floor(b3 / 128)
+  local mant = (b3 % 128) * 65536 + b2 * 256 + b1
+  if expo == 255 then
+    if mant == 0 then return sign * math.huge, p + 4 end
+    return 0, p + 4
+  end
+  if expo == 0 then return sign * mant * 2 ^ -149, p + 4 end
+  return sign * (1 + mant / 8388608) * 2 ^ (expo - 127), p + 4
+end
+
+-- 16.16 fixed point, which is how bone scales are stored (they run from
+-- about -31 to 100 across the set and a float would cost twice the bytes
+-- for precision nothing can see).
+local function fixed(s, p)
+  local v
+  v, p = i32(s, p)
+  return v / 65536, p
+end
+
+-- ------- the load
+
+local function readHeader(s, p, model)
+  model.species, p = u16(s, p)
+  model.boneCount, p = u16(s, p)
+  model.primCount, p = u16(s, p)
+  model.texCount, p = u16(s, p)
+  model.animCount, p = u16(s, p)
+  model.auxCount, p = u16(s, p)
+  model.rootScale, p = f32(s, p)
+  -- a species whose standby loop is corrupt in the source extraction, and
+  -- which the mod therefore holds at its bind pose (see the packer's
+  -- idle_is_broken). Three of the 151.
+  local static
+  static, p = u8(s, p)
+  model.staticPose = static ~= 0
+  model.height, p = f32(s, p)
+  model.floor, p = f32(s, p)
+  model.radius, p = f32(s, p)
+
+  local moveAnim, moveAux, ctx = {}, {}, {}
+  for i = 1, StadiumPack.N_MOVES do moveAnim[i], p = u16(s, p) end
+  for i = 1, StadiumPack.N_MOVES do moveAux[i], p = i16(s, p) end
+  for i = 1, #StadiumPack.CONTEXT do ctx[i], p = u16(s, p) end
+  model.moveAnim, model.moveAux, model.ctx = moveAnim, moveAux, ctx
+  return p
+end
+
+-- The bone tree, as flat parallel arrays: a rig walk touches every bone
+-- every frame and an array of little tables would be a cache miss per bone
+-- and a table per bone to collect.
+local function readBones(s, p, model)
+  local n = model.boneCount
+  local parent, t, r, sc = {}, {}, {}, {}
+  for i = 1, n do
+    -- 0-based in the file, 1-based here, and 0 for "no parent" so the rig's
+    -- walk can test it without a sentinel comparison
+    local par
+    par, p = i16(s, p)
+    parent[i] = par + 1
+    local b = (i - 1) * 3
+    t[b + 1], p = i16(s, p)
+    t[b + 2], p = i16(s, p)
+    t[b + 3], p = i16(s, p)
+    r[b + 1], p = i16(s, p)
+    r[b + 2], p = i16(s, p)
+    r[b + 3], p = i16(s, p)
+    sc[b + 1], p = fixed(s, p)
+    sc[b + 2], p = fixed(s, p)
+    sc[b + 3], p = fixed(s, p)
+  end
+  model.parent, model.restT, model.restR, model.restS = parent, t, r, sc
+  return p
+end
+
+-- One drawable piece: the triangles that share a texture and a cull mode.
+--
+-- Positions and normals stay in BONE-LOCAL space, exactly as the display
+-- list had them, because that is what makes the skinning a single matrix
+-- multiply per vertex (every vertex in the set is rigidly bound to one bone
+-- -- see model_extract/README.md) rather than a weighted blend.
+local function readPrims(s, p, model)
+  local prims = {}
+  for i = 1, model.primCount do
+    local prim = {}
+    prim.tex, p = u16(s, p)
+    prim.tex = prim.tex + 1
+    local cull, blend
+    cull, p = u8(s, p)
+    blend, p = u8(s, p)
+    prim.cull = cull ~= 0
+    prim.additive = blend ~= 0
+    prim.texAnim, p = i16(s, p)
+
+    -- the texture-animation channel's value -> which texture to swap in.
+    -- Keyed by the stream's own byte, so the rig can look one up without
+    -- searching.
+    local mapN
+    mapN, p = u8(s, p)
+    if mapN > 0 then
+      local map = {}
+      for _ = 1, mapN do
+        local key, tex
+        key, p = u8(s, p)
+        tex, p = u16(s, p)
+        map[key] = tex + 1
+      end
+      prim.texMap = map
+    end
+
+    local fxN
+    fxN, p = u16(s, p)
+    if fxN > 0 then
+      local frames = {}
+      for k = 1, fxN do
+        frames[k], p = u16(s, p)
+        frames[k] = frames[k] + 1
+      end
+      prim.fxFrames = frames
+    end
+
+    local nv, ni
+    nv, p = u16(s, p)
+    ni, p = u16(s, p)
+    prim.vertCount, prim.indexCount = nv, ni
+
+    -- five arrays rather than one array of vertices, for the same reason
+    -- the bones are flat: the skinning loop reads them in step and writes
+    -- one LOVE vertex row out
+    local px, py, pz = {}, {}, {}
+    local uv = {}
+    local nx, ny, nz = {}, {}, {}
+    local bone = {}
+    for k = 1, nv do
+      px[k], p = i16(s, p)
+      py[k], p = i16(s, p)
+      pz[k], p = i16(s, p)
+      local u, v
+      u, p = i16(s, p)
+      v, p = i16(s, p)
+      uv[k * 2 - 1], uv[k * 2] = u / 512, v / 512
+      local a, b, c
+      a, p = u8(s, p)
+      b, p = u8(s, p)
+      c, p = u8(s, p)
+      if a >= 128 then a = a - 256 end
+      if b >= 128 then b = b - 256 end
+      if c >= 128 then c = c - 256 end
+      nx[k], ny[k], nz[k] = a / 127, b / 127, c / 127
+      bone[k], p = u8(s, p)
+      bone[k] = bone[k] + 1
+    end
+    prim.px, prim.py, prim.pz = px, py, pz
+    prim.uv = uv
+    prim.nx, prim.ny, prim.nz = nx, ny, nz
+    prim.bone = bone
+
+    local idx = {}
+    for k = 1, ni do
+      idx[k], p = u16(s, p)
+      idx[k] = idx[k] + 1
+    end
+    prim.index = idx
+    prims[i] = prim
+  end
+  model.prims = prims
+  return p
+end
+
+-- The textures, kept as the raw RGBA8 they arrived as and turned into
+-- images on first use. A species carries every frame of every blink and
+-- every dizzy swirl; a fight that never shows one should not pay to
+-- upload it.
+--
+-- Raw rather than PNG, which is what DSM3 changed: an ImageData over these
+-- bytes is a memcpy where a PNG is a decode on the frame a battle starts,
+-- and -- the reason it was actually done -- uncompressed pixels are the same
+-- pixels whichever side wrote them, so the Lua extractor's output can be
+-- diffed against the Python packer's byte for byte. Two deflate
+-- implementations need not agree; two arrays of pixels do.
+local function readTextures(s, p, model)
+  local tex = {}
+  for i = 1, model.texCount do
+    local w, h, len
+    w, p = u16(s, p)
+    h, p = u16(s, p)
+    len, p = u32(s, p)
+    tex[i] = { w = w, h = h, rgba = s:sub(p, p + len - 1) }
+    p = p + len
+  end
+  model.textures = tex
+  return p
+end
+
+-- How many bytes one animation's track block occupies, without decoding
+-- any of it. This is the scan that makes lazy animations possible: nine
+-- components a bone, each either one value or one a frame, and the only
+-- thing that has to be READ is the byte that says which.
+local COMP_BYTES = { 2, 2, 2, 2, 2, 2, 4, 4, 4 }   -- t t t r r r s s s
+
+local function skipTracks(s, p, boneCount, frames)
+  for _ = 1, boneCount do
+    local present
+    present, p = u8(s, p)
+    if present ~= 0 then
+      for c = 1, 9 do
+        local kind
+        kind, p = u8(s, p)
+        p = p + COMP_BYTES[c] * (kind == 0 and 1 or frames)
+      end
+    end
+  end
+  return p
+end
+
+local function readAnims(s, p, model)
+  local anims = {}
+  for i = 1, model.animCount do
+    local len
+    len, p = u8(s, p)
+    local name = s:sub(p, p + len - 1)
+    p = p + len
+    local frames, loopStart, aux
+    frames, p = u16(s, p)
+    loopStart, p = u16(s, p)
+    aux, p = i16(s, p)
+    anims[i] = {
+      name = name, frames = frames, loopStart = loopStart,
+      aux = aux >= 0 and (aux + 1) or nil,
+      seconds = frames / StadiumPack.FPS,
+      offset = p,                    -- where its tracks start; decoded later
+    }
+    p = skipTracks(s, p, model.boneCount, frames)
+  end
+  model.anims = anims
+  return p
+end
+
+local function readAux(s, p, model)
+  local aux = {}
+  for i = 1, model.auxCount do
+    local frames, loopStart, chanN
+    frames, p = u16(s, p)
+    loopStart, p = u16(s, p)
+    chanN, p = u16(s, p)
+    local chans = {}
+    for c = 1, chanN do
+      local n
+      n, p = u16(s, p)
+      local stream = {}
+      for k = 1, n do stream[k], p = u16(s, p) end
+      chans[c] = stream
+    end
+    aux[i] = { frames = frames, loopStart = loopStart, channels = chans }
+  end
+  model.auxAnims = aux
+  return p
+end
+
+-- ------- a track block, decoded on demand
+--
+-- The shape a pose walk wants: `tracks[bone]` is either nil (this bone
+-- holds its rest transform for the whole animation) or nine entries, each
+-- either a number (constant) or an array of one value per frame.
+--
+-- That fold is the source data's own, not something imposed here: a bone
+-- that only rotates costs two bytes for each of its six other components,
+-- and across the 151 species it is most of the reason the whole set is 24
+-- megabytes rather than a hundred.
+function StadiumPack.tracks(model, index)
+  local anim = model.anims and model.anims[index]
+  if not anim then return nil end
+  if anim.tracks then return anim.tracks end
+  local s, p = model.bytes, anim.offset
+  if not (s and p) then return nil end
+  local frames = anim.frames
+  local out = {}
+  for b = 1, model.boneCount do
+    local present
+    present, p = u8(s, p)
+    if present ~= 0 then
+      local comps = {}
+      for c = 1, 9 do
+        local kind
+        kind, p = u8(s, p)
+        local read = (c >= 7) and fixed or i16
+        if kind == 0 then
+          comps[c], p = read(s, p)
+        else
+          local arr = {}
+          for k = 1, frames do arr[k], p = read(s, p) end
+          comps[c] = arr
+        end
+      end
+      out[b] = comps
+    end
+  end
+  anim.tracks = out
+  return out
+end
+
+-- One texture as a LOVE image, decoded on first ask.
+function StadiumPack.image(model, index)
+  local slot = model.textures and model.textures[index]
+  if not slot then return nil end
+  if slot.image ~= nil then return slot.image or nil end
+  local ok, img = pcall(function()
+    local data = love.image.newImageData(slot.w, slot.h, "rgba8", slot.rgba)
+    local image = love.graphics.newImage(data)
+    -- N64 art at N64 resolution: nearest keeps the texels the size the
+    -- artist drew them, exactly as every other texture in this mode
+    image:setFilter("nearest", "nearest")
+    return image
+  end)
+  slot.image = (ok and img) or false
+  return slot.image or nil
+end
+
+-- ------- the cache
+
+local cache = {}          -- species -> model
+local order = {}          -- species, least recently used first
+StadiumPack.KEEP = 4
+
+local function touch(species)
+  for i = #order, 1, -1 do
+    if order[i] == species then table.remove(order, i) end
+  end
+  order[#order + 1] = species
+  while #order > StadiumPack.KEEP do
+    local drop = table.remove(order, 1)
+    local model = cache[drop]
+    cache[drop] = nil
+    if model and model.textures then
+      for _, slot in ipairs(model.textures) do
+        if slot.image and slot.image.release then
+          pcall(slot.image.release, slot.image)
+        end
+        -- CLEARED, not just released. A released Image is still a truthy
+        -- value, and `image()` below hands back whatever is in this field
+        -- without looking at it -- so leaving the corpse here meant the next
+        -- ask returned a dead object, which reached mesh:setTexture and threw
+        -- "Cannot use object after it has been released" from inside the
+        -- scene pass. Nil means the next ask decodes it again, which is the
+        -- whole point of the slot being lazy.
+        slot.image = nil
+      end
+    end
+  end
+end
+
+-- Say that this species is IN USE, so the cache does not evict it.
+--
+-- The eviction order above is a least-recently-LOADED list, not a
+-- least-recently-used one: `touch` runs from `load`, and `load` is only
+-- reached when a side's species CHANGES (StadiumMon.setSpecies returns early
+-- otherwise). A Pokemon that stands on the field for several turns therefore
+-- never refreshes its position, drifts to the front of the queue, and is
+-- evicted -- its textures released -- while it is still being drawn sixty
+-- times a second. That is what a fifth species entering a battle did: call
+-- out a Clefairy and whatever had been standing longest lost its textures
+-- mid-fight.
+--
+-- So the mode says, every frame, which two species are actually standing
+-- there (see Stadium.update). With KEEP at 4 and two sides, the two in use
+-- are always the two most recent and cannot reach the front of the queue.
+function StadiumPack.keep(species)
+  if species and cache[species] then touch(species) end
+end
+
+-- Whether a pack for this species is on disk at all. Cheap enough to ask
+-- before a battle commits to the mode, and the honest test: a mod
+-- installed without its assets folder must decline rather than error.
+function StadiumPack.available(species)
+  if cache[species] then return true end
+  return readPack(species) ~= nil
+end
+
+-- The model for a National Dex number (1..151), or nil.
+function StadiumPack.load(species)
+  if not (species and species >= 1 and species <= 151) then return nil end
+  local hit = cache[species]
+  if hit ~= nil then
+    touch(species)
+    return hit or nil
+  end
+
+  local bytes = readPack(species)
+  if not bytes then
+    cache[species] = false
+    return nil
+  end
+
+  local ok, model = pcall(function()
+    if bytes:sub(1, 4) ~= "DSM3" then
+      error("not a DSM3 pack -- delete it and let the mod rebuild it", 0)
+    end
+    local m = { bytes = bytes }
+    local p = 5
+    p = readHeader(bytes, p, m)
+    p = readBones(bytes, p, m)
+    p = readPrims(bytes, p, m)
+    p = readTextures(bytes, p, m)
+    p = readAnims(bytes, p, m)
+    readAux(bytes, p, m)
+    return m
+  end)
+  if not ok then
+    V.mod.log:warn("stadium: %03d.dsm did not read: %s -- that Pokemon "
+                   .. "falls back to its flat pic", species, tostring(model))
+    cache[species] = false
+    return nil
+  end
+
+  cache[species] = model
+  touch(species)
+  return model
+end
+
+-- Drop everything (hot reload, or a graphics context that went away).
+function StadiumPack.invalidate()
+  for _, model in pairs(cache) do
+    if model and model.textures then
+      for _, slot in ipairs(model.textures) do
+        if slot.image and slot.image.release then
+          pcall(slot.image.release, slot.image)
+        end
+        slot.image = nil
+      end
+    end
+  end
+end
+
+function StadiumPack.forget()
+  StadiumPack.invalidate()
+  cache, order = {}, {}
+end
+
+return StadiumPack

lib/StadiumRig.lua

@@ -0,0 +1,834 @@
+-- STADIUM battles: posing a skeleton and skinning it, on the CPU.
+--
+-- One instance of this is one Pokemon standing on the map -- the meshes it
+-- draws through and the scratch space its pose is computed in. The MODEL
+-- (geometry, bones, animations, textures) is shared and read-only; this is
+-- everything about it that is per-Pokemon and changes every frame.
+--
+-- ------- why the CPU
+--
+-- Because these models are tiny and the mod's shader already exists. A
+-- battle model is 674 vertices on average and 1311 at the worst, of which
+-- exactly two are on screen at a time -- so skinning them by hand costs
+-- about two thousand vertex transforms a frame, which is less than the
+-- grass pass does on an empty route. What it buys is that the finished
+-- vertices go into Voxel3D's OWN vertex format, through Voxel3D's OWN
+-- shader, and therefore get every single thing the rest of the diorama
+-- gets for free: the depth buffer decides what is in front of what, the
+-- sun pass throws a real shadow of the actual pose, the hour's tint lands
+-- on it, the hit flash flattens it, and the tilt-shift and the
+-- depth-of-field see it as part of the picture. A GPU skinning path would
+-- have needed a second shader that then had to re-implement all of that,
+-- and a second shadow shader beside it.
+--
+-- It is also what makes the FORMAT work. Every vertex in the Stadium set is
+-- rigidly bound to ONE bone with weight 1 (model_extract/README.md), so
+-- skinning is a single matrix multiply per vertex with no blend -- and the
+-- per-vertex `shade` Voxel3D wants, which no glTF has, is computed here
+-- from the bone-local normal.
+--
+-- ------- the two matrix chains
+--
+-- The game keeps bone scale OUT of the matrix chain (func_800143C0): scale
+-- accumulates in its own stack, a bone's local translation is
+-- pre-multiplied by its parent's accumulated scale, and a bone's own
+-- accumulated scale is applied to the finished matrix only at draw time.
+-- glTF cannot express that -- its node scale propagates to children -- and
+-- the reference export works around it by splitting every bone into two
+-- nodes.
+--
+-- Here it falls out naturally, as two arrays:
+--
+--   pivot   rotation and translation only. This is what a CHILD inherits,
+--           and it is a pure rotation, which is also why the normals are
+--           transformed with it rather than with the draw matrix.
+--   draw    the same matrix with the bone's accumulated scale applied on
+--           the right, which is the one vertices go through.
+--
+-- Folding the scale into the chain instead is the obvious mistake and it
+-- applies every ancestor's scale once per generation. It is caught by the
+-- suite: tools/stadium_pack.py measures the bind pose with this exact walk
+-- and its answer matches the verified glTF export on all 151 species.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Voxel3D = V.require("Voxel3D")
+local StadiumPack = V.require("StadiumPack")
+
+local StadiumRig = {}
+StadiumRig.__index = StadiumRig
+
+local sin, cos, floor = math.sin, math.cos, math.floor
+
+-- binary angle (32768 = pi) to radians
+local ANG = math.pi / 32768
+
+-- ------- how a surface is lit
+--
+-- Voxel3D shades a face by its DIRECTION rather than by a light uniform:
+-- every terrain and character mesh in this mode carries a per-vertex
+-- `shade` baked from which way its face points, and the shadow map
+-- multiplies on top of that (see Voxel3D.FACE_SHADE). A skinned model has
+-- no fixed faces to bake, so the same answer is computed per vertex from
+-- the posed normal -- and these four numbers are FACE_SHADE's own six
+-- values, fitted:
+--
+--     +Y up 1.00   -Y down 0.55   +X east 0.84   -X west 0.72
+--     +Z south 0.90   -Z north 0.68
+--
+-- so a Pokemon's flank catches the same southeastern sun the roof of the
+-- house behind it does, and the two read as being in one picture.
+local SHADE_BASE = 0.7725
+local SHADE_X = 0.06
+local SHADE_Y = 0.225
+local SHADE_Z = 0.11
+
+-- ------- an instance
+
+-- `model` is a StadiumPack model. Returns nil where meshes cannot be made,
+-- which is the same "no 3D" answer every other GPU object in this mod gives.
+function StadiumRig.new(model)
+  if not (model and model.prims) then return nil end
+  if not (love.graphics and love.graphics.newMesh) then return nil end
+
+  local self = setmetatable({
+    model = model,
+    -- The two chains, flat: twelve numbers a bone, row-major 3x4.
+    --
+    -- Named with the M rather than `pivot` and `draw` because an instance
+    -- field called `draw` shadows the DRAW METHOD through __index, and the
+    -- failure that causes is a nasty one: the shadow pass calls caster()
+    -- and keeps working, so a Pokemon casts a perfect animated shadow onto
+    -- ground it is not standing on.
+    pivotM = {},
+    drawM = {},
+    -- the accumulated scale, which is the third thing the game's own walk
+    -- carries and neither matrix can hold
+    accX = {}, accY = {}, accZ = {},
+    parts = {},
+    -- what the pose walk last answered, so a frame that neither moved the
+    -- animation nor turned the model can skip the whole thing
+    poseKey = nil,
+    -- scratch for the body-centre estimate (see anchor), kept on the rig so
+    -- a per-frame measurement allocates nothing
+    cx = {}, cy = {}, cz = {},
+  }, StadiumRig)
+
+  -- One mesh per primitive: a primitive is already "the triangles sharing
+  -- one texture", which is exactly one draw call's worth.
+  --
+  -- "dynamic" rather than "static": every vertex is rewritten every frame
+  -- the pose changes, which is what the usage hint exists to say.
+  for i, prim in ipairs(model.prims) do
+    local rows = {}
+    local uv = prim.uv
+    for k = 1, prim.vertCount do
+      -- position and shade are filled by skin(); the texture coordinates
+      -- never change, so they are written once here
+      rows[k] = { 0, 0, 0, uv[k * 2 - 1], uv[k * 2], 1 }
+    end
+    local ok, mesh = pcall(love.graphics.newMesh, Voxel3D.FORMAT, rows,
+                           "triangles", "dynamic")
+    if not ok then return nil end
+    pcall(mesh.setVertexMap, mesh, prim.index)
+    self.parts[i] = { mesh = mesh, rows = rows, prim = prim }
+  end
+  -- the spot the animations are measured against, taken while there is no
+  -- pose to overwrite (see measureBind)
+  pcall(self.measureBind, self)
+  return self
+end
+
+function StadiumRig:release()
+  for _, part in ipairs(self.parts or {}) do
+    if part.mesh and part.mesh.release then
+      pcall(part.mesh.release, part.mesh)
+    end
+  end
+  self.parts = {}
+end
+
+-- ------- sampling one track
+--
+-- `c` is the pack's own fold: a bare number when the component holds still
+-- for the whole animation, or one value a frame when it does not. Two frame
+-- indices and a blend come in because the caller has already resolved what
+-- "between frame 12 and 13, three tenths of the way" means for THIS
+-- animation's looping.
+
+-- One component at one frame.
+local function sampleAt(c, i)
+  if type(c) == "number" then return c end
+  return c[i]
+end
+
+-- ------- interpolation, and the one place it must not happen
+--
+-- These streams are not keyframes: they carry ONE VALUE PER FRAME at 30 Hz,
+-- and the game steps them a frame at a time. So at 60 Hz the honest replay
+-- is each pose held for two frames -- which is exactly what it looks like,
+-- a set of models moving at half the frame rate of everything around them.
+-- Blending between consecutive entries is therefore not reconstructing
+-- something the source had; it is INVENTING the halfway pose. It is worth
+-- inventing, because a 30 Hz step against a 60 Hz camera reads as a stutter
+-- and the halfway pose is right far more often than it is wrong.
+--
+-- Where it IS wrong is the reason a naive version of this shipped once and
+-- had to be taken out: bones snapping to an upside-down pose for a frame,
+-- arms turning inside out for a few. Rotations here are EULER TRIPLES, and
+-- a Euler triple is not a direction you can walk along. Two triples can
+-- describe nearly the same orientation and be nowhere near each other
+-- component by component -- (0, 20976, 32736) and (0, -19936, -5904) are a
+-- real pair out of the set -- so walking from one to the other passes
+-- through orientations that are nothing like either end. That is precisely
+-- a bone flipping over and back inside one frame.
+--
+-- Shortest-arc wrapping (below) fixes the easy half of that, where a
+-- component crosses the +-pi seam. It cannot fix the hard half, where the
+-- source simply RE-EXPRESSES a rotation. So the hard half is not fixed, it
+-- is DETECTED: a bone whose rotation moves more than BREAK_ANGLE in a
+-- single frame is not being animated, it is being re-expressed or snapped,
+-- and that bone holds its frame instead of blending. Per bone and all three
+-- components together, because the three are one rotation and blending two
+-- of them while holding the third is its own wrong answer.
+--
+-- The same guard, in the same spirit, for TRANSLATION: BREAK_MOVE of the
+-- model's own height inside one frame is a teleport rather than a stride.
+-- Scale needs none -- a linear blend of two scales lies between them, and
+-- there is no way for that to be a pose neither end had.
+
+-- 32768 binary-angle units is pi, so this is a quarter turn in one 30 Hz
+-- frame -- 2700 degrees a second. Nothing in the set genuinely moves that
+-- fast; everything that reads as moving that fast is a re-expression.
+local BREAK_ANGLE = 16384
+
+-- and half the Pokemon's own height in one frame, which is fifteen body
+-- heights a second
+local BREAK_MOVE = 0.5
+
+-- The signed distance from `c[i0]` to `c[i1]` the SHORT way round, for a
+-- binary angle. Interpolating 32700 toward -32700 the long way spins the
+-- bone most of a full turn inside one frame; the short way is 136 units,
+-- which is what actually happened.
+local function angleDelta(c, i0, i1)
+  if type(c) == "number" then return 0 end
+  local d = c[i1] - c[i0]
+  if d > 32768 then d = d - 65536 elseif d < -32768 then d = d + 65536 end
+  return d
+end
+
+local function linearDelta(c, i0, i1)
+  if type(c) == "number" then return 0 end
+  return c[i1] - c[i0]
+end
+
+-- ------- the pose
+--
+-- `anim` is an index into model.anims (or nil for the bind pose), `frame` a
+-- FLOAT frame in that animation's own 30 Hz timeline, and `wrap` whether
+-- the far end joins back to loopStart (a standby loop) or holds on the last
+-- frame (a faint).
+function StadiumRig:pose(anim, frame, wrap)
+  local model = self.model
+  local n = model.boneCount
+  local tracks = anim and StadiumPack.tracks(model, anim) or nil
+  local frames = anim and model.anims[anim] and model.anims[anim].frames or 1
+
+  -- The two frames this instant falls between, and how far. `k` is 0 on
+  -- every whole frame, so a caller that steps in whole frames -- the test
+  -- suite, the blink probe -- sees exactly the frame it asked for.
+  local i0, i1, k = 1, 1, 0
+  if tracks and frames > 1 then
+    local f = frame
+    if f < 0 then f = 0 end
+    local base = floor(f)
+    k = f - base
+    local loop = model.anims[anim].loopStart or 0
+    if not (loop > 0 and loop < frames) then loop = 0 end
+    if base >= frames then
+      if wrap then
+        -- the far end joins back to loopStart, which is where the game's own
+        -- player sends the counter (func_80016FBC)
+        base = loop + (base - loop) % (frames - loop)
+      else
+        base = frames - 1                   -- a faint holds where it fell
+        k = 0
+      end
+    end
+    i0 = base + 1
+    if i0 > frames then i0 = frames end
+    if i0 < 1 then i0 = 1 end
+    -- and the frame after it, which past the end of a loop is loopStart --
+    -- the same seam the counter itself crosses. An animation that HOLDS
+    -- (a faint) has nothing after its last frame, so it blends with itself.
+    if i0 < frames then
+      i1 = i0 + 1
+    elseif wrap then
+      i1 = loop + 1
+    else
+      i1, k = i0, 0
+    end
+  end
+
+  -- The frame this animation is actually SHOWING, after the wrap or the
+  -- hold, 0-based -- the WHOLE frame, never the blend. A texture swap has no
+  -- halfway: an eye is open or it is shut, and a pupil interpolated toward a
+  -- swirl is not a thing the hardware could draw. So the skeleton runs at 60
+  -- and the textures step at 30, which is what the game does with both.
+  -- Stashed rather than recomputed because the texture
+  -- animation is sampled at the very same frame (see textures) -- in the
+  -- game one counter drives both, and 73% of the paired animations in the
+  -- set are the same length as each other, which is what that looks like
+  -- from the outside. Two copies of this arithmetic would be two things to
+  -- keep in step; one number cannot drift from itself.
+  self.frameAt = i0 - 1
+
+  local parent = model.parent
+  local restT, restR, restS = model.restT, model.restR, model.restS
+  local pivot, drw = self.pivotM, self.drawM
+  local accX, accY, accZ = self.accX, self.accY, self.accZ
+
+  -- how far a bone may travel in one frame before it is read as a teleport
+  -- rather than a stride. In the vertices' own RAW units, which is what the
+  -- tracks are in: model.height is measured after the model_root scale.
+  local moveBreak = nil
+  if k > 0 then
+    local root = model.rootScale
+    if not (root and root > 0) then root = 1 end
+    local h = (model.height or 0) / root
+    if h > 0 then moveBreak = h * BREAK_MOVE end
+  end
+
+  for b = 1, n do
+    local o3 = (b - 1) * 3
+    local tx, ty, tz, rx, ry, rz, kx, ky, kz
+    local comps = tracks and tracks[b]
+    if comps then
+      tx = sampleAt(comps[1], i0)
+      ty = sampleAt(comps[2], i0)
+      tz = sampleAt(comps[3], i0)
+      rx = sampleAt(comps[4], i0)
+      ry = sampleAt(comps[5], i0)
+      rz = sampleAt(comps[6], i0)
+      kx = sampleAt(comps[7], i0)
+      ky = sampleAt(comps[8], i0)
+      kz = sampleAt(comps[9], i0)
+      if k > 0 then
+        -- ROTATION, all three at once: a bone that snaps holds its frame,
+        -- and a bone that moves holds none of it (see BREAK_ANGLE)
+        local dx = angleDelta(comps[4], i0, i1)
+        local dy = angleDelta(comps[5], i0, i1)
+        local dz = angleDelta(comps[6], i0, i1)
+        if dx < 0 then dx = -dx end
+        if dy < 0 then dy = -dy end
+        if dz < 0 then dz = -dz end
+        if dx <= BREAK_ANGLE and dy <= BREAK_ANGLE and dz <= BREAK_ANGLE then
+          rx = rx + angleDelta(comps[4], i0, i1) * k
+          ry = ry + angleDelta(comps[5], i0, i1) * k
+          rz = rz + angleDelta(comps[6], i0, i1) * k
+        end
+        -- TRANSLATION, likewise together: the three are one offset
+        local mx = linearDelta(comps[1], i0, i1)
+        local my = linearDelta(comps[2], i0, i1)
+        local mz = linearDelta(comps[3], i0, i1)
+        local far = false
+        if moveBreak then
+          far = (mx > moveBreak or mx < -moveBreak)
+                or (my > moveBreak or my < -moveBreak)
+                or (mz > moveBreak or mz < -moveBreak)
+        end
+        if not far then
+          tx, ty, tz = tx + mx * k, ty + my * k, tz + mz * k
+        end
+        -- SCALE, which cannot land anywhere the two ends did not bracket
+        kx = kx + linearDelta(comps[7], i0, i1) * k
+        ky = ky + linearDelta(comps[8], i0, i1) * k
+        kz = kz + linearDelta(comps[9], i0, i1) * k
+      end
+    else
+      -- a bone this animation never touches keeps its rest transform
+      tx, ty, tz = restT[o3 + 1], restT[o3 + 2], restT[o3 + 3]
+      rx, ry, rz = restR[o3 + 1], restR[o3 + 2], restR[o3 + 3]
+      kx, ky, kz = restS[o3 + 1], restS[o3 + 2], restS[o3 + 3]
+    end
+
+    local p = parent[b]
+    local pax, pay, paz = 1, 1, 1
+    if p > 0 then pax, pay, paz = accX[p], accY[p], accZ[p] end
+    -- the parent's accumulated scale, applied to the CHILD's offset. This
+    -- is the whole of what the game does instead of propagating scale.
+    tx, ty, tz = tx * pax, ty * pay, tz * paz
+
+    -- Rx * Ry * Rz in the game's own row-vector form (src/F420.c
+    -- func_8000F730), written out as the rows of a 3x3
+    local ax, ay, az = rx * ANG, ry * ANG, rz * ANG
+    local sx, cx = sin(ax), cos(ax)
+    local sy, cy = sin(ay), cos(ay)
+    local sz, cz = sin(az), cos(az)
+    local m11, m12, m13 = cy * cz, sx * sy * cz - cx * sz, cx * sy * cz + sx * sz
+    local m21, m22, m23 = cy * sz, sx * sy * sz + cx * cz, cx * sy * sz - sx * cz
+    local m31, m32, m33 = -sy, sx * cy, cx * cy
+
+    local o = (b - 1) * 12
+    if p > 0 then
+      local q = (p - 1) * 12
+      local a1, a2, a3, a4 = pivot[q + 1], pivot[q + 2], pivot[q + 3], pivot[q + 4]
+      local b1, b2, b3, b4 = pivot[q + 5], pivot[q + 6], pivot[q + 7], pivot[q + 8]
+      local c1, c2, c3, c4 = pivot[q + 9], pivot[q + 10], pivot[q + 11], pivot[q + 12]
+      pivot[o + 1] = a1 * m11 + a2 * m21 + a3 * m31
+      pivot[o + 2] = a1 * m12 + a2 * m22 + a3 * m32
+      pivot[o + 3] = a1 * m13 + a2 * m23 + a3 * m33
+      pivot[o + 4] = a1 * tx + a2 * ty + a3 * tz + a4
+      pivot[o + 5] = b1 * m11 + b2 * m21 + b3 * m31
+      pivot[o + 6] = b1 * m12 + b2 * m22 + b3 * m32
+      pivot[o + 7] = b1 * m13 + b2 * m23 + b3 * m33
+      pivot[o + 8] = b1 * tx + b2 * ty + b3 * tz + b4
+      pivot[o + 9] = c1 * m11 + c2 * m21 + c3 * m31
+      pivot[o + 10] = c1 * m12 + c2 * m22 + c3 * m32
+      pivot[o + 11] = c1 * m13 + c2 * m23 + c3 * m33
+      pivot[o + 12] = c1 * tx + c2 * ty + c3 * tz + c4
+    else
+      pivot[o + 1], pivot[o + 2], pivot[o + 3], pivot[o + 4] = m11, m12, m13, tx
+      pivot[o + 5], pivot[o + 6], pivot[o + 7], pivot[o + 8] = m21, m22, m23, ty
+      pivot[o + 9], pivot[o + 10], pivot[o + 11], pivot[o + 12] = m31, m32, m33, tz
+    end
+
+    local ex, ey, ez = pax * kx, pay * ky, paz * kz
+    accX[b], accY[b], accZ[b] = ex, ey, ez
+    -- the bone's own accumulated scale, on the right: it scales the axes of
+    -- THIS bone's space and cannot reach the children, which is exactly the
+    -- game's draw-time application
+    drw[o + 1], drw[o + 2] = pivot[o + 1] * ex, pivot[o + 2] * ey
+    drw[o + 3], drw[o + 4] = pivot[o + 3] * ez, pivot[o + 4]
+    drw[o + 5], drw[o + 6] = pivot[o + 5] * ex, pivot[o + 6] * ey
+    drw[o + 7], drw[o + 8] = pivot[o + 7] * ez, pivot[o + 8]
+    drw[o + 9], drw[o + 10] = pivot[o + 9] * ex, pivot[o + 10] * ey
+    drw[o + 11], drw[o + 12] = pivot[o + 11] * ez, pivot[o + 12]
+  end
+end
+
+-- ------- keeping the Pokemon on its own tile
+--
+-- Stadium's animations MOVE the Pokemon, and they move it a long way. Half
+-- the set's send-out entrances walk the body more than its own height off
+-- the spot it started on; Dewgong's faint travels nearly ten body-heights,
+-- and its entrance seven and a half. Every one of them ends exactly where it
+-- began, because that game framed each Pokemon with a camera of its OWN that
+-- followed the performance around a stage.
+--
+-- This mode has one camera, solved to put two named map cells at two fixed
+-- points in a 160x144 frame (BattleCam), and a Pokemon that travels seven
+-- body-heights out of that frame is simply GONE -- which is what sending out
+-- a Farfetch'd looked like: an empty tile for three and a half seconds,
+-- while its animation played somewhere off to the left of the shot.
+--
+-- So the bulk travel is taken back out. The pose is measured, and whatever
+-- has carried the body further than `limit` from where the bind pose put it
+-- is subtracted from every bone.
+--
+-- ------- why a LIMIT and not an anchor
+--
+-- Pinning the body outright would flatten the animations into mime: a lunge,
+-- a hop, a recoil and a collapse are all the body moving, and they are the
+-- part worth having. What breaks the shot is not motion, it is EXCURSION --
+-- and the two are told apart by how far. Inside the limit nothing is touched
+-- at all, so the 83 species whose animations stay put are bit-for-bit what
+-- they were; past it the excess alone is removed, so a big move still reads
+-- as big and still comes back to the tile it left.
+--
+-- ------- where the body IS, and why it is not the median
+--
+-- The first version of this took the median bone origin, on the reasoning
+-- that a handful of bones flung anywhere cannot move a median. True, and it
+-- had a worse problem: a median is a RANK, and a rank flips. On a bird most
+-- of the skeleton is wing, so as the wings beat, which bone sits at the
+-- middle of the sorted list swaps between the up cluster and the down one --
+-- and the estimate jumps with it. Measured on Pidgey's standby loop the
+-- median moved a tenth of a body-height between adjacent half-frames, and on
+-- Pidgeot three whole body-heights. The anchor turns that straight into a
+-- translation of the ENTIRE Pokemon, so the body counter-shook against its
+-- own wings and the flapping read as twice its real speed. That is the
+-- "Pidgey's wings flap super fast" this comment exists because of.
+--
+-- The centre is now the bone origins averaged, WEIGHTED BY HOW MANY VERTICES
+-- EACH BONE MOVES. That fixes both halves at once:
+--
+--   * the weights are a property of the MESH, computed once and never
+--     changing, so there is no rank to flip and no discontinuity available
+--     to it -- the estimate is as smooth as the bones themselves
+--   * a bone with little geometry on it barely counts, which is exactly the
+--     robustness the median was for. Farfetch'd's trail is thirty vertices
+--     on five bones -- 1.6% of the model -- so streaking three thousand
+--     units out moves this by nothing worth measuring
+--
+-- Against the median it is two to five times smoother on every species
+-- tested and measures the same travel to within a few percent.
+
+-- How far the body estimate may move in ONE 30 Hz frame of a species' own
+-- standby loop before that species is judged unmeasurable and left
+-- unanchored (see measureBind). The fastest genuine motion in the set is
+-- about a fifth of a body-height a frame; the one species that fails this
+-- moves three.
+StadiumRig.ANCHOR_STEADY = 0.5
+
+-- Which context slot the standby loop is, without requiring StadiumPack --
+-- this module is below it and a require would be circular. Position 1 of
+-- StadiumPack.CONTEXT, which is the format's own contract.
+local IDLE_SLOT = 1
+
+-- How much of the model each bone actually carries. Cached on the shared
+-- model: it is a fact about the mesh, not about this instance.
+local function boneWeights(model)
+  if model.boneW then return model.boneW, model.boneWTotal end
+  local w, total = {}, 0
+  for b = 1, model.boneCount do w[b] = 0 end
+  for _, prim in ipairs(model.prims) do
+    local bone = prim.bone
+    for k = 1, prim.vertCount do
+      local b = bone[k]
+      if w[b] then w[b] = w[b] + 1; total = total + 1 end
+    end
+  end
+  model.boneW, model.boneWTotal = w, total
+  return w, total
+end
+
+-- The body centre of the pose currently in drawM.
+local function centre(self, n)
+  local model = self.model
+  local w, total = boneWeights(model)
+  if not (total > 0) then return nil end
+  local x, y, z = 0, 0, 0
+  local d = self.drawM
+  for b = 1, n do
+    local q = w[b]
+    if q and q > 0 then
+      local o = (b - 1) * 12
+      x = x + d[o + 4] * q
+      y = y + d[o + 8] * q
+      z = z + d[o + 12] * q
+    end
+  end
+  return x / total, y / total, z / total
+end
+
+-- Where the BIND pose puts it -- the spot every animation is measured
+-- against. Cached on the shared MODEL, because it is a fact about the model
+-- and not about this instance of it.
+--
+-- Called once, from new(), and deliberately not lazily from anchor(): taking
+-- this measurement means POSING the bind pose, which would overwrite the
+-- animated pose anchor() was called to correct. Doing it while the rig is
+-- still being built is the one moment there is no pose to lose.
+function StadiumRig:measureBind()
+  local model = self.model
+  if model.bindCX then return end
+  self:pose(nil, 0, false)
+  model.bindCX, model.bindCY, model.bindCZ = centre(self, model.boneCount)
+
+  -- ------- and whether this species can be anchored at all
+  --
+  -- Decided ONCE, per model, offline, by walking its standby loop and asking
+  -- how far the body estimate moves between one frame and the next.
+  --
+  -- Everything the anchor does rests on that estimate being a description of
+  -- where the Pokemon is. For 147 species it is: the fastest real motion in
+  -- the set moves the body about a fifth of a body-height per 30 Hz frame.
+  -- Pidgeot's standby loop moves it THREE, because a few of its rotation
+  -- frames are junk (the worst data in the set, and a known issue in its own
+  -- right). There is no filter setting that both tracks a real excursion and
+  -- rejects that -- measured, at four time constants, either the excursions
+  -- came back or the shake did -- because the two are only a factor of
+  -- fifteen apart and a filter is a proportion.
+  --
+  -- So a species whose own idle says its estimate cannot be trusted is not
+  -- anchored, and plays exactly as it did before the anchor existed: it
+  -- travels as far as its animation says, and it does not vibrate. One
+  -- species trading a framing problem for no problem beats 147 trading a
+  -- solved framing problem for a shake.
+  --
+  -- Cheap: forty-odd poses on a model that is about to be posed sixty times
+  -- a second anyway.
+  local idle = model.ctx and model.ctx[IDLE_SLOT]
+  local anim = (idle and idle ~= 0xFFFF) and (idle + 1) or nil
+  local rec = anim and model.anims and model.anims[anim]
+  model.anchorOk = true
+  if rec and rec.frames and rec.frames > 1 then
+    local root = model.rootScale
+    if not (root and root > 0) then root = 1 end
+    local h = (model.height or 0) / root
+    if h > 0 then
+      local px, py, pz, worst = nil, nil, nil, 0
+      for f = 0, rec.frames - 1 do
+        self:pose(anim, f, true)
+        local x, y, z = centre(self, model.boneCount)
+        if x and px then
+          local d = (((x - px) ^ 2 + (y - py) ^ 2 + (z - pz) ^ 2) ^ 0.5) / h
+          if d > worst then worst = d end
+        end
+        px, py, pz = x, y, z
+      end
+      if worst > StadiumRig.ANCHOR_STEADY then
+        model.anchorOk = false
+        V.mod.log:info("stadium: species %s moves its own body %.1f "
+                       .. "body-heights in one frame of its standby loop -- "
+                       .. "not anchoring it, the measurement cannot be "
+                       .. "trusted", tostring(model.species), worst)
+      end
+    end
+  end
+  -- and leave the bind pose behind, not the last frame of the idle
+  self:pose(nil, 0, false)
+end
+
+-- ------- and why the offset is SMOOTHED
+--
+-- A better centre is not enough on its own. Any estimate that follows the
+-- pose carries the pose's own frame-to-frame wobble into it, and the anchor
+-- multiplies that up into a translation of the whole Pokemon -- so a species
+-- whose source data is erratic (Pidgeot's standby loop has a few frames of
+-- junk in it, and no estimator can smooth data that is genuinely wrong)
+-- would shake bodily rather than in the one bone that is wrong.
+--
+-- So the offset is low-passed. What the anchor is FOR is a slow excursion --
+-- a Pokemon swimming seven body-heights away over two seconds -- and that
+-- survives a filter with this time constant untouched, while anything
+-- oscillating frame to frame is flattened. The correction ends up describing
+-- where the Pokemon has drifted TO, never how it is shaking on the way.
+--
+-- HALF_LIFE is in seconds: the time the offset takes to close half of any
+-- gap between where it is and where the pose says it should be. Short enough
+-- that a real excursion is caught within a few frames of starting, long
+-- enough that a 30 Hz wobble does not survive it.
+StadiumRig.ANCHOR_HALF_LIFE = 0.05
+
+
+-- ------- what this does NOT fix, and why it stops here
+--
+-- The filter is a proportion, so it divides the input wobble down rather than
+-- bounding it -- and one species' data is bad enough to get through anyway.
+-- Pidgeot's standby loop carries a few frames of junk rotation (the worst in
+-- the set, and a known issue since before the anchor existed), which moves
+-- the body estimate three body-heights inside a single frame; filtered, that
+-- is still about three pixels a frame on a fourteen-pixel model.
+--
+-- Two further mechanisms were built and MEASURED against the set, and both
+-- were taken back out:
+--
+--   a rate limit on the correction bounded the shake to a third of a pixel,
+--   and cost so much tracking that 33 of the 148 entrances went back to
+--   leaving the frame -- half the problem the anchor exists to solve
+--
+--   a rate limit on the MEASUREMENT, to tell a spike from an excursion by
+--   speed, could not separate them: the fastest real excursion (Dewgong's
+--   entrance, five and a half body-heights a second) is close enough to
+--   Pidgeot's sustained junk that any threshold either clipped Dewgong or
+--   passed Pidgeot, and freezing on distrust made both worse
+--
+-- So it stops here, at the setting that is right for the 147 species whose
+-- data is not broken. Pidgeot is a data problem and belongs with the other
+-- data problems in the CHANGELOG's Known section, not in this control loop:
+-- the alternative was distorting every other Pokemon's animation to flatter
+-- one whose source frames are wrong.
+
+-- Pull the pose back toward the tile. `limit` is in the Pokemon's own
+-- body-heights; nil or a non-positive value leaves the pose exactly as posed.
+-- `dt` is the frame's own delta; without one the offset is applied whole,
+-- which is what a still (the QA sweep, a probe) wants.
+function StadiumRig:anchor(limit, dt)
+  if not (limit and limit > 0) then return end
+  local model = self.model
+  local n = model.boneCount
+  -- the vertices are in RAW units, before the model_root scale that
+  -- model.height is measured after
+  local root = model.rootScale
+  if not (root and root > 0) then root = 1 end
+  local h = (model.height or 0) / root
+  if not (h > 0) then return end
+
+  local bx, by, bz = model.bindCX, model.bindCY, model.bindCZ
+  if not bx then return end          -- never measured; leave the pose alone
+  if model.anchorOk == false then return end   -- and unmeasurable, at that
+  local x, y, z = centre(self, n)
+  if not x then return end
+
+  local dx, dy, dz = x - bx, y - by, z - bz
+  local dist = (dx * dx + dy * dy + dz * dz) ^ 0.5
+  local allow = limit * h
+
+  -- what the pose alone asks for: the EXCESS beyond the limit, so what is
+  -- inside it stays and the motion keeps its shape
+  local ox, oy, oz = 0, 0, 0
+  if dist > allow and dist > 0 then
+    local k = (dist - allow) / dist
+    ox, oy, oz = dx * k, dy * k, dz * k
+  end
+
+  -- and then toward it rather than straight to it (see ANCHOR_HALF_LIFE),
+  -- and never faster than ANCHOR_RATE
+  if dt and dt > 0 then
+    local half = StadiumRig.ANCHOR_HALF_LIFE
+    local a = (half > 0) and (1 - 0.5 ^ (dt / half)) or 1
+    if a > 1 then a = 1 end
+    local px, py, pz = self.anchorX or ox, self.anchorY or oy, self.anchorZ or oz
+    ox = px + (ox - px) * a
+    oy = py + (oy - py) * a
+    oz = pz + (oz - pz) * a
+  end
+  self.anchorX, self.anchorY, self.anchorZ = ox, oy, oz
+  if ox == 0 and oy == 0 and oz == 0 then return end
+
+  local pivot, drw = self.pivotM, self.drawM
+  for b = 1, n do
+    local o = (b - 1) * 12
+    pivot[o + 4] = pivot[o + 4] - ox
+    pivot[o + 8] = pivot[o + 8] - oy
+    pivot[o + 12] = pivot[o + 12] - oz
+    drw[o + 4] = drw[o + 4] - ox
+    drw[o + 8] = drw[o + 8] - oy
+    drw[o + 12] = drw[o + 12] - oz
+  end
+end
+
+-- ------- the skin
+--
+-- Every vertex through its one bone's draw matrix, and its normal through
+-- the same bone's pivot (a pure rotation, so the normal survives a
+-- non-uniformly scaled bone -- which several species have).
+--
+-- `yaw` is the model matrix's own turn, and it is folded in HERE rather
+-- than left to the matrix because the shade has to be computed against the
+-- WORLD normal: a Pokemon turned to face its opponent has a differently lit
+-- flank than one facing the camera, and the sun does not turn with it.
+function StadiumRig:skin(yaw)
+  local cy, sy = cos(yaw or 0), sin(yaw or 0)
+  local drw, piv = self.drawM, self.pivotM
+  for _, part in ipairs(self.parts) do
+    local prim, rows = part.prim, part.rows
+    local px, py, pz = prim.px, prim.py, prim.pz
+    local nx, ny, nz = prim.nx, prim.ny, prim.nz
+    local bone = prim.bone
+    for k = 1, prim.vertCount do
+      local o = (bone[k] - 1) * 12
+      local x, y, z = px[k], py[k], pz[k]
+      local row = rows[k]
+      row[1] = drw[o + 1] * x + drw[o + 2] * y + drw[o + 3] * z + drw[o + 4]
+      row[2] = drw[o + 5] * x + drw[o + 6] * y + drw[o + 7] * z + drw[o + 8]
+      row[3] = drw[o + 9] * x + drw[o + 10] * y + drw[o + 11] * z + drw[o + 12]
+      local ax, ay, az = nx[k], ny[k], nz[k]
+      local wx = piv[o + 1] * ax + piv[o + 2] * ay + piv[o + 3] * az
+      local wy = piv[o + 5] * ax + piv[o + 6] * ay + piv[o + 7] * az
+      local wz = piv[o + 9] * ax + piv[o + 10] * ay + piv[o + 11] * az
+      -- the model matrix's yaw, by hand: (x, z) turned, y untouched
+      row[6] = SHADE_BASE + SHADE_X * (cy * wx + sy * wz) + SHADE_Y * wy
+               + SHADE_Z * (cy * wz - sy * wx)
+    end
+    pcall(part.mesh.setVertices, part.mesh, rows)
+  end
+end
+
+-- ------- which texture each part wears this frame
+--
+-- The eyes. A primitive whose display list carried geo command 0x23 with a
+-- channel index has its texture REPLACED every frame from a stream of
+-- texture-table indices (src/18140.c func_800176DC) -- which is how every
+-- Pokemon in the game blinks, and how a confused one gets swirls. glTF has
+-- no channel for that, so the .glb files carry only the first frame; the
+-- pack carries the streams.
+--
+-- `aux` is an index into model.auxAnims (the stream set) and `frame` its
+-- own frame counter, which runs independently of the skeletal one.
+-- The eyes, and everything else a material swaps per frame.
+--
+-- Sampled at the SKELETAL animation's own frame -- the one pose() just
+-- resolved -- and CLAMPED past the end of the stream rather than wrapped.
+-- Both halves of that matter, and getting either wrong is visible.
+--
+-- The frame is the skeleton's because in the game a single counter drives
+-- both; the data says so plainly, since 507 of the 691 paired animations in
+-- the set have a texture animation exactly as long as the skeletal one it
+-- rides with.
+--
+-- The clamp is what the game's own sampler does (func_80017540 indexes the
+-- stream and holds the last entry past its end), and it is the whole
+-- difference between a blink and a twitch. Rattata's standby loop is forty
+-- frames and its blink is FIVE -- `6 8 7 8 6`, open through closed and back.
+-- Wrapped on the blink's own length that plays six times a second, which is
+-- what it looked like. Clamped, the eye blinks once at the top of the loop
+-- and stays open for the remaining thirty-five frames, so it blinks about
+-- once a second and a half.
+function StadiumRig:textures(aux)
+  local model = self.model
+  local anim = aux and model.auxAnims and model.auxAnims[aux] or nil
+  local frame = self.frameAt or 0
+  for _, part in ipairs(self.parts) do
+    local prim = part.prim
+    local index = prim.tex
+    if anim and prim.texAnim and prim.texAnim >= 0 and prim.texMap then
+      local stream = anim.channels[prim.texAnim + 1]
+      local n = stream and #stream or 0
+      if n > 0 then
+        local at = frame + 1
+        if at > n then at = n end
+        if at < 1 then at = 1 end
+        local mapped = prim.texMap[stream[at]]
+        if mapped then index = mapped end
+      end
+    end
+    part.texture = StadiumPack.image(model, index)
+  end
+end
+
+-- ------- the draw
+--
+-- `model` here is the MODEL MATRIX -- where this Pokemon stands, how big
+-- and which way round -- and `sunModel` the transform the shadow pass drew
+-- it with, which for these is the same matrix (unlike a character's leaning
+-- card; see Voxel3D.draw).
+--
+-- Seams off for the whole of it: the voxel wireframe draws the integer
+-- planes of a mesh's own model space, and these vertices are in the N64's
+-- own units where an integer plane means nothing (see VoxelGrid). Glass off
+-- for the same reason the sprite passes turn it off -- the mask's
+-- coordinates belong to the tileset atlas, not to a Pokemon's texture.
+function StadiumRig:draw(matrix, pull)
+  Voxel3D.seams(false)
+  Voxel3D.glass(false)
+  local additive = nil
+  for _, part in ipairs(self.parts) do
+    if part.prim.additive then
+      -- held back to a second pass so the flames composite over the body
+      -- rather than depth-fighting it
+      additive = additive or {}
+      additive[#additive + 1] = part
+    elseif part.texture then
+      Voxel3D.draw(part.mesh, part.texture, matrix, pull)
+    end
+  end
+  if additive then
+    Voxel3D.blend("add")
+    for _, part in ipairs(additive) do
+      if part.texture then
+        Voxel3D.draw(part.mesh, part.texture, matrix, pull)
+      end
+    end
+    Voxel3D.blend(nil)
+  end
+  Voxel3D.glass(true)
+  Voxel3D.seams(true)
+end
+
+-- The same geometry as the SUN sees it: no camera-ward pull (a trick for
+-- the view's own depth buffer, which would drag a shadow off its owner) and
+-- through the shadow pass's own draw call. The generated flame prims are
+-- skipped -- a fire casts light, not a shadow.
+function StadiumRig:caster(shadowMap, matrix)
+  for _, part in ipairs(self.parts) do
+    if part.texture and not part.prim.additive then
+      shadowMap.draw(part.mesh, part.texture, matrix)
+    end
+  end
+end
+
+return StadiumRig

lib/StadiumRom.lua

@@ -0,0 +1,314 @@
+-- STADIUM battles: getting at the Pokemon Stadium ROM.
+--
+-- Byte order, the archive the battle models are packed into, the Yay0
+-- decompressor that unwraps each one, and the per-species battle tables. It
+-- is a port of model_extract/pipeline/rom.py, function for function, and the
+-- Python remains the reference: tools/stadium_pack.py drives that side and
+-- tests/stadium_extract_test.lua diffs this side's finished packs against it
+-- byte for byte.
+--
+-- ------- why this exists in Lua at all
+--
+-- The mod cannot ship the models. They are ROM data, so what ships is the
+-- READER, and the player supplies the ROM -- exactly the arrangement the
+-- engine itself already has for the Game Boy ROM it is a recompilation of
+-- (src/import/RomImporter.lua). Everything from `baserom.z64` to
+-- `assets/stadium/NNN.dsm` therefore has to happen here, on the machine, in
+-- Lua, with no Python and no build step.
+--
+-- ------- what makes that tractable
+--
+-- Three steps, and none of them needs a decompilation toolchain:
+--
+--   1. BYTE ORDER. The three N64 dump conventions differ by a swap that is
+--      detected from the magic word and undone once, on load.
+--   2. THE ARCHIVE. The segment at 0x920000 is a count and a table of
+--      (offset, size) records. No compression at that level, no names.
+--   3. Yay0. Nintendo's LZ variant: a bitstream where a 1 copies a literal
+--      byte and a 0 pulls a (distance, length) pair out of a side table.
+--      Thirty lines, and the same thirty lines the Python has.
+--
+-- Verified in the Python by decompressing all 215 entries and diffing against
+-- what the decompilation's own `make init` produces: 215/215 identical.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local StadiumRom = {}
+
+local byte = string.byte
+local char = string.char
+local concat = table.concat
+local sub = string.sub
+local floor = math.floor
+
+-- ROM offsets, from pokestadium-us.yaml by way of pipeline/rom.py.
+StadiumRom.POKEMON_MODELS = 0x920000    -- archive of the 215 battle models
+StadiumRom.BATTLE_DATA    = 0x70D3A0    -- per-species battle tables
+StadiumRom.MAIN_ROM       = 0x1000      -- main code segment ...
+StadiumRom.MAIN_VRAM      = 0x80000400  -- ... and where it lands in RAM
+StadiumRom.PTR_TABLE_VRAM = 0x80075BD0  -- D_80075BD0[species - 1]
+
+-- The revision every offset above is keyed to. A different ROM still runs --
+-- it may well be a regional variant with the same layout -- but the caller is
+-- told, because "the models came out as garbage" and "that is not the ROM
+-- this was written against" are the same fact and only one of them is useful.
+StadiumRom.US_MD5 = "ed1378bc12115f71209a77844965ba50"
+
+-- The battle table's shape: 0xB90 bytes a species, as 0x10-byte entries.
+-- Entries 0..164 are the moves (entry n drives move n + 1) and 165 up are the
+-- fixed battle contexts.
+StadiumRom.STRIDE = 0xB90
+StadiumRom.ENTRY = 0x10
+StadiumRom.N_MOVES = 165
+
+-- How many of the archive's 215 models are the battle Pokemon. The rest are
+-- props and trophies with no battle table.
+StadiumRom.N_POKEMON = 151
+
+-- ------- byte order
+--
+-- .z64 is big-endian and native; .v64 has each pair of bytes swapped; .n64
+-- has each word reversed. `gsub` with a capture-reversing replacement does
+-- either in one call through C rather than a Lua loop over 33 million bytes.
+
+local MAGIC_Z64 = "\128\055\018\064"
+local MAGIC_V64 = "\055\128\064\018"
+local MAGIC_N64 = "\064\018\055\128"
+
+-- Normalise a dump to .z64 order, or nil when it is not an N64 ROM at all.
+function StadiumRom.normalise(bytes)
+  if type(bytes) ~= "string" or #bytes < 0x1000 then return nil end
+  local magic = sub(bytes, 1, 4)
+  if magic == MAGIC_Z64 then return bytes end
+  if magic == MAGIC_V64 then return (bytes:gsub("(.)(.)", "%2%1")) end
+  if magic == MAGIC_N64 then
+    return (bytes:gsub("(.)(.)(.)(.)", "%4%3%2%1"))
+  end
+  return nil
+end
+
+-- ------- Yay0
+--
+-- The output has to be RANDOM ACCESS while it is being written -- a back
+-- reference copies from what has already been produced, and overlapping runs
+-- are legal and common -- so it is built in a flat table of byte values and
+-- turned into a string at the end.
+--
+-- The string.char conversion is the part that wants care: it is variadic and
+-- has an argument limit, so the table is walked in blocks and the blocks
+-- concatenated. Blocks of 4096 keep the call count and the intermediate
+-- string count both low; the whole 151-model set converts in well under a
+-- second on LuaJIT, which is what made an FFI buffer unnecessary here and
+-- kept this module portable to any Lua the engine runs on.
+
+local CHUNK = 4096
+
+-- LuaJIT keeps `unpack` global; 5.2+ moved it onto table.
+local unpack = unpack or table.unpack
+
+local function bytesToString(out, n)
+  if n == 0 then return "" end
+  local parts, np = {}, 0
+  local i = 1
+  while i <= n do
+    local j = i + CHUNK - 1
+    if j > n then j = n end
+    np = np + 1
+    parts[np] = char(unpack(out, i, j))
+    i = j + 1
+  end
+  return concat(parts)
+end
+
+-- Nintendo Yay0. Header: magic, decompressed size, link table offset, chunk
+-- offset; then a bitstream read a word at a time.
+function StadiumRom.yay0(src, base)
+  base = base or 0
+  if sub(src, base + 1, base + 4) ~= "Yay0" then return nil, "not Yay0" end
+  local function be32(o)
+    local a, b, c, d = byte(src, base + o + 1, base + o + 4)
+    return ((a * 256 + b) * 256 + c) * 256 + d
+  end
+  local size = be32(4)
+  -- all three cursors are 1-based indices into `src`; the mask stream starts
+  -- immediately after the 16-byte header
+  local maskP = base + 0x10 + 1
+  local linkP = base + be32(8) + 1
+  local chunkP = base + be32(12) + 1
+
+  local out = {}
+  local pos = 0                      -- bytes produced so far
+  local mask, bits = 0, 0
+
+  while pos < size do
+    if bits == 0 then
+      local a, b, c, d = byte(src, maskP, maskP + 3)
+      mask = ((a * 256 + b) * 256 + c) * 256 + d
+      maskP = maskP + 4
+      bits = 32
+    end
+    if mask >= 0x80000000 then
+      pos = pos + 1
+      out[pos] = byte(src, chunkP)
+      chunkP = chunkP + 1
+    else
+      local a, b = byte(src, linkP, linkP + 1)
+      linkP = linkP + 2
+      local link = a * 256 + b
+      local dist = link % 0x1000
+      local count = floor(link / 0x1000)
+      if count == 0 then
+        count = byte(src, chunkP) + 0x12
+        chunkP = chunkP + 1
+      else
+        count = count + 2
+      end
+      -- overlapping runs are legal: copying one byte at a time from the
+      -- output as it grows is the behaviour, not a naive version of it
+      local copy = pos - dist
+      for _ = 1, count do
+        pos = pos + 1
+        out[pos] = out[copy]
+        copy = copy + 1
+      end
+    end
+    mask = (mask * 2) % 0x100000000
+    bits = bits - 1
+  end
+
+  return bytesToString(out, size)
+end
+
+-- Unwrap whatever container an asset arrived in. The model archive's entries
+-- are PERS-SZP: an eight-byte magic plus a header size, wrapping a Yay0
+-- stream.
+function StadiumRom.decompress(blob)
+  if sub(blob, 1, 8) == "PERS-SZP" then
+    local a, b, c, d = byte(blob, 9, 12)
+    local header = ((a * 256 + b) * 256 + c) * 256 + d
+    return StadiumRom.yay0(blob, header)
+  end
+  if sub(blob, 1, 4) == "Yay0" then return StadiumRom.yay0(blob, 0) end
+  return blob
+end
+
+-- ------- the ROM
+
+local Rom = {}
+Rom.__index = Rom
+
+-- `bytes` is the whole file. Returns the ROM, or nil plus why.
+function StadiumRom.open(bytes)
+  local data = StadiumRom.normalise(bytes)
+  if not data then return nil, "not an N64 ROM (bad magic)" end
+  return setmetatable({ data = data }, Rom)
+end
+
+function Rom:u8(o)
+  return byte(self.data, o + 1)
+end
+
+function Rom:u32(o)
+  local a, b, c, d = byte(self.data, o + 1, o + 4)
+  if not d then return 0 end
+  return ((a * 256 + b) * 256 + c) * 256 + d
+end
+
+function Rom:vramToRom(vram)
+  return StadiumRom.MAIN_ROM + (vram - StadiumRom.MAIN_VRAM)
+end
+
+-- The md5 of the normalised image, or nil where LOVE's hash is not there
+-- (the headless suite). Only ever used to tell the player which ROM they
+-- gave us, never to refuse one.
+function Rom:md5()
+  if self.hash ~= nil then return self.hash or nil end
+  local ok, hex = pcall(function()
+    local digest = love.data.hash("md5", self.data)
+    if type(digest) == "userdata" and digest.getString then
+      digest = digest:getString()
+    end
+    return love.data.encode("string", "hex", digest)
+  end)
+  self.hash = (ok and hex) or false
+  return self.hash or nil
+end
+
+function Rom:isExpectedUS()
+  local hex = self:md5()
+  return hex == nil or hex == StadiumRom.US_MD5
+end
+
+-- ------- the archive
+--
+-- Segments that hold many files start with
+--     u32 tag, u32 0, u32 totalSize, u32 fileCount
+-- followed by fileCount { u32 offset, u32 size, u32 pad[2] } records, all
+-- relative to the start of the segment.
+--
+-- Only the top three bytes of the first word are reliably zero: the model
+-- archive puts a nonzero value in the low byte, which is the same quirk the
+-- decompilation's own tools/unpack_asset.py works around.
+--
+-- Returns a list of { start, size } rather than the bytes, so nothing is
+-- copied until a caller actually wants a file.
+function Rom:archive(off)
+  local tag = self:u32(off)
+  if (tag - tag % 256) ~= 0 or self:u32(off + 4) ~= 0 then return nil end
+  local count = self:u32(off + 12)
+  if count <= 0 or count >= 4096 then return nil end
+  local out = {}
+  for i = 0, count - 1 do
+    local rec = off + 0x10 + i * 0x10
+    out[i + 1] = { start = off + self:u32(rec), size = self:u32(rec + 4) }
+  end
+  return out
+end
+
+-- The entries of the battle-model archive, uncopied.
+function Rom:models()
+  if not self.modelDir then
+    self.modelDir = self:archive(StadiumRom.POKEMON_MODELS) or {}
+  end
+  return self.modelDir
+end
+
+function Rom:modelCount()
+  return #self:models()
+end
+
+-- One model fragment, decompressed. `fileno` is 0-based, as in the Python and
+-- in the source-file names: `N.bin` holds species N + 1.
+function Rom:model(fileno)
+  local rec = self:models()[fileno + 1]
+  if not rec then return nil end
+  return StadiumRom.decompress(sub(self.data, rec.start + 1,
+                                   rec.start + rec.size))
+end
+
+-- ------- the per-species battle tables
+--
+-- func_84302658 in src/fragments/62 DMAs 0xB90 bytes a species out of the
+-- 0x70D3A0 segment, addressed through the D_80075BD0 pointer table. Byte 0 of
+-- each 0x10-byte entry indexes that Pokemon's animation list and byte 1 its
+-- auxiliary (texture) animation list.
+--
+-- Returns a 0-based array-like table of { anim, aux }, aux 0xFF meaning none
+-- and coming back as -1 -- the shape the packer writes.
+function Rom:battleRows(species)
+  local ptrTable = self:vramToRom(StadiumRom.PTR_TABLE_VRAM)
+  local raw = self:u32(ptrTable + (species - 1) * 4)
+  local o = StadiumRom.BATTLE_DATA + raw % 0x1000000
+  local rows = {}
+  local n = StadiumRom.STRIDE / StadiumRom.ENTRY
+  for e = 0, n - 1 do
+    local anim = self:u8(o + e * StadiumRom.ENTRY)
+    local aux = self:u8(o + e * StadiumRom.ENTRY + 1)
+    rows[e] = { anim, aux == 0xFF and -1 or aux }
+  end
+  rows.n = n
+  return rows
+end
+
+return StadiumRom

lib/StadiumRomPick.lua

@@ -0,0 +1,309 @@
+-- STADIUM battles: importing the ROM, instead of being told where to put it.
+--
+-- The mod ships no Pokemon Stadium models and cannot -- they are that game's
+-- data -- so the player supplies the cartridge. The original instruction for
+-- that was "make a folder called baseroms next to the game and drop the file
+-- in it", which is a fine sentence to write and a poor thing to ask. It needs
+-- a folder the player has to create, in a place that is different on every
+-- platform and is inside an unwritable archive on a packaged build, and it
+-- fails SILENTLY: the two STADIUM rungs are simply not on the row, and
+-- nothing on screen says why.
+--
+-- So this opens a file picker instead, from a row on the OPTIONS menu, and
+-- the folder keeps working for anyone who prefers it (StadiumInstall).
+--
+-- ------- the picker is the host's, not LOVE's
+--
+-- LOVE 11.5 has no file dialog. love.window.showFileDialog arrived in 12 and
+-- love.system.pickFile is a native bridge this project ships for mobile
+-- rather than part of LOVE at all. What every desktop OS does have is a
+-- dialog reachable from a shell, so that is what is used here -- osascript on
+-- macOS, PowerShell's OpenFileDialog on Windows, zenity then kdialog on
+-- Linux.
+--
+-- This is deliberately the SAME four commands the engine's own ROM importer
+-- uses for the Game Boy cartridge (src/import/RomImporter.lua's chooseRom),
+-- down to writing the Windows pick as UTF-8 -- the console's OEM codepage
+-- mangles a non-ASCII path into something that crashes the next text draw.
+-- Being a second copy of that is worth it: a mod cannot call into the
+-- importer's private helpers, and the alternative is asking the engine to
+-- grow a seam for one caller.
+--
+-- The dialog BLOCKS. io.popen waits for the player to choose, and the game is
+-- frozen for as long as it is up. That is what the engine's importer does
+-- too, it is what a modal dialog means, and the frame it freezes on is an
+-- options menu.
+--
+-- ------- and the ROM is not kept
+--
+-- The picked file is read, built from, and forgotten -- nothing is copied
+-- anywhere. A Stadium cartridge is 32 MB and the models built out of it are
+-- 34, so keeping both would double the cost of a feature for a file that has
+-- no further use: the packs are what the game reads afterwards, and the
+-- marker records the ROM's md5 so a swapped cartridge is still noticed.
+--
+-- The one thing that costs is a format bump, which invalidates the packs and
+-- leaves nothing to rebuild from. That is what the row still being there is
+-- for -- it reads READY, and pressing it imports again.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local StadiumInstall = V.require("StadiumInstall")
+
+local StadiumRomPick = {}
+
+StadiumRomPick.LABEL = "STADIUM ROM"
+StadiumRomPick.ID = "DRAMATIC_SHAPE:stadiumRom"
+
+-- Names the REVISION, because that is the thing a player gets wrong: the
+-- model offsets are keyed to US 1.0 and nothing else is going to work.
+local PROMPT = "Choose your Pokemon Stadium (US) 1.0 ROM"
+
+-- ------- the host, at arm's length
+--
+-- Everything below is read through pcall and a presence test. The mod loader
+-- hands a mod the real `io` and `os` today, but a mod that TAKES that for
+-- granted is one that stops loading the day a sandbox arrives -- and this is
+-- a convenience on top of a folder scan that works without any of it.
+
+local function haveShell()
+  local ok, popen = pcall(function() return io and io.popen end)
+  return (ok and popen) and true or false
+end
+
+local function haveFiles()
+  local ok, open = pcall(function() return io and io.open end)
+  return (ok and open) and true or false
+end
+
+local function osName()
+  local ok, name = pcall(function() return love.system.getOS() end)
+  return ok and name or nil
+end
+
+-- Run a command and return its trimmed stdout, or nil for anything that did
+-- not produce a line -- a cancelled dialog, a missing zenity, a shell that
+-- is not there.
+local function commandOutput(cmd)
+  if not haveShell() then return nil end
+  local ok, pipe = pcall(io.popen, cmd)
+  if not (ok and pipe) then return nil end
+  local okRead, out = pcall(pipe.read, pipe, "*a")
+  pcall(pipe.close, pipe)
+  if not (okRead and type(out) == "string") then return nil end
+  out = out:gsub("^%s+", ""):gsub("%s+$", "")
+  return (out ~= "") and out or nil
+end
+
+-- ------- can this machine open a DIALOG
+--
+-- Desktop only, and honestly so.
+--
+-- On ANDROID the picker is a native bridge (love.system.pickFile) whose
+-- kind -> filename mapping is a fixed list of three in the engine's own C++,
+-- and an unrecognised kind falls through to `picked_rom.gb`. That is not
+-- merely the wrong name -- it is the file the engine's Game Boy importer is
+-- watching, and reading that code settles it: the importer's size test only
+-- SKIPS a 1 MB file it has already imported, so a 32 MB N64 ROM landing
+-- there falls straight through to `love.filesystem.remove` and
+-- `startData` -- deleted, and then reported to the player as a broken Game
+-- Boy ROM. So the bridge is not called until it learns the kind, which is a
+-- two-line change in System.cpp and an APK rebuild (see README).
+--
+-- Android is not stuck without it: conf.lua points the save directory at the
+-- app's external-files folder, so `baseroms/` there is reachable over USB or
+-- any file manager with no root and no permission prompt. What Android
+-- lacked was being TOLD that -- the row vanished, and the folder's absolute
+-- path was only ever written to a console no phone shows. That is what the
+-- note below is for.
+function StadiumRomPick.canDialog()
+  if not (haveShell() and haveFiles()) then return false end
+  local p = osName()
+  return p == "Windows" or p == "OS X" or p == "Linux"
+end
+
+-- Kept as the old name for callers that only wanted "is there a dialog".
+StadiumRomPick.available = StadiumRomPick.canDialog
+
+-- Where a SAF pick would land if the native bridge grows a Stadium kind.
+-- Watched unconditionally (see poll): on a build that never writes it this
+-- costs one getInfo a frame, and on one that does the mod needs no further
+-- change to use it.
+StadiumRomPick.PICKED = "picked_stadium.z64"
+
+-- Open the dialog. Returns the chosen absolute path, or nil when the player
+-- cancelled or no dialog could be opened.
+function StadiumRomPick.choose()
+  local p = osName()
+  if p == "OS X" then
+    return commandOutput(
+      ([[osascript -e 'POSIX path of (choose file with prompt "%s" of type ]]
+       .. [[{"z64", "n64", "v64"})' 2>/dev/null]]):format(PROMPT))
+  elseif p == "Windows" then
+    local script = table.concat({
+      "Add-Type -AssemblyName System.Windows.Forms;",
+      "$d=New-Object System.Windows.Forms.OpenFileDialog;",
+      "$d.Title='" .. PROMPT .. "';",
+      "$d.Filter='Nintendo 64 ROM (*.z64;*.n64;*.v64)|*.z64;*.n64;*.v64"
+      .. "|All files (*.*)|*.*';",
+      -- as UTF-8: the console's OEM codepage would mangle a non-ASCII path
+      -- and crash the next text draw that showed it
+      "if($d.ShowDialog() -eq 'OK'){[Console]::OutputEncoding="
+      .. "[Text.Encoding]::UTF8; [Console]::Write($d.FileName)}",
+    })
+    return commandOutput(
+      'powershell -NoProfile -STA -Command "' .. script .. '"')
+  elseif p == "Linux" then
+    local path = commandOutput(
+      ([[zenity --file-selection --title="%s" ]]
+       .. [[--file-filter="Nintendo 64 ROM | *.z64 *.n64 *.v64" 2>/dev/null]])
+        :format(PROMPT))
+    if path then return path end
+    -- zenity is absent on plenty of installs (and on most handheld Linux
+    -- distributions); KDE's own dialog is the usual second answer
+    return commandOutput(
+      [[kdialog --getopenfilename "$HOME" "*.z64 *.n64 *.v64|]]
+      .. [[Nintendo 64 ROM" 2>/dev/null]])
+  end
+  return nil
+end
+
+-- Read an ABSOLUTE path, which love.filesystem cannot: it only sees inside
+-- the physfs mount, and a picked file is anywhere on the disk. Returns the
+-- bytes, or nil plus a reason short enough to fit the loading screen.
+function StadiumRomPick.read(path)
+  if not haveFiles() then return nil, "no file access" end
+  local ok, fp = pcall(io.open, path, "rb")
+  if not (ok and fp) then return nil, "could not open that file" end
+  local okRead, bytes = pcall(fp.read, fp, "*a")
+  pcall(fp.close, fp)
+  if not (okRead and type(bytes) == "string" and #bytes > 0) then
+    return nil, "could not read that file"
+  end
+  return bytes
+end
+
+-- ------- the whole flow, from one keypress
+--
+-- Pick, read, start the build, and put the loading screen up over whatever
+-- asked -- which is the OPTIONS menu, so the row is there again underneath
+-- when the build finishes and now reads READY.
+--
+-- A CANCELLED dialog is not a failure and says nothing: the player opened a
+-- file browser and changed their mind, and a mod that made an announcement
+-- about that would be the second most annoying thing on the menu.
+--
+-- Everything else lands on the loading screen's own failure state, because it
+-- is the one surface in this mode with room for a sentence -- and because a
+-- player who has just chosen the wrong file is owed a reason and not a row
+-- that quietly goes on saying IMPORT.
+function StadiumRomPick.import(game)
+  if StadiumInstall.status.state == "building" then return false end
+  local StadiumScreen = V.require("StadiumScreen")
+
+  -- No dialog on this platform: say where the file goes, on screen, because
+  -- that is the whole of what the player is missing and the console is not
+  -- somewhere they can read it.
+  if not StadiumRomPick.canDialog() then
+    if game and game.stack then
+      game.stack:push(StadiumScreen.newNote(game, "STADIUM ROM",
+        "PUT STADIUM US 1.0 HERE:",
+        StadiumInstall.romHintFile()))
+    end
+    return false
+  end
+
+  local path = StadiumRomPick.choose()
+  if not path then return false end
+  local function fail(why)
+    StadiumInstall.status.state = "failed"
+    StadiumInstall.status.error = why
+    if game and game.stack then
+      game.stack:push(StadiumScreen.new(game, true))
+    end
+    return false
+  end
+
+  local bytes, err = StadiumRomPick.read(path)
+  if not bytes then return fail(err or "could not read that file") end
+
+  local ok, beginErr = StadiumInstall.beginFrom(bytes, path)
+  if not ok then return fail(tostring(beginErr)) end
+  if game and game.stack then
+    game.stack:push(StadiumScreen.new(game, true))
+  end
+  return true
+end
+
+-- ------- the row
+--
+-- An ACTION rather than a value, which is why it is not a ModSetting: there
+-- is no rung to store, nothing for the mod manager's page to persist, and
+-- nothing to restore on the next boot. What it shows is a STATE -- the models
+-- are there or they are not -- and what it does is the only thing it can do.
+--
+-- Still offered once they ARE there, reading READY. Pressing it imports
+-- again, which is how a player swaps to a different revision, and how they
+-- rebuild after a format bump has invalidated the packs and left nothing on
+-- disk to rebuild from (see the header: the ROM is not kept).
+--
+-- nil where no dialog can be opened, which takes the row off the menu
+-- entirely rather than offering a button that cannot do anything.
+function StadiumRomPick.row()
+  return {
+    id = StadiumRomPick.ID,
+    label = StadiumRomPick.LABEL,
+    value = function()
+      if StadiumInstall.status.state == "building" then return "BUILDING" end
+      if StadiumInstall.available() then return "READY" end
+      -- WHERE, not IMPORT, where pressing it can only tell you the folder:
+      -- a row that says IMPORT and then does not import is a worse row than
+      -- one that says what it actually does
+      return StadiumRomPick.canDialog() and "IMPORT" or "WHERE?"
+    end,
+    step = function(game)
+      pcall(StadiumRomPick.import, game)
+      return true
+    end,
+  }
+end
+
+-- ------- a pick that landed while we were not looking
+--
+-- The desktop dialog BLOCKS, so `import` above can read the answer on the
+-- next line. A SAF pick cannot work that way: it is a separate activity,
+-- Android is free to destroy the game while it is up, and the file appears
+-- some frames later -- so the only way to notice one is to look for it.
+--
+-- Nothing writes this filename today (see canDialog). It is watched anyway so
+-- that teaching the native bridge one more kind is the whole of the Android
+-- picker work, with no second change needed here.
+--
+-- Consumed and DELETED either way: a 32 MB file left in the save directory
+-- would be imported again on the next boot, and kept forever if the import
+-- failed.
+function StadiumRomPick.poll(game)
+  local f = love and love.filesystem
+  if not (f and f.getInfo) then return false end
+  if StadiumInstall.status.state == "building" then return false end
+  local ok, info = pcall(f.getInfo, StadiumRomPick.PICKED, "file")
+  if not (ok and info) then return false end
+
+  local okRead, bytes = pcall(f.read, StadiumRomPick.PICKED)
+  pcall(f.remove, StadiumRomPick.PICKED)
+  if not (okRead and type(bytes) == "string") then return false end
+
+  local StadiumScreen = V.require("StadiumScreen")
+  local started, err = StadiumInstall.beginFrom(bytes, StadiumRomPick.PICKED)
+  if not started then
+    StadiumInstall.status.state = "failed"
+    StadiumInstall.status.error = tostring(err)
+  end
+  if game and game.stack then
+    game.stack:push(StadiumScreen.new(game, true))
+  end
+  return true
+end
+
+return StadiumRomPick

lib/StadiumScreen.lua

@@ -0,0 +1,391 @@
+-- STADIUM battles: the one-time build, on screen.
+--
+-- A pushed game state, so it draws in the Game Boy's own 160x144 and stops
+-- everything under it -- which is what it should do, because it is doing real
+-- work and the player should not be walking around while it happens.
+--
+-- ------- why a species a frame
+--
+-- A species takes roughly fifty milliseconds to extract, and there are 151 of
+-- them. That is ten seconds, which has to go somewhere. Doing them one per
+-- frame puts the whole cost on this screen where it is explained, keeps the
+-- bar moving at a visible rate, and leaves the frame free to draw between
+-- them. Batching more per frame would finish no sooner -- the work is the
+-- same -- and would only make the bar jump.
+--
+-- ------- what it says
+--
+-- Three things, and each of them is answering a question the player would
+-- otherwise have to guess at while the game sits there:
+--
+--   WHAT is happening -- "STADIUM EXTRACTION", which is what it is.
+--
+--   HOW FAR through it is -- a bar, filled by species written rather than by
+--   elapsed time, so it cannot lie about the remaining work.
+--
+--   THAT IT IS ALIVE -- which Pokemon it is on, by name. Not decoration: it
+--   is the difference between a progress bar the player trusts and one they
+--   suspect has hung, and it costs one lookup a frame.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local StadiumInstall = V.require("StadiumInstall")
+
+local StadiumScreen = {}
+StadiumScreen.__index = StadiumScreen
+
+-- The Game Boy frame this draws in.
+local W, H = 160, 144
+
+-- How long the finished message stays up before the screen retires itself.
+StadiumScreen.HOLD = 1.1
+
+local Font = nil
+local function font()
+  if Font then return Font end
+  local ok, F = pcall(require, "src.render.Font")
+  if ok then Font = F end
+  return Font
+end
+
+-- Black glyphs, because that is the only colour the Game Boy font sheets
+-- have -- they are black on transparent, so setColor cannot lighten one.
+-- Everything here is therefore laid out dark-on-light.
+local function text(str, x, y)
+  local F = font()
+  if not F then return end
+  love.graphics.setColor(0, 0, 0, 1)
+  F.draw(str, math.floor(x), math.floor(y))
+end
+
+local function centred(str, y)
+  local F = font()
+  if not F then return end
+  text(str, (W - F.width(str)) / 2, y)
+end
+
+-- How many glyphs fit across the frame. The font is a fixed eight pixels, so
+-- twenty is the line -- and a centred string longer than that does not
+-- overflow tidily off one side, it clips off BOTH and loses its first word as
+-- well as its last ("that is not a Pokemon Stadium ROM" came out as "at is
+-- not a Pokemon").
+--
+-- Fixed, and it stays fixed: shrinking the text to fit more in was tried and
+-- the font will not take it. These are 1-bit 8x8 bitmaps, so a fractional
+-- downscale drops whole pixel rows out of every glyph -- at 0.75 the last
+-- line of an Android save path came out as mush. Long strings get more LINES
+-- instead (see the note layout in draw).
+local COLS = 20
+
+-- Break a string into lines that fit, on word boundaries, and never more than
+-- `limit` of them.
+local function wrapped(str, limit, cols)
+  limit = limit or 2
+  cols = cols or COLS
+  local lines, line = {}, nil
+  local function push(text)
+    if #lines < limit then lines[#lines + 1] = text end
+  end
+  for word in tostring(str):gmatch("%S+") do
+    local try = line and (line .. " " .. word) or word
+    if #try <= cols then
+      line = try
+    else
+      if line then push(line) end
+      -- A word longer than the line is BROKEN ACROSS lines rather than cut.
+      -- It is always a path, and a path is the one thing here that has to be
+      -- readable in full -- an absolute Android save directory runs to
+      -- ninety-odd characters with no spaces in it at all, so truncating at
+      -- twenty told the player almost nothing.
+      while #word > cols do
+        push(word:sub(1, cols))
+        word = word:sub(cols + 1)
+      end
+      line = word
+    end
+    if #lines >= limit then break end
+  end
+  if line then push(line) end
+  return lines
+end
+
+-- ------- dex number -> the engine's own species key
+--
+-- Built once, from the loaded data rather than from a list of names carried
+-- here: a list would be a second place for the same 151 facts to live, and
+-- would go stale against a mod that renames one.
+local dexNames = nil
+
+local function speciesName(dex)
+  if not dex then return nil end
+  if not dexNames then
+    dexNames = {}
+    local ok, data = pcall(function()
+      return require("src.core.Game").data
+    end)
+    if ok and data and data.pokemon then
+      for key, def in pairs(data.pokemon) do
+        if type(def) == "table" and def.dex then dexNames[def.dex] = key end
+      end
+    end
+  end
+  return dexNames[dex]
+end
+
+-- `adopt` means the caller has ALREADY started the build, or already decided
+-- it cannot start -- which is the imported path (StadiumRomPick opens the
+-- picked file itself, because love.filesystem cannot read an absolute path).
+-- Without it this screen would call begin() on the way in and throw away the
+-- job it was pushed to display, or overwrite the failure it was pushed to
+-- explain with a fresh "no ROM in baseroms" -- which would be true, and would
+-- have nothing to do with what just went wrong.
+function StadiumScreen.new(game, adopt)
+  return setmetatable({ game = game, hold = 0, started = adopt and true or false,
+                        adopted = adopt and true or false }, StadiumScreen)
+end
+
+-- ------- the same plate, saying something instead of doing something
+--
+-- A NOTE: title, a wrapped body, and a key to dismiss it. It exists because
+-- the one piece of information a player on a platform with no file dialog
+-- actually needs -- the absolute path of the folder to put the cartridge in
+-- -- is long, machine-specific, and was only ever written to the console,
+-- which nobody on a phone can read.
+--
+-- Same state shape and the same plate as the build screen, so there is one
+-- look and one set of stack manners rather than two.
+function StadiumScreen.newNote(game, title, lead, body)
+  return setmetatable({ game = game,
+                        note = { title = title, lead = lead, body = body } },
+                      StadiumScreen)
+end
+
+-- Opaque: the loading screen owns the frame, so the map underneath is not
+-- drawn and not paying for a render it cannot be seen through.
+StadiumScreen.isOpaque = true
+
+function StadiumScreen:enter()
+  if self.note or self.adopted then return end
+  local ok, err = StadiumInstall.begin()
+  self.started = ok and true or false
+  if not ok then
+    StadiumInstall.status.state = "failed"
+    StadiumInstall.status.error = err
+  end
+end
+
+-- The buttons that dismiss a note. Every face button and START, because the
+-- prompt says ANY and a player who has to hunt for the right one on a phone
+-- has been lied to.
+local DISMISS = { "a", "b", "start", "select" }
+
+function StadiumScreen:update()
+  -- ------- a note is dismissed by a BUTTON, not by a key
+  --
+  -- `onKeyPressed` is the keyboard, and a phone has none: the touch overlay
+  -- feeds the engine's Input as virtual buttons (Input.overlayPressed), so a
+  -- state that only listens for keys cannot be closed by touch at all. That
+  -- stranded a player on this screen with no way off it -- the one screen in
+  -- the mod whose entire job is to tell somebody something and then get out
+  -- of the way.
+  --
+  -- Polled here rather than handled as an event because `wasPressed` is the
+  -- edge test the engine's own battle screens use, and it is fed by the
+  -- keyboard, the gamepad AND the overlay through one path.
+  if self.note then
+    local input = self.game and self.game.input
+    if input and input.wasPressed then
+      for _, btn in ipairs(DISMISS) do
+        if input:wasPressed(btn) then
+          if self.game.stack and self.game.stack:top() == self then
+            self.game.stack:pop()
+          end
+          return
+        end
+      end
+    end
+    return
+  end
+  local status = StadiumInstall.status
+  if status.state == "building" then
+    if not StadiumInstall.step() then
+      -- fell out of building: either finished or failed, both of which hold
+      -- for a moment so the player sees which
+      self.hold = 0
+    end
+    return
+  end
+  self.hold = self.hold + 1 / 60
+  -- a failure stays up longer, because it is the one the player has to read
+  local wait = StadiumScreen.HOLD
+  if status.state == "failed" then
+    wait = StadiumScreen.HOLD * 4
+  elseif status.wrongVersion then
+    -- a warning nobody can read is not a warning
+    wait = StadiumScreen.HOLD * 3
+  end
+  if self.hold >= wait then
+    if self.game and self.game.stack and self.game.stack:top() == self then
+      self.game.stack:pop()
+    end
+  end
+end
+
+-- Let the player out of a build that has gone wrong, or that they would
+-- rather not wait for. Cancelling leaves the packs unbuilt, so the STADIUM
+-- rungs stay off the row until the next boot offers again -- which is
+-- honest, and better than a half-built set.
+local function pop(self)
+  if self.game and self.game.stack and self.game.stack:top() == self then
+    self.game.stack:pop()
+  end
+end
+
+function StadiumScreen:onKeyPressed(key)
+  -- A note takes any key too. This is the KEYBOARD path and it is not the
+  -- one that matters on a phone -- see update, which polls the engine's
+  -- Input so the touch overlay's virtual buttons work as well.
+  if self.note then pop(self) return true end
+  if key == "escape" or key == "x" or key == "backspace" then
+    StadiumInstall.cancel()
+    if self.game and self.game.stack and self.game.stack:top() == self then
+      self.game.stack:pop()
+    end
+    return true
+  end
+  return false
+end
+
+function StadiumScreen:draw()
+  local status = StadiumInstall.status
+  love.graphics.setColor(0.93, 0.94, 0.90, 1)
+  love.graphics.rectangle("fill", 0, 0, W, H)
+
+  if self.note then
+    centred(self.note.title, 12)
+    -- The sentence is kept SHORT so the path can have the rest of the plate
+    -- at full size. Shrinking the path was tried first and does not survive
+    -- the font: these are 1-bit 8x8 bitmaps, so a fractional downscale drops
+    -- whole pixel rows out of every glyph and the last line came out as
+    -- mush. Nine rows of twenty characters is 180, which is longer than any
+    -- real save path, so nothing has to be shrunk to fit.
+    local lead = wrapped(self.note.lead or "", 2)
+    for i, line in ipairs(lead) do centred(line, 30 + (i - 1) * 10) end
+    local y = 30 + #lead * 10 + 6
+    for i, line in ipairs(wrapped(self.note.body or "", 9)) do
+      centred(line, y + (i - 1) * 9)
+    end
+    centred("PRESS ANY KEY", 130)
+    love.graphics.setColor(1, 1, 1, 1)
+    return
+  end
+
+  -- One line, and it is the whole heading: eighteen glyphs at the font's
+  -- fixed eight pixels is 144 of the frame's 160.
+  centred("STADIUM EXTRACTION", 34)
+
+  if status.state == "failed" then
+    centred("COULD NOT BUILD", 68)
+    local lines = wrapped(status.error or "unknown", 2)
+    for i, line in ipairs(lines) do centred(line, 82 + (i - 1) * 10) end
+    centred("STADIUM IS OFF", 110)
+    love.graphics.setColor(1, 1, 1, 1)
+    return
+  end
+
+  local done = status.done or 0
+  local total = status.total or StadiumInstall.COUNT
+  local frac = (total > 0) and (done / total) or 1
+  if status.state == "done" then frac = 1 end
+  if frac < 0 then frac = 0 elseif frac > 1 then frac = 1 end
+
+  -- The bar: a dark frame, an EMPTY interior the same colour as the plate,
+  -- and a dark fill growing left to right.
+  --
+  -- The track has to be the plate's own white rather than a light grey. This
+  -- draws inside the Game Boy frame, so the colorization pass quantises
+  -- everything here into the four GB shades and paints them -- and a grey
+  -- track lands one shade down, which comes out as a bar that is GREEN where
+  -- the work is still to do and dark where it is done. The eye reads colour
+  -- as the filled part and gets the progress exactly backwards.
+  local bx, by, bw, bh = 24, 68, W - 48, 9
+  love.graphics.setColor(0.06, 0.05, 0.09, 1)
+  love.graphics.rectangle("fill", bx - 1, by - 1, bw + 2, bh + 2)
+  love.graphics.setColor(0.93, 0.94, 0.90, 1)
+  love.graphics.rectangle("fill", bx, by, bw, bh)
+  love.graphics.setColor(0.06, 0.05, 0.09, 1)
+  love.graphics.rectangle("fill", bx, by, math.floor(bw * frac + 0.5), bh)
+
+  if status.state == "done" then
+    centred("READY", 86)
+    -- and say so if it was built from something other than the revision every
+    -- offset in the reader was measured against: it may look fine, it may be
+    -- subtly wrong, and the player is the only one who can swap the file
+    if status.wrongVersion then
+      centred("NOT US 1.0 --", 104)
+      centred("MODELS MAY BE WRONG", 114)
+    end
+  else
+    local name = speciesName(status.species)
+    centred(("%d/%d"):format(done, total), 86)
+    if name then centred(name, 98) end
+  end
+  love.graphics.setColor(1, 1, 1, 1)
+end
+
+-- ------- when this comes up
+--
+-- The first frame the player is actually IN the world, rather than at boot.
+-- Two reasons. The engine has its own launcher and ROM importer before the
+-- game starts, and pushing over those would be fighting them for the screen.
+-- And `Game.data` has to be loaded for the species names above to resolve.
+--
+-- Asked once. If the player cancels, or there is no ROM, this does not come
+-- back until the next run -- a loading screen that reappears every time you
+-- step outside would be worse than no stadium models.
+local asked = false
+
+function StadiumScreen.maybePush()
+  if asked then return false end
+  local ok, Game = pcall(require, "src.core.Game")
+  if not (ok and Game and Game.stack and Game.overworld) then return false end
+  if Game.stack:top() ~= Game.overworld then return false end
+  asked = true
+  if not StadiumInstall.pending() then
+    -- Say where to put a cartridge, ONCE, and only when there is nothing to
+    -- build from and nothing already built. The two STADIUM rungs are simply
+    -- absent in that case (ModSetting.setGate), which is the right thing for
+    -- a row to do and tells the player nothing about why -- and the answer
+    -- they need is an absolute path that depends on how the game was
+    -- installed, so it cannot be written into the options help text.
+    if not StadiumInstall.available() then
+      -- The IMPORT row is the answer wherever a file dialog can be opened,
+      -- and it is the better one: no folder to create, no path to get right,
+      -- no restart. The folder is still said, once, for the platforms with no
+      -- dialog (Android, a handheld Linux with neither zenity nor kdialog)
+      -- and for anyone who would rather drop a file than click through one.
+      -- The STADIUM ROM row is on the OPTIONS menu on every platform now, so
+      -- point at it rather than reciting a path here: where a file dialog can
+      -- be opened it opens one, and where it cannot it shows this same folder
+      -- on screen -- which is the part a phone could not otherwise find out.
+      local okPick, pick = pcall(V.require, "StadiumRomPick")
+      local label = (okPick and pick and pick.LABEL) or "STADIUM ROM"
+      local how = (okPick and pick and pick.canDialog())
+                  and "opens a file picker" or "says where to put one"
+      V.mod.log:info("stadium: no Pokemon Stadium (US) 1.0 ROM found, so the "
+                     .. "STADIUM battle rungs are off. OPTIONS -> %s %s; the "
+                     .. "folder is %s", label, how, StadiumInstall.romHint())
+    end
+    return false
+  end
+  Game.stack:push(StadiumScreen.new(Game))
+  return true
+end
+
+-- named for the suite, which drives the screen without a boot
+function StadiumScreen._reset()
+  asked = false
+end
+
+return StadiumScreen

lib/StadiumStage.lua

@@ -0,0 +1,340 @@
+-- The B rungs: the two discs the fight is staged on.
+--
+-- Where an A rung puts the fight on the MAP -- real ground, whatever the
+-- route happens to look like -- a B rung puts it on two platforms against
+-- the sky and draws no map at all.
+--
+-- ------- one stage, two rungs
+--
+-- The discs do not know what is standing on them. 2D-3D B stands the Game
+-- Boy's own battle pics there and STADIUM B stands the Pokemon Stadium
+-- models, and this file is identical for both: it draws two platforms at two
+-- cells and sizes each to whatever footprint it is given. That is why the
+-- flat disc rung cost a value in the 3D-BTL ladder and nothing else.
+--
+-- ------- why this is a rung and not a fix
+--
+-- Staging on the map is the better picture when the map cooperates, and it
+-- often does not. Half of Kanto's interiors are furniture; a cave floor can
+-- be nothing but two-cell corridors; some maps have nowhere a fight can be
+-- SEEN from a low camera and are declined outright (see BattleArena), which
+-- drops the player back to the flat battle screen with no warning. And even
+-- where a spot exists, the ground behind the foe is a hedge or a shop counter
+-- rather than anything a battle wants behind it.
+--
+-- Discs have none of those problems, because the stage is CARRIED rather than
+-- found: it works on every map, in every building, at every step, and the
+-- framing is the same every time. What it gives up is the thing STADIUM A is
+-- for -- fighting somewhere real.
+--
+-- ------- what stays
+--
+-- The sky, and the light. A battle outdoors is under the hour's own sky, with
+-- its bands and its sun or moon (Voxel3D.beginScene paints it when handed a
+-- dressed one); a battle in a cave or a room is under that place's own void
+-- and its own neutral light, exactly as the map itself would be. So the mode
+-- is abstracted from the GROUND, not from the world -- walk into a cave at
+-- midnight and the fight looks like a cave at midnight.
+--
+-- And the framing. The camera, the pins, the HUDs, the text box, the move
+-- animations and the depth of field are all identical, because every one of
+-- them is hung off the arena's CELLS rather than off what is under them. That
+-- is the same reason STADIUM A could be an option on the mode rather than a
+-- second mode, and it is why this file is a few hundred lines and not a few
+-- thousand.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Mat4 = V.require("Mat4")
+local Voxel3D = V.require("Voxel3D")
+
+local StadiumStage = {}
+
+local floor = math.floor
+local sin, cos = math.sin, math.cos
+local pi = math.pi
+
+-- ------- the shape of a disc
+--
+-- Radius in world pixels, where a map cell is 16 and the two mons stand three
+-- cells apart.
+--
+-- A PLATFORM FOLLOWS WHAT STANDS ON IT rather than being one fixed size,
+-- because the set's footprints run nearly tenfold: a Caterpie is under four
+-- world pixels across and Moltres, wings out, is twenty-six. One radius for
+-- both is either a dinner plate under the caterpillar or a doily under the
+-- bird.
+--
+-- RADIUS is the floor, and it is the number most species land on -- it is a
+-- little over the map cell a Pokemon is sized to cover, which is the
+-- proportion the Game Boy's own battle platforms have. PAD is the margin
+-- around a mon that needs more than that, and MAX_RADIUS stops Moltres from
+-- being handed something the frame cannot hold.
+--
+-- These are the FULL radius, out to where the fade has finished; the solid
+-- centre a Pokemon actually stands on is SOLID of it. PAD is sized so that a
+-- mon's own footprint fits inside that centre rather than out over the
+-- stipple -- 1.8 x 0.70 is a little over 1.25, so a big Pokemon still has
+-- solid ground under its edges.
+StadiumStage.RADIUS = 18
+StadiumStage.MAX_RADIUS = 34
+StadiumStage.PAD = 1.8
+
+-- The platform for a mon of this footprint. `r` may be nil -- nothing is
+-- standing there yet, which is every frame of the send-out before the model
+-- appears, and it is also the whole of the flat 2D-3D B rung, where a
+-- Pokemon is a battle pic sized to cover exactly one map cell and RADIUS is
+-- already a little over that. Either way the platform is the plain one, and
+-- it has to be there BEFORE the Pokemon lands on it.
+function StadiumStage.radiusFor(r)
+  local want = (r or 0) * StadiumStage.PAD
+  if want < StadiumStage.RADIUS then return StadiumStage.RADIUS end
+  if want > StadiumStage.MAX_RADIUS then return StadiumStage.MAX_RADIUS end
+  return want
+end
+
+-- Per-vertex shading, in the same terms StadiumRig lights the models with, so
+-- a disc and the Pokemon standing on it agree about where the sun is. Fitted
+-- to Voxel3D.FACE_SHADE's six values: the constant is the average, and each
+-- axis term is half the spread between that axis's two faces.
+local SHADE_BASE = 0.7725
+local SHADE_X = 0.06
+local SHADE_Y = 0.225
+local SHADE_Z = 0.11
+
+local function shadeFor(nx, ny, nz)
+  local s = SHADE_BASE + nx * SHADE_X + ny * SHADE_Y + nz * SHADE_Z
+  if s < 0.30 then return 0.30 end
+  if s > 1.00 then return 1.00 end
+  return s
+end
+
+-- ------- the texture
+--
+-- The platform is a FLAT painted disc that fades out at its rim -- no rim
+-- wall, no thickness, the whole thing carried in one texture on one quad
+-- lying on the ground plane. That is what the Game Boy's own battle
+-- platforms are, and it is what keeps the stage from competing with the
+-- Pokemon standing on it.
+--
+-- ------- why the fade is DITHERED
+--
+-- The scene shader discards any texel under half alpha outright (it has to:
+-- that is what keeps a sprite's transparent corners out of the depth buffer).
+-- So a smooth alpha ramp does not fade -- it comes out as a hard circle cut
+-- at wherever the ramp crosses 0.5, which is the one thing this must not be.
+--
+-- The fade is therefore an ORDERED DITHER baked into the texture's alpha:
+-- every texel is fully on or fully off, and the proportion that are on falls
+-- away toward the rim. It is the same trick the sky already uses for its
+-- bands (Sky.DITHER), it needs no shader change and so risks nothing in any
+-- other pass, and on a mode built out of visible texels it reads as intended
+-- rather than as a limitation.
+--
+-- The COLOUR is deliberately neutral. Everything the shader does to it after
+-- this is the environment's: Voxel3D.tint carries the hour outdoors and the
+-- room's own flat light indoors, and the shadow pass darkens whatever the
+-- Pokemon standing on it occludes. So one texture is a sunlit platform, a
+-- dusk platform and a cave platform, without a variant for each.
+StadiumStage.TEX = 128
+
+-- Where the solid centre ends, as a fraction of the disc's radius. Inside
+-- this everything is opaque; from here to the rim the dither thins out.
+StadiumStage.SOLID = 0.76
+
+local TOP = { 0.74, 0.71, 0.63 }
+local TOP_ALT = { 0.67, 0.64, 0.57 }
+
+local texture = nil
+
+-- A small deterministic scatter, for the surface itself. Not a random one: an
+-- authored constant that happens to look unpatterned is worth more here than
+-- a seed, because it can never change under a different Lua.
+--
+-- Quantised into blocks, so the surface reads as TEXELS rather than as noise.
+-- Per-pixel it came out as a fine mottle that fought the dithered rim for
+-- attention -- and the rim is the thing worth looking at. At this size the
+-- grain is roughly the size of the voxels everywhere else in the mode.
+StadiumStage.GRAIN = 4
+
+local function grain(x, y)
+  local bx = (x - x % StadiumStage.GRAIN) / StadiumStage.GRAIN
+  local by = (y - y % StadiumStage.GRAIN) / StadiumStage.GRAIN
+  local v = (bx * 37 + by * 71 + ((bx * by) % 13) * 17) % 100
+  return v < 34
+end
+
+-- The 8x8 ordered (Bayer) matrix, as thresholds in 0..63. Ordered rather than
+-- random because a random dither crawls: this pattern is fixed in the
+-- texture, so the fade holds still while the camera drifts across it.
+local BAYER = {
+  { 0, 32,  8, 40,  2, 34, 10, 42 },
+  { 48, 16, 56, 24, 50, 18, 58, 26 },
+  { 12, 44,  4, 36, 14, 46,  6, 38 },
+  { 60, 28, 52, 20, 62, 30, 54, 22 },
+  {  3, 35, 11, 43,  1, 33,  9, 41 },
+  { 51, 19, 59, 27, 49, 17, 57, 25 },
+  { 15, 47,  7, 39, 13, 45,  5, 37 },
+  { 63, 31, 55, 23, 61, 29, 53, 21 },
+}
+
+function StadiumStage.texture()
+  if texture ~= nil then return texture or nil end
+  local ok, img = pcall(function()
+    local n = StadiumStage.TEX
+    local data = love.image.newImageData(n, n)
+    local half = (n - 1) / 2
+    local solid = StadiumStage.SOLID
+    for y = 0, n - 1 do
+      local dy = (y - half) / half
+      for x = 0, n - 1 do
+        local dx = (x - half) / half
+        local d = (dx * dx + dy * dy) ^ 0.5
+        -- how much of this texel's neighbourhood should survive: everything
+        -- inside the solid core, nothing past the rim, and a smooth ramp
+        -- between the two that the dither turns into a stipple
+        local cover
+        if d <= solid then
+          cover = 1.0
+        elseif d >= 1.0 then
+          cover = 0.0
+        else
+          local t = (d - solid) / (1.0 - solid)
+          cover = 1.0 - t * t * (3 - 2 * t)     -- smoothstep, falling
+        end
+        local threshold = (BAYER[y % 8 + 1][x % 8 + 1] + 0.5) / 64
+        local a = (cover > threshold) and 1 or 0
+        local c = grain(x, y) and TOP_ALT or TOP
+        data:setPixel(x, y, c[1], c[2], c[3], a)
+      end
+    end
+    local image = love.graphics.newImage(data)
+    -- nearest, like every other texture in this mode: the grain and the
+    -- stipple are both meant to read as texels. Clamped rather than
+    -- repeating now that one texture covers the whole disc.
+    image:setFilter("nearest", "nearest")
+    image:setWrap("clampzero", "clampzero")
+    return image
+  end)
+  texture = (ok and img) or false
+  return texture or nil
+end
+
+-- ------- the mesh
+--
+-- One quad, lying flat on the ground plane, spanning -1..1 in x and z with
+-- the whole texture stretched across it. The DISC is the texture's business,
+-- not the geometry's -- everything outside the painted circle is alpha the
+-- shader discards -- which is what "a flat texture that fades out at the
+-- edges" means and what makes this four vertices rather than a hundred and
+-- fifty.
+--
+-- Shaded as a face pointing straight up, because it is one.
+
+local mesh = nil
+
+local function build()
+  local s = shadeFor(0, 1, 0)
+  local verts = {
+    { -1, 0, -1, 0, 0, s },
+    {  1, 0, -1, 1, 0, s },
+    {  1, 0,  1, 1, 1, s },
+    { -1, 0,  1, 0, 1, s },
+  }
+  return Voxel3D.newMesh(verts, { 1, 2, 3, 1, 3, 4 })
+end
+
+function StadiumStage.mesh()
+  if mesh == nil then mesh = build() or false end
+  return mesh or nil
+end
+
+function StadiumStage.invalidate()
+  if texture and texture.release then pcall(texture.release, texture) end
+  if mesh and mesh.release then pcall(mesh.release, mesh) end
+  texture, mesh = nil, nil
+end
+
+-- How far under the ground plane the disc actually sits. A hair, and only so
+-- that a flat-footed Pokemon's sole -- which is AT the ground plane -- is not
+-- coplanar with it and left to the depth buffer's mercy.
+StadiumStage.SINK = 0.06
+
+-- Where one disc sits: centred on a cell, at the ground plane, so a Pokemon
+-- placed at that same height stands ON it rather than in it.
+function StadiumStage.matrix(x, groundY, z, radius)
+  radius = radius or StadiumStage.RADIUS
+  return Mat4.mul(Mat4.translate(x, groundY - StadiumStage.SINK, z),
+                  Mat4.scale(radius, 1, radius))
+end
+
+-- The two platforms this frame, as (side, matrix) -- shared by the camera's
+-- pass and the sun's, so the two can never disagree about where they are.
+local function each(arena, groundY, fn)
+  local ok, Stadium = pcall(V.require, "Stadium")
+  for _, side in ipairs({ "enemy", "player" }) do
+    local cell = arena[side]
+    if cell then
+      local footprint = ok and Stadium and Stadium.footprint(side) or nil
+      fn(StadiumStage.matrix(cell[1], groundY, cell[2],
+                             StadiumStage.radiusFor(footprint)))
+    end
+  end
+end
+
+-- ------- the synthetic arena
+--
+-- A B rung does not search the map, because it does not stand on it. The
+-- arena is the same WIDE shape every other staged fight uses -- so the two
+-- cells are three apart down the middle and BattleCam frames them exactly as
+-- it always has -- just placed at a fixed spot rather than a found one.
+--
+-- Away from the origin on purpose. The coordinates run through the camera
+-- solve, the sun's frustum fit and the projection to Game Boy pixels, and
+-- putting a stage at (0, 0) is the kind of thing that hides a sign error for
+-- months.
+StadiumStage.ORIGIN = { 16, 16 }
+
+function StadiumStage.arena(map)
+  local BattleArena = V.require("BattleArena")
+  local arena = BattleArena.at(StadiumStage.ORIGIN[1], StadiumStage.ORIGIN[2],
+                               "wide")
+  if not arena then return nil end
+  -- the map is carried for its SKY and its palette only -- what kind of place
+  -- the fight is happening in -- never for its geometry
+  arena.map = map
+  arena.discs = true
+  return arena
+end
+
+-- ------- the draws
+
+-- The discs, in the main pass. No wireframe: everything else in this frame is
+-- built a unit per voxel and wears the seams that fall out of that, and a
+-- disc is a turned solid with no grid to draw.
+function StadiumStage.draw(arena, groundY)
+  if not (arena and arena.discs) then return end
+  local m = StadiumStage.mesh()
+  local tex = StadiumStage.texture()
+  if not (m and tex) then return end
+  Voxel3D.seams(false)
+  Voxel3D.glass(false)
+  each(arena, groundY, function(matrix) Voxel3D.draw(m, tex, matrix) end)
+  Voxel3D.glass(true)
+  Voxel3D.seams(true)
+end
+
+-- And into the sun, so the two Pokemon put real shadows on the platforms they
+-- are standing on. Without this the shadow map is empty where the discs are
+-- and a mon casts onto nothing at all -- which, with no ground behind it
+-- either, reads as the pair floating.
+function StadiumStage.cast(shadowMap, arena, groundY)
+  if not (arena and arena.discs and shadowMap) then return end
+  local m = StadiumStage.mesh()
+  local tex = StadiumStage.texture()
+  if not (m and tex) then return end
+  each(arena, groundY, function(matrix) shadowMap.draw(m, tex, matrix) end)
+end
+
+return StadiumStage

lib/TerrainAtlas.lua

@@ -270,7 +270,12 @@ local function readback(image)
   local prev = love.graphics.getCanvas()
   local ok, data = pcall(function()
     local w, h = image:getDimensions()
-    local canvas = love.graphics.newCanvas(w, h)
+    -- dpiscale = 1, or this is not a copy. On a highdpi surface (Android,
+    -- iOS -- see conf.lua) newCanvas takes the surface's scale by default,
+    -- so the atlas would be drawn into a texture 2.75x its size and read
+    -- back magnified -- and every tile coordinate below, which counts in
+    -- eights from the top-left, would land somewhere between two tiles.
+    local canvas = love.graphics.newCanvas(w, h, { dpiscale = 1 })
     love.graphics.setCanvas(canvas)
     love.graphics.clear(0, 0, 0, 0)
     -- straight copy: no blending against the cleared target, no tint from

lib/ThirdPerson.lua

@@ -0,0 +1,407 @@
+-- Voxel world mode: the third-person camera -- the 3RD rung.
+--
+-- 3RD is 1ST with the eye pulled off the back of the head. Everything that
+-- makes the first-person rung work -- the steered attitude, the placed
+-- camera on Voxel3D's seam, the cards that turn to face the eye, the
+-- continuous camera-relative walk -- is already general over WHERE the eye
+-- stands, so this module adds exactly one thing to it: a BOOM.
+--
+-- What the boom owns:
+--
+--   the LENGTH    how far behind the pivot the eye sits, eased in and out
+--                 so stepping between 1ST and 3RD slides rather than cuts,
+--                 and clamped every frame by what the world will allow.
+--
+--   the COLLISION a march back along the boom line through the terrain
+--                 height field and the map's own walkability, so backing
+--                 into a wall walks the camera in toward the player's
+--                 shoulders instead of through the wall into the void.
+--                 The recovery is deliberately slower than the intrusion:
+--                 a camera must never be a frame late leaving geometry,
+--                 and must never snap back out the instant a corner clears.
+--
+--   the SHOULDER  the small lateral rail offset that keeps the character
+--                 off dead centre, faded out with the boom so a camera
+--                 jammed against a wall does not also slide sideways into
+--                 it.
+--
+-- Deliberately NOT here: the attitude, the look inputs, the blend, the
+-- move intent (all lib/FirstPerson.lua, which drives this module and reads
+-- its answer while building the frame's rig), and movement itself
+-- (lib/FreeMove.lua, unchanged -- the walk is camera-relative either way,
+-- and the camera's yaw is the same number on both rungs).
+--
+-- Nothing here is required for the rung to draw: with no overworld to ask
+-- (a headless run, the test suite) every query answers "clear" and the boom
+-- extends to its full length over an empty world.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Voxel = V.require("VoxelState")
+
+local ThirdPerson = {}
+
+-- ------- the boom's numbers
+--
+-- BOOM is world pixels behind the pivot at full extension. A cell is 16 and
+-- a character card is 16 tall, so 48 stands the camera three cells back:
+-- with the first-person lens (65 degrees vertical) that frames the player
+-- at roughly a quarter of the frame height -- the modern action-game
+-- middle ground, close enough to read the four-frame sprite and far enough
+-- to see the cell you are about to walk into.
+--
+-- PIVOT_LIFT raises the orbit point above the first-person eye, so the
+-- boom looks slightly DOWN across the player's shoulder rather than
+-- straight through the back of their head.
+--
+-- SHOULDER is the lateral rail offset, in world pixels, positive to the
+-- camera's right -- which puts the player left of centre, leaving the
+-- larger half of the frame in front of them.
+ThirdPerson.BOOM = 48
+ThirdPerson.PIVOT_LIFT = 4
+ThirdPerson.SHOULDER = 4
+
+-- how long the eye takes to slide out to the boom (and back into the head
+-- when 1ST is picked), in seconds -- the same order as FirstPerson's own
+-- dive so stepping 75 -> 1ST -> 3RD reads as one continuous camera
+ThirdPerson.BOOM_TIME = 0.35
+
+-- ------- the player's own zoom
+--
+-- A multiplier on BOOM, stepped by the wheel, Q/E or a pinch (see
+-- CamControl, which owns every one of those and decides which camera a
+-- given input is aimed at). The range is deliberately wider IN than OUT:
+-- close is the shot people reach for, and far enough out the character is
+-- a few pixels and the rung may as well be an orbit rung.
+--
+-- Stepped in fractions rather than world pixels so a notch feels the same
+-- at both ends -- the near end of a linear step would crawl and the far
+-- end would leap.
+ThirdPerson.ZOOM_MIN = 0.45           -- ~22px: over the shoulder, close
+ThirdPerson.ZOOM_MAX = 2.4            -- ~115px: the character in a landscape
+ThirdPerson.ZOOM_STEP = 1.18          -- one wheel notch / key press
+ThirdPerson.ZOOM_TIME = 0.18          -- how fast the eye eases to a new one
+
+ThirdPerson.zoom = 1                  -- eased, what place() actually uses
+ThirdPerson.zoomGoal = 1              -- what the input asked for
+
+-- Step the zoom by `notches` (positive pulls the camera OUT). Returns true
+-- when the goal actually moved, so a caller can tell "zoomed" from "already
+-- at the stop" and let the input fall through.
+function ThirdPerson.stepZoom(notches)
+  local was = ThirdPerson.zoomGoal
+  local goal = was * (ThirdPerson.ZOOM_STEP ^ (notches or 0))
+  ThirdPerson.zoomGoal = math.max(ThirdPerson.ZOOM_MIN,
+                          math.min(ThirdPerson.ZOOM_MAX, goal))
+  return ThirdPerson.zoomGoal ~= was
+end
+
+-- Scale the zoom by a continuous factor -- what a pinch hands over, where
+-- the gesture's own scale IS the answer and there are no notches.
+function ThirdPerson.scaleZoom(factor)
+  if not (factor and factor > 0) then return false end
+  return ThirdPerson.stepZoom(math.log(factor) / math.log(ThirdPerson.ZOOM_STEP))
+end
+
+-- ------- the collision's numbers
+--
+-- STEP is how far apart the samples along the boom line are, in world
+-- pixels, and REFINE how many bisections narrow the first blocked one --
+-- four halvings of a 4px step lands the eye within a quarter pixel of the
+-- face, which is finer than the boom ever needs to be.
+--
+-- PAD is the clearance kept between the eye and whatever stopped it. It
+-- has to beat the placed camera's near plane (|eye - focus| * 0.05, which
+-- at full extension is about 3.6 world pixels -- see Voxel3D) or the near
+-- plane clips a hole in the very wall the boom stopped at.
+--
+-- CLEAR is how high above a cell's ground the eye must be to pass OVER
+-- something unwalkable rather than being stopped by it: a fence, a kerb or
+-- a plant pot should not shove the camera in, a building should. Roughly
+-- head height, so the eye clears the props and never the walls.
+ThirdPerson.STEP = 4
+ThirdPerson.REFINE = 4
+ThirdPerson.PAD = 5
+ThirdPerson.CLEAR = 20
+
+-- How fast the boom is allowed to grow BACK once whatever shortened it is
+-- out of the way, in world pixels per second. Shortening is instant (a
+-- camera inside a wall is a hole in the frame); lengthening is rationed,
+-- so rounding a corner eases the eye back out instead of snapping it.
+ThirdPerson.RETURN = 150
+
+-- ------- state
+--
+-- `out` is the eased extension, 0 in the head and 1 fully boomed -- the
+-- number that carries 1ST into 3RD. `len` is the boom's actual length in
+-- world pixels after the world has had its say, which is what place()
+-- stands the eye at and update() eases back toward `want`.
+ThirdPerson.out = 0
+ThirdPerson.len = 0
+ThirdPerson.want = 0
+
+local function ease(t)
+  return t * t * (3 - 2 * t)
+end
+
+-- ------- gates
+
+-- Whether the 3RD rung is the one selected. Not "is the boom out" -- that
+-- is extended() below, which stays true through the ease after the rung is
+-- left, the same way FirstPerson.blend outlives its own rung.
+--
+-- A live headset declines the boom outright: VR builds its own eye cameras
+-- from the tracked pose and never asks place() where to stand, and a
+-- headset that seats its wearer three cells behind their own body is a
+-- well-known way to make people ill. Answering false here is what keeps
+-- everything ELSE the extension decides -- the player's own card, the body
+-- that turns as it walks -- honest about the head VR actually puts you in.
+-- Required lazily and guarded: VR reaches this module through FirstPerson,
+-- and a headless run has no VR module worth loading at all.
+local function headset()
+  local ok, on = pcall(function() return V.require("VR").active() end)
+  return ok and on or false
+end
+
+function ThirdPerson.selected()
+  return Voxel.isThirdPerson(Voxel.level) and not headset()
+end
+
+-- The eased extension, 0 at the head and 1 at the full boom.
+function ThirdPerson.extension()
+  return ease(ThirdPerson.out)
+end
+
+-- Whether the boom is out far enough to be a third-person camera at all --
+-- read off the TARGET extension rather than the live length, so it is
+-- steady while the world shoves the eye about. What the body reads to
+-- decide whether it turns along its own travel.
+function ThirdPerson.extended()
+  return ThirdPerson.extension() > 0.5
+end
+
+-- How far back the eye must ACTUALLY be, in world pixels, for the player's
+-- own card to be worth drawing: a shade under a cell, which is the point
+-- where a 16-pixel card stops being a character and starts being a wall of
+-- pixels across the lens.
+ThirdPerson.SHOW_AT = 14
+
+-- Whether the player's own card belongs in the frame. Not the same
+-- question as extended(): back into a fence and the boom collapses into
+-- the head whatever the rung says, and a card drawn there fills the lens
+-- from inside exactly as it would in first person -- so it comes out, and
+-- the rung reads as first person for as long as the world insists on it.
+function ThirdPerson.showsPlayer()
+  return ThirdPerson.extension() > 0 and ThirdPerson.len >= ThirdPerson.SHOW_AT
+end
+
+-- ------- the world the boom has to fit through
+--
+-- Everything below asks the live overworld and pcall-guards the asking:
+-- with no map (headless, the suite, a frame mid-warp) the boom simply
+-- extends to its full length, which is the right answer for a world with
+-- nothing in it.
+
+local function overworld()
+  local ok, ow = pcall(function()
+    return require("src.core.Game").overworld
+  end)
+  if not ok or not ow or not ow.map then return nil end
+  return ow
+end
+
+-- Which map, and which of its cells, covers a world point. The player's own
+-- map first, then the neighbours the scene streams in around it (same ox/oy
+-- offsets VoxelScene draws them at) -- without that pass the boom would
+-- shorten against "off the map" every time the player walked within three
+-- cells of a route connection, which is most of the time.
+--
+-- nil means no map covers it: genuinely off the world, where the border
+-- ring is drawn and the camera has no business going.
+local function cellAt(ow, wx, wz)
+  local map = ow.map
+  local cx, cy = math.floor(wx / 16), math.floor(wz / 16)
+  if map:inBounds(cx, cy) then return map, cx, cy end
+  for _, nb in ipairs(ow.neighbors or {}) do
+    if nb.map then
+      local nx = math.floor((wx - (nb.ox or 0)) / 16)
+      local ny = math.floor((wz - (nb.oy or 0)) / 16)
+      if nb.map:inBounds(nx, ny) then return nb.map, nx, ny end
+    end
+  end
+  return nil
+end
+
+-- Whether the eye may not stand at this world point. Two refusals, and
+-- they are different questions:
+--
+--   the GROUND is the terrain height field the mesh is actually built from
+--   (VoxelScene.groundAt -- the same answer a character stands on), so a
+--   ledge, a raised bank or a cliff stops the boom exactly where it stops
+--   the geometry, at any pitch.
+--
+--   the WALKABILITY is the map's own, and stands in for everything built
+--   ON the ground that the height field does not describe: house walls,
+--   trees, signs, counters. Held to CLEAR above that cell's ground so the
+--   short furniture of the world is passed over rather than bumped into.
+local function occupied(ow, wx, y, wz)
+  local map, cx, cy = cellAt(ow, wx, wz)
+  if not map then return true end
+  local VoxelScene = V.require("VoxelScene")
+  local okG, gh = pcall(VoxelScene.groundAt, map, cx, cy)
+  gh = (okG and gh) or 0
+  if y < gh + ThirdPerson.PAD then return true end
+  local okW, walkable = pcall(function() return map:isWalkableCell(cx, cy) end)
+  if okW and not walkable and y < gh + ThirdPerson.CLEAR then return true end
+  return false
+end
+
+ThirdPerson._occupied = occupied       -- named for the suite
+
+-- How far back along (bx, by, bz) from `pivot` the eye can stand, up to
+-- `want`. March at STEP, and when a sample refuses, bisect back into the
+-- gap between it and the last clear one -- so the answer is the face's own
+-- position rather than the sampling grid's, and walking toward a wall
+-- draws the camera in smoothly instead of in four-pixel jerks. PAD comes
+-- off whatever survives.
+function ThirdPerson.reach(ow, pivot, bx, by, bz, want)
+  if not ow or want <= 0 then return math.max(0, want) end
+  local function clear(t)
+    return not occupied(ow, pivot[1] + bx * t, pivot[2] + by * t,
+                        pivot[3] + bz * t)
+  end
+  local lo = 0
+  local steps = math.ceil(want / ThirdPerson.STEP)
+  local hi = nil
+  for i = 1, steps do
+    local t = math.min(want, i * ThirdPerson.STEP)
+    if clear(t) then
+      lo = t
+    else
+      hi = t
+      break
+    end
+  end
+  if not hi then return want end
+  for _ = 1, ThirdPerson.REFINE do
+    local mid = (lo + hi) / 2
+    if clear(mid) then lo = mid else hi = mid end
+  end
+  return math.max(0, lo - ThirdPerson.PAD)
+end
+
+-- ------- the tick
+--
+-- Rides FirstPerson.update, which is itself on the pipeline's own update
+-- hook, so this runs every frame whatever the rung -- the extension has to
+-- keep easing back in after 3RD is left. `blend` is FirstPerson's dive into
+-- the head: while it is fully out (the diorama), the extension SNAPS to its
+-- target rather than easing, so picking 3RD from an orbit rung is one
+-- motion (the dive) rather than two (a dive, then a slide backwards).
+function ThirdPerson.update(dt, blend)
+  -- the player's own zoom FIRST, so everything below measures itself
+  -- against the boom length this frame actually wants. A step is a request
+  -- rather than a jump: three notches of wheel should read as one glide.
+  local zg = ThirdPerson.zoomGoal
+  if ThirdPerson.zoom ~= zg then
+    local k = math.min(1, dt / ThirdPerson.ZOOM_TIME)
+    local z = ThirdPerson.zoom + (zg - ThirdPerson.zoom) * k
+    ThirdPerson.zoom = (math.abs(zg - z) < 1e-4) and zg or z
+  end
+
+  local target = ThirdPerson.selected() and 1 or 0
+  if (blend or 0) <= 0 then
+    ThirdPerson.out = target
+    ThirdPerson.len = ThirdPerson.reachFor() * target
+    -- and the wanted length with it: place() is what normally maintains it
+    -- and it does not run at all while the rig is out of the frame, so a
+    -- stale want left here would have the recovery below creeping the boom
+    -- back out over a camera that is not on screen
+    ThirdPerson.want = ThirdPerson.len
+  else
+    local step = dt / ThirdPerson.BOOM_TIME
+    if ThirdPerson.out < target then
+      ThirdPerson.out = math.min(target, ThirdPerson.out + step)
+    elseif ThirdPerson.out > target then
+      ThirdPerson.out = math.max(target, ThirdPerson.out - step)
+    end
+  end
+
+  -- the rationed recovery: place() already pulled `len` in to whatever the
+  -- world allowed this frame, and this is the only thing that lets it back
+  -- out again
+  if ThirdPerson.len < ThirdPerson.want then
+    ThirdPerson.len = math.min(ThirdPerson.want,
+                               ThirdPerson.len + ThirdPerson.RETURN * dt)
+  end
+end
+
+-- The boom's full length right now, before the world has its say: BOOM at
+-- the player's own zoom. Named so the collision march and the shoulder
+-- fade measure themselves against the same number.
+function ThirdPerson.reachFor()
+  return ThirdPerson.BOOM * ThirdPerson.zoom
+end
+
+-- ------- the eye
+--
+-- Where the camera stands, given the pivot the first-person rig would have
+-- put the eye at and the unit look direction it would have looked along.
+-- Returns the eye and the focus: both slide by the shoulder offset, so the
+-- view direction is untouched and only the frame's contents shift.
+--
+-- With the boom fully in this is exactly the first-person answer, to the
+-- pixel -- which is what makes 1ST and 3RD one rig with a number between
+-- them rather than two cameras to keep in sync.
+function ThirdPerson.place(pivot, lx, ly, lz, focus)
+  local e = ThirdPerson.extension()
+  if e <= 0 then
+    ThirdPerson.want, ThirdPerson.len = 0, 0
+    return pivot, focus
+  end
+
+  local up = ThirdPerson.PIVOT_LIFT * e
+  local orbit = { pivot[1], pivot[2] + up, pivot[3] }
+
+  local want = ThirdPerson.reachFor() * e
+  ThirdPerson.want = want
+  local room = ThirdPerson.reach(overworld(), orbit, -lx, -ly, -lz, want)
+  -- in instantly, out only as fast as update() allows
+  ThirdPerson.len = math.min(ThirdPerson.len, room)
+  local len = ThirdPerson.len
+
+  -- the rail offset, faded with how much boom actually survived: a camera
+  -- squeezed against a wall gives up its shoulder before it gives up its
+  -- distance. Right of the look, flat: cross(look, worldUp) normalized,
+  -- which for a look of (sin y, *, cos y) is (-cos y, 0, sin y) -- the same
+  -- right hand FirstPerson.moveWorld strafes along.
+  -- The rail rides the ZOOM as well, so it stays the same fraction of the
+  -- frame at every distance: a fixed four pixels would swamp the close shot
+  -- and vanish from the wide one.
+  local flat = math.sqrt(lx * lx + lz * lz)
+  local sx, sz = 0, 0
+  if flat > 1e-6 then
+    local s = ThirdPerson.SHOULDER * ThirdPerson.zoom * e
+              * (len / math.max(want, 1e-6))
+    sx, sz = -lz / flat * s, lx / flat * s
+  end
+
+  local eye = { orbit[1] - lx * len + sx,
+                orbit[2] - ly * len,
+                orbit[3] - lz * len + sz }
+  local aim = focus and { focus[1] + sx, focus[2] + up, focus[3] + sz }
+              or nil
+  return eye, aim
+end
+
+-- What a shadow signature has to include about the boom: the sun's box is
+-- fitted around this camera, so sliding the eye back (or having a wall
+-- shove it in) re-fits it even standing still.
+function ThirdPerson.signature()
+  if ThirdPerson.extension() <= 0 then return "" end
+  return math.floor(ThirdPerson.len) .. "/" ..
+         math.floor(ThirdPerson.extension() * 64)
+end
+
+return ThirdPerson

lib/TileShape.lua

@@ -54,6 +54,12 @@ local FALLBACK_HEIGHTS = {
   sign = 12,
   wall = 16,
   tree = 16,
+  -- masonry drawn TWO courses tall: the Indigo Plateau's rim and the
+  -- badge-check gates down Route 23 are drawn 32px, the same height as a
+  -- statue on its plinth, and read as a step in the terrain rather than a
+  -- room's wall.  Same fold as `wall`, twice the height -- and its own
+  -- class because `wall` is 16px for every interior in the game.
+  cliff = 32,
   roof = 28,
   cylinder = 16,
   -- big round scenery: a 2x2-CELL drawing carved as ONE 32px voxel hull
@@ -65,6 +71,29 @@ local FALLBACK_HEIGHTS = {
   -- body builds from the bark rows and the drawn ellipse projects onto
   -- the hull's round top
   stump = 16,
+  -- the same hull cut at both ends, hollowed and tapered: an OPEN bin
+  -- standing on a floor (the Vermilion Gym trash cans).  The drawn mouth
+  -- ellipse projects onto the round top and down the well, the drawn base
+  -- ellipse is ground contact rather than body, and the plan narrows toward
+  -- the floor.  Height is AUTHORED (the profile's can_height, which this
+  -- pin must be kept equal to so anything riding a can lands on its rim) --
+  -- the drawing's own straight run is only a couple of rows, because a GB
+  -- cell spends most of itself on the opening
+  can = 9,
+  -- the same hull SQUASHED front to back (the profile's sapling_squash,
+  -- a percent of the revolved depth): the little trees drawn one cell
+  -- wide -- Celadon Gym's garden trees and the overworld's cuttable
+  -- tree, which are the same drawing on two atlases. A tree is round in
+  -- its canopy but is not a boulder: revolved at full width it fills a
+  -- whole cell of depth, so the plan keeps its circle and shrinks toward
+  -- an ellipse
+  sapling = 16,
+  -- round scenery drawn ONE cell wide and TWO cells TALL, standing on one
+  -- cell of plot: the Pokemon Centers' potted plants. Carved as one
+  -- 16x32x16 hull in the SOUTH (pot) cell -- the drawing's upper cell is
+  -- the object's height, not its depth. BOTH cells take the class; the
+  -- group build anchors on the north one (Structures.buildCylinders)
+  planter = 32,
   billboard = 16,
   signpost = 16,
   post = 16,
@@ -77,10 +106,18 @@ local FALLBACK_HEIGHTS = {
   bed = 7,
   stool = 8,
   counter = 8,
+  -- the raised back band of low seating: the Center couch's west strip
+  -- is drawn from above like the rest of the couch, but depicts the
+  -- back and arm rising over the 8px seat
+  backrest = 12,
   table = 12,
   desk = 24,
   prop = 16,
   cutout = 16,
+  -- a vehicle drawn SIDE-ON: the showroom bicycles.  Standee height like
+  -- every other cutout pool -- what differs is the thickness (see
+  -- Structures' PINNED_DEPTH)
+  bike = 16,
   console = 16,
   relief = 3,
   bookcase = 32,
@@ -110,12 +147,16 @@ local ART = {
   ledge = "top",
   roof = "top",
   wall = "upright",
+  cliff = "upright",
   tree = "upright",
   fence = "upright",
   sign = "upright",
   cylinder = "cylinder",
   canopy = "canopy",
   stump = "cylinder",
+  can = "cylinder",
+  sapling = "cylinder",
+  planter = "planter",
   billboard = "billboard",
   -- signposts share the billboard treatment but as their own pool at a
   -- 2-voxel depth: a sign is a thin plate on a stick, and the standard
@@ -138,6 +179,9 @@ local ART = {
   -- profile archetype Structures builds real steps for -- rising flights
   -- for stairs leading up, sunken stairwells for stairs leading down
   bed = "top",
+  -- a backrest's art is the couch seen from above, so like the bed it
+  -- rides the top face of its taller box
+  backrest = "top",
   stool = "billboard",
   -- half-cell furniture: a service counter, a low couch.  One 8px band,
   -- so exactly the drawing's bottom row stands up as the front and
@@ -151,6 +195,13 @@ local ART = {
   desk = "upright",
   prop = "billboard",
   cutout = "billboard",
+  -- a bicycle is a LINE drawing seen side-on, and its negative space --
+  -- the air inside the frame, between the wheel and the fork -- is what
+  -- makes it read as a bicycle at all.  Its own pool at two voxels: any
+  -- thicker and the side faces of neighbouring strokes close those gaps
+  -- from every angle but dead-on, and six of them in a showroom come out
+  -- as one dark lump (which is what the 5px `prop` pool gave)
+  bike = "billboard",
   -- a machine standing on furniture: the billboard treatment with
   -- body, plus the one-object contract `cutout` has -- the drawing is
   -- ringed by the furniture it sits on, and those edges must not be
@@ -168,6 +219,9 @@ local ART = {
 
 local spec = nil          -- the loaded data file, or false when absent
 local cache = {}          -- tileset id -> resolved shape list
+local figCache = {}       -- tileset id -> parsed figure masks, or false
+local mntCache = {}       -- tileset id -> parsed mounted masks, or false
+local bgCache = {}        -- tileset id -> prop background shades, or false
 
 -- The shape profile ships with the mod (data/voxel_heights.lua) and is read
 -- through the mod's own file loader rather than package.path: a mod's
@@ -224,29 +278,42 @@ end
 -- class = "..." } } }`, evaluated per POSITION in TileShape.at, where
 -- the map and coordinates are in hand. First match wins; no match keeps
 -- the tile's ordinary pin.
+-- `when_below` is the mirror, and it exists because ABOVE is not always the
+-- side that tells the two uses apart.  The Plateau's $0D is the case: it is
+-- the gate wall's top band AND the base course under a column of rock face,
+-- and scanned over both maps the tile above is $03 for 64 of the first and
+-- 140 of the second -- no rule on `above` can split them.  What is BELOW
+-- does, exactly: the wall's own face $0F sits under the top band and under
+-- nothing else (336 vs 352, clean).
 local function authoredConditions(tilesetId, heights)
   local s = load()
   local entry = s and s.tilesets and s.tilesets[tilesetId]
-  local spec = entry and entry.when_above
-  if type(spec) ~= "table" then return nil end
+  if type(entry) ~= "table" then return nil end
   local out, any = {}, false
-  for tile, rules in pairs(spec) do
-    if type(tile) == "number" and type(rules) == "table" then
-      local list = {}
-      for _, rule in ipairs(rules) do
-        if type(rule) == "table" and heights[rule.class]
-           and type(rule.above) == "table" then
-          local set = {}
-          for _, t in ipairs(rule.above) do set[t] = true end
-          list[#list + 1] = { above = set, class = rule.class }
+
+  local function collect(spec, side)
+    if type(spec) ~= "table" then return end
+    for tile, rules in pairs(spec) do
+      if type(tile) == "number" and type(rules) == "table" then
+        local list = out[tile] or {}
+        for _, rule in ipairs(rules) do
+          if type(rule) == "table" and heights[rule.class]
+             and type(rule[side]) == "table" then
+            local set = {}
+            for _, t in ipairs(rule[side]) do set[t] = true end
+            list[#list + 1] = { side = side, set = set, class = rule.class }
+          end
+        end
+        if #list > 0 then
+          out[tile] = list
+          any = true
         end
-      end
-      if #list > 0 then
-        out[tile] = list
-        any = true
       end
     end
   end
+
+  collect(entry.when_above, "above")
+  collect(entry.when_below, "below")
   return any and out or nil
 end
 
@@ -273,6 +340,24 @@ function TileShape.forMap(map)
   if cache[id] then return cache[id] end
 
   local heights = TileShape.heights()
+  -- Per-tileset height overrides (a tileset entry's `heights`): the class
+  -- vocabulary is global but the drawings are not -- the DOJO lab tables
+  -- are drawn 6px tall where the default `table` is 12 -- and the height
+  -- a sprite RIDES at (VoxelScene.groundAt) must be the height the art
+  -- actually stands, or the starter balls float over their own table.
+  -- Same gate as the global list: known classes, numbers only.
+  do
+    local s = load()
+    local entry = s and s.tilesets and s.tilesets[id]
+    local over = entry and entry.heights
+    if type(over) == "table" then
+      for class, h in pairs(over) do
+        if type(h) == "number" and FALLBACK_HEIGHTS[class] then
+          heights[class] = h
+        end
+      end
+    end
+  end
   local authored = authoredGroups(id, heights)
   local count = math.floor((tileset.imageWidth or 128) / 8)
                 * math.floor((tileset.imageHeight or 48) / 8)
@@ -348,9 +433,12 @@ function TileShape.at(map, shapes, tile, tx, ty)
   -- tile and the cell rules below (see authoredConditions)
   local rules = shapes.cond and shapes.cond[tile]
   if rules then
-    local above = map:tileAt(tx, ty - 1)
     for _, rule in ipairs(rules) do
-      if above and rule.above[above] then
+      -- NOTE map:tileAt border-EXTENDS: one row off an edge answers the
+      -- map's borderBlock, never nil.  A rule listing whatever that block
+      -- draws will fire along that whole edge (it did, on the Marts).
+      local n = map:tileAt(tx, rule.side == "above" and ty - 1 or ty + 1)
+      if n and rule.set[n] then
         -- shapes.condShape, NOT shapes.classes: the canonical class
         -- shapes are SHARED, and `wall` in particular is the very object
         -- rule 4 hands every unauthored solid tile. Marking that one
@@ -369,11 +457,266 @@ function TileShape.at(map, shapes, tile, tx, ty)
   return s
 end
 
+-- Hand-authored FIGURES for one tileset: a drawing painted INTO furniture,
+-- cut out by an explicit pixel mask and stood up on top of it.
+--
+-- Every other route in this file resolves a whole 8x8 TILE, which is
+-- exactly why none of them can reach a figure that shares its tiles with
+-- the thing it sits on -- and the detector's segmentation cannot either
+-- when the drawing has no background margin to flood from and wears the
+-- same shades as its furniture.  So the profile authors the silhouette
+-- pixel by pixel (see data/voxel_heights.lua):
+--
+--   figures = { { w      = <tiles across>,
+--                 depth  = <voxels of body; ABSENT for a person>,
+--                 thin   = { rows = <top rows>, depth = <voxels> },
+--                 flat   = { x = { <lx0>, <lx1> }, rows = { <r0>, <r1> } },
+--                 tiles  = { ...w*h tile ids, row-major... },
+--                 under  = { ...w*h ids: what each tile wears once the
+--                            figure is lifted off it... },
+--                 pixels = { ...h*8 strings of w*8 chars, "." = not the
+--                            figure... } } }
+--
+-- No class -- what the entry carries instead is a `depth`, or does not:
+--
+--   WITHOUT one it is a flat sprite card, drawn the way SpriteBillboards
+--   draws a character.  That is the right reading for a PERSON: a Gen 1
+--   figure is a face-on 2D icon, and extruding one reconstructs a body
+--   nobody drew (see Structures.buildFigures).
+--   WITH one it is an OBJECT and gets the standee treatment every other
+--   solid here gets -- a per-pixel slab in world space, standing on the
+--   same furniture the card would have stood on.  The Marts' cash
+--   register is the case: a machine on a counter is a box, not an icon.
+--
+-- Two fields say which parts of such a drawing are NOT the extrusion,
+-- because a solid drawn in one 16x16 GB cell still packs more than one
+-- facing:
+--
+--   `thin` caps the thickness over the mask's top rows, for the part of
+--   the drawing that is not the machine (the register's receipt curl).
+--   `flat` names a rect of the mask that is a TOP-VIEW surface rather
+--   than a face -- the register's keypad, whose keys lie ON its deck.
+--   The rect lays horizontal one voxel proud of whatever the extrusion
+--   leaves below it, at the elevation its BOTTOM row would have had,
+--   with drawn row = depth row 1:1 (the mapping the lab tabletop is
+--   drawn with).  So a drawing whose front elevation is an L reads as
+--   one: body up the side and along the base, keys lying in the notch.
+--
+-- Returned normalized: `mask` as a set keyed by ly * (w * 8) + lx, so
+-- Structures can read it as a bitmap without re-parsing per position.
+-- A malformed entry is dropped rather than half-applied -- a typo in a
+-- mask should leave the couch alone, not carve a hole in it.
+--
+-- `mounted` (below) carries the same four fields, so the parse is shared,
+-- and so are the optional ones that give an authored mask a BODY: `depth`,
+-- `thin` and `flat` above.  `depth` is left nil when unstated, because
+-- absence is meaningful on a figure: no depth means the flat sprite card a
+-- person is drawn as.
+local function authoredMasks(list)
+  local out = {}
+  if type(list) ~= "table" then return out end
+  for _, f in ipairs(list) do
+    local ok = type(f) == "table" and type(f.w) == "number"
+               and type(f.tiles) == "table" and type(f.under) == "table"
+               and type(f.pixels) == "table"
+    local w = ok and math.floor(f.w) or 0
+    local h = (w >= 1) and (#f.tiles / w) or 0
+    ok = ok and w >= 1 and h >= 1 and h == math.floor(h)
+         and #f.under == #f.tiles and #f.pixels == h * 8
+    if ok then
+      for i = 1, h * 8 do
+        local row = f.pixels[i]
+        if type(row) ~= "string" or #row ~= w * 8 then
+          ok = false
+          break
+        end
+      end
+    end
+    if ok then
+      local mask, n = {}, 0
+      for ly = 0, h * 8 - 1 do
+        local row = f.pixels[ly + 1]
+        for lx = 0, w * 8 - 1 do
+          if row:sub(lx + 1, lx + 1) ~= "." then
+            mask[ly * (w * 8) + lx] = true
+            n = n + 1
+          end
+        end
+      end
+      local depth = tonumber(f.depth)
+      local thin = nil
+      if type(f.thin) == "table" and tonumber(f.thin.rows)
+         and tonumber(f.thin.depth) then
+        thin = { rows = math.floor(tonumber(f.thin.rows)),
+                 depth = math.floor(tonumber(f.thin.depth)) }
+      end
+      local flat = nil
+      if type(f.flat) == "table" and type(f.flat.x) == "table"
+         and type(f.flat.rows) == "table" then
+        flat = { x0 = math.floor(f.flat.x[1]), x1 = math.floor(f.flat.x[2]),
+                 r0 = math.floor(f.flat.rows[1]),
+                 r1 = math.floor(f.flat.rows[2]) }
+      end
+      if n > 0 then
+        out[#out + 1] = { w = w, h = h, n = n, mask = mask,
+                          tiles = f.tiles, under = f.under,
+                          depth = depth and math.floor(depth) or nil,
+                          thin = thin, flat = flat }
+      end
+    end
+  end
+  return out
+end
+
+function TileShape.figures(tilesetId)
+  local hit = figCache[tilesetId]
+  if hit ~= nil then return hit or nil end
+
+  local s = load()
+  local entry = s and s.tilesets and s.tilesets[tilesetId]
+  local out = authoredMasks(entry and entry.figures)
+
+  figCache[tilesetId] = (#out > 0) and out or false
+  return figCache[tilesetId] or nil
+end
+
+-- Hand-authored MOUNTED objects for one tileset: a thing drawn INTO the
+-- wall band it hangs on, cut out by an explicit pixel mask and stood
+-- proud of the wall's face.
+--
+-- Same authoring problem as `figures` and the same answer -- a class pin
+-- resolves a whole 8x8 tile, and the detector cannot segment a drawing
+-- that has no background margin to flood from.  The Bike Shop's two wall
+-- bicycles are the case: the shop's striped wall panel runs BEHIND them,
+-- and its #555 stripes are a flood boundary, so a silhouette flood comes
+-- back with the stripes attached to the bike.
+--
+-- Two things differ from a figure, and both follow from the object being
+-- an object rather than a character:
+--
+--   it keeps its DRAWN ELEVATION.  A figure stands on its own feet; a
+--   mounted thing sits where the wall band draws it, so a bicycle hung
+--   clear of the floor stays hung.
+--   it has THICKNESS (`depth`, default 2), and it is built in world
+--   space as a per-pixel slab jutting south of the band -- not as a
+--   camera-facing sprite card.  A bicycle drawn side-on is a plane
+--   parallel to the wall, not a face-on icon.
+--
+--   mounted = { { w      = <tiles across>,
+--                 depth  = <voxels it juts into the room>,
+--                 tiles  = { ...w*h tile ids, row-major... },
+--                 under  = { ...w*h ids: what each tile wears once the
+--                            object is lifted off it (the plain panel)... },
+--                 pixels = { ...h*8 strings of w*8 chars, "." = wall... } } }
+function TileShape.mounted(tilesetId)
+  local hit = mntCache[tilesetId]
+  if hit ~= nil then return hit or nil end
+
+  local s = load()
+  local entry = s and s.tilesets and s.tilesets[tilesetId]
+  local out = authoredMasks(entry and entry.mounted)
+
+  mntCache[tilesetId] = (#out > 0) and out or false
+  return mntCache[tilesetId] or nil
+end
+
+-- Which GB shades count as BACKGROUND for a pinned per-pixel prop, per tile
+-- (a tileset entry's prop_bg). Returns tile id -> set of shade names, or nil.
+--
+-- Structures normally votes on this by reading the shades that touch the
+-- drawing's own bounding box, which is right whenever the drawing has a
+-- margin of floor around it and wrong when it does not: a prop whose body
+-- reaches its own edge votes itself out. Naming the shades is the override,
+-- and it is keyed by TILE because the answer is per drawing rather than per
+-- tileset -- two props in one atlas can want opposite calls on the same
+-- shade (see the POKECENTER entry).
+--
+--   prop_bg = { { tiles = { ...ids... }, shades = { "light", "white" } } }
+--
+-- Only the four GB shade names exist; anything else is dropped, so a typo
+-- degrades to the ordinary vote rather than emptying the background.
+local SHADES = { black = true, dark = true, light = true, white = true }
+
+function TileShape.propBg(tilesetId)
+  local hit = bgCache[tilesetId]
+  if hit ~= nil then return hit or nil end
+
+  local s = load()
+  local entry = s and s.tilesets and s.tilesets[tilesetId]
+  local list = entry and entry.prop_bg
+  local out, any = {}, false
+  if type(list) == "table" then
+    for _, rule in ipairs(list) do
+      if type(rule) == "table" and type(rule.tiles) == "table"
+         and type(rule.shades) == "table" then
+        local set, n = {}, 0
+        for _, name in ipairs(rule.shades) do
+          if SHADES[name] then
+            set[name] = true
+            n = n + 1
+          end
+        end
+        if n > 0 then
+          for _, t in ipairs(rule.tiles) do
+            if type(t) == "number" then
+              out[t] = set
+              any = true
+            end
+          end
+        end
+      end
+    end
+  end
+
+  bgCache[tilesetId] = any and out or false
+  return bgCache[tilesetId] or nil
+end
+
+-- What a bookcase rank does with the rows it VACATES -- the ones behind the
+-- one-cell-deep box it collapses onto (a tileset entry's
+-- bookcase_backfill).  Returns the mode name, or nil for the default.
+--
+--   "above"   hand them the cell immediately above the run: its shape and
+--             its art.  A wall set INTO a terrace wants this -- the ground
+--             behind it is more terrace, not a trench.
+--   nil       skip them and paint the map's commonest ground underneath,
+--             which is right for a free-standing shelf against a wall.
+--
+-- Per tileset because it is a statement about what the drawing depicts, and
+-- the answer differs: the Mart's racks and Red's shelves stand in a room,
+-- the Plateau's gate walls are cut into a hillside.
+function TileShape.bookcaseBackfill(tilesetId)
+  local s = load()
+  local entry = s and s.tilesets and s.tilesets[tilesetId]
+  local mode = entry and entry.bookcase_backfill
+  return mode == "above" and mode or nil
+end
+
+--- Does this tileset's `bookcase` run carry the measured pane RELIEF on
+--- its front (a tileset entry's bookcase_relief)?  Default yes: the class
+--- almost always collapses a shelf, a rack or a display case, and every
+--- one of those seals its contents behind a frame that should stand proud
+--- of them.
+---
+--- A tileset says `bookcase_relief = false` when it borrows the collapse
+--- for something that is NOT a shelf -- the League's gate walls and
+--- pilasters, Bill's transporter drums -- where the drawing's light
+--- regions are the masonry and the barrel, not panes, and sinking them
+--- carves the surface instead of describing it.
+function TileShape.bookcaseRelief(tilesetId)
+  local s = load()
+  local entry = s and s.tilesets and s.tilesets[tilesetId]
+  return not (entry and entry.bookcase_relief == false)
+end
+
 -- Drop the cache: a mod that shadows data/voxel_heights.lua or a tileset
 -- record needs the next lookup to re-resolve (hot reload, mod toggle).
 function TileShape.invalidate()
   spec = nil
   cache = {}
+  figCache = {}
+  mntCache = {}
+  bgCache = {}
 end
 
 return TileShape

lib/TiltShift.lua

@@ -25,6 +25,7 @@
 -- failure -- headless, no shader support) apply() hands the canvas back
 -- untouched, so every other path is byte-for-byte what it always was.
 
+local V = ...
 local TiltShift = {}
 
 TiltShift.level = 0
@@ -85,9 +86,10 @@ end
 
 local function getCanvases(w, h)
   if not ping or cw ~= w or ch ~= h then
-    local ok, a = pcall(love.graphics.newCanvas, w, h)
+    local PixelCanvas = V.require("PixelCanvas")
+    local ok, a = PixelCanvas.new(w, h)
     if not ok then return nil end
-    local okB, b = pcall(love.graphics.newCanvas, w, h)
+    local okB, b = PixelCanvas.new(w, h)
     if not okB then return nil end
     -- the gaussian's fractional tap offsets need linear filtering
     a:setFilter("linear", "linear")

lib/VR.lua

@@ -0,0 +1,987 @@
+-- VR: the conductor -- one call per game frame that runs the whole
+-- headset side, and the row that switches it on.
+--
+-- The shape of a VR frame, from the pipeline's update hook (which ticks
+-- every frame whatever is on the stack, which is exactly what a headset
+-- needs -- the world must keep arriving through menus, dialogs and
+-- battles):
+--
+--   poll the runtime's events (begin the session when it says READY)
+--   xrWaitFrame            <- BLOCKS until the headset wants a frame;
+--                             with vsync handed off (set to 0 while the
+--                             session runs) this is what paces the whole
+--                             app at headset rate, while FixedStep keeps
+--                             the game's own logic at its 60 Hz
+--   locate the two eyes
+--   render the world once per eye (VoxelScene.render's `eyes` path:
+--     shared shadow map, shared pose capture, per-eye cameras from VRRig)
+--   blit each eye canvas into its swapchain image (VRGL)
+--   copy the window's front buffer into the UI quad when a menu, dialog,
+--     battle or wipe is what the flat screen is showing
+--   xrEndFrame with the projection layer and/or the quad
+--
+-- WHICH VR YOU GET is the row's own rung first (see VR.setting), and only
+-- then the VOXEL ladder. STANDARD is the mode described below. The two
+-- DIORAMA rungs are one presentation instead of a ladder -- the world is
+-- always a model on the table, cut to a square viewport (a ball with a
+-- dissolved rim while V-CURVE is on) that the grips pick up, turn and
+-- open out, with a staged fight arriving as a floating disc of map.
+-- lib/Diorama owns all of that; what this file owns is pointing the
+-- mapping at it. DIORAMA-MR is the same with the background keyed green
+-- for a mixed-reality capture.
+--
+-- Within STANDARD, which VR you get mirrors the VOXEL ladder: on the orbit
+-- rungs the world is a TABLETOP DIORAMA pinned below and ahead of where
+-- your head started -- lean in, walk around it; on 1ST you stand inside
+-- at life scale, the HMD steers FirstPerson's yaw and pitch, and FreeMove
+-- walks where you look exactly as it does on the flat screen. A STAGED
+-- FIGHT takes the camera from both: the headset snaps -- through a fade
+-- to black and back -- to the flat battle's own over-the-shoulder seat
+-- (VRRig.battleMount), and returns the same way when the fight ends;
+-- the 2D battle screen lights up on the POKEDEX in the tracked left
+-- hand (lib/Pokedex.lua) and NO floating panel is submitted at all --
+-- the fight itself owns the view. The flat window keeps
+-- running as the mirror (left eye when the world is up), so menus stay
+-- usable at the desk and every existing input keeps working alongside
+-- the XR controllers.
+--
+-- Failure is a status, never a crash: no runtime, no headset, no GL
+-- interop, or a mid-session loss all land back on the flat screen with
+-- the reason readable off VR.status().
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local ModSetting = V.require("ModSetting")
+local Voxel = V.require("VoxelState")
+local Voxel3D = V.require("Voxel3D")
+local VoxelScene = V.require("VoxelScene")
+local FirstPerson = V.require("FirstPerson")
+local BattleCam = V.require("BattleCam")
+local VRRig = V.require("VRRig")
+local VRXR = V.require("VRXR")
+local VRGL = V.require("VRGL")
+local Pokedex = V.require("Pokedex")
+local Diorama = V.require("Diorama")
+
+local VR = {}
+
+-- The row: OFF, and then WHICH VR. No hotkey -- the engine's display keys
+-- are spoken for, and a headset is not something to toggle by accident.
+--
+--   STANDARD     what this mod shipped: the headset follows the VOXEL
+--                ladder, orbit rungs becoming a tabletop and 1ST standing
+--                you inside the world at life size.
+--   DIORAMA      one presentation instead of a ladder -- the world is
+--                always a model on the table, cut to a viewport you can
+--                pick up, turn and open out (see lib/Diorama). There is no
+--                2D and no first person in it: both are a different promise
+--                about where the player is standing.
+--   DIORAMA-MR   the same, with the background keyed pure green for a
+--                mixed-reality capture.
+--
+-- `true` is still STANDARD's stored value, deliberately: the row used to be
+-- a toggle, and a save that stored it as one must come back on the rung it
+-- was left on rather than falling to OFF.
+VR.setting = ModSetting.new("vr", "VR",
+                            { false, true, "diorama", "diorama-mr" },
+                            { "OFF", "STANDARD", "DIORAMA", "DIORAMA-MR" })
+
+-- How the right stick turns you in first person. OFF is the 45-degree
+-- SNAP this mod shipped with and the reason for it is comfort, not
+-- taste: a software turn moves the world past a head that did not move,
+-- which is vection with no vestibular signal to match it, and it is the
+-- single most reliable way to make somebody ill in a headset. A snap
+-- gives the inner ear nothing to disagree with.
+--
+-- But snap turning is not free either -- it costs continuity, and the
+-- players who have their sea legs generally want the stick. So it is a
+-- row rather than a decision: OFF by default, on for anyone who asks,
+-- and the row only exists while there is a headset to use it in.
+VR.smoothTurn = ModSetting.new("smoothturn", "SMOOTH TURN",
+                               { false, true }, { "OFF", "ON" })
+
+-- radians per second at full deflection, with a squared response so the
+-- first half of the throw aims and the rest turns -- the same curve
+-- FirstPerson gives the flat screen's right stick
+VR.SMOOTH_TURN_RATE = 2.2
+
+-- Where the diorama's UI panel floats vs first person's. These are the
+-- FALLBACK screens: wherever the pokedex is up and lit -- first
+-- person's menus, a battle's 2D scene -- no quad is submitted at all
+-- (see updateQuad), and these serve only the diorama and the no-tracked-
+-- controller case.
+local QUAD_DIORAMA = { pos = { 0, 0.1, -1.0 }, width = 0.8 }
+local QUAD_FP = { pos = { 0, 0, -1.4 }, width = 1.1 }
+
+local started = false           -- start() succeeded this enablement
+local failed = nil              -- start() failed; wait for a re-toggle
+local wasOn = false
+local savedVsync = nil
+local fboCache = setmetatable({}, { __mode = "k" })   -- canvas -> GL FBO id
+local mirrorSrc = nil           -- last left-eye canvas, for the window
+local mirrorCanvas = nil
+local status = "off"
+
+-- the diorama's live adjustments: the right stick's zoom (a multiplier on
+-- the model's size) and the grab-drag's height (metres of world travel)
+local zoom = 1
+local heightOff = 0
+local held = {}                 -- GB buttons this module is holding down
+local lastHandY = nil           -- the gripping hand's height, last frame
+
+-- First person's SNAP TURN: the right stick flicked left or right steps
+-- the whole XR-to-world mapping 45 degrees at a time (a smooth software
+-- turn is the classic comfort mistake -- vection with no vestibular
+-- signal; a snap is instant and the head does the rest). The offset
+-- turns the mapping itself, so the eyes, the walk direction and the
+-- pokedex all agree about which way the world now faces.
+local SNAP_TURN = math.rad(45)
+local fpYawOff = 0              -- accumulated snaps, radians
+local snapArmed = true          -- re-arms when the stick returns to centre
+
+local function wrapPi(a)
+  return (a + math.pi) % (2 * math.pi) - math.pi
+end
+
+-- The battle snap, made a FADE rather than a cut: when a fight is staged
+-- on the world (or stops being), black rises over both eyes, the camera
+-- swaps mounts behind it, and black lifts. A teleport inside VR is the
+-- one camera move that should never be SEEN happening -- the world
+-- sliding to a new seat reads as the room moving.
+local FADE_TIME = 0.35          -- seconds each way: out, then back in
+local camMode = "explore"       -- "explore" (diorama / 1ST) or "battle"
+local fadeAlpha = 0             -- the black over the eyes right now
+
+-- The staged fight to look at, if there is one: arena, floor height.
+local function battleStage()
+  local ok, arena, groundY = pcall(function()
+    return V.require("OverworldBattle").stage()
+  end)
+  if not ok then return nil end
+  return arena, groundY
+end
+
+-- the palette closure the engine hands drawWorld; stashed there (see
+-- main.lua) because the VR frame renders from update, where no ctx exists
+VR.paletteFor = nil
+
+-- Whether this platform can do VR AT ALL: the shipped loader and the GL
+-- interop are Win32 (openxr_loader.dll, wgl), so only Windows qualifies.
+-- Everywhere else -- Android above all -- the row is not offered on any
+-- menu, and a stored vr=true is ignored rather than read: a save that
+-- migrated over from the desktop must not leave a phone trying to start
+-- an OpenXR session (or silently forcing the battle rows). Headless runs
+-- have no love.system and answer true, which costs nothing: enabling VR
+-- there stops at VRXR.start like it always did.
+function VR.supported()
+  local ok, os = pcall(function() return love.system.getOS() end)
+  if not ok or not os then return true end
+  return os == "Windows"
+end
+
+-- Which VR the row is asking for: "off", "standard", "diorama" or
+-- "diorama-mr". The one place the stored value is interpreted -- everything
+-- else asks this, so a rung added to the ladder is a change here and
+-- nowhere else.
+function VR.mode()
+  if not VR.supported() then return "off" end
+  local v = VR.setting:get()
+  if v == true then return "standard" end
+  if v == "diorama" or v == "diorama-mr" then return v end
+  return "off"
+end
+
+function VR.enabled()
+  return VR.mode() ~= "off"
+end
+
+-- Whether the row is on one of the DIORAMA rungs -- the modes where the
+-- world is a model with an edge to it rather than a place to stand in.
+function VR.dioramaMode()
+  local m = VR.mode()
+  return m == "diorama" or m == "diorama-mr"
+end
+
+function VR.active()
+  return started and VRXR.isRunning()
+end
+
+function VR.status()
+  if not VR.enabled() then return "off" end
+  if failed then return failed end
+  return VRXR.status()
+end
+
+-- Let go of every input this module was holding: the GB buttons pressed
+-- through the overlay path, and the synthetic left stick. Runs when the
+-- session ends and whenever a frame has no controller state to read.
+local function releaseInputs()
+  local ok, Game = pcall(require, "src.core.Game")
+  if not ok or not Game.input then return end
+  for btn in pairs(held) do
+    pcall(function() Game.input:overlayReleased(btn) end)
+    held[btn] = nil
+  end
+  pcall(function()
+    Game.input:gamepadaxis(nil, "leftx", 0)
+    Game.input:gamepadaxis(nil, "lefty", 0)
+  end)
+  lastHandY = nil
+end
+
+local function shutdown(reason)
+  if started then
+    VRXR.stop()
+    started = false
+  end
+  if savedVsync ~= nil then
+    pcall(love.window.setVSync, savedVsync)
+    savedVsync = nil
+  end
+  -- the placed camera may still be a VR eye's; the orbit must get the
+  -- pass back clean
+  Voxel3D.camera = nil
+  mirrorSrc = nil
+  releaseInputs()
+  BattleCam.still = false
+  VoxelScene.spriteLean = nil
+  Pokedex.clear()
+  -- the horde's gun too: its VR frame is a matrix built from a hand pose,
+  -- and a stale one left behind would pin the model to wherever the
+  -- controller was when the session died -- on the FLAT screen, where the
+  -- view model should have taken over
+  V.require("HordeGun").clear()
+  zoom, heightOff = 1, 0
+  fpYawOff, snapArmed = 0, true
+  camMode, fadeAlpha = "explore", 0
+  -- the model goes back on the table where it started: the grab, the turn,
+  -- the viewport's size and the meshes cut for it
+  Diorama.reset()
+  status = reason or "off"
+end
+
+VR.shutdown = shutdown          -- named for the probe driver
+
+-- Whether the flat screen is showing something the world pass cannot: a
+-- menu, a dialog, a battle, a transition wipe. The quad and the pokedex's
+-- screen both key on it.
+local function uiShowing()
+  local ok, showing = pcall(function()
+    local Game = require("src.core.Game")
+    local top = Game.stack and Game.stack:top()
+    return top ~= Game.overworld
+           or (Game.overworld and Game.overworld.transitioning) or false
+  end)
+  return ok and showing or false
+end
+
+-- ------- the pokedex's screen
+--
+-- What the device in the hand shows during a battle: the flat window --
+-- which IS the 2D battle screen for as long as the battle state draws --
+-- copied into a canvas the scene pass can texture with, cropped by UV to
+-- the battle's own letterbox so the screen wears the GB frame edge to
+-- edge. Menus over the battle (the party, the bag) ride along for free:
+-- they are the flat screen too, and reading them on the device in your
+-- hand is exactly the point.
+local dexCanvas = nil
+
+local function dexScreen()
+  local ok, out = pcall(function()
+    local ww, wh = love.graphics.getPixelDimensions()
+    if not (ww and ww > 0 and wh and wh > 0) then return nil end
+    if not (dexCanvas and dexCanvas:getWidth() == ww
+            and dexCanvas:getHeight() == wh) then
+      dexCanvas = love.graphics.newCanvas(ww, wh)
+      pcall(dexCanvas.setFilter, dexCanvas, "nearest", "nearest")
+    end
+    local fbo = fboCache[dexCanvas]
+    if not fbo then
+      fbo = VRGL.canvasFBO(dexCanvas)
+      fboCache[dexCanvas] = fbo
+    end
+    if not (fbo and VRGL.copyFrontToCanvas(fbo, ww, wh)) then return nil end
+    local BattleScene = V.require("BattleScene")
+    local lx, ly, s = BattleScene.letterbox()
+    return { dexCanvas,
+             lx / ww, ly / wh,
+             (lx + BattleScene.GB_W * s) / ww,
+             (ly + BattleScene.GB_H * s) / wh }
+  end)
+  return ok and out or nil
+end
+
+-- ------- the world, once per eye
+
+local function renderWorld(views, ctl)
+  local ok, Game = pcall(require, "src.core.Game")
+  local ow = ok and Game.overworld or nil
+  if not (ow and ow.map and ow.camera and Voxel.active()
+          and Voxel3D.available()) then
+    return false
+  end
+  local vw, vh = 320, 288
+  pcall(function() vw, vh = Game.renderer:worldViewSize() end)
+
+  -- Whatever the camera does, the CARDS hold the top rung's near-upright
+  -- lean: a head that roams has no one pitch for them to match, and 75
+  -- degrees is the pose that reads as "standing" from anywhere. Cleared
+  -- on shutdown, so the flat screen leans with the rung as ever.
+  VoxelScene.spriteLean = math.rad(75)
+
+  local pivot, anchor, scale, mountYaw
+  -- Either free-roam rung puts the headset in the player's head: 3RD's boom
+  -- is a FLAT-SCREEN framing device, and a headset that stands its wearer
+  -- three cells behind their own body is a well-known way to make people
+  -- ill. The rung still changes the walk and the cards the same way; only
+  -- the eye stays where a head belongs.
+  --
+  -- A DIORAMA mode never does either: the world is a model on the table
+  -- whatever the rung says, so first person is refused here rather than
+  -- being made to work at a scale it does not mean.
+  local dio = VR.dioramaMode()
+  local fp = (not dio) and FirstPerson.engaged()
+  local battle, battleFloor
+  if camMode == "battle" then battle, battleFloor = battleStage() end
+  if dio then
+    -- ------- the diorama modes
+    --
+    -- The model presents exactly as the standard view frames it -- the
+    -- pivot VIEW_DIST away along the rung's angle, at the scale that
+    -- reproduces that framing -- and then everything the player has done
+    -- to it goes on top: the carry, the turn, the stick's zoom.
+    --
+    -- A STAGED FIGHT does not move the head here (that is the standard
+    -- mode's over-the-shoulder seat, and it is a first-person answer):
+    -- the MODEL re-centres on the arena and the viewport becomes a
+    -- vertical pillar about it, so the fight arrives as a disc of map
+    -- lifted out of the world and left floating on the table.
+    -- what the model is FRAMED to fill: the view the flat screen would
+    -- have shown ordinarily, and the DISC itself while a fight is staged
+    -- -- a disc left at map scale is a coin on a table across the room.
+    local frame = vh
+    if battle then
+      pivot = VRRig.dioramaPivot(battle.mid[1], battle.mid[2])
+      local cut = Diorama.pillar(battle)
+      if cut then frame = cut.r * 2.6 end
+    else
+      pivot = VRRig.dioramaPivot(ow.camera.x + vw / 2, ow.camera.y + vh / 2)
+      Diorama.viewport(pivot[1], pivot[3], vh)
+    end
+    anchor = VRRig.dioramaAnchor(Voxel.angle, Diorama.offset)
+    scale = VRRig.dioramaScale(frame, Voxel.FOCAL) / zoom
+    -- the hand-turn, and -- while a fight is staged -- the arena's own
+    -- quarter turn taken back out, so a turned arena arrives on the table
+    -- facing the head rather than lying across it (Diorama.battleYaw)
+    local dioYaw = battle and Diorama.battleYaw(battle) or Diorama.yaw
+    if dioYaw ~= 0 then mountYaw = dioYaw end
+  elseif battle then
+    -- the over-the-shoulder seat the flat battle shot stands in, pulled
+    -- close enough for a headset's own lens (see VRRig.battleMount), at
+    -- life scale, turned to face the arena
+    local rec = BattleCam.rig(battle, battleFloor)
+    pivot, mountYaw = VRRig.battleMount(rec.eye, rec.focus)
+    anchor = { 0, 0, 0 }
+    scale = VRRig.FP_SCALE
+  elseif fp then
+    local p = ow.player
+    local gh = 0
+    pcall(function() gh = VoxelScene.groundAt(ow.map, p.cellX, p.cellY) end)
+    pivot = VRRig.fpPivot(p.px, p.py, gh, FirstPerson.EYE_HEIGHT)
+    anchor = { 0, 0, 0 }
+    scale = VRRig.FP_SCALE
+    -- the snap turn is a yaw on the MAPPING, same seam the battle mount
+    -- turns through
+    if fpYawOff ~= 0 then mountYaw = fpYawOff end
+    -- the HMD is the head: its yaw and pitch (plus the snaps) become
+    -- FirstPerson's, so FreeMove walks where you look and A talks to
+    -- what you face
+    local yaw, pitch = VRRig.headYawPitch(views[1].pose.quat)
+    FirstPerson.yaw = wrapPi(yaw + fpYawOff)
+    FirstPerson.pitch = math.max(FirstPerson.PITCH_UP,
+                          math.min(FirstPerson.PITCH_DOWN, pitch))
+  else
+    -- The table presents the world exactly as the flat screen does at
+    -- rest: the pivot sits VIEW_DIST away along the RUNG'S own angle
+    -- (stepping rungs re-tilts the model, easing with the rung tween),
+    -- at the scale that reproduces the flat framing -- then the player's
+    -- own adjustments go on top: the stick's zoom, the grip's height.
+    pivot = VRRig.dioramaPivot(ow.camera.x + vw / 2, ow.camera.y + vh / 2)
+    anchor = VRRig.dioramaAnchor(Voxel.angle, heightOff)
+    scale = VRRig.dioramaScale(vh, Voxel.FOCAL) / zoom
+  end
+
+  -- The pokedex, on the tracked left hand, under this very mapping --
+  -- but only where it earns its keep: FIRST PERSON, where its screen is
+  -- every menu, dialog and wipe the flat screen shows (and the floating
+  -- billboard is retired outright -- see updateQuad), and the BATTLE
+  -- seat, where its screen is the fight's own 2D scene. The diorama
+  -- does without: a hand-sized device hovering over a tabletop town is
+  -- clutter, and the panel serves there. No hand tracked, no device.
+  -- (`not dio` for the same reason the diorama never had one: a hand-sized
+  -- device hovering over a tabletop town is clutter, and that is as true
+  -- of a tabletop FIGHT -- the panel serves both.)
+  local hand = ctl and ctl.handl or nil
+  if hand and not dio and (battle or fp) then
+    Pokedex.place(hand, pivot, anchor, scale, mountYaw)
+    if uiShowing() then
+      local scr = dexScreen()
+      if scr then
+        Pokedex.screen(scr[1], scr[2], scr[3], scr[4], scr[5])
+      end
+    elseif V.require("Horde").active then
+      -- HORDE MODE's readout, on the device already in the player's left
+      -- hand. It cannot be a flat overlay: the eye buffers have
+      -- ASYMMETRIC frusta, so the same canvas pixel is a different ANGLE
+      -- in each eye and a 2D HUD drawn into both tears down the middle.
+      -- The Pokedex is real geometry both eyes see from their own
+      -- position, so the stereo is correct by construction -- and it is
+      -- already tracked, already lit, and already the thing this mod
+      -- puts information on. (The gun wore it briefly and that was
+      -- worse: a screen on the slide sits exactly where the iron sights
+      -- need to be looked through.)
+      --
+      -- The UV rect goes over the usual way up: v = 0 at the TOP, which
+      -- is how the device's screen quad reads every other texture it
+      -- wears. An inverted rect was tried first, on the theory that a
+      -- self-drawn canvas samples from the bottom -- it does not here,
+      -- and it stood the readout on its head.
+      local tex = V.require("HordeHud").panelTexture()
+      if tex then Pokedex.screen(tex, 0, 0, 1, 1) end
+    end
+  else
+    Pokedex.clear()
+  end
+
+  -- and the horde's gun on the tracked RIGHT hand, under the same
+  -- mapping. The AIM pose where the runtime offers one -- the barrel
+  -- should point where the player is pointing, not along their wrist --
+  -- and the grip pose as the fallback. Placed here rather than in the
+  -- draw because the shot is traced down the model's own axis, so the
+  -- matrix has to exist before anything can be hit with it.
+  do
+    local HordeGun = V.require("HordeGun")
+    local right = ctl and (ctl.aimr or ctl.handr) or nil
+    if right and fp and not battle and V.require("Horde").active then
+      HordeGun.place(right, pivot, anchor, scale, mountYaw)
+    else
+      HordeGun.clear()
+    end
+  end
+
+  -- THE WORLD CURVE, for the diorama modes alone. Standing inside a bent
+  -- world is what first person declines on the flat screen too, and the
+  -- battle mount is a placed shot -- but a diorama is a model being looked
+  -- AT, so the bend turns it into a little globe curling over its own
+  -- horizon, which is the whole point of the throw the left stick's click
+  -- makes. Measured against the FLAT view height, so a rung's bend is the
+  -- same bend the flat screen would have drawn.
+  --
+  -- It bends about the scene centre, which for these eyes is the pivot --
+  -- the model's own middle -- so the globe is centred on the model rather
+  -- than on wherever a head happens to be standing.
+  local curveK = dio and V.require("WorldCurve").k(vh) or 0
+
+  local eyes = {}
+  for i = 1, 2 do
+    local v = views[i]
+    eyes[i] = {
+      camera = VRRig.eyeCamera(v.pose, v.fov, pivot, anchor, scale, mountYaw,
+                               curveK),
+      w = v.w, h = v.h,
+      slot = i == 1 and "vrL" or "vrR",
+      -- the battle seat is a placed shot, not the first-person rig: the
+      -- cards keep their stage lean rather than yawing at this eye, and
+      -- the player's own card stays visible in it
+      adopt = not battle,
+    }
+  end
+  eyes.cx, eyes.cy = pivot[1], pivot[3]
+
+  local okR, canvases = pcall(VoxelScene.render, ow, 0, 0, vw, vh,
+                              VR.paletteFor, eyes)
+  if not (okR and type(canvases) == "table" and canvases[1] and canvases[2])
+  then
+    return false
+  end
+
+  -- the snap's fade, over the finished eyes: plain black at this moment's
+  -- strength, drawn before the blit so the headset never sees the swap.
+  -- A full-frame fill is the ONE 2D thing that is safe to draw into an
+  -- eye buffer -- it covers everything, so it does not matter that the
+  -- two frusta disagree about where any given pixel points.
+  if fadeAlpha > 0 then
+    pcall(function()
+      for i = 1, 2 do
+        local c = canvases[i]
+        love.graphics.setCanvas(c)
+        love.graphics.setColor(0, 0, 0, math.min(1, fadeAlpha))
+        love.graphics.rectangle("fill", 0, 0, c:getWidth(), c:getHeight())
+      end
+      love.graphics.setCanvas()
+      love.graphics.setColor(1, 1, 1, 1)
+    end)
+  end
+
+  for i = 1, 2 do
+    local canvas = canvases[i]
+    local tex, tw, th = VRXR.acquireEye(i)
+    if tex then
+      local fbo = fboCache[canvas]
+      if not fbo then
+        fbo = VRGL.canvasFBO(canvas)
+        fboCache[canvas] = fbo
+      end
+      if fbo then
+        VRGL.blitToTexture(fbo, canvas:getWidth(), canvas:getHeight(),
+                           tex, tw, th)
+      end
+    end
+    VRXR.releaseEye(i)
+  end
+  mirrorSrc = canvases[1]
+  return true
+end
+
+-- ------- the UI panel
+
+-- Whether the flat screen is showing something the world pass cannot: a
+-- menu, a dialog, a battle, a transition wipe -- or everything, when the
+-- world pass is off entirely.
+local function wantQuad(worldUp)
+  if not worldUp then return true end
+  return uiShowing()
+end
+
+local function updateQuad(worldUp, fp)
+  if not wantQuad(worldUp) then return nil end
+  -- Wherever the pokedex is up and lit -- first person's menus, the
+  -- battle seat's 2D fight -- it IS the screen, and no floating
+  -- billboard is submitted at all. (No tracked left hand still gets
+  -- the panel: the UI must be readable somewhere.)
+  if Pokedex.frame and Pokedex.frame.tex then return nil end
+  local tex, qw, qh = VRXR.acquireQuad()
+  if not tex then return nil end
+  local ww, wh = qw, qh
+  pcall(function() ww, wh = love.graphics.getPixelDimensions() end)
+  -- The panel wears the GB FRAME, not the window: everything the flat
+  -- screen has to say lives in the 160x144 letterbox (the world around
+  -- it is just the mirror's picture). The frame region is blitted OUT
+  -- of the window and SCALED into the swapchain image -- never copied
+  -- pixel-for-pixel, because the swapchain's size is fixed at session
+  -- start and a fullscreened window outgrows it, running the frame (and
+  -- the START menu flush with its right edge) off the copy. Scaled, the
+  -- panel shows the identical picture at the identical ratio whatever
+  -- size the window is. Source coordinates are GL's, origin bottom-left.
+  local crop = nil
+  local copied = false
+  pcall(function()
+    local BattleScene = V.require("BattleScene")
+    local lx, ly, s = BattleScene.letterbox()
+    local wpx = math.ceil(BattleScene.GB_W * s)
+    local hpx = math.ceil(BattleScene.GB_H * s)
+    local sx = math.max(0, math.floor(lx))
+    local sy = math.max(0, math.floor(wh - ly - hpx))
+    wpx = math.min(wpx, ww - sx)
+    hpx = math.min(hpx, wh - sy)
+    if wpx < 1 or hpx < 1 then return end
+    -- fitted to the swapchain image at the REGION's own aspect: the
+    -- crop then presents exactly that rect, so the panel's shape is the
+    -- GB frame's at any window and any swapchain size
+    local fit = math.min(qw / wpx, qh / hpx)
+    local dw = math.max(1, math.floor(wpx * fit))
+    local dh = math.max(1, math.floor(hpx * fit))
+    if VRGL.copyFrontRegionToTexture(tex, sx, sy, wpx, hpx, dw, dh) then
+      copied = true
+      crop = { 0, 0, dw, dh }
+    end
+  end)
+  if not copied then
+    -- no letterbox to cut (or the blit refused): the old whole-window
+    -- copy, clamped, is still a readable panel
+    VRGL.copyFrontBuffer(tex, math.min(qw, ww), math.min(qh, wh))
+  end
+  VRXR.releaseQuad()
+  local base = fp and QUAD_FP or QUAD_DIORAMA
+  if not crop then return base end
+  return { pos = base.pos, width = base.width, crop = crop }
+end
+
+-- ------- the controllers
+--
+-- The mapping the mod ships (rebindable in the runtime's own UI):
+--
+--   both modes    left stick moves (through the engine's own stick path,
+--                 so it grid-walks the diorama and free-walks 1ST);
+--                 A/B are A/B; either trigger is START; clicking the
+--                 LEFT stick steps the VOXEL angle ladder exactly as
+--                 the "3" key (and the pad's SELECT) does.
+--   1ST only      right stick left/right SNAP-TURNS 45 degrees a flick.
+--   diorama only  right stick up/down zooms the model; squeezing a grip
+--                 and moving that hand up or down drags the whole table
+--                 with it.
+--
+-- The DIORAMA modes rebind two of those, because in them there is no
+-- ladder to step and no table-height to be the only thing worth dragging:
+--
+--   left stick click   throws V-CURVE to its top rung and back.
+--   grips              one carries the model anywhere in the room; both
+--                      turn it and open the viewport out (Diorama.gesture).
+--
+-- Leaving VR is the VR row's job alone (OPTIONS menu or the manager) --
+-- no controller button does it. VR.leave below stays as the API for it.
+
+-- The left stick click makes EXACTLY the step the "3" key makes: one
+-- rung up the VOXEL angle ladder, wrapping, stepping over FULL, clearing
+-- TILT and GBC FX in the save -- by calling the very function the key
+-- and the pad's SELECT button already share. main.lua installs it below
+-- (cycleVoxel is a local of that file); the free-roam gate is the
+-- registry's own, inside it, so a click over a menu or mid-warp is a
+-- no-op exactly like the key.
+VR.cycleVoxel = nil             -- cycleVoxel(game), set by main.lua
+
+function VR.stepView()
+  pcall(function()
+    if not VR.cycleVoxel then return end
+    VR.cycleVoxel(require("src.core.Game"))
+  end)
+end
+
+-- Put the VOXEL ladder on a given rung, for the one caller that needs to
+-- rather than to step: a DIORAMA mode holding the ladder off 2D and off
+-- both free-roam rungs (see dioramaRung). Handed over by main.lua next to
+-- cycleVoxel and for the same reason.
+VR.setVoxelLevel = nil          -- setVoxelLevel(game, level), set by main.lua
+
+-- The rung a diorama mode holds the ladder on when it finds it somewhere
+-- the mode cannot present: 35 degrees, the standard view's own angle.
+VR.DIORAMA_RUNG = 3
+
+-- 2D is not a diorama and neither is standing inside the world, so while a
+-- diorama mode is live the ladder is held on an orbit rung. Cheap enough to
+-- ask every frame: it is a table read and, almost always, no write.
+local function dioramaRung()
+  pcall(function()
+    if not VR.setVoxelLevel then return end
+    local Pipelines = require("src.render.Pipelines")
+    local level = Pipelines.level("voxel") or 0
+    if level == 0 or Voxel.isFreeCam(level) then
+      VR.setVoxelLevel(require("src.core.Game"), VR.DIORAMA_RUNG)
+    end
+  end)
+end
+
+-- The V-CURVE row, thrown to its top rung and back -- what the left stick's
+-- click does in a diorama, where there is no ladder for it to step.
+--
+-- A toggle rather than a cycle, because in a headset the curve is not a
+-- taste setting with four values: it is the one control that decides
+-- whether the model is a flat slab of map or a little world curling away
+-- over its own horizon, and the player wants to see both, now, without
+-- counting clicks. The rung it was on is remembered so the click gives it
+-- back rather than dropping the row to OFF.
+--
+-- It changes the CUT with it (see lib/Diorama): flat world, square box,
+-- hard edge; curved world, ball, dissolve. One click swaps the whole
+-- reading of the model, which is why it is the click worth having here.
+local curveWas = nil
+
+function VR.toggleCurve()
+  pcall(function()
+    local Game = require("src.core.Game")
+    local WorldCurve = V.require("WorldCurve")
+    local top = WorldCurve.setting.values[#WorldCurve.setting.values]
+    if WorldCurve.setting:get() == top then
+      WorldCurve.setting:setValue(curveWas or WorldCurve.setting.values[1],
+                                  Game)
+      curveWas = nil
+    else
+      curveWas = WorldCurve.setting:get()
+      WorldCurve.setting:setValue(top, Game)
+    end
+  end)
+end
+
+-- Leave VR: the VR row toggled back off and persisted, exactly as if
+-- stepped on the OPTIONS menu, so the next update tears the session down
+-- and the flat screen takes the picture back. Deliberately bound to NO
+-- controller button (a click that ejects you from the headset is a trap
+-- mid-fight); kept as the one programmatic door out.
+function VR.leave()
+  pcall(function()
+    local Game = require("src.core.Game")
+    -- OFF by VALUE, not by stepping the row: the row is a ladder now, and
+    -- one step off STANDARD is DIORAMA rather than the way out
+    VR.setting:setValue(false, Game)
+  end)
+end
+
+local function setGB(inp, btn, down)
+  if down and not held[btn] then
+    held[btn] = true
+    inp:overlayPressed(btn)
+  elseif not down and held[btn] then
+    held[btn] = nil
+    inp:overlayReleased(btn)
+  end
+end
+
+local function driveControls(ctl, dt, fp, dio)
+  if not ctl then
+    releaseInputs()
+    Diorama.releaseGrab()
+    return
+  end
+  local ok, Game = pcall(require, "src.core.Game")
+  if not (ok and Game.input) then return end
+  local inp = Game.input
+
+  -- HORDE MODE re-reads the right hand as a weapon: the trigger fires
+  -- (its own OpenXR action, suggested alongside START on the same input
+  -- -- see VRXR.setupInput), and B reloads. START is dropped rather than
+  -- forwarded, because the mode does not pause. Everything else -- the
+  -- stick's walk, the snap turn, A -- keeps working, so the player can
+  -- still move and look while they are being chased.
+  local Horde = V.require("Horde")
+  if Horde.playing() then
+    local Gun = V.require("HordeGun")
+    if ctl.fireChanged and ctl.fire then Gun.fire() end
+    if ctl.bChanged and ctl.b then Gun.reload() end
+    setGB(inp, "a", ctl.a)
+    setGB(inp, "b", false)
+    setGB(inp, "start", false)
+  else
+    setGB(inp, "a", ctl.a)
+    setGB(inp, "b", ctl.b)
+    setGB(inp, "start", ctl.start)
+  end
+
+  -- the left stick, through the engine's OWN stick handler: it quantises
+  -- to the grid d-pad for the diorama, and FirstPerson.moveVector reads
+  -- the same raw pair for the free walk. OpenXR's +Y is up; the engine's
+  -- lefty is +down.
+  inp:gamepadaxis(nil, "leftx", ctl.moveX or 0)
+  inp:gamepadaxis(nil, "lefty", -(ctl.moveY or 0))
+
+  -- the left stick click: the VOXEL ladder ordinarily, the V-CURVE throw in
+  -- a diorama (where the ladder is held on one rung and the click would
+  -- otherwise do nothing), and the way out of horde mode while it runs (the
+  -- rung is locked there too, and a headset has no ESCAPE key)
+  if ctl.toggleChanged and ctl.toggle then
+    if Horde.active then
+      Horde.askExit()
+    elseif dio then
+      VR.toggleCurve()
+    else
+      VR.stepView()
+    end
+  end
+
+  -- first person's turn on the right stick. SMOOTH TURN ON makes it a
+  -- rate -- hold and the world rotates under you -- and OFF (the
+  -- default) makes it a 45-degree snap per flick: see the row's own
+  -- reasoning where it is declared. Either way the offset turns the
+  -- MAPPING, so the eyes, the walk direction, the pokedex and the gun
+  -- all agree about which way the world now faces.
+  if fp and camMode ~= "battle" and VR.smoothTurn:get() == true then
+    local sx = ctl.lookX or 0
+    local a = math.abs(sx)
+    if a > 0.2 then
+      a = (a - 0.2) / 0.8
+      -- increasing yaw turns LEFT in this mod's compass, so a stick
+      -- pushed right subtracts -- the same sign the snap below uses
+      fpYawOff = wrapPi(fpYawOff
+                        - (sx > 0 and 1 or -1) * a * a
+                          * VR.SMOOTH_TURN_RATE * (dt or 0))
+    end
+    snapArmed = true       -- so a switch back to snap mid-flick re-arms
+  elseif fp and camMode ~= "battle" then
+    local sx = ctl.lookX or 0
+    if math.abs(sx) > 0.65 then
+      if snapArmed then
+        snapArmed = false
+        -- increasing yaw turns LEFT in this mod's compass, so a stick
+        -- pushed right subtracts
+        fpYawOff = wrapPi(fpYawOff + (sx > 0 and -SNAP_TURN or SNAP_TURN))
+      end
+    elseif math.abs(sx) < 0.35 then
+      snapArmed = true
+    end
+  end
+
+  -- THE DIORAMA'S GRIPS take the model itself: one hand carries it through
+  -- the room, both turn it and open the viewport out (see Diorama.gesture).
+  -- The stick's zoom still sizes the model under all of that -- the two
+  -- are different questions, "how big is it" and "how much of it is there".
+  if dio then
+    lastHandY = nil
+    local zy = ctl.lookY or 0
+    if math.abs(zy) > 0.15 then
+      zoom = math.max(0.35, math.min(4, zoom * math.exp(zy * (dt or 0) * 1.6)))
+    end
+    Diorama.gesture(ctl)
+    return
+  end
+
+  if not fp and camMode ~= "battle" then
+    local zy = ctl.lookY or 0
+    if math.abs(zy) > 0.15 then
+      zoom = math.max(0.35, math.min(4, zoom * math.exp(zy * (dt or 0) * 1.6)))
+    end
+    -- the grab-drag: while a grip is squeezed, the table follows that
+    -- hand's height, metre for metre
+    local gl, gr = ctl.gripL or 0, ctl.gripR or 0
+    local y = (gr >= gl) and ctl.handrY or ctl.handlY
+    if math.max(gl, gr) > 0.6 and y then
+      if lastHandY then
+        heightOff = math.max(-1.5, math.min(1.5, heightOff + (y - lastHandY)))
+      end
+      lastHandY = y
+    else
+      lastHandY = nil
+    end
+  else
+    lastHandY = nil
+  end
+end
+
+-- ------- the per-frame drive
+
+function VR.update(dt)
+  local mode = VR.mode()
+  local on = mode ~= "off"
+  if not on then
+    if wasOn then
+      shutdown("off")
+      failed = nil
+    end
+    wasOn = false
+    return
+  end
+
+  if not wasOn then failed = nil end   -- a fresh toggle earns a fresh try
+  wasOn = true
+  if failed then return end
+
+  if not started then
+    local qw, qh = 1024, 768
+    pcall(function() qw, qh = love.graphics.getPixelDimensions() end)
+    if VRXR.start(qw, qh) then
+      started = true
+      status = "session created"
+      print("[DRAMATIC_SHAPE] VR: " .. VRXR.status())
+    else
+      failed = VRXR.status()
+      print("[DRAMATIC_SHAPE] VR unavailable: " .. failed
+            .. " -- fix that, then toggle the VR row to retry")
+      return
+    end
+  end
+
+  if not VRXR.poll() then
+    -- the runtime took the session away (headset off, runtime shut down)
+    shutdown("session lost")
+    failed = "session lost -- toggle VR off and on to retry"
+    return
+  end
+  if not VRXR.isRunning() then return end
+
+  -- the headset paces the app now; vsync would fight it
+  if savedVsync == nil then
+    savedVsync = 1
+    pcall(function() savedVsync = love.window.getVSync() end)
+    pcall(love.window.setVSync, 0)
+  end
+
+  -- Which VR this frame is, before anything reads it: the diorama's own
+  -- fields (the viewport, the chroma key) are open for the length of the
+  -- frame and shut with the session. The rung guard rides it -- there is
+  -- no 2D diorama and no first-person one.
+  if Diorama.begin(mode) then dioramaRung() end
+
+  -- the battle camera holds still for as long as a headset is watching:
+  -- its drift is a flat screen's depth cue, and a swaying picture inside
+  -- VR reads as the world lurching
+  BattleCam.still = true
+
+  -- The battle snap's fade: while the camera the frame WANTS is not the
+  -- one it is showing, black rises; at full black the mount swaps; then
+  -- black lifts. Driven here, on game time, so a fight that ends during
+  -- the fade just turns it around.
+  local want = battleStage() and "battle" or "explore"
+  if want ~= camMode then
+    fadeAlpha = math.min(1, fadeAlpha + (dt or 0) / FADE_TIME)
+    if fadeAlpha >= 1 then camMode = want end
+  else
+    fadeAlpha = math.max(0, fadeAlpha - (dt or 0) / FADE_TIME)
+  end
+
+  local time, should = VRXR.waitFrame()
+  if not time then return end
+
+  -- the controllers, before the world renders: the frame the toggle
+  -- flips rungs on should be the frame that renders the new rig. The
+  -- state is kept in hand for renderWorld too -- the pokedex stands on
+  -- the same frame's left-hand pose.
+  local dio = VR.dioramaMode()
+  local ctl = VRXR.input(time)
+  driveControls(ctl, dt, (not dio) and FirstPerson.engaged(), dio)
+
+  local worldUp = false
+  if should then
+    local views = VRXR.locateViews(time)
+    if views then
+      worldUp = renderWorld(views, ctl)
+    end
+  end
+  -- the diorama's panel is the tabletop one whatever the rung says: there
+  -- is no first person in the mode to float it closer for
+  local quadPose = updateQuad(worldUp, (not dio) and FirstPerson.engaged())
+  VRXR.endFrame(time, worldUp or nil, quadPose)
+end
+
+-- ------- the window while a headset owns the picture
+
+-- The flat window becomes the mirror: the left eye, fitted to the window.
+-- Returns nil when there is nothing to mirror (the caller draws the flat
+-- path as ever).
+function VR.mirror(sw, sh)
+  if not (VR.active() and mirrorSrc) then return nil end
+  if not (mirrorCanvas and mirrorCanvas:getWidth() == sw
+          and mirrorCanvas:getHeight() == sh) then
+    local ok, c = pcall(love.graphics.newCanvas, sw, sh)
+    if not ok then return nil end
+    mirrorCanvas = c
+  end
+  local ok = pcall(function()
+    love.graphics.setCanvas(mirrorCanvas)
+    love.graphics.clear(0, 0, 0, 1)
+    local mw, mh = mirrorSrc:getDimensions()
+    local s = math.min(sw / mw, sh / mh)
+    love.graphics.setColor(1, 1, 1, 1)
+    love.graphics.draw(mirrorSrc, (sw - mw * s) / 2, (sh - mh * s) / 2, 0, s, s)
+    love.graphics.setCanvas()
+  end)
+  pcall(love.graphics.setCanvas)
+  return ok and mirrorCanvas or nil
+end
+
+-- window resize, hot reload: the eye canvases are Voxel3D's and go with
+-- its invalidate; ours is the mirror and the FBO ids learned from dead
+-- canvases
+function VR.invalidate()
+  if mirrorCanvas and mirrorCanvas.release then
+    pcall(mirrorCanvas.release, mirrorCanvas)
+  end
+  mirrorCanvas, mirrorSrc = nil, nil
+  if dexCanvas and dexCanvas.release then pcall(dexCanvas.release, dexCanvas) end
+  dexCanvas = nil
+  Pokedex.invalidate()
+  Diorama.invalidate()      -- the base's mesh and its cave-floor texture
+  V.require("HordeGun").invalidate()
+  V.require("HordeHud").invalidate()
+  for k in pairs(fboCache) do fboCache[k] = nil end
+end
+
+return VR

lib/VRGL.lua

@@ -0,0 +1,237 @@
+-- VR: the raw OpenGL this mod is otherwise proud to never need.
+--
+-- OpenXR hands over its swapchain images as GL TEXTURE IDS, and LOVE never
+-- exposes the GL names behind its own canvases -- so getting a rendered
+-- eye from a love Canvas into a headset means dropping below LOVE for a
+-- few calls a frame: discover the canvas's framebuffer, blit it into the
+-- swapchain texture, and put the pipeline back exactly as LOVE believes it
+-- to be. Everything here is that, and only that.
+--
+-- Three rules keep this safe:
+--
+--   discovery over spelunking. The canvas's FBO id is read from the
+--   driver with documented queries (bind the canvas THROUGH LOVE, ask
+--   GL_DRAW_FRAMEBUFFER_BINDING) rather than from LOVE's internals, so a
+--   LOVE patch cannot move it out from under us.
+--
+--   restore what LOVE caches. LOVE tracks the bound framebuffer and skips
+--   redundant binds, so raw binds must end back at the exact binding LOVE
+--   thinks is current -- the default framebuffer, 0, since every call
+--   here runs between LOVE passes -- or LOVE's next draw lands in ours.
+--
+--   pcall at the rim, ffi inside. The FFI setup can fail (headless, a GL
+--   context without FBO entry points); it fails ONCE, at load(), and
+--   callers see `nil, reason` rather than an error mid-frame.
+
+local VRGL = {}
+
+local ffi = nil
+local gl = nil                -- opengl32 exports (GL 1.1 + wgl)
+local ext = {}                -- post-1.1 entry points via wglGetProcAddress
+local ready = false
+local reason = nil
+local fbo = nil               -- our scratch framebuffer, made once
+
+local GL = {
+  FRAMEBUFFER = 0x8D40,
+  READ_FRAMEBUFFER = 0x8CA8,
+  DRAW_FRAMEBUFFER = 0x8CA9,
+  DRAW_FRAMEBUFFER_BINDING = 0x8CA6,
+  COLOR_ATTACHMENT0 = 0x8CE0,
+  COLOR_BUFFER_BIT = 0x4000,
+  NEAREST = 0x2600,
+  LINEAR = 0x2601,
+  TEXTURE_2D = 0x0DE1,
+  FRONT = 0x0404,
+  BACK = 0x0405,
+}
+VRGL.GL = GL
+
+local CDEF = [[
+typedef void (__stdcall *PROC)();
+void* wglGetCurrentDC(void);
+void* wglGetCurrentContext(void);
+PROC wglGetProcAddress(const char*);
+unsigned int glGetError(void);
+void glGetIntegerv(unsigned int pname, int* params);
+void glReadBuffer(unsigned int mode);
+void glFlush(void);
+void glCopyTexSubImage2D(unsigned int target, int level, int xoffset,
+                         int yoffset, int x, int y, int width, int height);
+void glBindTexture(unsigned int target, unsigned int texture);
+typedef void (__stdcall *pfn_glBindFramebuffer)(unsigned int, unsigned int);
+typedef void (__stdcall *pfn_glGenFramebuffers)(int, unsigned int*);
+typedef void (__stdcall *pfn_glDeleteFramebuffers)(int, const unsigned int*);
+typedef void (__stdcall *pfn_glFramebufferTexture2D)(unsigned int,
+    unsigned int, unsigned int, unsigned int, int);
+typedef void (__stdcall *pfn_glBlitFramebuffer)(int, int, int, int,
+    int, int, int, int, unsigned int, unsigned int);
+]]
+
+-- One-time FFI setup. Idempotent, and every path out records why it
+-- stopped, so VR's status line can say something better than "no".
+function VRGL.load()
+  if ready then return true end
+  if reason then return false, reason end
+  local ok, err = pcall(function()
+    ffi = require("ffi")
+    -- cdef survives a reload; redefinition is the only error worth eating
+    pcall(ffi.cdef, CDEF)
+    gl = ffi.load("opengl32")
+    local function proc(name, typ)
+      local p = gl.wglGetProcAddress(name)
+      if p == nil then error(name .. " not exposed by this GL context", 0) end
+      return ffi.cast(typ, p)
+    end
+    ext.glBindFramebuffer = proc("glBindFramebuffer", "pfn_glBindFramebuffer")
+    ext.glGenFramebuffers = proc("glGenFramebuffers", "pfn_glGenFramebuffers")
+    ext.glDeleteFramebuffers =
+      proc("glDeleteFramebuffers", "pfn_glDeleteFramebuffers")
+    ext.glFramebufferTexture2D =
+      proc("glFramebufferTexture2D", "pfn_glFramebufferTexture2D")
+    ext.glBlitFramebuffer = proc("glBlitFramebuffer", "pfn_glBlitFramebuffer")
+  end)
+  if not ok then
+    reason = "GL interop unavailable: " .. tostring(err)
+    return false, reason
+  end
+  ready = true
+  return true
+end
+
+-- The window's device and GL contexts, which the OpenXR session binds to.
+function VRGL.contexts()
+  if not VRGL.load() then return nil, nil end
+  return gl.wglGetCurrentDC(), gl.wglGetCurrentContext()
+end
+
+-- The GL framebuffer behind a LOVE canvas. Bound through LOVE (so LOVE's
+-- own cache stays truthful), read from the driver, then released.
+function VRGL.canvasFBO(canvas)
+  if not VRGL.load() then return nil end
+  local id = nil
+  local ok = pcall(function()
+    love.graphics.setCanvas(canvas)
+    local out = ffi.new("int[1]")
+    gl.glGetIntegerv(GL.DRAW_FRAMEBUFFER_BINDING, out)
+    id = out[0]
+    love.graphics.setCanvas()
+  end)
+  pcall(love.graphics.setCanvas)
+  return ok and id or nil
+end
+
+-- Blit a LOVE canvas's pixels into a GL texture (an XR swapchain image),
+-- flipped vertically on the way: LOVE renders its canvases y-down, GL
+-- textures composite y-up, and the blit is the one place the two meet.
+--
+-- `srcFBO` comes from canvasFBO (cache it -- it is stable for the
+-- canvas's lifetime). Ends with framebuffer 0 bound, which is the binding
+-- LOVE believes in between its passes.
+function VRGL.blitToTexture(srcFBO, sw, sh, tex, tw, th)
+  if not ready then return false end
+  local ok = pcall(function()
+    if not fbo then
+      local out = ffi.new("unsigned int[1]")
+      ext.glGenFramebuffers(1, out)
+      fbo = out[0]
+    end
+    ext.glBindFramebuffer(GL.DRAW_FRAMEBUFFER, fbo)
+    ext.glFramebufferTexture2D(GL.DRAW_FRAMEBUFFER, GL.COLOR_ATTACHMENT0,
+                               GL.TEXTURE_2D, tex, 0)
+    ext.glBindFramebuffer(GL.READ_FRAMEBUFFER, srcFBO)
+    ext.glBlitFramebuffer(0, sh, sw, 0, 0, 0, tw, th,
+                          GL.COLOR_BUFFER_BIT, GL.LINEAR)
+    ext.glBindFramebuffer(GL.FRAMEBUFFER, 0)
+  end)
+  if not ok then pcall(function() ext.glBindFramebuffer(GL.FRAMEBUFFER, 0) end) end
+  return ok
+end
+
+-- Copy the WINDOW's currently displayed image (the front buffer -- the
+-- back buffer's contents are undefined after a swap) into a GL texture:
+-- the UI quad the headset floats in front of the world. Restores the read
+-- buffer to BACK, the default LOVE never changes.
+function VRGL.copyFrontBuffer(tex, w, h)
+  if not ready then return false end
+  local ok = pcall(function()
+    ext.glBindFramebuffer(GL.FRAMEBUFFER, 0)
+    gl.glReadBuffer(GL.FRONT)
+    gl.glBindTexture(GL.TEXTURE_2D, tex)
+    gl.glCopyTexSubImage2D(GL.TEXTURE_2D, 0, 0, 0, 0, 0, w, h)
+    gl.glBindTexture(GL.TEXTURE_2D, 0)
+    gl.glReadBuffer(GL.BACK)
+  end)
+  if not ok then pcall(function() gl.glReadBuffer(GL.BACK) end) end
+  return ok
+end
+
+-- Blit a REGION of the window's front buffer into a GL texture (an XR
+-- swapchain image), SCALED to (dw, dh) at the texture's origin. This is
+-- the panel's route: the whole-window copy above is pixel-for-pixel, so
+-- a window larger than the swapchain image simply ran off its edges --
+-- fullscreen cut the GB frame's own menu off the panel. A scaled blit
+-- has no such cliff: the letterbox region lands whole at the texture's
+-- own resolution whatever size the window is. Source coordinates are GL
+-- window space, origin bottom-left; LINEAR, because the region rarely
+-- matches the target size exactly and dropped rows read worse than a
+-- soft one. Restores the read buffer and framebuffer LOVE believes in.
+function VRGL.copyFrontRegionToTexture(tex, sx, sy, sw, sh, dw, dh)
+  if not ready then return false end
+  local ok = pcall(function()
+    if not fbo then
+      local out = ffi.new("unsigned int[1]")
+      ext.glGenFramebuffers(1, out)
+      fbo = out[0]
+    end
+    ext.glBindFramebuffer(GL.READ_FRAMEBUFFER, 0)
+    gl.glReadBuffer(GL.FRONT)
+    ext.glBindFramebuffer(GL.DRAW_FRAMEBUFFER, fbo)
+    ext.glFramebufferTexture2D(GL.DRAW_FRAMEBUFFER, GL.COLOR_ATTACHMENT0,
+                               GL.TEXTURE_2D, tex, 0)
+    ext.glBlitFramebuffer(sx, sy, sx + sw, sy + sh, 0, 0, dw, dh,
+                          GL.COLOR_BUFFER_BIT, GL.LINEAR)
+    ext.glBindFramebuffer(GL.FRAMEBUFFER, 0)
+    gl.glReadBuffer(GL.BACK)
+  end)
+  if not ok then
+    pcall(function()
+      ext.glBindFramebuffer(GL.FRAMEBUFFER, 0)
+      gl.glReadBuffer(GL.BACK)
+    end)
+  end
+  return ok
+end
+
+-- Copy the window's front buffer into a LOVE CANVAS (by its FBO id, from
+-- canvasFBO), flipped so the canvas reads top-down exactly like the
+-- window: what LOVE then draws from that canvas at (0,0) is the screen,
+-- row for row. The battle's VR quad is the caller: it needs the screen as
+-- something LOVE can CUT UP (scissored cutouts of the UI), not just as a
+-- finished texture -- copyFrontBuffer above is for the finished case.
+function VRGL.copyFrontToCanvas(dstFBO, w, h)
+  if not ready then return false end
+  local ok = pcall(function()
+    ext.glBindFramebuffer(GL.READ_FRAMEBUFFER, 0)
+    gl.glReadBuffer(GL.FRONT)
+    ext.glBindFramebuffer(GL.DRAW_FRAMEBUFFER, dstFBO)
+    ext.glBlitFramebuffer(0, 0, w, h, 0, h, w, 0,
+                          GL.COLOR_BUFFER_BIT, GL.NEAREST)
+    ext.glBindFramebuffer(GL.FRAMEBUFFER, 0)
+    gl.glReadBuffer(GL.BACK)
+  end)
+  if not ok then
+    pcall(function()
+      ext.glBindFramebuffer(GL.FRAMEBUFFER, 0)
+      gl.glReadBuffer(GL.BACK)
+    end)
+  end
+  return ok
+end
+
+function VRGL.status()
+  if ready then return "ok" end
+  return reason or "not loaded"
+end
+
+return VRGL

lib/VRRig.lua

@@ -0,0 +1,274 @@
+-- VR: the pose arithmetic -- how a headset eye becomes one of this mod's
+-- cameras. Pure math on purpose: no FFI, no OpenXR types, nothing a
+-- headless test cannot hold still. Everything device-shaped stays in
+-- VRXR/VRGL; everything world-shaped is here.
+--
+-- Two ways the world can sit around a headset, and they mirror the VOXEL
+-- ladder exactly:
+--
+--   DIORAMA   every orbit rung. The map is a tabletop miniature: a point
+--             of the world (the view centre) is pinned VIEW_DIST away
+--             along the rung's own viewing angle (dioramaAnchor), at the
+--             scale that reproduces the flat screen's framing
+--             (dioramaScale) -- so at rest the model presents exactly as
+--             the standard view does, and the head moves freely around it
+--             -- lean in and the town grows, walk around the table and
+--             see the far side of the buildings honest occlusion has been
+--             hiding.
+--
+--   FIRST_PERSON   the 1ST rung. The player's head is pinned to where the
+--             headset started, at FP_SCALE, so a 16-pixel person stands
+--             about 1.6 m tall and a cell is a stride. The HMD's own
+--             orientation becomes FirstPerson's yaw and pitch, so movement
+--             stays "push forward, go where you look" through the same
+--             FreeMove the flat screen uses.
+--
+-- SPACES AND UNITS. OpenXR LOCAL space is metres, +Y up, -Z the way the
+-- head faced at session start. World space is world PIXELS, +Y up, +Z
+-- south. The two are aligned axis-for-axis -- "away from you" is north --
+-- so the whole mapping is one translate-and-scale:
+--
+--   worldFromXr(p) = pivot + s * (p - anchor)
+--
+-- with `pivot` a world point, `anchor` the LOCAL-space point pinned to it,
+-- and `s` the scale in px/m. An eye's camera is then
+--
+--   worldFromEye = T(pivot) * S(s) * T(-anchor) * T(pose.pos) * R(pose.q)
+--   view         = the same chain inverted piece by rigid piece
+--
+-- and the VIEW deliberately ends in METRES: it un-scales the world, so eye
+-- space -- where the projection's near and far live -- is real-world
+-- metres whatever the mode's scale. Depth precision and clip planes stay
+-- sane at both 10 px/m and 128 px/m.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local Mat4 = V.require("Mat4")
+
+local VRRig = {}
+
+-- first person's life size: 10 px/m makes a 16 px tile a 1.6 m stride
+VRRig.FP_SCALE = 10
+
+-- How far the diorama's pivot sits from the resting head, in metres --
+-- the arm's-length viewing distance the anchor and the scale below are
+-- both built around.
+VRRig.VIEW_DIST = 0.95
+
+-- Where, in LOCAL metres, the diorama's pivot sits: VIEW_DIST away along
+-- the RUNG'S OWN viewing angle. The flat screen's camera looks at the
+-- world `a` radians off vertical; putting the pivot at (-d cos a) below
+-- and (-d sin a) ahead of the resting head reproduces exactly that line
+-- of sight -- step onto the 35 rung and the table presents at 35 degrees,
+-- onto 75 and it rises toward eye level, easing between them as the rung
+-- tween runs.
+--
+-- `off` is the grab-drag adjustment, in metres of LOCAL travel -- where
+-- the player has carried the model to. A bare number is the height alone,
+-- which is what the standard mode's one-axis drag has always sent; the
+-- DIORAMA modes hand over all three (see lib/Diorama). Positive Y drags
+-- the world up: the anchor is the LOCAL point pinned to the pivot, so
+-- moving it moves the model with the hand rather than against it.
+function VRRig.dioramaAnchor(angleRad, off)
+  local d = VRRig.VIEW_DIST
+  local ox, oy, oz = 0, 0, 0
+  if type(off) == "table" then
+    ox, oy, oz = off[1] or 0, off[2] or 0, off[3] or 0
+  elseif type(off) == "number" then
+    oy = off
+  end
+  return { ox,
+           -d * math.cos(angleRad or 0) + oy,
+           -d * math.sin(angleRad or 0) + oz }
+end
+
+-- The diorama's scale, in world px per metre: the one that makes the
+-- table subtend the same field the flat screen frames. The flat camera
+-- fits `vh` world pixels in a lens of focal `focal` (Voxel.FOCAL); at
+-- VIEW_DIST the same framing needs vh * focal / d pixels to the metre --
+-- so the resting head sees the standard view's angle AND its apparent
+-- size, and the zoom rows (which change vh) keep working in VR.
+function VRRig.dioramaScale(vh, focal)
+  return math.max(16, (vh or 288) * (focal or 1) / VRRig.VIEW_DIST)
+end
+
+-- kept as the test suite's fixed example anchor, and as the fallback for
+-- an angle nobody supplied
+VRRig.TABLE = { 0, -0.45, -0.75 }
+
+-- ------- the battle mount
+--
+-- A staged fight snaps the headset to an OVER-THE-SHOULDER seat: the same
+-- line the flat battle camera stands on (eye through focus, so the player's
+-- mon is near-left and the foe far-right exactly as the flat shot frames
+-- them), but pulled in to BATTLE_DIST -- the flat rig is a long lens from
+-- fifteen metres back, and a headset's lens is its own eyes, so keeping the
+-- distance would shrink the fight to a stage seen from the back row. 66 px
+-- is the wide rig's own standing distance: six and a half metres at life
+-- scale, close enough to fill the view, far enough to hold both mons in it
+-- -- and short enough to stay inside the small rooms the wide rig exists
+-- for.
+VRRig.BATTLE_DIST = 66
+
+-- Where the head sits for a staged fight, and which way the mapping must
+-- turn so that seat FACES it. Returns the pivot (world px -- pin the XR
+-- origin here at FP_SCALE) and the yaw for eyeCamera: the flat camera
+-- looks along focus - eye, the resting headset looks along XR -Z (world
+-- north), and the yaw is what closes that gap.
+function VRRig.battleMount(eye, focus)
+  local dx = eye[1] - focus[1]
+  local dy = eye[2] - focus[2]
+  local dz = eye[3] - focus[3]
+  local len = math.sqrt(dx * dx + dy * dy + dz * dz)
+  if len < 1e-6 then return { eye[1], eye[2], eye[3] }, 0 end
+  local k = VRRig.BATTLE_DIST / len
+  -- Ry(yaw) sends XR forward (0,0,-1) to (-sin yaw, 0, -cos yaw); aiming
+  -- that along the horizontal of focus - eye solves to atan2 of eye - focus
+  return { focus[1] + dx * k, focus[2] + dy * k, focus[3] + dz * k },
+         math.atan2(dx, dz)
+end
+
+-- eye-space clip planes, in metres (see the unit note above)
+VRRig.NEAR = 0.05
+VRRig.FAR = 400
+
+-- ------- one eye's camera
+
+-- Build the placed-camera record for one eye.
+--
+--   pose    { pos = {x,y,z} metres, quat = {x,y,z,w} }  (OpenXR LOCAL)
+--   fov     { angleLeft, angleRight, angleUp, angleDown }  signed radians
+--   pivot   {x,y,z} world px pinned to `anchor`
+--   anchor  {x,y,z} LOCAL metres (VRRig.TABLE, or 0,0,0 for first person)
+--   scale   world px per metre
+--   yaw     optional turn of the whole mapping about +Y, radians: the
+--           battle mount faces the resting head at the arena with it.
+--           worldFromXr(p) becomes pivot + s * Ry(yaw) * (p - anchor).
+--   curveK  the world curve this eye is to be drawn with (see WorldCurve);
+--           omitted is 0, the curve DECLINED.
+--
+-- Off by default because standing inside a bent world is what first person
+-- already declines on the flat screen, and the battle mount is a placed
+-- shot. The DIORAMA modes are the case that wants it and asks for it: the
+-- model is a thing being looked AT, so bending it into a little globe is
+-- the whole point rather than a broken tabletop -- and it is what the left
+-- stick's click throws (see lib/VR). Passed in rather than read here
+-- because a rig has no business deciding what a row means.
+--
+-- Beware the shape of the answer: Voxel3D reads `camera.curve` with `or`,
+-- and 0 is TRUE in Lua, so a 0 here really does pin the bend off -- which
+-- is exactly why the diorama's curve did nothing until this became a
+-- parameter.
+--
+-- Returns a table shaped for Voxel3D.camera: raw view + proj, the world
+-- eye and focus (for setLook, the water's lean, the sky), fov as a
+-- vertical span, and that curve.
+function VRRig.eyeCamera(pose, fov, pivot, anchor, scale, yaw, curveK)
+  local px, py, pz = pose.pos[1], pose.pos[2], pose.pos[3]
+  local q = pose.quat
+  local R = Mat4.fromQuat(q[1], q[2], q[3], q[4])
+
+  -- view = R^T * T(-pos) * T(anchor) * Ry(-yaw) * S(1/s) * T(-pivot)
+  local view = Mat4.mul(Mat4.transpose(R), Mat4.translate(-px, -py, -pz))
+  view = Mat4.mul(view, Mat4.translate(anchor[1], anchor[2], anchor[3]))
+  if yaw and yaw ~= 0 then
+    view = Mat4.mul(view, Mat4.rotateY(-yaw))
+  end
+  view = Mat4.mul(view, Mat4.scale(1 / scale, 1 / scale, 1 / scale))
+  view = Mat4.mul(view, Mat4.translate(-pivot[1], -pivot[2], -pivot[3]))
+
+  local proj = Mat4.fovProjection(fov.angleLeft, fov.angleRight,
+                                  fov.angleUp, fov.angleDown,
+                                  VRRig.NEAR, VRRig.FAR)
+
+  -- The eye's RAY FAN, in world axes: the direction a canvas point
+  -- (u, v in 0..1, left-to-right and top-to-bottom) looks along is
+  -- base + u * du + v * dv. The sky reads its per-pixel TRUE elevation
+  -- off this (a real skybox cannot be painted from any per-frame row
+  -- mapping -- that is exact only at the view's own azimuth and swims
+  -- everywhere else). Directions only, so the mapping's scale drops out;
+  -- the yaw must not (the battle mount and the snap turn swing the world).
+  local Rw = R
+  if yaw and yaw ~= 0 then Rw = Mat4.mul(Mat4.rotateY(yaw), R) end
+  local tl, tr = math.tan(fov.angleLeft), math.tan(fov.angleRight)
+  local tu, td = math.tan(fov.angleUp), math.tan(fov.angleDown)
+  -- world columns of the head's rotation: right (X), up (Y), forward (-Z)
+  local rxc, ryc, rzc = Rw[1], Rw[5], Rw[9]
+  local uxc, uyc, uzc = Rw[2], Rw[6], Rw[10]
+  local fxc, fyc, fzc = -Rw[3], -Rw[7], -Rw[11]
+  local skyRay = {
+    base = { fxc + rxc * tl + uxc * tu,
+             fyc + ryc * tl + uyc * tu,
+             fzc + rzc * tl + uzc * tu },
+    du = { rxc * (tr - tl), ryc * (tr - tl), rzc * (tr - tl) },
+    dv = { uxc * (td - tu), uyc * (td - tu), uzc * (td - tu) },
+  }
+
+  -- the eye and its forward, in world pixels: worldFromEye applied to the
+  -- origin and to -Z
+  local ax, ay, az = px - anchor[1], py - anchor[2], pz - anchor[3]
+  -- R's third column is the eye's +Z axis; forward is its negation
+  local fx, fy, fz = -R[3], -R[7], -R[11]
+  if yaw and yaw ~= 0 then
+    local c, s = math.cos(yaw), math.sin(yaw)
+    ax, az = c * ax + s * az, -s * ax + c * az
+    fx, fz = c * fx + s * fz, -s * fx + c * fz
+  end
+  local ex = pivot[1] + scale * ax
+  local ey = pivot[2] + scale * ay
+  local ez = pivot[3] + scale * az
+
+  return {
+    view = view,
+    proj = proj,
+    eye = { ex, ey, ez },
+    focus = { ex + fx * scale, ey + fy * scale, ez + fz * scale },
+    fov = fov.angleUp - fov.angleDown,
+    curve = curveK or 0,
+    skyRay = skyRay,
+  }
+end
+
+-- The WORLD model matrix a hand-held prop stands on: worldFromXr (the
+-- same mapping the eyes use -- so the prop is exactly where the hand is,
+-- whatever mode the mapping is in) composed with the hand's own tracked
+-- pose. A mesh authored in METRES rides it straight: the mapping's scale
+-- is what turns metres into world pixels, so the prop keeps its real
+-- size in the hand at the diorama's scale and at life scale alike.
+--
+--   model = T(pivot) * S(s) * Ry(yaw) * T(-anchor) * T(hand.pos) * R(hand.quat)
+function VRRig.propMatrix(pose, pivot, anchor, scale, yaw)
+  local m = Mat4.translate(pivot[1], pivot[2], pivot[3])
+  m = Mat4.mul(m, Mat4.scale(scale, scale, scale))
+  if yaw and yaw ~= 0 then m = Mat4.mul(m, Mat4.rotateY(yaw)) end
+  m = Mat4.mul(m, Mat4.translate(-anchor[1], -anchor[2], -anchor[3]))
+  m = Mat4.mul(m, Mat4.translate(pose.pos[1], pose.pos[2], pose.pos[3]))
+  local q = pose.quat
+  return Mat4.mul(m, Mat4.fromQuat(q[1], q[2], q[3], q[4]))
+end
+
+-- The flat compass numbers a head orientation implies, for driving
+-- FirstPerson (and through it FreeMove) from the HMD: yaw in this mod's
+-- convention (0 south, pi/2 east) and pitch positive-down.
+function VRRig.headYawPitch(quat)
+  local R = Mat4.fromQuat(quat[1], quat[2], quat[3], quat[4])
+  local fx, fy, fz = -R[3], -R[7], -R[11]
+  local flat = math.sqrt(fx * fx + fz * fz)
+  local yaw = flat > 1e-6 and math.atan2(fx, fz) or 0
+  local pitch = -math.asin(math.max(-1, math.min(1, fy)))
+  return yaw, pitch
+end
+
+-- The two pivots. First person pins the player's head; the diorama pins
+-- the view centre at the ground plane. `gh` is the ground height under
+-- the player (VoxelScene.groundAt), `eyeH` FirstPerson.EYE_HEIGHT.
+function VRRig.fpPivot(pxTopLeft, pyTopLeft, gh, eyeH)
+  return { pxTopLeft + 8, (gh or 0) + (eyeH or 13), pyTopLeft + 8 }
+end
+
+function VRRig.dioramaPivot(cx, cy)
+  return { cx, 0, cy }
+end
+
+return VRRig

lib/ViewBox.lua

@@ -0,0 +1,321 @@
+-- RENDER DIST: how much of the map the orbit rungs bother to draw.
+--
+-- lib/Diorama cuts a headset's model out of the world with a box the
+-- player opens and closes with their hands. This is the same cut on the
+-- flat screen, asked the other way round: not "how much world do I want to
+-- be holding" but "how much world can this camera actually SEE" -- so that
+-- nothing off screen is drawn, and nothing on screen is missing.
+--
+-- THE FOOTPRINT IS NOT THE WINDOW. That is the whole difficulty, and the
+-- first cut of this file got it wrong: it took the flat game's own vw-by-vh
+-- rectangle about the view centre, which is exactly right at 0 degrees and
+-- wrong at every rung the mode actually has. Tilt the camera and the ground
+-- it frames stops being that rectangle and becomes a TRAPEZOID -- reaching
+-- much further north (the far edge of the frame is further away, so it
+-- covers more ground per pixel), flaring much wider there for the same
+-- reason, and pulling IN at the south edge, which is nearer the eye than
+-- the focus is. A window-sized box cuts the north field and both far
+-- corners off a world that is plainly on screen: gaps at the top and down
+-- the sides, with sky showing through them.
+--
+-- So the footprint is derived from the camera rather than guessed. The
+-- orbit is one number (see Voxel3D.viewProjection): eye at distance
+-- FOCAL*vh, pitched `a` off straight down, looking at the view centre,
+-- with a fov chosen so a straight-down camera frames exactly vh. Cast the
+-- frame's own corner rays at the ground plane and the trapezoid falls out
+-- in closed form -- see footprint() for the derivation, which is three
+-- lines of algebra and no tuning at all.
+--
+-- The CUT is still a rectangle (the shader's box kind), so what is stored
+-- is the trapezoid's bounding rect: never narrower than the picture, so it
+-- can never take a bite out of it. It is off-centre in z, because the
+-- trapezoid is -- the box sits north of the view centre at every rung but
+-- the top one.
+--
+-- THE HORIZON IS WHY THERE IS A ROW AT ALL. Past about 63 degrees (exactly
+-- atan(2*FOCAL), where the top of the frame lifts off the ground plane) the
+-- trapezoid stops being finite: the camera can see to the horizon, and "all
+-- the ground on screen" is an infinite answer. Something has to name a
+-- distance, and that is what RENDER DIST names -- MAX_REACH view heights,
+-- times the row's own multiplier. Below that pitch the row does nothing to
+-- the picture at all, because the honest footprint is already smaller than
+-- the reach; at 75 it is what decides where the world ends.
+--
+-- AND IT PAYS FOR ITSELF. A cut this file can describe in world pixels is
+-- one VoxelScene can test a whole neighbour map against BEFORE drawing it
+-- -- see shows() -- so a connected map that lands entirely outside the box
+-- costs no terrain mesh, no water, no grass, no flowers and no shadow
+-- pass. Most of the win is at the HIGH rungs, where the camera is nearly
+-- overhead and the footprint is barely bigger than the window; at 75 it
+-- sees half the region and skips almost nothing, which is the truth about
+-- that rung rather than a shortcoming of the test.
+--
+-- WHAT IT DOES NOT TOUCH. The free-roam rungs (1ST and 3RD): the player is
+-- standing IN the world there, and a box around a walking eye is a
+-- fog-of-war circle rather than a model on a table. The rung tween into
+-- them opens the box out with the blend rather than dropping it on a
+-- frame, so diving into a head does not pop the sides away. A headset's
+-- frame is not touched either -- lib/Diorama owns the cut there, and VR's
+-- STANDARD rungs are a tabletop already.
+
+-- the mod namespace (see main.lua): V.require loads a sibling module
+local V = ...
+
+local ModSetting = V.require("ModSetting")
+
+local ViewBox = {}
+
+ViewBox.KEY = "viewbox"
+-- RENDER DIST rather than a V- name like the rows either side of it: what
+-- the player is choosing is HOW MUCH WORLD gets drawn, which is the thing
+-- every game with this row calls a render distance. The mode read -- the
+-- slab with sides -- is what that buys, not what the row is asking.
+ViewBox.LABEL = "RENDER DIST"
+
+-- The ladder, as a multiplier on the footprint the camera actually frames.
+-- Rung 0 is FIT and it is the default, and FIT means exactly that: the
+-- ground on screen and no more. It cannot open a gap -- 1.0 times the
+-- honest answer is the honest answer -- so the only thing the wider rungs
+-- buy below the horizon pitch is margin around a cut nobody can see.
+--
+-- Where they DO decide the picture is at 75, and at the tween rungs either
+-- side of it, where the footprint is infinite and MAX_REACH below stands in
+-- for it: there the ladder is a real render distance and FIT is the closest
+-- horizon of the four.
+--
+-- Geometric rather than even, for the reason WorldCurve's ladder is: what
+-- the player sees change between two rungs is the AREA inside the box, and
+-- that goes as the square -- even steps bunch the whole ladder at the
+-- near end.
+--
+-- The last rung is 0, which is no cut at all. It sits at the TOP because
+-- "everything" is where the ladder is going: FIT, wider, wider, wider,
+-- all of it.
+ViewBox.FRACS = { 1.0, 1.5, 2.25, 3.5, 0 }
+
+ViewBox.setting = ModSetting.new(ViewBox.KEY, ViewBox.LABEL,
+                                 { 0, 1, 2, 3, 4 },
+                                 { "FIT", "WIDE", "WIDER", "WIDEST", "OFF" })
+
+-- How far the world may reach when the camera can see the HORIZON and the
+-- honest footprint is infinite, in view heights. Generous on purpose: this
+-- is a backstop for an unbounded answer, not a curtain to draw across the
+-- middle distance, and it wants to land well past the edge of the loaded
+-- neighbourhood so the world runs out before the cut does. Multiplied by
+-- the row, so a player who can see the seam can push it away.
+ViewBox.MAX_REACH = 6
+
+-- The rim under V-CURVE, as a fraction of the shorter half-extent, and for
+-- the reason Diorama.FADE_FRAC exists: a bent world has no straight sides,
+-- so a hard edge across one is a lie about what is being looked at. Flat,
+-- the box keeps its hard edge -- that IS the sides.
+ViewBox.FADE_FRAC = 0.16
+
+-- How far outside the box a map may still have geometry inside it: the
+-- border ring ChunkMesher meshes around a body (RING = 3 blocks of 32
+-- world pixels), which is the one thing a map draws beyond its own
+-- rectangle. A neighbour kept by this margin that turns out to be entirely
+-- outside is drawn and then cut per fragment, which is what would have
+-- happened without the test -- the margin can only cost a draw, never a
+-- hole.
+ViewBox.PAD = 96
+
+function ViewBox.level()
+  return ViewBox.setting:get() or 0
+end
+
+-- The multiplier in force, or nil for OFF -- which is also every caller's
+-- "there is no cut this frame" answer.
+function ViewBox.frac()
+  local f = ViewBox.FRACS[ViewBox.level() + 1]
+  if not f or f <= 0 then return nil end
+  return f
+end
+
+-- Whether this rung is one the box is about: an ORBIT rung, which is every
+-- level the mode has except OFF (level 0, where there is no 3D pass to cut)
+-- and the two free-roam rungs (see the header).
+function ViewBox.appliesTo(level)
+  local ok, applies = pcall(function()
+    local Voxel = V.require("VoxelState")
+    local l = level or Voxel.level or 0
+    return l > 0 and not Voxel.isFreeCam(l)
+  end)
+  return ok and applies or false
+end
+
+-- ------- what the live frame is
+--
+-- Set by VoxelScene for the length of one flat frame and cleared with it,
+-- exactly as Diorama's is for a headset's. Nothing else writes it, and
+-- every reader -- the shader uniforms, the neighbour skip -- hangs off this
+-- one field being nil or not.
+ViewBox.cull = nil        -- { x, y, z, r, rx, rz, invFade, kind }
+
+local function curved()
+  local ok, on = pcall(function()
+    return V.require("WorldCurve").active()
+  end)
+  return ok and on or false
+end
+
+-- How far out of the orbit and into a walking head the rung tween has got,
+-- 0..1. The box opens out by one over what is LEFT of the orbit, so it has
+-- grown past every edge of the frame by the time the eye arrives in the
+-- head and the cut is dropped -- rather than the sides vanishing on the
+-- frame the rung number changed, which is a pop in the middle of a move.
+local function orbitLeft()
+  local ok, blend = pcall(function()
+    return V.require("FirstPerson").blendEased()
+  end)
+  if not ok or type(blend) ~= "number" then return 1 end
+  return 1 - math.max(0, math.min(1, blend))
+end
+
+-- ------- the ground this camera frames
+--
+-- The orbit (Voxel3D.viewProjection's else branch) is: eye at distance
+-- k = FOCAL*vh, pitched `a` off straight down and due south of the focus;
+-- focus on the ground at the view centre; a symmetric frustum whose
+-- half-tangents are tanY = 1/(2*FOCAL) vertically and tanY*(vw/vh)
+-- horizontally. Screen coordinates run sx, sy in [-1, 1] with sy = +1 the
+-- TOP of the frame, which is north.
+--
+-- The ray through a screen point is forward + right*sx*tanX + up*sy*tanY,
+-- and with the orbit's basis (right = +x, forward = (0, -cos a, -sin a),
+-- up = (0, sin a, -cos a)) that comes out as
+--
+--     d = ( sx*tanX,  -cos a + sy*tanY*sin a,  -sin a - sy*tanY*cos a )
+--
+-- Drop it to the ground plane from an eye at height k*cos a and the whole
+-- trapezoid collapses to ONE denominator,
+--
+--     D(sy) = cos a - sy*tanY*sin a
+--
+-- with (the sin^2 + cos^2 cancels most of the algebra away):
+--
+--     north of centre : (vh/2) * sy / D(sy)
+--     half-width      : (vw/2) * cos a / D(sy)
+--
+-- because k*tanY is exactly vh/2 and tanX*k is exactly vw/2, whatever FOCAL
+-- is. At a = 0 both reduce to vh/2 and vw/2 -- the flat window, which is
+-- the case the first cut of this file mistook for all of them.
+--
+-- D shrinks as sy climbs, so BOTH grow toward the top of the frame, and
+-- both blow up where D reaches zero: sy* = cot(a)/tanY, the row the horizon
+-- sits on. Past 63 degrees that row is inside the frame and the answer is
+-- infinite -- which is what `reach` is for.
+--
+-- Returns three DISTANCES from the view centre, all positive: how far the
+-- picture runs north, how far south, and how far to each side.
+function ViewBox.footprint(a, vw, vh, reach)
+  local Voxel = V.require("VoxelState")
+  local halfW, halfH = (vw or 320) * 0.5, (vh or 288) * 0.5
+  local tanY = 1 / (2 * (Voxel.FOCAL or 1))
+  -- the orbit never reaches level (75 degrees is the last rung) but a tween
+  -- reads a live angle, and a cos of zero is a horizon through the middle
+  -- of the frame rather than a number
+  local ca = math.max(math.cos(a or 0), 1e-3)
+  local sa = math.max(math.sin(a or 0), 0)
+  -- The screen row the far edge is taken at: the TOP of the frame, or the
+  -- row whose ray lands `reach` out, whichever comes first. Inverting the
+  -- north formula for sy gives
+  --
+  --     sy = reach*cos a / (vh/2 + reach*tanY*sin a)
+  --
+  -- which is always strictly below the horizon row (it approaches it from
+  -- underneath as reach grows), so D below is always positive -- with the
+  -- horizon in frame this never even reaches 1 and the clamp is inert.
+  local sy = reach * ca / (halfH + reach * tanY * sa)
+  if sy > 1 then sy = 1 end
+  local D = ca - sy * tanY * sa
+  if D < 1e-3 then D = 1e-3 end
+  return halfH * sy / D,                 -- north
+         halfH / (ca + tanY * sa),        -- south: the sy = -1 row
+         halfW * ca / D                   -- and the widest row is the far one
+end
+
+-- Open the frame's cut: the bounding rectangle of the ground this camera
+-- frames, times the row's multiplier. Returns the cut, or nil when this
+-- frame has none -- which is the row at OFF, a rung the box is not about,
+-- and a camera that has finished its dive into a head.
+function ViewBox.frame(cx, cy, vw, vh, level)
+  ViewBox.cull = nil
+  local frac = ViewBox.frac()
+  if not (frac and ViewBox.appliesTo(level)) then return nil end
+  local left = orbitLeft()
+  if left <= 0.001 then return nil end
+  frac = frac / left
+  local Voxel = V.require("VoxelState")
+  local north, south, side = ViewBox.footprint(
+    Voxel.angle or 0, vw, vh, ViewBox.MAX_REACH * (vh or 288))
+  north, south, side = north * frac, south * frac, side * frac
+  -- The rectangle around it. Off-centre in z, because the trapezoid is:
+  -- the camera looks NORTH from south of its focus, so there is far more
+  -- picture ahead of the view centre than behind it -- at 35 degrees
+  -- roughly twice as much, at 75 the whole frame.
+  --
+  -- The same floor Diorama.radius keeps: a box smaller than a couple of
+  -- tiles is not a viewport, it is a hole the player is standing in.
+  local rx = math.max(24, side)
+  local rz = math.max(24, (north + south) * 0.5)
+  local bent = curved()
+  local fade = bent and math.max(1, math.min(rx, rz) * ViewBox.FADE_FRAC) or 0
+  ViewBox.cull = {
+    x = cx, y = 0, z = cy - (north - south) * 0.5,
+    -- `r` is what the ball and the pillar kinds are sized by and the box
+    -- is not; carried so the cut table has one shape whoever made it
+    r = math.max(rx, rz), rx = rx, rz = rz,
+    -- a zero band is a hard edge: half a pixel of ramp, which is one pixel
+    -- of antialiasing rather than a stair (Diorama says the same)
+    invFade = 1 / math.max(fade, 0.5),
+    kind = V.require("Diorama").BOX,
+  }
+  return ViewBox.cull
+end
+
+function ViewBox.stop()
+  ViewBox.cull = nil
+end
+
+-- ------- the coarse half of the cut
+--
+-- Whether anything inside the world-pixel rectangle (x0, z0)-(x1, z1) can
+-- be inside this frame's box. True whenever there is no box, so a caller
+-- may guard every draw with it unconditionally.
+function ViewBox.shows(x0, z0, x1, z1)
+  local c = ViewBox.cull
+  if not c then return true end
+  local pad = ViewBox.PAD
+  return x0 - pad <= c.x + c.rx and x1 + pad >= c.x - c.rx
+     and z0 - pad <= c.z + c.rz and z1 + pad >= c.z - c.rz
+end
+
+-- The same question about a connected neighbour, in the shape VoxelScene
+-- keeps them: { map, ox, oy } with the offset in world pixels and the map's
+-- own size in blocks of 32 (the shape prefetch's masks are built from).
+function ViewBox.showsMap(nb)
+  if not (nb and nb.map and nb.map.def) then return true end
+  return ViewBox.shows(nb.ox or 0, nb.oy or 0,
+                       (nb.ox or 0) + (nb.map.def.width or 0) * 32,
+                       (nb.oy or 0) + (nb.map.def.height or 0) * 32)
+end
+
+-- What the shadow pass has to notice: WHICH neighbours it drew is now a
+-- function of the row, and the row is the one input to that the sun's own
+-- signature does not already carry (the centre, the view size and the
+-- rung are all in it). Widening the box brings a neighbour back into the
+-- light's frustum, and a map recorded without it must be redrawn.
+function ViewBox.signature()
+  return ViewBox.frac() or 0
+end
+
+function ViewBox.row()
+  return ViewBox.setting:row()
+end
+
+function ViewBox.sync(value)
+  ViewBox.setting:sync(value)
+end
+
+return ViewBox

lib/VoxelGrid.lua

@@ -44,11 +44,36 @@ VoxelGrid.DARK = 0.45
 -- 1.0 here is the one-pixel wireframe.
 VoxelGrid.WIDTH = 1.0
 
+-- The same width in the CANVAS pixels the shader measures in, which is what
+-- every sender of it actually wants.
+--
+-- The two are the same number until AA renders the pass larger than the
+-- window (see AntiAlias): there a canvas pixel is a fraction of a display
+-- one, and a width left at 1.0 would come out a half or a quarter of a line
+-- after the fold -- the wireframe fading as the smoothing goes up, which
+-- reads as one row breaking the other. Scaled, it stays a one-pixel seam and
+-- simply gains the antialiasing everything else in the frame just gained.
+function VoxelGrid.width()
+  return VoxelGrid.WIDTH * V.require("AntiAlias").factor()
+end
+
 -- where it persists and the rows that cycle it (see ModSetting)
 VoxelGrid.setting = ModSetting.new(VoxelGrid.KEY, VoxelGrid.LABEL,
                                    { false, true }, { "OFF", "ON" })
 
+-- A pass that needs the wireframe whatever the player left the row on sets
+-- this for the length of its own draw and puts it back after. nil means
+-- "follow the setting", which is every frame outside such a pass.
+--
+-- The overworld battle is the one user: a fight is a STAGED shot, not the
+-- world being walked around in, and the seams are what make it read as
+-- constructed rather than as a photograph of somewhere. The row still owns
+-- what free-roam looks like, and is not written to -- switching the mode off
+-- mid-battle would silently rewrite the player's own setting.
+VoxelGrid.override = nil
+
 function VoxelGrid.enabled()
+  if VoxelGrid.override ~= nil then return VoxelGrid.override end
   return VoxelGrid.setting:get() and true or false
 end
 

lib/VoxelState.lua

@@ -23,10 +23,100 @@
 
 local Voxel = {}
 
-Voxel.ANGLES_DEG = { 0, 15, 35, 50, 75 }
-Voxel.ANGLE_LABELS = { "OFF", "15", "35", "50", "75" }
+-- FULL is a PRESET, not another angle: one rung that puts the whole mode in
+-- its intended state at once -- this camera, the miniature blur at full, the
+-- horizon flat, the view fitted -- so a player who wants "the diorama" picks
+-- it rather than assembling it from four rows. It sits directly after OFF
+-- because that is the order those two get used in.
+--
+-- Its ANGLE is 35 degrees, the same as the rung of that name. The duplicate
+-- in the table is deliberate: the ladder is a list of what each rung LOOKS
+-- like, and two rungs may look the same while meaning different things.
+--
+-- 1ST and 3RD are the other rungs that are more than an angle: the camera
+-- steps off its orbit entirely and stands with the player -- in their eyes
+-- (lib/FirstPerson.lua), or on a boom behind their shoulder
+-- (lib/ThirdPerson.lua) -- with free look and free movement on both. Their
+-- ANGLE entries are 75 -- the orbit rung they hand over from -- because the
+-- tween in and out starts from whatever the orbit shows, and the lowest rung
+-- is the one a dive into a head should start from. Everything angle-derived
+-- (the sky's fade, the billboard lean the blend eases away) reads that 75
+-- while the free-roam rig owns the actual camera.
+Voxel.ANGLES_DEG = { 0, 35, 15, 35, 50, 75, 75, 75 }
+Voxel.ANGLE_LABELS = { "OFF", "FULL", "15", "35", "50", "75",
+                       "1ST (EXPERIMENTAL)", "3RD (EXPERIMENTAL)" }
 Voxel.MAX_LEVEL = #Voxel.ANGLES_DEG - 1
 
+-- the rung FULL sits on, so nothing has to hunt for it by label
+Voxel.FULL_LEVEL = 1
+
+function Voxel.isFull(level)
+  return (level or Voxel.level) == Voxel.FULL_LEVEL
+end
+
+-- the rung the first-person camera sits on, likewise
+Voxel.FP_LEVEL = 6
+
+function Voxel.isFirstPerson(level)
+  return (level or Voxel.level) == Voxel.FP_LEVEL
+end
+
+-- and the third-person one, which is the same rig with the eye boomed off
+-- the back of the head (lib/ThirdPerson.lua)
+Voxel.TP_LEVEL = 7
+
+function Voxel.isThirdPerson(level)
+  return (level or Voxel.level) == Voxel.TP_LEVEL
+end
+
+-- The two of them together: the rungs where the camera stands WITH the
+-- player rather than orbiting the view centre, which is what decides that
+-- the look inputs are read, the walk goes free and the cards turn to face
+-- the eye. Everything that used to ask isFirstPerson for those asks this.
+function Voxel.isFreeCam(level)
+  level = level or Voxel.level
+  return Voxel.isFirstPerson(level) or Voxel.isThirdPerson(level)
+end
+
+-- ------- what the hotkey walks
+--
+-- The ANGLE rungs only, with FULL left out. The key is a display-mode
+-- cycler: pressing it should change the camera and nothing else, and FULL
+-- reaches in and rewrites four other settings. Landing on it by accident,
+-- mid-walk, would silently turn the blur to maximum and flatten the horizon
+-- with no indication that a keypress had done so. FULL stays on the OPTIONS
+-- row, which is where a preset that changes other rows belongs.
+--
+-- 1ST and 3RD are on the path: they change the camera and only the camera,
+-- which is exactly what the key promises -- and the key is also the way back
+-- OUT of them on a keyboard, where the mouse is captured and the OPTIONS
+-- menu is a trip.
+Voxel.HOTKEY_ORDER = { 0, 2, 3, 4, 5, 6, 7 }  -- OFF,15,35,50,75,1ST,3RD
+
+-- The rung a press moves to from `level`.
+--
+-- A level that is not on the key's path -- FULL, reached from the menu --
+-- steps on from whichever rung shows the SAME camera it does. FULL is 35
+-- degrees, so a press from it goes to 50 rather than back to 35, and the key
+-- never appears to do nothing. Matched by ANGLE rather than by a hardcoded
+-- rung, so retuning FULL moves the key's answer with it.
+function Voxel.nextHotkeyLevel(level)
+  level = level or Voxel.level
+  local order = Voxel.HOTKEY_ORDER
+  local at = nil
+  for i, rung in ipairs(order) do
+    if rung == level then at = i break end
+  end
+  if not at then
+    local deg = Voxel.ANGLES_DEG[level + 1]
+    for i, rung in ipairs(order) do
+      if Voxel.ANGLES_DEG[rung + 1] == deg then at = i break end
+    end
+  end
+  if not at then return order[1] end
+  return order[at % #order + 1]
+end
+
 Voxel.level = 0
 Voxel.angle = 0
 Voxel.from = 0

lib/WorldCurve.lua

@@ -56,11 +56,28 @@ WorldCurve.LABEL = "V-CURVE"
 -- of the town -- which stops being a look and starts being an occlusion
 -- bug, since what has rolled away is still there to walk into. (The first
 -- cut ran 0.18/0.35/0.60 and every rung of it was a marble.)
-WorldCurve.AMOUNTS = { 0, 0.05, 0.10, 0.18 }
+--
+-- 4 AND 5 ARE PAST THAT LINE ON PURPOSE, and they are for the DIORAMA:
+-- once the world is a model being looked at from outside rather than a
+-- place being walked around in, "the horizon has closed over the next
+-- block" stops being a bug and becomes the entire effect -- the town on
+-- top of a little planet.
+--
+-- 5 is the HALF SPHERE, and it is not eyeballed. The drop is a parabola,
+-- y = k d^2 with k = amount / vh, and the parabola that osculates a sphere
+-- of radius R at its pole is y = d^2 / 2R -- so k = 1 / 2R, and an amount
+-- of 1.0 gives R = vh / 2. The diorama's box is cut at exactly half a view
+-- height (Diorama.BOX_FRAC), so at amount 1.0 the model's own rim is that
+-- sphere's EQUATOR: the ground turns 45 degrees by the edge of the cut and
+-- is falling vertically a view-height out. A dome, ending where the model
+-- ends. 4 is the step between it and 3, geometrically rather than
+-- arithmetically -- the effect goes as the square of distance, so even
+-- steps in `amount` would bunch the whole ladder at the bottom.
+WorldCurve.AMOUNTS = { 0, 0.05, 0.10, 0.18, 0.42, 1.00 }
 
 WorldCurve.setting = ModSetting.new(WorldCurve.KEY, WorldCurve.LABEL,
-                                    { 0, 1, 2, 3 },
-                                    { "OFF", "1", "2", "3" })
+                                    { 0, 1, 2, 3, 4, 5 },
+                                    { "OFF", "1", "2", "3", "4", "5" })
 
 function WorldCurve.level()
   return WorldCurve.setting:get() or 0

manifest.json

@@ -1,17 +1,20 @@
 {
   "id": "DRAMATIC_SHAPE",
   "name": "Dramatic Shape Voxel Mod",
-  "version": "1.0.6",
+  "version": "1.7.1",
   "api": 2,
   "entry": "main.lua",
   "profile": "content",
   "category": "GRAPHICS",
-  "game_version": "0.0.0-dev || >=0.1.28 <2.0.0",
+  "game_version": "0.0.0-dev || >=0.1.37 <2.0.0",
   "priority": 100,
   "dependencies": [],
   "optional_dependencies": [],
-  "conflicts": [],
-  "permissions": ["engine_internals"],
+  "conflicts": ["ds_fp_ceiling"],
+  "permissions": [
+    "engine_internals"
+  ],
   "affects_link": false,
-  "description": "A full 3D diorama overworld: extruded terrain, depth-buffered occlusion, voxel characters and a tilt-shift miniature pass. Registers two render pipelines and claims hotkeys 3, 5, 6 and 7 -- 3 and 5 displace the engine's TILT and GBC FX keys, both still reachable on the OPTIONS menu. Presentational only."
+  "description": "Draws the overworld as a 3D diorama.",
+  "github": "DramaticShape/DramaticShapeVoxelMod"
 }

mod.card

@@ -1,33 +1,85 @@
 -- Sharing metadata (25-community-and-ecosystem.md 3.2).  Read by tooling
 -- and the manager detail pane; never by the loader's merge.
 return {
-  summary = "The overworld as a 3D diorama: extruded terrain, real occlusion, voxel characters, tilt-shift miniature blur.",
+  summary = "The overworld as a 3D diorama, and battles fought on it: real occlusion, tilt-shift, over-the-shoulder fights.",
   author = "DramaticShape",
   contact = "https://github.com/DramaticShape/DRAMATIC_SHAPE",
-  tags = { "graphics", "3d", "voxel", "render-pipeline", "presentation" },
+  tags = { "graphics", "3d", "voxel", "render-pipeline", "presentation",
+           "battle" },
   differences = {
     changed = {
       "with VOXEL on, the overworld draws as 3D geometry instead of flat tiles",
       "occlusion comes from a depth buffer rather than a y-sort, so buildings really hide what is behind them",
-      "VOXEL and the engine's TILT are mutually exclusive -- turning one on switches the other off",
-      "hotkeys 3 and 5 are taken over from the engine's TILT and GBC FX; both remain on the OPTIONS menu",
-      "the VOXEL key (3) turns TILT and GBC FX off on every press -- both fight the diorama, and 3 is now the only key that reaches either",
+      "with 3D-BTL on 2D-3D A, a battle draws over the map's nearest clear ground instead of over a white field",
+      "with 3D-BTL on a B rung, the fight is staged on two discs against the sky with no map drawn at all, which works on every map including the caves and shop floors that have nowhere to stage a fight",
+      "with 3D-BTL on STADIUM A or STADIUM B, the same fight is staged with the Pokemon Stadium battle models in place of the flat pics -- 148 of the 151 species, skinned and animated, playing the animation the move being used actually calls for; Exeggutor, Tangela and Magmar have corrupt animation data at source and keep their battle sprites",
+      "the battle's text box and menu are frosted glass over that ground rather than an opaque white slab, on the same panels the HUDs sit on",
+      "the map's NPCs are culled for the length of a battle, so the wipe plays over an empty map",
+      "a battle's letterbox voids go black rather than white, because the battle canvas is no longer white",
+      "the engine's TILT and GBC FX rows are taken OFF the OPTIONS menu and held at off for as long as this mod is installed -- TILT is the flat fake of what this mode does for real, GBC FX is a full-screen pass over the top of it; uninstalling puts both rows back",
+      "hotkeys 3 and 5 are taken over from those two, which have no key and no row while this is loaded",
+      "SELECT in free roam steps the VOXEL ladder exactly as hotkey 3 does -- the button has no overworld job in Gen 1, and phones and pads have no number row; menus keep it untouched",
+      "on the 1ST and 3RD rungs ONLY, the grid walk is replaced by free camera-relative movement: collision, warps, ledges, encounters and scripts still run through the engine's own machinery, and every other rung leaves movement untouched",
+      "on the 1ST and 3RD rungs the mouse cursor is captured for free look; left click is A, right click is B, and any touch off the overlay's controls drags the view",
+      "on the 3RD rung the character turns to face where they are walking rather than where the camera looks, so a strafe reads as one; standing still they come back round to the camera's bearing, which is the one A talks along",
+      "on 1ST and 3RD the wall-collision sound is gone: a free walk slides along every wall it grazes rather than refusing a discrete step, so the bonk rang twice a second for walking down a corridor",
+      "the BATTLE BG options row is taken OFF the menu and pinned to WHITE for as long as this mod is installed -- the mode fills the window with the map, so the row's own question (what to put in the voids around the battle) has no voids left to be about, and its WORLD setting drew a second dimmed copy of the overworld under the arena; uninstalling puts the row back",
+      "a staged battle's camera can be steered by the player -- right stick, touch drag or mouse to swing it around the arena and raise it, wheel / Q / E / pinch / stick click for the lens -- between the shot the rig was solved for and a side-on view of the arena, and it opens the lens as it goes so both Pokemon stay framed; the angle and lens carry into the next battle",
+      "with BACK SPRITES on the battle camera is held at the solved shot, because that setting pins your own Pokemon to the menu's slot while the foe stands on the map and no angle holds a half-framed, half-solid composition",
     },
     added = {
-      "VOXEL options row and hotkey 3 (OFF / 15 / 35 / 50 / 75 degrees)",
+      "VOXEL options row and hotkey 3 (OFF / 15 / 35 / 50 / 75 degrees / 1ST / 3RD -- a first-person camera and a third-person one, both with free look and free movement)",
       "T-SHIFT options row and hotkey 6 (OFF / 1 / 2 / 3), the miniature blur",
       "V-GRID on hotkey 5 and V-CURVE on hotkey 7",
+      "Q and E zoom whichever camera is in front of you -- the third-person boom, a staged battle's lens, or the engine's own survey zoom on an orbit rung -- alongside the mouse wheel, a two-finger pinch, and the pad's left and right stick clicks (out and in). 1ST claims none of them: the eye is in the player's head and there is no distance to change",
+      "WATER on hotkey 9 (FULL / SKY / OFF, FULL by default): the water surface becomes a field of pixel-tall voxel columns rising and falling as waves, reflecting the sky, the sun, the moon and the cast standing beside it -- and, on FULL, the shoreline, trees and buildings behind it, by a screen-space ray march",
+      "3D-BTL on hotkey 8 (2D-3D A / 2D-3D B / STADIUM A / STADIUM B / OFF, 2D-3D A by default), battles fought in 3D -- 2D-3D stands the game's own pics up as cards and STADIUM replaces them with the Pokemon Stadium battle models, while A stages the fight on the map and B on two carried discs against the sky. Only the STADIUM rungs need a ROM, and they are on the row once those models have been built (see below); 2D-3D B is generated in Lua and needs nothing",
+      "the STADIUM animations are driven from the fight: a move plays the animation that species' own battle table names for it (so DIG really does put Diglett into the ground), fainting plays the faint and holds there, and a send-out grows the Pokemon out of the ball and plays the entrance. Damage plays nothing -- the set has no reaction animation in it, and the engine's own flash, blink and HP drain already say so. The eyes blink and go dizzy, and Charmander's tail flame and Weezing's gas are drawn over the body",
+      "BACK SPRITES options row (OFF / ON, off by default), which keeps your own Pokemon on the battle menu in its classic slot while the foe stands out on the map",
+      "VR options row (OFF / STANDARD / DIORAMA / DIORAMA-MR, off by default; a save that stored the old toggle as true comes back on STANDARD). STANDARD is the mode below. DIORAMA is one presentation instead of a ladder: the world is always the model on the table, cut to an invisible BOX centred on the view -- a square slab of world with a HARD edge, because a flat world is a thing with sides -- which V-CURVE turns into a BALL whose rim is a gradient fade into the same sky (the cut reaches terrain, cast, grass, water and the forest's beams alike), with a staged fight ignoring both and cutting a vertical PILLAR about the arena -- always dissolved at the rim -- and framing the model to it: the fight lifted out of the map as a floating disc. The grips take hold of it: one hand carries the model through the room, both hands turn it and open the viewport out. The left stick's click throws V-CURVE to its top rung and back instead of stepping views; there is no 2D diorama and no first-person one, so the VOXEL ladder is held on an orbit rung while the mode runs and the Pokedex stays away. DIORAMA-MR is the same with the background keyed pure green (no bands, no sun, no haze) for a mixed-reality capture",
+      "VR STANDARD (the row's second rung): PCVR through OpenXR on Windows -- the diorama as a head-tracked tabletop model presented at the rung's own angle and framing on the orbit rungs, life-size first person on 1ST, a staged battle snapping the headset (through a fade to black) into the flat game's own over-the-shoulder seat at life scale, a voxel Pokedex flush along the left controller in first person and in battles (menus, dialogs and the 2D battle screen on its screen; the diorama does without it), the sky and its sun and moon anchored in space (bands, GBC dither and twilight glow alike -- nothing in the sky reacts to the head), the floating panel wearing the GB frame near-square rather than the whole monitor-wide window (scaled into the headset, so the picture and its ratio are identical at every window size, fullscreen included), the window as mirror; needs a runtime (SteamVR/Oculus/WMR) and the mod on a real folder",
+      "VR controllers (Touch/Index/WMR, rebindable in the runtime): left stick moves, A/B are A/B, either trigger is START, left stick click steps the VOXEL angle ladder exactly as the 3 key and SELECT do; in 1ST the right stick snap-turns 45 degrees a flick; in the tabletop the right stick zooms; under STANDARD a squeezed grip drags the table's height, and in a DIORAMA the grips take the model itself -- one carries it, both turn it and resize the viewport, and the left stick's click throws V-CURVE instead; no controller button leaves VR -- that is the VR row's job",
+      "a day/night clock that reaches the flat 2D overworld as well as the diorama -- outdoor maps only, and only when the hour is not midday",
+      "an over-the-shoulder battle camera on a slow parallax orbit, with a depth-of-field pass that holds both mons sharp",
       "a sky behind the diorama at the 75-degree rung, outdoor maps only, coloured by the active palette mode",
       "a hand-authored tile shape profile (data/voxel_heights.lua) a mod can extend",
+      "SMOOTH TURN options row (OFF / ON, off by default, and only on the menu while VR is ON): turn continuously with the right stick instead of snapping 45 degrees a flick. The snap is the default because a software turn moves the world past a head that did not move, which is the reliable way to make somebody ill in a headset -- but it costs continuity, so the choice is the player's",
+      "HORDE MODE, on the konami code (Up Up Down Down Left Right Left Right B A) standing in the overworld: the sky drops to a starless violet night, the Lavender Town theme comes up, the camera locks into the player's own head (in VR too), a voxel handgun with working iron sights appears in the right hand, and waves of people -- the map's own NPCs among them -- walk out of the dark to kill you. Score per kill, a random Pokemon cry for each one that falls, no pausing; the horde follows you through doors. Health out is a GAME OVER card with the score and PRESS A, which puts the map, the cell, the facing, the camera rung, the hour, the music and every NPC back exactly as they were. Fire on left click, the pad's right trigger or B, a tap on a touch screen, or the right trigger in VR; reload on R, the pad's X, or B on the right controller; aim down the sights on right click or the left trigger",
+      "the horde's gunshot, dry fire, magazine and slide sounds, synthesized on the game's own emulated Game Boy sound hardware (no audio files ship with the mod)",
     },
     known = {
-      "needs shader and depth-canvas support; without them the row still cycles but the world stays 2D",
-      "battles, menus and cutscenes are unaffected -- the mode only draws the free-roam overworld",
+      "needs shader and depth-canvas support; without them the rows still cycle but the world stays 2D and battles draw plainly",
+      "water reflections additionally need a READABLE depth canvas; a driver without one draws the flat animated water this mode always drew",
+      "WATER on FULL ray-marches the depth buffer per water pixel, so a map that is mostly sea costs real fill rate on a weak GPU -- SKY is the same look minus the ray march, and OFF is the flat water",
+      "a screen-space reflection can only reflect what is in the frame: a tree just off the top edge is not in the water below it, and a ray that runs off the side fades into the sky rather than ending on a line",
+      "a map with no 3x6 clearing falls back to a 1x4 one, and a map with neither draws the plain battle screen",
+      "the STADIUM rungs need the Pokemon Stadium battle models, and the mod ships none of them -- they are that game's data. Press STADIUM ROM on the OPTIONS menu to pick one with the system file dialog, or drop one in a baseroms/ folder beside the game. It must be Pokemon Stadium (US) 1.0 (md5 ed1378bc12115f71209a77844965ba50) -- every offset in the reader is keyed to that cartridge, and anything else is refused or builds wrong models; either way the 151 models are built out of it on a loading screen, in about ten seconds, into the save directory, and the ROM itself is not kept. Until then the two rungs are simply not on the row. Once built, a rung declines per POKEMON rather than per battle: a species with no pack, a standing substitute doll, and the trainer's own pic before the send-out each fall back to the flat card on that side alone, with the other side keeping its model",
+      "the STADIUM rungs size a Pokemon by its own model against the set's median, with the range compressed -- the authored heights span sixteenfold, from Caterpie to Gyarados, and a shared over-the-shoulder shot cannot hold that. The order and the feel of the differences survive; the literal ratios do not",
+      "three species -- Exeggutor, Tangela and Magmar -- have standby loops that are corrupt in the source extraction, and are held at their bind pose so they stand still rather than coming apart",
+      "the arena is where the CAMERA goes -- nobody is moved, so a fight staged across the map is a shot of that ground, not a trip to it",
+      "the battle backdrop renders at the GB's 160x144 to match the pics composited over it, so it is chunkier than the free-roam pass",
+      "menus and cutscenes are unaffected -- outside a battle the mode only draws the free-roam overworld",
       "terrain meshes are cached per map, so the first frame after entering a large map costs a build",
+      "1ST and 3RD need the 3D pass like every rung; without it the level still persists but the world stays 2D and the grid walk stays in charge",
+      "in 1ST and 3RD, scripted walks, ledge hops and spinner slides play out as the grid moves they are, with the camera riding along; free control resumes when they land",
+      "3RD's boom shortens against whatever stands behind the player, so backing into a wall walks the camera in to their shoulders; squeezed all the way in it draws as 1ST until they step clear",
+      "3RD in VR is 1ST in VR: a headset that seats its wearer three cells behind their own body is a well-known way to make people ill, so the boom is declined while a headset is live",
+      "rooms have no ceilings, so a first-person look over an interior wall shows the void the diorama always had behind it",
+      "VR is Windows x64 only (the shipped loader and the Win32 GL binding): on any other platform -- mobile above all -- the VR row is absent from the OPTIONS menu and the manager's page both, and a stored vr=true carried over in a save is ignored. On Windows it renders the scene once per eye (heavy with WATER FULL or AA up); pad/keyboard/mouse keep working alongside the XR controllers. The loader DLL is found wherever the mod was put -- the dev tree, an installed release's save directory, or an imported archive, from which it is copied once into the save directory so the FFI has a real disk path",
+      "VR on and off are both the VR row's job (options menu or manager); no controller button does either",
+      "the Pokedex needs a TRACKED left controller; without one there is no device in hand and the floating panel carries the UI as before",
+      "while the VR row is ON, 3D-BTL is held ON and BACK SPRITES held OFF (the headset's battle staging assumes both), and both rows leave the OPTIONS menu until VR goes off -- their stored values come back with them",
+      "while a headset is live the battle HUDs keep their classic in-frame slots instead of snapping to the window's edges, and the engine's edge-anchored menus (the START menu above all) are held inside the frame the same way, on the flat mirror too -- both VR screens crop to the GB frame, and a block at the window's edge would be cropped away with it",
+      "VR swapchains prefer plain RGBA8; a runtime that only offers sRGB shows slightly lifted colours",
+      "HORDE MODE needs the 3D pass, like every rung that has a camera in it: without one the code is refused and nothing happens",
+      "the horde's crowd are the overworld's own sprite billboards, so at close range they are flat cards the size of a person -- they hold two cells off the player for that reason, close enough to swing and far enough to be seen past",
+      "a run is not saved: the score and the best score ride the save slot, but the mode itself has no state to resume, and quitting mid-run simply ends it",
     },
   },
   credits = {
     { who = "pret/pokered", for_ = "the tile and sprite data the geometry is derived from" },
+    { who = "pret/pokestadium", for_ = "the decompilation the STADIUM extractor was written against -- the bone matrix chain and where scale is applied (func_800143C0), the rotation basis (func_8000F730), the animation and texture-animation samplers (func_80016FBC / func_80017540), the battle context slots and the move-id constants. No code or data from it is included or redistributed here; see README.md" },
+    { who = "The Khronos Group", for_ = "the OpenXR loader shipped unmodified in assets/vr (Apache-2.0; full license text alongside the DLL)" },
   },
-  compat = { engine = ">=0.1.28 <2.0.0", modApi = 2 },
+  compat = { engine = ">=0.1.37 <2.0.0", modApi = 2 },
 }

model_extract/README.md

@@ -0,0 +1,181 @@
+# Pokemon Stadium (US) — battle model export
+
+> **Built on [pret/pokestadium](https://github.com/pret/pokestadium).** This
+> pipeline is original code, but it could not have been written without that
+> project's decompilation: the bone matrix chain and the fact that scale is
+> kept out of it (`func_800143C0`), the rotation basis (`func_8000F730`), the
+> animation and texture-animation samplers (`func_80016FBC`, `func_80017540`),
+> the battle context slots, and the move-id constants all came from reading
+> it. **No code or data from that project is vendored here or required to run
+> this** — see the mod's [README](../README.md#acknowledgements--pretpokestadium),
+> and get anything you want to reuse from upstream under its own terms.
+>
+> No ROM data is committed either: everything below is generated from a
+> cartridge you supply.
+
+All 151 battle Pokemon plus 64 other models from the same segment, in standard
+formats. Regenerate straight from the ROM — stdlib only, no `make init`, no
+splat, no crunch64:
+
+```bash
+model_extract/pipeline/build.py
+```
+
+Put a US 1.0 ROM in [baseroms/](baseroms/) (`.z64`, `.n64` or `.v64`), or pass
+`--rom=PATH`. See [pipeline/README.md](pipeline/README.md) for the module layout,
+how the ROM is unpacked, and the generated-effects notes.
+
+```
+viewer.html            browse everything in the browser — open it directly
+manifest.json          every model + what each of its animations is used for
+moves.json             all 165 moves + the animation each species plays for them
+glb/025_pikachu.glb    glTF 2.0 binary: mesh, skeleton, skin, animations, textures
+glb/x152_model.glb     non-Pokemon models from the same segment (props, trophies…)
+textures/025_pikachu/  the same textures as loose PNGs, named <n>_<w>x<h>.png
+js/                    viewer payloads, one per model, plus index.js and moves.js
+```
+
+`viewer.html` has a filterable picker for every model plus prev/next/random, a
+**move picker** that jumps to whichever animation the current Pokemon plays for
+that move, per-animation playback with a frame scrubber, an eye/texture-animation
+selector, and texture/lighting/wireframe/skeleton toggles. It reads `js/`, not
+`glb/`, because browsers block `fetch` of local files from `file://` — script
+injection is what lets the page work when you just double-click it.
+
+Sizes: 73 MB `glb/`, 54 MB `js/`, 7.4 MB `textures/`. Two flags if you want less:
+`--no-js` skips the viewer payloads and `viewer.html` (leaving the glTF export
+alone), and `--manifest-only` rebuilds just `manifest.json`.
+
+`.glb` files are self-contained and open directly in Blender, Maya, Unity, Unreal,
+three.js, Godot, Windows 3D Viewer, macOS Quick Look, and https://gltf-viewer.donmccurdy.com.
+Source file `N.bin` holds species `N + 1`.
+
+## Conventions
+
+- Y up, +Z front, right-handed — glTF standard.
+- Animations are authored at **30 fps**; keyframe times are `frame / 30`.
+- Units are game units. Models are authored 10x and scaled down by the
+  `model_root` node, matching the geo layout's scale command.
+- Textures are `CLAMP_TO_EDGE`, materials are `alphaMode: MASK` with cutoff 0.5
+  (N64 RGBA5551 has one bit of alpha). `doubleSided` follows the display list's
+  cull mode.
+
+## Skeleton
+
+The game keeps bone scale *out* of the matrix chain (`func_800143C0` in
+[src/12D80.c](../src/12D80.c)): scale accumulates in its own stack, a bone's local
+translation is pre-multiplied by the parent's accumulated scale, and the
+accumulated scale is applied to the rows of the finished world matrix only at
+draw time. glTF node TRS instead propagates scale multiplicatively to children,
+so a 1:1 node mapping would be wrong wherever a non-uniformly scaled bone has
+descendants.
+
+Each game bone is therefore exported as two nodes:
+
+| node | role |
+| --- | --- |
+| `boneNN` | pivot: `translation = t * accScale(parent)`, `rotation = R`, scale 1 |
+| `boneNN_scale` | leaf child holding `scale = accScale(bone)`, so it cannot propagate |
+
+The skin binds to the `boneNN_scale` nodes, whose world matrices then equal the
+game's draw matrices exactly. Vertices are already in bone-local space and each is
+rigidly bound to one bone, so all inverse bind matrices are identity.
+
+This was verified by parsing each exported `.glb` back and diffing every joint
+matrix against a reference implementation of the game's own math, over the bind
+pose and four sampled frames of every animation. Worst-case disagreement is
+~1e-2 game units on models spanning 20–40 units, entirely from storing rotations
+as spec-normalised `SHORT` quaternions.
+
+## Animation semantics
+
+Per-species battle data lives in `assets/us/70D3A0.bin`, 0xB90 bytes per species,
+DMA'd into the battle system by `func_84302658` via the `D_80075BD0[species-1]`
+pointer table. It is an array of 0x10-byte entries; byte 0 of each entry is an
+index into that Pokemon's animation list and byte 1 indexes the auxiliary list:
+
+- **entries 0–164** — one per move, in the move ID order of
+  [oldnotes/stadium1/constants/move_constants.s](../oldnotes/stadium1/constants/move_constants.s).
+  Entry *n* gives the animation played when the Pokemon uses move *n + 1*.
+- **entries 165+** — fixed battle contexts (idle, hit, faint, …).
+
+Every one of the 151 species' tables indexes only animations that exist in that
+species' list, which is what confirms the layout.
+
+`manifest.json` reports, for each animation, the exact list of moves that trigger
+it plus which context slots reference it. `moves.json` inverts that: every move,
+and the animation each of the 151 species plays for it.
+
+One caveat when reading move data: the table is **dense**. Every species has a
+row for every move, including moves it can never learn, and those unreachable
+rows overwhelmingly point at the species' generic reaction animation — the same
+one the `hit` slot uses. So "118 species play Thunderbolt" is an artifact, not a
+fact about the game. `moves.json` marks each row with `differsFromDefault` and
+gives a `speciesWithOwnAnimation` count per move; treat those as the signal. The `animationSlots` section carries an
+`evidence` field per slot:
+
+- `code` — the battle code in `src/fragments/62` names the slot outright.
+- `data` — inferred from what the referenced animation actually does, measured
+  across all 151 species. For example slot 167 is labelled `faint` because its
+  animation always ends far from the standing pose (the model drops to
+  0.03–0.84x idle height, or leaves the frame entirely for fliers), while slot
+  168's animation always ends at exactly idle height.
+
+`endBehavior` reports what the animation player does past the last frame
+(`func_80016FBC`): every animation in the game wraps back to `loopStartFrame`, so
+one-shots like `faint` are ended by the battle state machine switching animation,
+not by the player clamping. glTF has no loop flag, so importers will loop clips by
+default.
+
+The common layout, consistent across nearly every species:
+
+| animation | role |
+| --- | --- |
+| 0 | idle / standby loop (all 151 species) |
+| 1 | second idle-length animation, rarely referenced by the context slots |
+| 2 | hit / damage reaction (149–151 species across slots 166, 178–181) |
+| 3 … n-3 | attack animations, selected per move |
+| n-2 | faint (slots 167, 177) |
+| n-1 | entrance / return-to-idle cycle (slots 168, 183) |
+
+## Texture animations (blinking, dizzy eyes)
+
+The second animation list in the model root is a *texture* animation, not a
+skeletal one (`src/18140.c`). Geo command `0x23` carries a channel index at
+offset `0x02`; when it is `>= 0`, `func_800176DC` replaces that material's
+texture every frame from a per-frame stream of texture-table indices.
+
+Charmander's eyes are the clearest example — texture 2 is the open eye, 3 and 4
+are blink frames, and 5–7 are the dizzy swirl:
+
+| aux animation | frames | texture stream |
+| --- | --- | --- |
+| 0 | 10 | `2 2 3 3 4 4 4 3 3 2` — a blink |
+| 2 | 122 | cycles `5 6 7` — confusion swirl |
+| 4 | 18 | a slower blink |
+
+The viewer plays these. Each skeletal animation is paired with the texture
+animation the battle table most often sets alongside it, and the `eyes` dropdown
+overrides that. glTF 2.0 has no texture-swap animation channel, so this data
+lives in `js/` and `moves.json` rather than the `.glb` — the `.glb` files carry
+the first frame's texture on each material.
+
+## Known gaps
+
+- **Move effect visuals are not here.** Geo command `0x24` does not draw
+  anything: `func_80014CB8` just records an attachment point (an id plus a world
+  position) on the Pokemon, and the battle system spawns particles there. Ids
+  1–14 are generic and used by nearly every species. So Charmander's tail flame,
+  beams, explosions and the like are drawn by the effect system in the battle
+  fragments and are not present in these model files — Charmander's texture set
+  contains eyes, claws, teeth and skin, and no flame.
+- **The Poke Ball throw/open model was not found.** It is not in this segment,
+  no other `assets/us/**.bin` contains a model fragment, and scanning the ROM
+  ranges of fragments 62–64 for embedded model headers found none. What does
+  exist is Poke Ball *2D* artwork in fragment 29
+  (`fragments/29/fragment29_unk_bin_*`, flagged in the splat yaml). The throw is
+  most likely built from raw display lists rather than a geo-layout model.
+- Files 151–214 are exported as `x<file>_model` with generic names. They are
+  props, trophies, minigame pieces and similar; only Surfing Pikachu (file 152,
+  the same 37-bone / 723-triangle rig as Pikachu) is named with confidence. They
+  carry no battle table, so their animations are left unnamed.

model_extract/baseroms/.gitignore

@@ -0,0 +1,5 @@
+baserom.z64
+*.z64
+*.n64
+*.v64
+*:Zone.Identifier

model_extract/baseroms/README.md

@@ -0,0 +1,25 @@
+# Put the ROM here
+
+`pipeline/build.py` looks for a Pokemon Stadium (US 1.0) ROM in this folder:
+
+    model_extract/baseroms/baserom.z64
+
+`.z64`, `.n64` and `.v64` byte orders are all accepted — the pipeline detects the
+magic and normalises on load. Any ROM file dropped in this folder is picked up.
+
+Expected md5 of the US 1.0 ROM: `ed1378bc12115f71209a77844965ba50`. A different
+ROM still runs, but the build prints a warning since the offsets are keyed to
+this revision.
+
+Search order (first hit wins):
+
+1. `model_extract/baseroms/baserom.z64`
+2. `model_extract/baseroms/us/baserom.z64`
+3. `baseroms/us/baserom.z64` at the repo root — the location `make init` uses
+4. any `*.z64` / `*.n64` / `*.v64` in this folder
+
+Or point at one explicitly:
+
+    model_extract/pipeline/build.py --rom=/path/to/baserom.z64
+
+The ROM is not included and is not tracked by git.

model_extract/pipeline/README.md

@@ -0,0 +1,93 @@
+# Export pipeline
+
+End-to-end: `baserom.z64` in, everything in `model_extract/` out. **Stdlib only** —
+no `make init`, no splat, no crunch64, no build directory.
+
+```bash
+model_extract/pipeline/build.py                    # finds the ROM automatically
+model_extract/pipeline/build.py --rom=/path/to.z64 --out=/tmp/out
+```
+
+The ROM is looked for in `model_extract/baseroms/` first, so this folder stands
+on its own; the repo's own `baseroms/us/` is the fallback. Search order:
+
+1. `model_extract/baseroms/baserom.z64`
+2. `model_extract/baseroms/us/baserom.z64`
+3. `baseroms/us/baserom.z64` at the repo root — where `make init` expects it
+4. any `*.z64` / `*.n64` / `*.v64` sitting in `model_extract/baseroms/`
+
+`.z64`, `.n64` and `.v64` all work — the byte order is detected from the magic
+and normalised on load. See [../baseroms/README.md](../baseroms/README.md).
+
+| flag | effect |
+| --- | --- |
+| `--only=3,91` | restrict to those model file numbers (fast iteration) |
+| `--no-glb` | skip the glTF binaries and PNG dumps |
+| `--no-js` | skip the viewer payloads and `viewer.html` |
+| `--no-effects` | skip the generated fire/gas stand-ins |
+
+## Modules
+
+| file | does |
+| --- | --- |
+| `rom.py` | byte-order fixup (.z64/.v64/.n64), md5 check, archive unpacking, Yay0 and PERS-SZP decompression |
+| `fragment.py` | FRAGMENT module → geo layout walk, F3DEX2 execution, textures, skeleton, animations |
+| `battle.py` | per-species battle tables, move names, animation-context slot meanings |
+| `glb.py` | glTF 2.0 binary writer |
+| `effects.py` | **generated** fire/gas stand-ins (see below) |
+| `build.py` | driver: ties it together, writes manifests |
+
+## Getting from ROM to models without the build system
+
+Three steps, all in `rom.py`:
+
+1. **Byte order.** `.z64` is native; `.v64` swaps byte pairs; `.n64` reverses
+   words. Detected from the magic and normalised on load.
+2. **Archive.** The segment at `0x920000` starts with
+   `u32 tag, u32 0, u32 totalSize, u32 fileCount`, then one
+   `{u32 offset, u32 size, u32 pad[2]}` record per file. Only the top three
+   bytes of the first word are reliably zero — the model archive puts a nonzero
+   value in the low byte, which is the quirk `tools/unpack_asset.py` works
+   around too.
+3. **Decompression.** Each entry is `PERS-SZP` (an 8-byte magic plus a header
+   size, wrapping a Yay0 stream). The Yay0 decoder is ~30 lines: a bitstream
+   where a 1 copies a literal byte and a 0 pulls a (distance, length) pair.
+
+Verified by decompressing all 215 entries and diffing against what
+`make init` produces: **215/215 byte-identical**.
+
+The battle tables need one more hop — `D_80075BD0[species - 1]` lives in the main
+code segment, so `Rom.vram_to_rom` converts `0x80075BD0` using the segment's
+`start`/`vram` from the splat yaml.
+
+## Generated effects
+
+`effects.py` produces **original, procedurally generated** fire and gas. It is
+not extracted game data, and everything it emits is tagged `generated: true` in
+the manifest, the viewer payloads and the PNG filenames (`*_fx.png`).
+
+This exists because the real effects are not in the model files at all. Geo
+command `0x08` attaches a callback (`func_80014A60` calls `node->unk_10`), and
+the model supplies only two empty display lists and zeroed scratch buffers for
+it to fill. The callback lives in another fragment and has not been ported, so
+there is no flame mesh or flame texture to extract — Charmander's texture set is
+eyes, claws, teeth and skin.
+
+The stand-ins are anchored to the exact bone the callback hangs off, so they sit
+where the real effect would and follow the animation:
+
+| callback | species | stand-in |
+| --- | --- | --- |
+| `0x810000D8` | Charmander, Charmeleon, Charizard, Magmar, Moltres | tail/crest flame |
+| `0x81000108` | Ponyta, Rapidash, Moltres wings | small flame |
+| `0x810000E0` | Gastly (only) | gas cloud |
+
+Both are looping flipbooks built from tileable value noise, drawn on a pair of
+crossed quads — glTF cannot billboard, so crossed quads are the portable way to
+make them read from any angle. Sizes are expressed as a fraction of the model's
+**height** and divided by the anchor bone's accumulated scale, so an effect comes
+out the intended size wherever in the skeleton it hangs. Seeds derive from the
+species number, so a given Pokemon always generates the same effect.
+
+In the viewer they draw in a second pass with depth writes off — additive for
+fire, alpha for gas — and there is a *generated effects* toggle to hide them.

model_extract/pipeline/battle.py

@@ -0,0 +1,125 @@
+#!/usr/bin/env python3
+"""
+Per-species battle data.
+
+`func_84302658` in src/fragments/62 DMAs a 0xB90-byte table per species out of
+the 0x70D3A0 segment, addressed through the D_80075BD0 pointer table. It is an
+array of 0x10-byte entries: byte 0 is an index into that Pokemon's animation
+list, byte 1 indexes the auxiliary (texture) animation list.
+
+  entries 0..164   one per move, so entry n drives move n + 1
+  entries 165+     fixed battle contexts
+
+Every one of the 151 species' tables indexes only animations that species
+actually has, which is what confirms the layout.
+"""
+import os
+import struct
+
+STRIDE = 0xB90
+ENTRY = 0x10
+N_MOVES = 165
+
+# `evidence` records how far each label can be trusted:
+#   code  - the battle code in src/fragments/62 names the slot outright
+#   data  - inferred from what the referenced animation does, measured over all
+#           151 species
+CONTEXT_SLOTS = {
+    165: ('idle', 'code',
+          'The standby loop. func_8432B0A4 restores this slot whenever the Pokemon '
+          'returns to neutral, and it resolves to animation 0 for all 151 species.'),
+    166: ('attack_default', 'data',
+          'Resolves to animation 2 for 149/151 species, the same animation slots '
+          '178-181 use in the reaction paths. Called "hit" until the move table '
+          'was read against it: it is the animation most of a species\' MOVES '
+          'play, the default attack rather than a damage reaction (the name has '
+          'to match lib/StadiumPack.lua\'s CONTEXT and StadiumBuild\'s CONTEXTS).'),
+    167: ('faint', 'data',
+          'The referenced animation always ends far from the standing pose - the '
+          'model collapses to 0.03-0.84x its idle height, or leaves the frame '
+          'entirely for fliers.'),
+    168: ('entrance', 'code+data',
+          'The default slot in func_8430506C / func_8432AF70. The referenced '
+          'animation ends at exactly idle height, so it is a full cycle that '
+          'settles back into the standby pose.'),
+    169: ('reaction_169', 'data', 'Resolves to the idle animation for 139/151 species.'),
+    170: ('reaction_170', 'data', 'Split between the idle and hit animations.'),
+    171: ('reaction_171', 'data', 'Resolves to the idle animation for 138/151 species.'),
+    172: ('reaction_172', 'data', 'Resolves to the idle animation for 148/151 species.'),
+    173: ('reaction_173', 'data', 'Resolves to the hit animation for 97/151 species.'),
+    174: ('reaction_174', 'data', 'Resolves to the idle animation for 138/151 species.'),
+    175: ('struggle', 'code', 'Passed as slot 0xAF to func_84305A74.'),
+    176: ('idle_alt', 'code',
+          'Substituted for the idle slot when battle flag 0x200 is set.'),
+    177: ('faint_alt', 'data', 'Same animation as slot 167 for almost every species.'),
+    178: ('flinch', 'code',
+          'Used when the incoming move is one of the two listed in D_84384598.'),
+    179: ('reaction_179', 'data', 'Resolves to the hit animation for all 151 species.'),
+    180: ('reaction_180', 'data', 'Resolves to the hit animation for all 151 species.'),
+    181: ('reaction_181', 'data', 'Resolves to the hit animation for all 151 species.'),
+    182: ('reaction_182', 'data',
+          'Resolves to animation 0 for 136 species and animation 1 for the other 15.'),
+    183: ('entrance_alt', 'data', 'Same animation as slot 168 for every species.'),
+    184: ('idle_return', 'code', 'Passed as slot 0xB8 to func_84305A74.'),
+}
+
+MOVE_CONSTANTS = 'oldnotes/stadium1/constants/move_constants.s'
+
+
+def load_move_names(repo_root='.'):
+    """Move IDs come from the repo's own extracted constants when available."""
+    path = os.path.join(repo_root, MOVE_CONSTANTS)
+    names = {}
+    if os.path.exists(path):
+        for line in open(path, encoding='utf-8', errors='replace'):
+            # the file also carries an ABC_* section indexing moves alphabetically
+            # by their Japanese names; only the real move IDs are wanted
+            if ' EQU ' not in line or line.startswith('ABC_'):
+                continue
+            name, val = line.split(' EQU ')
+            val = val.split(';', 1)[0].strip()
+            if val:
+                names[int(val, 0)] = name.strip().replace('_', ' ').title()
+    return {i: names.get(i, f'Move {i}') for i in range(1, N_MOVES + 1)}
+
+
+class BattleTables:
+    def __init__(self, rom):
+        from rom import BATTLE_DATA, PTR_TABLE_VRAM
+        self.rom = rom
+        self.base = BATTLE_DATA
+        self.ptr_table = rom.vram_to_rom(PTR_TABLE_VRAM)
+
+    def offset(self, species):
+        raw = self.rom.u32(self.ptr_table + (species - 1) * 4)
+        return self.base + (raw & 0xFFFFFF)
+
+    def rows(self, species):
+        """Returns [(animIndex, auxIndex)] for every entry, aux 0xFF -> -1."""
+        o = self.offset(species)
+        out = []
+        for e in range(STRIDE // ENTRY):
+            anim = self.rom.data[o + e * ENTRY]
+            aux = self.rom.data[o + e * ENTRY + 1]
+            out.append((anim, -1 if aux == 0xFF else aux))
+        return out
+
+
+SPECIES = {}
+_NAMES = (
+    "Bulbasaur Ivysaur Venusaur Charmander Charmeleon Charizard Squirtle Wartortle Blastoise "
+    "Caterpie Metapod Butterfree Weedle Kakuna Beedrill Pidgey Pidgeotto Pidgeot Rattata Raticate "
+    "Spearow Fearow Ekans Arbok Pikachu Raichu Sandshrew Sandslash NidoranF Nidorina Nidoqueen "
+    "NidoranM Nidorino Nidoking Clefairy Clefable Vulpix Ninetales Jigglypuff Wigglytuff Zubat "
+    "Golbat Oddish Gloom Vileplume Paras Parasect Venonat Venomoth Diglett Dugtrio Meowth Persian "
+    "Psyduck Golduck Mankey Primeape Growlithe Arcanine Poliwag Poliwhirl Poliwrath Abra Kadabra "
+    "Alakazam Machop Machoke Machamp Bellsprout Weepinbell Victreebel Tentacool Tentacruel Geodude "
+    "Graveler Golem Ponyta Rapidash Slowpoke Slowbro Magnemite Magneton Farfetchd Doduo Dodrio "
+    "Seel Dewgong Grimer Muk Shellder Cloyster Gastly Haunter Gengar Onix Drowzee Hypno Krabby "
+    "Kingler Voltorb Electrode Exeggcute Exeggutor Cubone Marowak Hitmonlee Hitmonchan Lickitung "
+    "Koffing Weezing Rhyhorn Rhydon Chansey Tangela Kangaskhan Horsea Seadra Goldeen Seaking "
+    "Staryu Starmie MrMime Scyther Jynx Electabuzz Magmar Pinsir Tauros Magikarp Gyarados Lapras "
+    "Ditto Eevee Vaporeon Jolteon Flareon Porygon Omanyte Omastar Kabuto Kabutops Aerodactyl "
+    "Snorlax Articuno Zapdos Moltres Dratini Dragonair Dragonite Mewtwo Mew").split()
+for _i, _n in enumerate(_NAMES):
+    SPECIES[_i + 1] = _n

model_extract/pipeline/build.py

@@ -0,0 +1,345 @@
+#!/usr/bin/env python3
+"""
+End-to-end export: baserom.z64 -> glb / textures / viewer payloads / manifests.
+
+    model_extract/pipeline/build.py [--rom PATH] [--out DIR] [options]
+
+Stdlib only. Nothing here needs `make init`, splat or crunch64 -- the ROM is
+read, decompressed and parsed directly.
+
+Options:
+    --no-js        skip the viewer payloads and viewer.html
+    --no-glb       skip the glTF binaries and PNG dumps
+    --no-effects   skip the generated fire/gas stand-ins
+    --only N[,N]   restrict to these model file numbers (for quick iteration)
+"""
+import base64
+import collections
+import json
+import math
+import os
+import sys
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+sys.path.insert(0, HERE)
+REPO = os.path.abspath(os.path.join(HERE, '..', '..'))
+
+import battle
+import effects as fx_gen
+import fragment
+import glb as glb_mod
+import rom as rom_mod
+
+N_POKEMON = 151
+EXTRA_NAMES = {152: 'Surfing Pikachu'}   # only the one identified with confidence
+
+# Where to look for the ROM, in order. model_extract/baseroms/ comes first so the
+# folder can stand on its own; the repo's own baseroms/ is the fallback.
+BASEROMS = os.path.join(os.path.dirname(HERE), 'baseroms')
+ROM_CANDIDATES = [
+    os.path.join(BASEROMS, 'baserom.z64'),
+    os.path.join(BASEROMS, 'us', 'baserom.z64'),
+    os.path.join(REPO, 'baseroms', 'us', 'baserom.z64'),
+]
+
+
+def find_rom():
+    for p in ROM_CANDIDATES:
+        if os.path.exists(p):
+            return p
+    if os.path.isdir(BASEROMS):                 # any ROM dropped in the folder
+        for f in sorted(os.listdir(BASEROMS)):
+            if f.lower().endswith(('.z64', '.n64', '.v64')):
+                return os.path.join(BASEROMS, f)
+    return None
+
+
+# --------------------------------------------------------------- bind extent
+
+def bind_extent(data):
+    """World-space bounding box of the bind pose, used to size the effects."""
+    def trs(t, r, s):
+        S = lambda v: math.sin(v / 32768 * math.pi)
+        C = lambda v: math.cos(v / 32768 * math.pi)
+        sx, cx = S(r[0]), C(r[0]); sy, cy = S(r[1]), C(r[1]); sz, cz = S(r[2]), C(r[2])
+        return [cy*cz*s[0], cy*sz*s[0], -sy*s[0], 0,
+                (sx*sy*cz-cx*sz)*s[1], (sx*sy*sz+cx*cz)*s[1], sx*cy*s[1], 0,
+                (cx*sy*cz+sx*sz)*s[2], (cx*sy*sz-sx*cz)*s[2], cx*cy*s[2], 0,
+                t[0], t[1], t[2], 1]
+
+    def mul(a, b):
+        r = [0]*16
+        for c in range(4):
+            for i in range(4):
+                r[c*4+i] = a[i]*b[c*4] + a[4+i]*b[c*4+1] + a[8+i]*b[c*4+2] + a[12+i]*b[c*4+3]
+        return r
+
+    root = trs([0, 0, 0], [0, 0, 0], data['rootScale'])
+    acc, uns, mats = [], [], []
+    for b in data['bones']:
+        pa = acc[b['parent']] if b['parent'] >= 0 else [1.0, 1.0, 1.0]
+        pu = uns[b['parent']] if b['parent'] >= 0 else root
+        u = mul(pu, trs([b['t'][k]*pa[k] for k in range(3)], b['r'], [1, 1, 1]))
+        a = [pa[k]*b['s'][k] for k in range(3)]
+        m = list(u)
+        for k in range(4):
+            m[k] *= a[0]; m[4+k] *= a[1]; m[8+k] *= a[2]
+        acc.append(a); uns.append(u); mats.append(m)
+
+    lo = [1e9]*3; hi = [-1e9]*3
+    for p in data['prims']:
+        for i, bi in enumerate(p['skin']):
+            m = mats[bi]
+            x, y, z = p['pos'][i*3:i*3+3]
+            w = (m[0]*x+m[4]*y+m[8]*z+m[12], m[1]*x+m[5]*y+m[9]*z+m[13],
+                 m[2]*x+m[6]*y+m[10]*z+m[14])
+            for k in range(3):
+                lo[k] = min(lo[k], w[k]); hi[k] = max(hi[k], w[k])
+    # height, not the largest dimension: sizing off the max would scale Moltres'
+    # flames to its wingspan
+    extent = (hi[1] - lo[1]) if lo[0] <= hi[0] else 1.0
+    # how much each bone scales its own local space, so effects can compensate
+    scales = [math.sqrt(m[0]*m[0] + m[1]*m[1] + m[2]*m[2]) for m in mats]
+    return extent, scales
+
+
+# ------------------------------------------------------------ animation names
+
+# Which context name wins when several claim the same animation. The battle
+# table points many slots at one clip, and these are the ones worth naming.
+NAME_PREF = ['idle', 'attack_default', 'faint', 'entrance', 'struggle', 'flinch']
+
+
+def label_animations(data, rows, moves):
+    """Name each animation after what the battle table uses it for, and pair it
+    with the texture animation that table most often sets alongside it.
+
+    Mutates `data['anims']`, giving each a `name` and an `aux`, and hands back
+    the per-animation context and move lists the manifest reports. Factored out
+    of main() because the mod's packer (tools/stadium_pack.py) has to label them
+    exactly the same way for its output to be comparable with the Lua extractor
+    that reads the same ROM at runtime.
+    """
+    entries = [r[0] for r in rows]
+    aux = [r[1] for r in rows]
+    uses = [[] for _ in data['anims']]
+    move_uses = [[] for _ in data['anims']]
+    for e, ai in enumerate(entries):
+        if ai >= len(uses):
+            continue
+        if e < battle.N_MOVES:
+            move_uses[ai].append(moves[e + 1])
+        elif e in battle.CONTEXT_SLOTS:
+            uses[ai].append(battle.CONTEXT_SLOTS[e][0])
+    pairs = [collections.Counter() for _ in data['anims']]
+    for e, ai in enumerate(entries):
+        if ai < len(pairs) and 0 <= aux[e] < len(data['auxAnims']):
+            pairs[ai][aux[e]] += 1
+    for i, a in enumerate(data['anims']):
+        ctx = sorted(set(uses[i]))
+        named = [n for n in NAME_PREF if n in ctx]
+        a['name'] = (named[0] if named else 'attack' if move_uses[i]
+                     else ctx[0] if ctx else f'anim{i}')
+        a['aux'] = pairs[i].most_common(1)[0][0] if pairs[i] else -1
+    seen = {}
+    for a in data['anims']:
+        n = seen.get(a['name'], 0)
+        seen[a['name']] = n + 1
+        if n:
+            a['name'] = f'{a["name"]}_{n + 1}'
+    return uses, move_uses
+
+
+def attach_effects(data, species, raw=False):
+    """Append generated fire/gas prims + their flipbook textures.
+
+    `raw` matches fragment.extract's: the flipbook frames are already RGBA8, so
+    they are stored as-is rather than encoded, for the packer that wants pixels.
+    """
+    if not data.get('fx'):
+        return 0
+    extent, bone_scale = bind_extent(data)
+    made = fx_gen.build_for(species, data['fx'], extent, bone_scale)
+    for e in made:
+        first = len(data['textures'])
+        for i, frame in enumerate(e['frames']):
+            rec = dict(index=-1, w=e['w'], h=e['h'], generated=True)
+            if raw:
+                rec['rgba'] = frame
+            else:
+                rec['png'] = ('data:image/png;base64,' + base64.b64encode(
+                    fragment.png(e['w'], e['h'], frame)).decode())
+            data['textures'].append(rec)
+        g = e['geo']
+        data['prims'].append(dict(
+            tex=first, cull=0, texAnim=-1, texMap={},
+            generated=True, effect=e['kind'],
+            blend='add' if e['kind'] == 'fire' else 'alpha',
+            fxFrames=list(range(first, first + len(e['frames']))),
+            pos=g['pos'], uv=g['uv'], nrm=g['nrm'], skin=g['skin'], idx=g['idx']))
+    return len(made)
+
+
+# --------------------------------------------------------------------- main
+
+def main(argv):
+    args = {a.split('=')[0]: (a.split('=', 1)[1] if '=' in a else True) for a in argv}
+    rom_path = args.get('--rom') or find_rom()
+    outdir = args.get('--out') or os.path.join(REPO, 'model_extract')
+    want_js = '--no-js' not in args
+    want_glb = '--no-glb' not in args
+    want_fx = '--no-effects' not in args
+    only = {int(x) for x in args['--only'].split(',')} if '--only' in args else None
+
+    if not rom_path or not os.path.exists(rom_path):
+        sys.exit('ROM not found. Put a Pokemon Stadium (US 1.0) ROM at\n'
+                 f'  {os.path.join(BASEROMS, "baserom.z64")}\n'
+                 'or pass --rom=PATH. Searched:\n  '
+                 + '\n  '.join(ROM_CANDIDATES))
+
+    print(f'reading {rom_path}')
+    rom = rom_mod.Rom(rom_path)
+    print(f'  md5 {rom.md5}' + ('' if rom.is_expected_us else '  (NOT the expected US 1.0 ROM)'))
+
+    blobs = rom_mod.pokemon_models(rom)
+    print(f'  {len(blobs)} model fragments')
+    tables = battle.BattleTables(rom)
+    moves = battle.load_move_names(REPO)
+
+    for sub in ('glb', 'textures', 'js'):
+        os.makedirs(os.path.join(outdir, sub), exist_ok=True)
+
+    manifest = dict(
+        source='Pokemon Stadium (US) 1.0', romMd5=rom.md5,
+        generator='model_extract/pipeline/build.py',
+        coordinateSystem='Y up, +Z front, units are game units (models authored 10x, '
+                         'baked into the model_root node scale)',
+        frameRate=30,
+        generatedEffects='Prims and textures tagged generated:true are NOT extracted '
+                         'game data -- see pipeline/effects.py.',
+        animationSlots={str(k): dict(name=v[0], evidence=v[1], description=v[2])
+                        for k, v in battle.CONTEXT_SLOTS.items()},
+        pokemon=[], extra=[])
+    move_rows, anim_names, index, fx_count = {}, {}, [], 0
+
+    for fileno, blob in enumerate(blobs):
+        if only is not None and fileno not in only:
+            continue
+        try:
+            data = fragment.extract(blob, f'{fileno}.bin')
+        except Exception as exc:
+            print(f'  skip {fileno}: {exc}')
+            continue
+        species = data['species']
+        pokemon = fileno < N_POKEMON
+
+        if pokemon:
+            rows = tables.rows(species)
+            uses, move_uses = label_animations(data, rows, moves)
+            slug = f'{species:03d}_{battle.SPECIES.get(species, str(species)).lower()}'
+            data['name'] = battle.SPECIES.get(species, f'#{species}')
+            move_rows[species] = [[rows[e][0], rows[e][1]]
+                                  for e in range(battle.N_MOVES)]
+            anim_names[species] = [a['name'] for a in data['anims']]
+        else:
+            slug = f'x{fileno:03d}_model'
+            data['name'] = EXTRA_NAMES.get(fileno, f'Model {fileno}')
+            for i, a in enumerate(data['anims']):
+                a['name'] = f'anim{i}'
+                a['aux'] = 0 if data['auxAnims'] else -1
+
+        nfx = attach_effects(data, species) if want_fx else 0
+        fx_count += nfx
+
+        pngs = [base64.b64decode(t['png'].split(',', 1)[1]) for t in data['textures']]
+        if want_glb:
+            with open(os.path.join(outdir, 'glb', slug + '.glb'), 'wb') as fp:
+                fp.write(glb_mod.build_glb(data, pngs))
+            texdir = os.path.join(outdir, 'textures', slug)
+            os.makedirs(texdir, exist_ok=True)
+            for i, (t, p) in enumerate(zip(data['textures'], pngs)):
+                tag = '_fx' if t.get('generated') else ''
+                with open(os.path.join(texdir, f'{i:02d}_{t["w"]}x{t["h"]}{tag}.png'), 'wb') as fp:
+                    fp.write(p)
+        if want_js:
+            with open(os.path.join(outdir, 'js', slug + '.js'), 'w') as fp:
+                fp.write('PKMN_LOAD(' + json.dumps(data, separators=(',', ':')) + ');\n')
+
+        entry = dict(
+            species=species, name=data['name'], slug=slug,
+            group='pokemon' if pokemon else 'extra',
+            sourceFile=f'{fileno}.bin', glb=f'glb/{slug}.glb',
+            textureDir=f'textures/{slug}',
+            triangles=sum(len(p['idx']) // 3 for p in data['prims']),
+            vertices=sum(len(p['pos']) // 3 for p in data['prims']),
+            bones=len(data['bones']), textures=len(data['textures']),
+            generatedEffects=nfx,
+            animations=[dict(
+                index=i, name=a['name'], frames=a['frames'],
+                seconds=round(a['frames'] / 30.0, 3),
+                endBehavior='clamp' if (a['flags'] & 2) else 'wrap',
+                loopStartFrame=a['loopStart'],
+                **(dict(contexts=sorted(set(uses[i])),
+                        moves=sorted(set(move_uses[i])),
+                        moveCount=len(set(move_uses[i]))) if pokemon else {}))
+                for i, a in enumerate(data['anims'])])
+        (manifest['pokemon'] if pokemon else manifest['extra']).append(entry)
+        index.append(dict(species=species, name=data['name'], slug=slug,
+                          group=entry['group'], triangles=entry['triangles'],
+                          bones=entry['bones'], animations=len(data['anims'])))
+        print(f'  {slug:<22} {len(data["anims"]):2d} anims  {entry["triangles"]:5d} tris'
+              + (f'  +{nfx} effect' if nfx else ''))
+
+    # ---- move index ------------------------------------------------------
+    moves_out = []
+    if move_rows:
+        default_anim = {p['species']: next(
+            (a['index'] for a in p['animations'] if 'attack_default' in a.get('contexts', [])), -1)
+            for p in manifest['pokemon']}
+        for mid in range(1, battle.N_MOVES + 1):
+            users, tally, ndiff = [], collections.Counter(), 0
+            for sp in sorted(move_rows):
+                ai, ax = move_rows[sp][mid - 1]
+                name = anim_names[sp][ai] if ai < len(anim_names[sp]) else f'anim{ai}'
+                diff = ai != default_anim.get(sp, -1)
+                ndiff += diff
+                tally[name] += 1
+                users.append(dict(species=sp, animation=ai, animationName=name,
+                                  aux=ax, differsFromDefault=diff))
+            moves_out.append(dict(
+                id=mid, name=moves[mid], speciesWithOwnAnimation=ndiff,
+                animationNames=[dict(name=n, species=c) for n, c in tally.most_common()],
+                users=users))
+        with open(os.path.join(outdir, 'moves.json'), 'w') as fp:
+            json.dump(dict(source=manifest['source'], note=(
+                'Entry n of the per-species battle table (0-indexed) selects the '
+                'animation played when that Pokemon uses move n+1. The table is dense '
+                '- every species has a row for every move, including moves it can '
+                'never learn - and those unreachable rows overwhelmingly point at the '
+                'species\' generic reaction animation. Use differsFromDefault.'),
+                moves=moves_out), fp, indent=1)
+
+    with open(os.path.join(outdir, 'manifest.json'), 'w') as fp:
+        json.dump(manifest, fp, indent=2)
+
+    if want_js:
+        with open(os.path.join(outdir, 'js', 'index.js'), 'w') as fp:
+            fp.write('window.PKMN_INDEX = ' + json.dumps(index, separators=(',', ':')) + ';\n')
+        if moves_out:
+            with open(os.path.join(outdir, 'js', 'moves.js'), 'w') as fp:
+                fp.write('window.PKMN_MOVES = ' + json.dumps(
+                    [dict(id=m['id'], name=m['name'],
+                          bySpecies={str(u['species']): [u['animation'], u['aux']]
+                                     for u in m['users']}) for m in moves_out],
+                    separators=(',', ':')) + ';\n')
+        viewer_src = os.path.join(REPO, 'tools/model_viewer/viewer.html')
+        if os.path.exists(viewer_src):
+            with open(viewer_src) as s, open(os.path.join(outdir, 'viewer.html'), 'w') as d:
+                d.write(s.read())
+
+    print(f'\n{len(manifest["pokemon"])} Pokemon + {len(manifest["extra"])} other models'
+          f', {fx_count} generated effects')
+
+
+if __name__ == '__main__':
+    main(sys.argv[1:])

model_extract/pipeline/effects.py

@@ -0,0 +1,225 @@
+#!/usr/bin/env python3
+"""
+Generated stand-in effects.
+
+IMPORTANT: nothing in this file is extracted game data. The real tail flame,
+mane fire and gas are drawn by procedural callbacks that live in another
+fragment (geo command 0x08 -> func_80014A60 calls node->unk_10, and the model
+file supplies only two empty display lists plus zeroed scratch buffers). Those
+callbacks have not been ported, so the models genuinely contain no flame mesh
+and no flame texture.
+
+What follows is an original, procedurally generated replacement: looping
+flipbook textures plus a pair of crossed quads anchored to the bone the
+callback hangs off. It is meant to make the models look right in the viewer,
+and it is tagged `generated: true` everywhere it appears so it is never
+mistaken for ripped content.
+"""
+import math
+
+# geo cmd 0x08 callback ids -> which effect to stand in for. The grouping is the
+# game's own: every species sharing a callback shares an effect.
+FIRE_TAIL = 0x810000D8      # Charmander, Charmeleon, Charizard, Magmar, Moltres
+FIRE_SMALL = 0x81000108     # Ponyta, Rapidash, Moltres wings
+AURA = 0x810000E0           # Gastly, Koffing, Weezing, Vaporeon, Articuno, Moltres
+
+
+class Rng:
+    """Deterministic PRNG so a given species always generates the same effect."""
+
+    def __init__(self, seed):
+        self.s = seed & 0xFFFFFFFF or 0x9E3779B9
+
+    def next(self):
+        x = self.s
+        x ^= (x << 13) & 0xFFFFFFFF
+        x ^= x >> 17
+        x ^= (x << 5) & 0xFFFFFFFF
+        self.s = x & 0xFFFFFFFF
+        return self.s
+
+    def unit(self):
+        return self.next() / 0x100000000
+
+
+def _lattice(rng, w, h):
+    return [[rng.unit() for _ in range(w)] for _ in range(h)]
+
+
+def _smooth(t):
+    return t * t * (3 - 2 * t)
+
+
+def _sample(grid, x, y):
+    """Bilinear value noise on a torus, so the field tiles in both axes."""
+    h, w = len(grid), len(grid[0])
+    x0, y0 = int(math.floor(x)) % w, int(math.floor(y)) % h
+    x1, y1 = (x0 + 1) % w, (y0 + 1) % h
+    fx, fy = _smooth(x - math.floor(x)), _smooth(y - math.floor(y))
+    a = grid[y0][x0] + (grid[y0][x1] - grid[y0][x0]) * fx
+    b = grid[y1][x0] + (grid[y1][x1] - grid[y1][x0]) * fx
+    return a + (b - a) * fy
+
+
+def _fbm(grids, x, y, scale):
+    """Sum octaves of tileable noise."""
+    total, amp, norm = 0.0, 1.0, 0.0
+    for i, g in enumerate(grids):
+        f = scale * (2 ** i)
+        total += _sample(g, x * f, y * f) * amp
+        norm += amp
+        amp *= 0.5
+    return total / norm
+
+
+def _ramp(stops, t):
+    t = max(0.0, min(1.0, t))
+    for i in range(len(stops) - 1):
+        a, b = stops[i], stops[i + 1]
+        if t <= b[0]:
+            k = 0.0 if b[0] == a[0] else (t - a[0]) / (b[0] - a[0])
+            return tuple(int(a[1 + j] + (b[1 + j] - a[1 + j]) * k) for j in range(4))
+    return tuple(stops[-1][1:])
+
+
+FIRE_RAMP = [                       # intensity -> RGBA
+    (0.00, 0, 0, 0, 0),
+    (0.30, 120, 24, 8, 90),
+    (0.52, 226, 78, 16, 205),
+    (0.74, 252, 176, 44, 245),
+    (1.00, 255, 246, 214, 255),
+]
+
+GAS_RAMP = [
+    (0.00, 0, 0, 0, 0),
+    (0.34, 52, 26, 78, 70),
+    (0.60, 96, 52, 140, 140),
+    (0.82, 148, 96, 196, 190),
+    (1.00, 208, 176, 236, 215),
+]
+
+
+def fire_frames(seed, w=32, h=64, frames=8, wisp=1.0):
+    """Upward-advected noise plume. Scrolling by an exact multiple of the noise
+    lattice over the frame count makes the loop seamless."""
+    rng = Rng(seed)
+    grids = [_lattice(rng, 8, 8), _lattice(rng, 16, 16), _lattice(rng, 32, 32)]
+    out = []
+    for f in range(frames):
+        t = f / frames
+        buf = bytearray(w * h * 4)
+        for y in range(h):
+            v = y / (h - 1)                     # 0 at the base, 1 at the tip
+            # plume envelope: wide and hot at the base, pinched at the tip
+            taper = max(0.0, 1.0 - v) ** 0.42
+            for x in range(w):
+                u = (x / (w - 1)) * 2 - 1       # -1 .. 1 across the flame
+                radial = (1.0 - min(1.0, abs(u) / max(0.10, taper * 0.95))) ** 0.7
+                if radial <= 0:
+                    continue
+                n = _fbm(grids, x / w, (y / h) - t, 3.0)
+                lick = 0.55 + 0.75 * (n - 0.5) * wisp
+                inten = radial * (0.55 + 0.8 * taper) * lick
+                inten -= 0.16 * v                # cool towards the tip
+                if inten <= 0.02:
+                    continue
+                r, g, b, a = _ramp(FIRE_RAMP, inten)
+                i = ((h - 1 - y) * w + x) * 4    # +Y in texture space is up
+                buf[i:i+4] = bytes((r, g, b, a))
+        out.append(bytes(buf))
+    return w, h, out
+
+
+def gas_frames(seed, w=48, h=48, frames=10):
+    """Slow swirling haze that fades out towards the rim."""
+    rng = Rng(seed)
+    grids = [_lattice(rng, 8, 8), _lattice(rng, 16, 16), _lattice(rng, 32, 32)]
+    out = []
+    for f in range(frames):
+        t = f / frames
+        buf = bytearray(w * h * 4)
+        ang = t * 2 * math.pi
+        for y in range(h):
+            for x in range(w):
+                dx = (x / (w - 1)) * 2 - 1
+                dy = (y / (h - 1)) * 2 - 1
+                d = math.hypot(dx, dy)
+                if d >= 1.0:
+                    continue
+                falloff = (1.0 - d) ** 0.85
+                # rotate the sample point so the haze churns without popping
+                sx = dx * math.cos(ang) - dy * math.sin(ang)
+                sy = dx * math.sin(ang) + dy * math.cos(ang)
+                n = _fbm(grids, sx * 0.5 + 0.5, sy * 0.5 + 0.5 - t, 2.5)
+                inten = falloff * (0.78 + 1.30 * (n - 0.44))
+                if inten <= 0.03:
+                    continue
+                r, g, b, a = _ramp(GAS_RAMP, inten)
+                i = (y * w + x) * 4
+                buf[i:i+4] = bytes((r, g, b, a))
+        out.append(bytes(buf))
+    return w, h, out
+
+
+def crossed_quads(bone, length, width, axis='y', centred=False):
+    """Two quads at right angles so the effect reads from any angle -- the
+    portable stand-in for a billboard, since glTF cannot billboard.
+
+    `axis` picks which bone-local direction the quad grows along. Bone-local +X
+    runs down the limb, so a flame laid out along X comes out lying sideways;
+    'y' is that same quad rotated 90 degrees left about Z, which stands it up.
+    `centred` straddles the origin instead of growing from it."""
+    pos, uv, nrm, skin, idx = [], [], [], [], []
+    for q in range(2):
+        base = len(pos) // 3
+        for (s, t) in ((0, 0), (1, 0), (1, 1), (0, 1)):
+            a = (s - 0.5) * width
+            b = (t - 0.5) * length if centred else t * length
+            if axis == 'x':
+                p = (b, a, 0.0) if q == 0 else (b, 0.0, a)
+            else:                                   # (x, y) -> (-y, x)
+                p = (-a, b, 0.0) if q == 0 else (0.0, b, a)
+            pos += list(p)
+            uv += [s, 1.0 - t]
+            nrm += [0.0, 0.0, 1.0] if q == 0 else [1.0, 0.0, 0.0]
+            skin.append(bone)
+        idx += [base, base + 1, base + 2, base, base + 2, base + 3]
+    return dict(pos=pos, uv=uv, nrm=nrm, skin=skin, idx=idx)
+
+
+# desired size as a fraction of the model's world-space extent
+SIZES = {
+    'fire_tail':  (0.40, 0.22),     # length, width
+    'fire_small': (0.075, 0.042),
+    'gas':        (1.05, 1.05),
+}
+
+
+def build_for(species, fx, extent, bone_scale):
+    """Returns [{kind, bone, geo, w, h, frames}] for one model, or [].
+
+    `extent` is the model's world-space size and `bone_scale[i]` how much bone i
+    already scales its local space; dividing by it keeps every effect the size we
+    asked for regardless of where in the skeleton it hangs."""
+    out = []
+    for node in fx:
+        cb, bone = node['callback'], node['bone']
+        if bone < 0 or bone >= len(bone_scale):
+            continue
+        k = bone_scale[bone] or 1.0
+        if cb == FIRE_TAIL:
+            fl, fw = SIZES['fire_tail']
+            w, h, fr = fire_frames(species * 7919 + 1, 32, 64, 8)
+            geo = crossed_quads(bone, extent * fl / k, extent * fw / k, axis='y')
+            out.append(dict(kind='fire', bone=bone, geo=geo, w=w, h=h, frames=fr))
+        elif cb == FIRE_SMALL:
+            fl, fw = SIZES['fire_small']
+            w, h, fr = fire_frames(species * 6271 + bone, 24, 40, 8, wisp=1.25)
+            geo = crossed_quads(bone, extent * fl / k, extent * fw / k, axis='y')
+            out.append(dict(kind='fire', bone=bone, geo=geo, w=w, h=h, frames=fr))
+        elif cb == AURA and species == 92:              # Gastly only
+            fl, fw = SIZES['gas']
+            w, h, fr = gas_frames(species * 5237 + 3, 48, 48, 10)
+            geo = crossed_quads(bone, extent * fl / k, extent * fw / k, axis='y', centred=True)
+            out.append(dict(kind='gas', bone=bone, geo=geo, w=w, h=h, frames=fr))
+    return out

model_extract/pipeline/fragment.py

@@ -0,0 +1,747 @@
+#!/usr/bin/env python3
+"""
+Model extraction: FRAGMENT module -> geometry, textures, skeleton, animations.
+
+Self-contained copy of tools/model_viewer/extract_model.py, taking raw bytes so
+it can be fed straight from the ROM. See ../README.md for the format notes.
+"""
+import json, os, struct, sys, zlib
+
+BASE = 0x8FF00000
+
+# ---------------------------------------------------------------- geo layout
+
+CMD_SIZES = {
+    0x00:0x08, 0x01:0x04, 0x02:0x08, 0x03:0x08, 0x04:0x04, 0x05:0x04, 0x06:0x04,
+    0x07:0x08, 0x08:0x0C, 0x09:0x04, 0x0A:0x08, 0x0B:0x18, 0x0C:0x04, 0x0D:0x04,
+    0x0E:0x04, 0x0F:0x04, 0x10:0x04, 0x11:0x04, 0x12:0x04, 0x13:0x08, 0x14:0x0C,
+    0x15:0x0C, 0x16:0x04, 0x17:0x14, 0x18:0x08, 0x19:0x08, 0x1A:0x04, 0x1B:0x10,
+    0x1C:0x10, 0x1D:0x1C, 0x1E:0x08, 0x1F:0x18, 0x20:0x14, 0x21:0x10, 0x22:0x08,
+    0x23:0x10, 0x24:0x04, 0x25:0x04, 0x26:0x14,
+}
+
+
+class Fragment:
+    def __init__(self, data, name='<bytes>'):
+        self.d = data if isinstance(data, (bytes, bytearray)) else open(data, 'rb').read()
+        self.name = name if isinstance(data, (bytes, bytearray)) else str(data)
+        if self.d[8:0x10] != b'FRAGMENT':
+            raise ValueError(f'{self.name}: not a FRAGMENT module')
+        self.hdrSize, self.relocOff, self.sizeRom, self.sizeRam = struct.unpack_from('>4I', self.d, 0x10)
+
+    def off(self, ptr):
+        return None if ptr == 0 else ptr - BASE
+
+    def u8(self, o):  return self.d[o]
+    def s8(self, o):  return struct.unpack_from('>b', self.d, o)[0]
+    def u16(self, o): return struct.unpack_from('>H', self.d, o)[0]
+    def s16(self, o): return struct.unpack_from('>h', self.d, o)[0]
+    def u32(self, o): return struct.unpack_from('>I', self.d, o)[0]
+    def s32(self, o): return struct.unpack_from('>i', self.d, o)[0]
+    def ptr(self, o): return self.off(self.u32(o))
+
+    def root(self):
+        """The entry stub ends with `lui rX, hi; addiu rX, rX, lo` loading the root struct."""
+        for o in range(0x20, 0x80, 4):
+            w = self.u32(o)
+            if (w >> 26) != 0x0F:                       # lui
+                continue
+            reg = (w >> 16) & 0x1F
+            w2 = self.u32(o + 4)
+            if (w2 >> 26) == 0x09 and ((w2 >> 21) & 0x1F) == reg:   # addiu rX, rX, imm
+                return ((self.u16(o + 2) << 16) + self.s16(o + 6)) - BASE
+        raise RuntimeError('could not locate root struct')
+
+    def ptr_list(self, o):
+        out = []
+        while True:
+            p = self.ptr(o)
+            if p is None:
+                return out
+            out.append(p)
+            o += 4
+
+
+# --------------------------------------------------------------- F3DEX2 exec
+
+def signed(v, bits):
+    m = 1 << (bits - 1)
+    return (v ^ m) - m
+
+
+class Model:
+    """Walks the geo layout, executes the display lists, accumulates draw data."""
+
+    def __init__(self, frag):
+        self.f = frag
+        r = frag.root()
+        self.species = frag.u16(r)
+        self.geoLayouts = frag.ptr_list(frag.ptr(r + 0x08))
+        self.anims     = frag.ptr_list(frag.ptr(r + 0x0C))
+        self.auxAnims  = frag.ptr_list(frag.ptr(r + 0x10))
+
+        self.textures = []      # {fmt, siz, w, h, texels, data}
+        self.tluts = []         # palettes: {count, data, dl}
+        self.bones = []         # {parent, boneId, chan, t, r, s}
+        self.boneById = {}
+        self.prims = []         # {tex, cull, verts:[...], tris:[...]}
+        self.primsByKey = {}
+        self.vtxBase = None
+        self.rootScale = [1.0, 1.0, 1.0]
+        self.fx = []            # geo cmd 0x08 procedural effect nodes
+        self.warnings = []
+
+    # ---- textures -------------------------------------------------------
+    def read_texture_table(self, off, count):
+        f = self.f
+        for i in range(count):
+            o = off + i * 0xC
+            self.textures.append(dict(
+                fmt=f.u8(o), siz=f.u8(o + 1), w=f.s16(o + 2),
+                h=f.u16(o + 4), texels=f.u16(o + 6), data=f.ptr(o + 8)))
+
+    def read_tlut_table(self, off, count):
+        """Palettes reuse the texture-record layout: the count sits in the width
+        field, the palette data in the next word, and unk_08 is the DL that loads
+        it (src/12D80.c func_80015B20). The DL is authoritative, so run it."""
+        f = self.f
+        for i in range(count):
+            o = off + i * 0xC
+            rec = dict(count=f.u16(o + 2), data=f.ptr(o + 4), dl=f.ptr(o + 8))
+            dl = rec['dl']
+            if dl is not None:
+                for _ in range(16):
+                    w0, w1 = struct.unpack_from('>II', f.d, dl)
+                    op = w0 >> 24
+                    if op == 0xFD:                          # G_SETTIMG
+                        rec['data'] = f.off(w1)
+                    elif op == 0xF0:                        # G_LOADTLUT
+                        rec['count'] = ((w1 >> 14) & 0x3FF) + 1
+                    elif op == 0xDF:
+                        break
+                    dl += 8
+            self.tluts.append(rec)
+
+    # ---- geo layout -----------------------------------------------------
+    def build(self):
+        self.curTex = -1
+        self.curTlut = -1
+        self.curMat = None
+        self.curTexAnim = -1
+        # Mirrors gCurGraphNodeList in src/geo_layout.c: stack[-1] is the slot the
+        # next node command writes to, and a node's parent -- and the bone whose
+        # matrix is live -- is the slot *below* it (func_80017AC4).
+        self.stack = [-1]
+        # The RSP vertex cache persists across display lists: a bone's list often
+        # preloads verts that the *next* bone's list then indexes, which is how
+        # these models get blended joints. Each slot remembers the bone whose
+        # matrix was current when it was loaded.
+        self.vbuf = [None] * 64
+        self.walk(self.geoLayouts[0])
+
+    def walk(self, o, depth=0):
+        f = self.f
+        if depth > 32:
+            return
+        while True:
+            cmd = f.u8(o)
+            size = CMD_SIZES.get(cmd)
+            if size is None:
+                self.warnings.append(f'unknown geo cmd {cmd:#04x} at {o:#x}')
+                return
+            if cmd == 0x01 or cmd == 0x04:              # end / return
+                return
+            if cmd in (0x00, 0x03):                     # branch (with return)
+                self.walk(f.ptr(o + 4), depth + 1)
+            elif cmd == 0x02:                           # jump (no return)
+                o = f.ptr(o + 4)
+                continue
+            elif cmd == 0x05:                           # open node
+                self.stack.append(self.stack[-1])
+            elif cmd == 0x06:                           # close node
+                self.stack.pop()
+            elif cmd == 0x17:                           # model header
+                self.read_texture_table(f.ptr(o + 8), f.s16(o + 2))
+                if f.ptr(o + 0xC):
+                    self.read_tlut_table(f.ptr(o + 0xC), f.s16(o + 4))
+                self.vtxBase = f.ptr(o + 0x10)
+                self.nVerts = f.s16(o + 6)
+            elif cmd == 0x08:                           # procedural effect callback
+                self.fx.append(dict(bone=self.curBone(), callback=f.u32(o + 4),
+                                    arg=f.ptr(o + 8)))
+            elif cmd == 0x1C:                           # uniform scale node
+                self.rootScale = [f.s32(o + 4) / 65536.0, f.s32(o + 8) / 65536.0,
+                                  f.s32(o + 0xC) / 65536.0]
+            elif cmd == 0x1D:                           # bone / joint node
+                idx = len(self.bones)
+                self.bones.append(dict(
+                    parent=self.curBone(), boneId=f.u8(o + 1), flags=f.u8(o + 2),
+                    chan=f.s8(o + 3),
+                    t=[f.s16(o + 4), f.s16(o + 6), f.s16(o + 8)],
+                    r=[f.s16(o + 0xA), f.s16(o + 0xC), f.s16(o + 0xE)],
+                    s=[f.s32(o + 0x10) / 65536.0, f.s32(o + 0x14) / 65536.0,
+                       f.s32(o + 0x18) / 65536.0]))
+                self.boneById[f.u8(o + 1)] = idx
+                self.stack[-1] = idx
+            elif cmd == 0x23:                           # set texture / material
+                self.curTex = f.s16(o + 8)
+                self.curTlut = f.s16(o + 0xA)
+                self.curMat = f.ptr(o + 4)
+                # offset 0x02 is the texture-animation channel; -1 means static.
+                # func_800176DC swaps this material's texture per frame from the
+                # auxiliary animation's channel stream.
+                self.curTexAnim = f.s16(o + 2)
+            elif cmd == 0x22:                           # display list on current bone
+                self.run_dl(f.ptr(o + 4), self.curBone())
+            elif cmd == 0x1E:                           # display list on named bone
+                self.run_dl(f.ptr(o + 4), self.boneById.get(f.s16(o + 2), self.curBone()))
+            elif cmd in (0x20, 0x21):                   # display list + own transform
+                self.run_dl(f.ptr(o + (0x10 if cmd == 0x20 else 0xC)), self.curBone())
+            o += size
+
+    def curBone(self):
+        return self.stack[-2] if len(self.stack) >= 2 else -1
+
+    # ---- display lists --------------------------------------------------
+    def run_dl(self, o, bone, depth=0):
+        if o is None or depth > 8:
+            return
+        f = self.f
+        vbuf = self.vbuf
+        cull = 0x400
+        while True:
+            w0, w1 = struct.unpack_from('>II', f.d, o)
+            op = w0 >> 24
+            o += 8
+            if op == 0xDF:                              # G_ENDDL
+                return
+            if op == 0xDE:                              # G_DL
+                self.run_dl(f.off(w1), bone, depth + 1)
+                if (w0 >> 16) & 0xFF:                   # branch, not call
+                    return
+                continue
+            if op == 0x01:                              # G_VTX
+                n = (w0 >> 12) & 0xFF
+                v0 = ((w0 & 0xFFF) >> 1) - n
+                a = f.off(w1)
+                for i in range(n):
+                    p = a + i * 0x10
+                    if 0 <= v0 + i < len(vbuf):
+                        vbuf[v0 + i] = (
+                            f.s16(p), f.s16(p + 2), f.s16(p + 4),       # position
+                            f.s16(p + 8) / 32.0, f.s16(p + 10) / 32.0,  # s, t (S10.5)
+                            f.s8(p + 12), f.s8(p + 13), f.s8(p + 14),   # normal
+                            f.u8(p + 15),                               # alpha
+                            bone)                                       # owning bone
+                continue
+            if op == 0xD9:                              # G_GEOMETRYMODE
+                cull = (cull & (w0 & 0xFFFFFF)) | w1
+                continue
+            if op in (0x05, 0x06):                      # G_TRI1 / G_TRI2
+                prim = self.prim_for(self.curTex, self.curTlut, self.curMat,
+                                     self.curTexAnim, cull & 0x600)
+
+                def emit(a, b, c):
+                    tri = []
+                    for idx in (a, b, c):
+                        v = vbuf[idx] if idx < len(vbuf) else None
+                        if v is None:
+                            return
+                        j = prim['_remap'].get(v)
+                        if j is None:
+                            j = len(prim['verts'])
+                            prim['_remap'][v] = j
+                            prim['verts'].append(v)
+                        tri.append(j)
+                    if (cull & 0x200) and not (cull & 0x400):
+                        tri.reverse()
+                    prim['tris'].append(tri)
+
+                emit(((w0 >> 16) & 0xFF) // 2, ((w0 >> 8) & 0xFF) // 2, (w0 & 0xFF) // 2)
+                if op == 0x06:
+                    emit(((w1 >> 16) & 0xFF) // 2, ((w1 >> 8) & 0xFF) // 2, (w1 & 0xFF) // 2)
+                continue
+            # everything else (SETTILE / sync / ...) is state we reconstruct
+            # from the texture table instead, so it is skipped.
+
+    def prim_for(self, tex, tlut, mat, texAnim, cull):
+        key = (tex, tlut, mat, texAnim, cull)
+        p = self.primsByKey.get(key)
+        if p is None:
+            p = dict(tex=tex, tlut=tlut, mat=mat, texAnim=texAnim, cull=cull,
+                     verts=[], tris=[], _remap={})
+            self.primsByKey[key] = p
+            self.prims.append(p)
+        return p
+
+    def tile_palette(self, mat):
+        """CI4 selects a 16-entry block of the TLUT via the render tile's palette
+        field; read it from the material display list's final G_SETTILE."""
+        if mat is None:
+            return 0
+        pal = 0
+        for _ in range(16):
+            w0, w1 = struct.unpack_from('>II', self.f.d, mat)
+            op = w0 >> 24
+            if op == 0xF5 and ((w1 >> 24) & 7) == 0:        # G_SETTILE, render tile
+                pal = (w1 >> 20) & 0xF
+            elif op == 0xDF:
+                break
+            mat += 8
+        return pal
+
+
+# ---------------------------------------------------------------- animations
+
+def bitfield(f, base, index, bits):
+    """src/F420.c func_80010500: signed `bits`-wide field at bit index*bits.
+
+    C integer division truncates toward zero; Python's floors. That only differs
+    for negative indices, which is exactly what an empty channel produces, so the
+    truncating form is used here to match the hardware."""
+    bitpos = index * bits
+    word = bitpos // 16 if bitpos >= 0 else -((-bitpos) // 16)   # C: trunc to zero
+    rem = bitpos - word * 16                                     # C: sign follows bitpos
+    o = base + word * 2
+    v = (f.u16(o) << 16) | f.u16(o + 2)
+    v = (v << (rem & 31)) & 0xFFFFFFFF          # MIPS masks the shift to 5 bits
+    return signed(v >> (32 - bits), bits)
+
+
+class Animation:
+    """src/17300.c. Two sampling modes: packed per-frame streams (default) and
+    hermite keyframes (flags & 8)."""
+
+    def __init__(self, frag, off):
+        f = self.f = frag
+        self.off = off
+        # The flags live in the LOW byte of the u16 at +0 -- reading the byte
+        # AT +0 gets the always-zero high byte, which silently turns every
+        # hermite animation (flags & 8: Pidgeot, Dodrio, Exeggutor, Tangela,
+        # Magmar) into a packed-stream read of keyframe tables.
+        self.flags     = f.u16(off)
+        self.startFrame= f.u16(off + 4)
+        self.loopStart = f.u16(off + 6)
+        self.nChannels = f.u16(off + 8)
+        self.nFrames   = f.u16(off + 0xA)
+        self.chanTable = f.ptr(off + 0xC)
+        self.scaleData = f.ptr(off + 0x10)
+        self.rotData   = f.ptr(off + 0x14)
+        self.transData = f.ptr(off + 0x18)
+
+    def chan(self, i):
+        o = self.chanTable + i * 0xA
+        f = self.f
+        return dict(nScale=f.u8(o), nRot=f.u8(o + 1), nTrans=f.u8(o + 2),
+                    interp=f.u8(o + 3), oScale=f.u16(o + 4),
+                    oRot=f.u16(o + 6), oTrans=f.u16(o + 8))
+
+    # -- packed stream sampling (flags & 8 == 0) --------------------------
+    # A count of 0 means the component has no stream. In the ROM that only
+    # ever happens in HERMITE animations, where a count under 2 means "the
+    # offset field IS the constant value" -- no packed animation of any of the
+    # 151 species carries an empty channel, so the bind-pose fallback here is
+    # dead code kept as a safety net.
+    def _trans_packed(self, c, frame):
+        if c['nTrans'] == 0:
+            return None
+        bits = 16 if (self.flags & 4) else 12
+        if c['nTrans'] == 1:
+            # (s16) casts both ways: func_80016848 reads the u16 offset field
+            # back as a signed constant.
+            return float(signed(c['oTrans'], 16) if (self.flags & 4)
+                         else signed((c['oTrans'] * 16) & 0xFFFF, 16) >> 4)
+        i = c['oTrans'] + min(frame, c['nTrans'] - 1)
+        return float(bitfield(self.f, self.transData, i, bits))
+
+    def _rot_packed(self, c, frame):
+        if c['nRot'] == 0:
+            return None
+        if c['nRot'] == 1:
+            return signed((c['oRot'] * 16) & 0xFFFF, 16)
+        i = c['oRot'] + min(frame, c['nRot'] - 1)
+        return signed((bitfield(self.f, self.rotData, i, 12) * 16) & 0xFFFF, 16)
+
+    def _scale_packed(self, c, frame):
+        if c['nScale'] == 0:
+            return None
+        if c['nScale'] == 1:
+            return c['oScale'] / 1000.0
+        i = c['oScale'] + min(frame, c['nScale'] - 1)
+        return self.f.s16(self.scaleData + i * 2) / 1000.0
+
+    # -- hermite keyframe sampling (flags & 8) ----------------------------
+    def _hermite(self, base, n, frame, wide):
+        f = self.f
+        stride = 8 if wide else 6
+
+        def key(i):
+            o = base + i * stride
+            return (f.s16(o), f.s16(o + 2), f.s16(o + 4),
+                    f.s16(o + 6) if wide else f.s16(o + 4))
+
+        k0 = key(0)
+        if k0[0] >= frame:
+            return float(k0[1])
+        last = key(n - 1)
+        if frame >= last[0]:
+            return float(last[1])
+        i = 0
+        while i < n - 2:
+            if frame < key(i + 1)[0]:
+                break
+            i += 1
+        a, b = key(i), key(i + 1)
+        x = (frame - a[0]) / 30.0
+        y = 30.0 / (b[0] - a[0])
+        x2, x3 = x * x, x * x * x
+        y2, y3 = y * y, y * y * y
+        return (a[1] * (2 * x3 * y3 - 3 * x2 * y2 + 1)
+                + b[1] * (-2 * x3 * y3 + 3 * x2 * y2)
+                + (a[3] if wide else a[2]) * (x3 * y2 - 2 * x2 * y + x)
+                + b[2] * (x3 * y2 - x2 * y))
+
+    def _trans_key(self, c, frame):
+        if c['nTrans'] < 2:
+            return float(signed(c['oTrans'], 16))
+        return self._hermite(self.transData + c['oTrans'] * 2, c['nTrans'], frame, c['interp'] & 1)
+
+    def _rot_key(self, c, frame):
+        if c['nRot'] < 2:
+            deg = signed(c['oRot'], 16) / 10.0
+        else:
+            deg = self._hermite(self.rotData + c['oRot'] * 2, c['nRot'], frame, c['interp'] & 2) / 10.0
+        deg %= 360.0
+        # func_80016DE0 returns s16: the f32 -> s16 cast WRAPS an angle above
+        # 180 degrees to its negative twin. Same binary angle either way, but
+        # the packer stores i16 with clamping, so an unwrapped 350-degree
+        # value would pin at 32767 (= 180 degrees) instead.
+        return signed(int(deg / 360.0 * 65536.0) & 0xFFFF, 16)
+
+    def _scale_key(self, c, frame):
+        if c['nScale'] < 2:
+            return signed(c['oScale'], 16) / 100.0
+        return self._hermite(self.scaleData + c['oScale'] * 2, c['nScale'], frame, c['interp'] & 4) / 100.0
+
+    def sample_trs(self, chanIndex, frame, bind=None):
+        """Returns (translation, rotation, scale) triples for one bone. Components
+        whose channel carries no data fall back to the bone's bind value."""
+        base = chanIndex * 3
+        if base < 0 or base + 2 >= self.nChannels:
+            return None
+        cs = [self.chan(base + i) for i in range(3)]
+        if self.flags & 8:
+            out = ([self._trans_key(c, frame) for c in cs],
+                   [self._rot_key(c, frame) for c in cs],
+                   [self._scale_key(c, frame) for c in cs])
+        else:
+            out = ([self._trans_packed(c, frame) for c in cs],
+                   [self._rot_packed(c, frame) for c in cs],
+                   [self._scale_packed(c, frame) for c in cs])
+        if bind is None:
+            bind = ([0, 0, 0], [0, 0, 0], [1.0, 1.0, 1.0])
+        return tuple([v if v is not None else bind[k][i] for i, v in enumerate(comp)]
+                     for k, comp in enumerate(out))
+
+
+class AuxAnimation:
+    """Texture animation (src/18140.c). Same header shape as the skeletal
+    animations, but each channel is a per-frame stream of texture-table indices
+    that func_800176DC substitutes into a material."""
+
+    def __init__(self, frag, off):
+        f = self.f = frag
+        self.flags     = f.u16(off)         # low byte, same layout as Animation
+        self.startFrame= f.u16(off + 4)
+        self.loopStart = f.u16(off + 6)
+        self.nChannels = f.u16(off + 8)
+        self.nFrames   = f.u16(off + 0xA)
+        self.chanTable = f.ptr(off + 0xC)
+        self.data      = f.ptr(off + 0x10)
+
+    def sample(self, chan, frame):
+        """func_80017540: index into the stream, clamped to the channel length."""
+        if not (0 <= chan < self.nChannels) or self.chanTable is None:
+            return None
+        o = self.chanTable + chan * 4
+        count, base = self.f.u16(o), self.f.u16(o + 2)
+        if count == 0:
+            return None
+        i = base + (frame if frame < count else count - 1)
+        return self.f.u8(self.data + i)
+
+    def track(self, chan):
+        n = max(1, self.nFrames)
+        return [self.sample(chan, i) for i in range(n)]
+
+
+# ------------------------------------------------------------------ textures
+
+def rgba5551(p):
+    return (((p >> 11) & 0x1F) * 255 // 31, ((p >> 6) & 0x1F) * 255 // 31,
+            ((p >> 1) & 0x1F) * 255 // 31, 255 if (p & 1) else 0)
+
+
+def decode_texture(f, tex, tlut=None, palette=0):
+    """Returns (w, h, RGBA8 bytes) for the N64 texture formats these models use."""
+    w, h, fmt, siz, addr = tex['w'], tex['h'], tex['fmt'], tex['siz'], tex['data']
+    out = bytearray(w * h * 4)
+    d = f.d
+    n = w * h
+
+    def nibble(i):
+        return (d[addr + i // 2] >> (0 if i & 1 else 4)) & 0xF
+
+    if fmt == 0 and siz == 2:                       # RGBA16 (5/5/5/1)
+        for i in range(n):
+            out[i*4:i*4+4] = bytes(rgba5551(struct.unpack_from('>H', d, addr + i * 2)[0]))
+    elif fmt == 0 and siz == 3:                     # RGBA32
+        out[:] = d[addr:addr + n * 4]
+    elif fmt == 2:                                  # CI4 / CI8 -> RGBA16 palette
+        pal = []
+        if tlut is not None and tlut['data'] is not None:
+            base = tlut['data'] + (palette * 16 * 2 if siz == 0 else 0)
+            for i in range(16 if siz == 0 else 256):
+                pal.append(bytes(rgba5551(struct.unpack_from('>H', d, base + i * 2)[0])))
+        if not pal:
+            pal = [b'\xff\x00\xff\xff'] * 256
+        for i in range(n):
+            idx = nibble(i) if siz == 0 else d[addr + i]
+            out[i*4:i*4+4] = pal[idx % len(pal)]
+    elif fmt == 3:                                  # IA16 / IA8 / IA4
+        for i in range(n):
+            if siz == 2:
+                v = struct.unpack_from('>H', d, addr + i * 2)[0]
+                l, a = v >> 8, v & 0xFF
+            elif siz == 1:
+                v = d[addr + i]
+                l, a = (v >> 4) * 17, (v & 0xF) * 17
+            else:
+                v = nibble(i)
+                l, a = ((v >> 1) * 255) // 7, 255 if (v & 1) else 0
+            out[i*4:i*4+4] = bytes((l, l, l, a))
+    elif fmt == 4:                                  # I8 / I4
+        for i in range(n):
+            l = d[addr + i] if siz == 1 else nibble(i) * 17
+            out[i*4:i*4+4] = bytes((l, l, l, 255))
+    else:
+        for i in range(n):                          # unsupported: magenta
+            out[i*4:i*4+4] = b'\xff\x00\xff\xff'
+    return w, h, bytes(out)
+
+
+def png(w, h, rgba):
+    """Minimal PNG encoder (no PIL dependency)."""
+    raw = b''.join(b'\x00' + rgba[y*w*4:(y+1)*w*4] for y in range(h))
+
+    def chunk(tag, data):
+        c = tag + data
+        return struct.pack('>I', len(data)) + c + struct.pack('>I', zlib.crc32(c) & 0xFFFFFFFF)
+
+    return (b'\x89PNG\r\n\x1a\n'
+            + chunk(b'IHDR', struct.pack('>IIBBBBB', w, h, 8, 6, 0, 0, 0))
+            + chunk(b'IDAT', zlib.compress(raw, 9))
+            + chunk(b'IEND', b''))
+
+
+# ---------------------------------------------------------------------- main
+
+def unique(seq):
+    """The distinct values of `seq`, in the order they first appear.
+
+    Used where a set used to be. A set of small ints iterates in hash-slot
+    order, which is stable across runs but is neither insertion nor sort order
+    and is a CPython implementation detail -- and here it decided the order
+    textures get REGISTERED in, and so their indices in the packed file. Order
+    of appearance is a property of the data instead of the interpreter, which
+    is what lets the Lua extractor produce the same file.
+    """
+    seen, out = set(), []
+    for v in seq:
+        if v in seen:
+            continue
+        seen.add(v)
+        out.append(v)
+    return out
+
+
+def dedupe_fx(nodes):
+    """The geo layout's effect callbacks, once each, IN THE ORDER THEY APPEAR.
+
+    A geo layout can name the same callback on the same bone more than once
+    (the walk visits a subtree twice), so these have to be deduplicated, and it
+    used to be done by dropping them through a set. That was a real bug rather
+    than a style point: the set held tuples containing strings, so its iteration
+    order moved with PYTHONHASHSEED, and the generated flames of every species
+    carrying more than one -- Ponyta, Rapidash and Moltres -- came out in a
+    different order, with different seeds and therefore different pixels, on
+    different runs of the same build.
+
+    Order of appearance is the game's own order, it is stable, and it is what
+    the Lua extractor can reproduce.
+    """
+    seen, out = set(), []
+    for node in nodes:
+        key = (node['bone'], node['callback'], node['arg'])
+        if key in seen:
+            continue
+        seen.add(key)
+        out.append(dict(node))
+    return out
+
+
+def extract(path, name=None, raw=False):
+    """`raw=True` carries each texture's decoded RGBA8 bytes as `rgba` instead
+    of encoding a PNG data URI into `png`.
+
+    The viewer and the glTF export both want a PNG, so that stays the default.
+    The mod's own packer wants the pixels: it stores them uncompressed, so that
+    its Lua counterpart -- which has no zlib whose output is guaranteed to
+    agree with this one's byte for byte -- can be checked against it exactly.
+    """
+    f = Fragment(path, name or str(path))
+    m = Model(f)
+    m.build()
+
+    import base64
+    auxAnims = [AuxAnimation(f, o) for o in m.auxAnims]
+
+    texIndexMap, texOut = {}, []
+
+    def register(texIdx, tlut, pal):
+        key = (texIdx, tlut, pal)
+        if key in texIndexMap:
+            return texIndexMap[key]
+        if not (0 <= texIdx < len(m.textures)):
+            return -1
+        texIndexMap[key] = len(texOut)
+        tl = m.tluts[tlut] if 0 <= tlut < len(m.tluts) else None
+        w, h, rgba = decode_texture(f, m.textures[texIdx], tl, pal)
+        rec = dict(index=texIdx, w=w, h=h)
+        if raw:
+            rec['rgba'] = rgba
+        else:
+            rec['png'] = ('data:image/png;base64,'
+                          + base64.b64encode(png(w, h, rgba)).decode())
+        texOut.append(rec)
+        return texIndexMap[key]
+
+    for p in m.prims:
+        if not p['tris']:
+            continue
+        pal = m.tile_palette(p['mat'])
+        register(p['tex'], p['tlut'], pal)
+        # An animated material can swap to any texture its channel names, so all
+        # of them have to be decoded up front.
+        if p['texAnim'] >= 0:
+            for a in auxAnims:
+                for t in unique(a.track(p['texAnim'])):
+                    if t is not None:
+                        register(t, p['tlut'], pal)
+
+    prims = []
+    for p in m.prims:
+        if not p['tris']:
+            continue
+        pos, uv, nrm, skin = [], [], [], []
+        pal = m.tile_palette(p['mat'])
+        ti = texIndexMap.get((p['tex'], p['tlut'], pal), -1)
+        # texture-table index -> slot in texOut, for the animated swap
+        texMap = {}
+        if p['texAnim'] >= 0:
+            for a in auxAnims:
+                for t in unique(a.track(p['texAnim'])):
+                    if t is not None and (t, p['tlut'], pal) in texIndexMap:
+                        texMap[t] = texIndexMap[(t, p['tlut'], pal)]
+        tw, th = (m.textures[p['tex']]['w'], m.textures[p['tex']]['h']) if ti >= 0 else (32, 32)
+        for v in p['verts']:
+            pos += [v[0], v[1], v[2]]
+            uv += [v[3] / tw, v[4] / th]
+            nrm += [v[5] / 127.0, v[6] / 127.0, v[7] / 127.0]
+            skin.append(v[9])
+        prims.append(dict(tex=ti, cull=p['cull'], texAnim=p['texAnim'],
+                          texMap={str(k): v for k, v in sorted(texMap.items())},
+                          pos=pos, uv=uv, nrm=nrm, skin=skin,
+                          idx=[i for t in p['tris'] for i in t]))
+
+    def compress(values, nd):
+        """Constant tracks collapse to a scalar; most channels never move."""
+        r = [round(v, nd) for v in values]
+        return r[0] if all(v == r[0] for v in r) else r
+
+    anims = []
+    for i, off in enumerate(m.anims):
+        a = Animation(f, off)
+        nf = max(1, a.nFrames)
+        tracks = []
+        for b in m.bones:
+            ch = b['chan']
+            bind = (b['t'], b['r'], b['s'])
+            if ch < 0 or a.sample_trs(ch, 0, bind) is None:
+                tracks.append(None)
+                continue
+            samples = [a.sample_trs(ch, fr, bind) for fr in range(nf)]
+            tracks.append(dict(
+                t=[compress([s[0][k] for s in samples], 3) for k in range(3)],
+                r=[compress([s[1][k] for s in samples], 0) for k in range(3)],
+                s=[compress([s[2][k] for s in samples], 5) for k in range(3)]))
+        anims.append(dict(index=i, frames=nf, flags=a.flags,
+                          channels=a.nChannels, loopStart=a.loopStart, tracks=tracks))
+
+    auxOut = []
+    for i, a in enumerate(auxAnims):
+        auxOut.append(dict(index=i, frames=max(1, a.nFrames), flags=a.flags,
+                           loopStart=a.loopStart,
+                           channels=[a.track(c) for c in range(a.nChannels)]))
+
+    return dict(
+        species=m.species,
+        name=SPECIES.get(m.species, f'#{m.species}'),
+        file=os.path.basename(f.name),
+        rootScale=m.rootScale,
+        bones=[dict(parent=b['parent'], boneId=b['boneId'], chan=b['chan'],
+                    flags=b['flags'], t=b['t'], r=b['r'], s=b['s']) for b in m.bones],
+        textures=texOut,
+        prims=prims,
+        anims=anims,
+        auxAnims=auxOut,
+        fx=dedupe_fx(m.fx),
+        warnings=m.warnings,
+    )
+
+
+SPECIES = {}
+_NAMES = (
+    "Bulbasaur Ivysaur Venusaur Charmander Charmeleon Charizard Squirtle Wartortle Blastoise "
+    "Caterpie Metapod Butterfree Weedle Kakuna Beedrill Pidgey Pidgeotto Pidgeot Rattata Raticate "
+    "Spearow Fearow Ekans Arbok Pikachu Raichu Sandshrew Sandslash NidoranF Nidorina Nidoqueen "
+    "NidoranM Nidorino Nidoking Clefairy Clefable Vulpix Ninetales Jigglypuff Wigglytuff Zubat "
+    "Golbat Oddish Gloom Vileplume Paras Parasect Venonat Venomoth Diglett Dugtrio Meowth Persian "
+    "Psyduck Golduck Mankey Primeape Growlithe Arcanine Poliwag Poliwhirl Poliwrath Abra Kadabra "
+    "Alakazam Machop Machoke Machamp Bellsprout Weepinbell Victreebel Tentacool Tentacruel Geodude "
+    "Graveler Golem Ponyta Rapidash Slowpoke Slowbro Magnemite Magneton Farfetchd Doduo Dodrio "
+    "Seel Dewgong Grimer Muk Shellder Cloyster Gastly Haunter Gengar Onix Drowzee Hypno Krabby "
+    "Kingler Voltorb Electrode Exeggcute Exeggutor Cubone Marowak Hitmonlee Hitmonchan Lickitung "
+    "Koffing Weezing Rhyhorn Rhydon Chansey Tangela Kangaskhan Horsea Seadra Goldeen Seaking "
+    "Staryu Starmie MrMime Scyther Jynx Electabuzz Magmar Pinsir Tauros Magikarp Gyarados Lapras "
+    "Ditto Eevee Vaporeon Jolteon Flareon Porygon Omanyte Omastar Kabuto Kabutops Aerodactyl "
+    "Snorlax Articuno Zapdos Moltres Dratini Dragonair Dragonite Mewtwo Mew").split()
+for _i, _n in enumerate(_NAMES):
+    SPECIES[_i + 1] = _n
+
+
+if __name__ == '__main__':
+    here = os.path.dirname(os.path.abspath(__file__))
+    src = sys.argv[1] if len(sys.argv) > 1 else 'assets/us/pokemon_models/24.bin'
+    dst = sys.argv[2] if len(sys.argv) > 2 else os.path.join(here, 'model.js')
+    data = extract(src)
+    body = json.dumps(data, separators=(',', ':'))
+    with open(dst, 'w') as fp:
+        fp.write('window.PKMN_MODEL = ' + body + ';\n')
+    tris = sum(len(p['idx']) // 3 for p in data['prims'])
+    print(f"{data['name']} (#{data['species']})  bones={len(data['bones'])}  prims={len(data['prims'])}  "
+          f"tris={tris}  textures={len(data['textures'])}  anims={len(data['anims'])}")
+    print(f"frames per anim: {[a['frames'] for a in data['anims']]}")
+    if data['warnings']:
+        print('warnings:', data['warnings'][:5])
+    print(f'wrote {dst} ({os.path.getsize(dst)/1024:.0f} KB)')

model_extract/pipeline/glb.py

@@ -0,0 +1,274 @@
+#!/usr/bin/env python3
+"""
+glTF 2.0 binary writer.
+
+Each game bone becomes two nodes -- a pivot carrying translation/rotation and a
+leaf carrying the accumulated scale -- because the game keeps scale out of the
+matrix chain while glTF propagates it to children. See ../README.md.
+"""
+import json
+import math
+import struct
+
+ND = 7          # decimals kept on node rest transforms
+
+
+def quat_from_euler(r):
+    """The game's rotation is Rx*Ry*Rz in row-vector form (src/F420.c
+    func_8000F730); build that basis as glTF columns and convert."""
+    sx, cx = math.sin(r[0] / 32768 * math.pi), math.cos(r[0] / 32768 * math.pi)
+    sy, cy = math.sin(r[1] / 32768 * math.pi), math.cos(r[1] / 32768 * math.pi)
+    sz, cz = math.sin(r[2] / 32768 * math.pi), math.cos(r[2] / 32768 * math.pi)
+    # rows of the game matrix become the columns of the glTF rotation
+    m = ((cy*cz, sx*sy*cz - cx*sz, cx*sy*cz + sx*sz),
+         (cy*sz, sx*sy*sz + cx*cz, cx*sy*sz - sx*cz),
+         (-sy,   sx*cy,            cx*cy))
+    tr = m[0][0] + m[1][1] + m[2][2]
+    if tr > 0:
+        s = math.sqrt(tr + 1.0) * 2
+        w = 0.25 * s
+        x = (m[2][1] - m[1][2]) / s
+        y = (m[0][2] - m[2][0]) / s
+        z = (m[1][0] - m[0][1]) / s
+    elif m[0][0] > m[1][1] and m[0][0] > m[2][2]:
+        s = math.sqrt(1.0 + m[0][0] - m[1][1] - m[2][2]) * 2
+        w = (m[2][1] - m[1][2]) / s
+        x = 0.25 * s
+        y = (m[0][1] + m[1][0]) / s
+        z = (m[0][2] + m[2][0]) / s
+    elif m[1][1] > m[2][2]:
+        s = math.sqrt(1.0 + m[1][1] - m[0][0] - m[2][2]) * 2
+        w = (m[0][2] - m[2][0]) / s
+        x = (m[0][1] + m[1][0]) / s
+        y = 0.25 * s
+        z = (m[1][2] + m[2][1]) / s
+    else:
+        s = math.sqrt(1.0 + m[2][2] - m[0][0] - m[1][1]) * 2
+        w = (m[1][0] - m[0][1]) / s
+        x = (m[0][2] + m[2][0]) / s
+        y = (m[1][2] + m[2][1]) / s
+        z = 0.25 * s
+    n = math.sqrt(x*x + y*y + z*z + w*w) or 1.0
+    return [x/n, y/n, z/n, w/n]
+
+
+def pose(bones, sample_fn):
+    """Returns (pivotT, pivotQ, jointS) for every bone at one instant."""
+    acc, pt, pq, js = [], [], [], []
+    for i, b in enumerate(bones):
+        t, r, s = sample_fn(i, b)
+        pa = acc[b['parent']] if b['parent'] >= 0 else (1.0, 1.0, 1.0)
+        pt.append([t[0]*pa[0], t[1]*pa[1], t[2]*pa[2]])
+        pq.append(quat_from_euler(r))
+        a = (pa[0]*s[0], pa[1]*s[1], pa[2]*s[2])
+        acc.append(a)
+        js.append(list(a))
+    return pt, pq, js
+
+
+# ------------------------------------------------------------------ glTF build
+
+class Glb:
+    def __init__(self):
+        self.buf = bytearray()
+        self.views = []
+        self.accessors = []
+
+    def view(self, data, target=None):
+        while len(self.buf) % 4:
+            self.buf.append(0)
+        off = len(self.buf)
+        self.buf += data
+        v = dict(buffer=0, byteOffset=off, byteLength=len(data))
+        if target:
+            v['target'] = target
+        self.views.append(v)
+        return len(self.views) - 1
+
+    def accessor(self, data, ctype, atype, count, target=None,
+                 minmax=None, normalized=False):
+        a = dict(bufferView=self.view(data, target), componentType=ctype,
+                 count=count, type=atype)
+        if normalized:
+            a['normalized'] = True
+        if minmax:
+            a['min'], a['max'] = minmax
+        self.accessors.append(a)
+        return len(self.accessors) - 1
+
+    def floats(self, values, atype, target=None, minmax=None):
+        n = {'SCALAR': 1, 'VEC2': 2, 'VEC3': 3, 'VEC4': 4, 'MAT4': 16}[atype]
+        return self.accessor(struct.pack(f'<{len(values)}f', *values),
+                             5126, atype, len(values) // n, target, minmax)
+
+    def finish(self, gltf):
+        gltf['buffers'] = [dict(byteLength=len(self.buf))]
+        gltf['bufferViews'] = self.views
+        gltf['accessors'] = self.accessors
+        js = json.dumps(gltf, separators=(',', ':')).encode()
+        js += b' ' * (-len(js) % 4)
+        bin_ = bytes(self.buf) + b'\0' * (-len(self.buf) % 4)
+        return (struct.pack('<III', 0x46546C67, 2, 12 + 8 + len(js) + 8 + len(bin_))
+                + struct.pack('<II', len(js), 0x4E4F534A) + js
+                + struct.pack('<II', len(bin_), 0x004E4942) + bin_)
+
+
+def build_glb(data, pngs):
+    bones = data['bones']
+    nb = len(bones)
+    g = Glb()
+    gltf = dict(asset=dict(version='2.0',
+                           generator='pokestadium tools/model_viewer/export_gltf.py'))
+
+    # ---- nodes: root scale, then a pivot/joint pair per bone ----------------
+    bind_t, bind_q, bind_s = pose(bones, lambda i, b: (b['t'], b['r'], b['s']))
+    nodes = [dict(name='model_root', scale=[round(v, 6) for v in data['rootScale']])]
+    pivot_id = [0] * nb
+    joint_id = [0] * nb
+    for i, b in enumerate(bones):
+        pivot_id[i] = len(nodes)
+        nodes.append(dict(name=f'bone{b["boneId"]:02d}',
+                          translation=[round(v, ND) for v in bind_t[i]],
+                          rotation=[round(v, ND) for v in bind_q[i]]))
+        joint_id[i] = len(nodes)
+        nodes.append(dict(name=f'bone{b["boneId"]:02d}_scale',
+                          scale=[round(v, ND) for v in bind_s[i]]))
+        nodes[pivot_id[i]]['children'] = [joint_id[i]]
+    for i, b in enumerate(bones):
+        parent = pivot_id[b['parent']] if b['parent'] >= 0 else 0
+        nodes[parent].setdefault('children', []).append(pivot_id[i])
+
+    # ---- textures / materials ---------------------------------------------
+    images, samplers, textures, materials = [], [], [], []
+    if pngs:
+        samplers.append(dict(magFilter=9729, minFilter=9729,
+                             wrapS=33071, wrapT=33071))       # LINEAR, CLAMP
+    for i, blob in enumerate(pngs):
+        images.append(dict(mimeType='image/png',
+                           bufferView=g.view(blob), name=f'tex{i:02d}'))
+        textures.append(dict(sampler=0, source=i))
+
+    prims_out = []
+    for p in data['prims']:
+        nv = len(p['pos']) // 3
+        pos = [float(v) for v in p['pos']]
+        mn = [min(pos[k::3]) for k in range(3)]
+        mx = [max(pos[k::3]) for k in range(3)]
+        attrs = dict(
+            POSITION=g.floats(pos, 'VEC3', 34962, (mn, mx)),
+            NORMAL=g.floats([float(v) for v in p['nrm']], 'VEC3', 34962),
+            TEXCOORD_0=g.floats([float(v) for v in p['uv']], 'VEC2', 34962),
+            JOINTS_0=g.accessor(
+                struct.pack(f'<{nv*4}H', *[v for j in p['skin'] for v in (j, 0, 0, 0)]),
+                5123, 'VEC4', nv, 34962),
+            WEIGHTS_0=g.floats([v for _ in range(nv) for v in (1.0, 0.0, 0.0, 0.0)],
+                               'VEC4', 34962),
+        )
+        idx = g.accessor(struct.pack(f'<{len(p["idx"])}H', *p['idx']),
+                         5123, 'SCALAR', len(p['idx']), 34963)
+        blend = p.get('blend')
+        mat = dict(
+            name=f'mat{len(materials):02d}',
+            alphaMode='BLEND' if blend else 'MASK',
+            doubleSided=bool(blend) or not (p['cull'] & 0x400),
+            pbrMetallicRoughness=dict(metallicFactor=0.0, roughnessFactor=0.9),
+        )
+        if blend:
+            # generated effects are unlit so they read as emissive fire/gas
+            mat['emissiveFactor'] = [1.0, 1.0, 1.0]
+        else:
+            mat['alphaCutoff'] = 0.5
+        if p['tex'] >= 0:
+            mat['pbrMetallicRoughness']['baseColorTexture'] = dict(index=p['tex'])
+            if blend:
+                mat['emissiveTexture'] = dict(index=p['tex'])
+        materials.append(mat)
+        prims_out.append(dict(attributes=attrs, indices=idx,
+                              material=len(materials) - 1))
+
+    skin_node = len(nodes)
+    nodes.append(dict(name=data['name'], mesh=0, skin=0))
+
+    ident = [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1]
+    gltf['skins'] = [dict(joints=joint_id, skeleton=0,
+                          inverseBindMatrices=g.floats(ident * nb, 'MAT4'))]
+    gltf['meshes'] = [dict(name=data['name'], primitives=prims_out)]
+
+    # ---- animations --------------------------------------------------------
+    anims = []
+    for a in data['anims']:
+        nf = a['frames']
+        times = [round(fr / 30.0, 6) for fr in range(nf)]   # authored at 30 fps
+
+        def sample_fn(i, b, _a=a):
+            tr = _a['tracks'][i]
+            if not tr:
+                return b['t'], b['r'], b['s']
+            pick = lambda c, fr: (c if isinstance(c, (int, float))
+                                  else c[min(fr, len(c) - 1)])
+            return ([pick(c, sample_fn.fr) for c in tr['t']],
+                    [pick(c, sample_fn.fr) for c in tr['r']],
+                    [pick(c, sample_fn.fr) for c in tr['s']])
+
+        seq_t = [[] for _ in range(nb)]
+        seq_q = [[] for _ in range(nb)]
+        seq_s = [[] for _ in range(nb)]
+        for fr in range(nf):
+            sample_fn.fr = fr
+            pt, pq, js = pose(bones, sample_fn)
+            for i in range(nb):
+                if seq_q[i] and sum(x*y for x, y in zip(seq_q[i][-1], pq[i])) < 0:
+                    pq[i] = [-v for v in pq[i]]     # keep quaternions continuous
+                seq_t[i].append(pt[i]); seq_q[i].append(pq[i]); seq_s[i].append(js[i])
+
+        channels, samplers_a = [], []
+        cache = {}
+
+        def time_accessor(keys):
+            if keys not in cache:
+                t = times if keys == nf else [times[0], times[-1]]
+                cache[keys] = g.floats(t, 'SCALAR', minmax=([t[0]], [t[-1]]))
+            return cache[keys]
+
+        for i in range(nb):
+            for seq, path, node, dflt in (
+                    (seq_t[i], 'translation', pivot_id[i], nodes[pivot_id[i]]['translation']),
+                    (seq_q[i], 'rotation', pivot_id[i], nodes[pivot_id[i]]['rotation']),
+                    (seq_s[i], 'scale', joint_id[i], nodes[joint_id[i]]['scale'])):
+                const = all(v == seq[0] for v in seq)
+                # A constant channel can only be dropped when it already equals the
+                # node's rest value; otherwise the node would sit in its bind pose.
+                if const and [round(c, ND) for c in seq[0]] == dflt:
+                    continue
+                if const:
+                    seq = [seq[0], seq[0]]
+                time_acc = time_accessor(len(seq))
+                flat = [c for v in seq for c in v]
+                if path == 'rotation':
+                    out = g.accessor(
+                        struct.pack(f'<{len(flat)}h',
+                                    *[max(-32768, min(32767, round(c * 32767)))
+                                      for c in flat]),
+                        5122, 'VEC4', len(seq), normalized=True)
+                else:
+                    out = g.floats(flat, 'VEC3')
+                samplers_a.append(dict(input=time_acc, output=out,
+                                       interpolation='LINEAR'))
+                channels.append(dict(sampler=len(samplers_a) - 1,
+                                     target=dict(node=node, path=path)))
+        if channels:
+            anims.append(dict(name=a['name'], channels=channels, samplers=samplers_a))
+    if anims:
+        gltf['animations'] = anims
+
+    gltf['nodes'] = nodes
+    gltf['scenes'] = [dict(nodes=[0, skin_node])]
+    gltf['scene'] = 0
+    if images:
+        gltf['images'] = images
+        gltf['samplers'] = samplers
+        gltf['textures'] = textures
+    gltf['materials'] = materials
+    return g.finish(gltf)
+
+

model_extract/pipeline/rom.py

@@ -0,0 +1,120 @@
+#!/usr/bin/env python3
+"""
+Raw ROM access for the Pokemon Stadium (US) model export.
+
+Everything here is stdlib-only: byte-order fixup, the Yay0 decompressor, the
+PERS-SZP wrapper the assets use, and the little archive format that packs many
+files into one segment. That is all it takes to get from baserom.z64 to model
+data, so the export does not need `make init`, splat or crunch64.
+"""
+import hashlib
+import struct
+
+# ROM offsets taken from pokestadium-us.yaml.
+POKEMON_MODELS = 0x920000       # archive of the 215 battle models
+BATTLE_DATA    = 0x70D3A0       # per-species battle tables, indexed by D_80075BD0
+MAIN_ROM       = 0x1000         # main code segment ...
+MAIN_VRAM      = 0x80000400     # ... and where it lands in RAM
+PTR_TABLE_VRAM = 0x80075BD0     # D_80075BD0[species - 1] -> offset into BATTLE_DATA
+
+US_MD5 = 'ed1378bc12115f71209a77844965ba50'
+
+
+class Rom:
+    def __init__(self, path):
+        data = bytearray(open(path, 'rb').read())
+        magic = struct.unpack_from('>I', data, 0)[0]
+        if magic == 0x37804012:                     # .v64, byte-swapped pairs
+            data[0::2], data[1::2] = data[1::2], data[0::2]
+        elif magic == 0x40123780:                   # .n64, word-reversed
+            data = bytearray(b''.join(data[i:i+4][::-1] for i in range(0, len(data), 4)))
+        elif magic != 0x80371240:                   # .z64, native big endian
+            raise ValueError(f'{path}: not an N64 ROM (magic {magic:#010x})')
+        self.data = bytes(data)
+        self.md5 = hashlib.md5(self.data).hexdigest()
+
+    @property
+    def is_expected_us(self):
+        return self.md5 == US_MD5
+
+    def u32(self, o):
+        return struct.unpack_from('>I', self.data, o)[0]
+
+    def vram_to_rom(self, vram):
+        return MAIN_ROM + (vram - MAIN_VRAM)
+
+    # ---- archive ---------------------------------------------------------
+    def archive(self, off):
+        """Segments that hold many files start with
+             u32 tag, u32 0, u32 totalSize, u32 fileCount
+           followed by fileCount { u32 offset, u32 size, u32 pad[2] } records,
+           all relative to the start of the segment (tools/unpack_asset.py).
+           Only the top three bytes of the first word are reliably zero -- the
+           model archive puts a nonzero value in the low byte."""
+        if (self.u32(off) & 0xFFFFFF00) != 0 or self.u32(off + 4) != 0:
+            return [self.data[off:]]
+        count = self.u32(off + 12)
+        if not 0 < count < 4096:
+            return [self.data[off:]]
+        out = []
+        for i in range(count):
+            rec = off + 0x10 + i * 0x10
+            start, size = self.u32(rec), self.u32(rec + 4)
+            out.append(self.data[off + start: off + start + size])
+        return out
+
+
+# ------------------------------------------------------------- decompression
+
+def yay0_decompress(src):
+    """Nintendo Yay0. Header: magic, decompressed size, link offset, chunk
+    offset; then a bitstream where a 1 copies one literal byte and a 0 pulls a
+    (distance, length) pair from the link table."""
+    if src[:4] != b'Yay0':
+        raise ValueError('not Yay0')
+    size, link_off, chunk_off = struct.unpack_from('>3I', src, 4)
+    out = bytearray(size)
+    mask_p, link_p, chunk_p, pos = 0x10, link_off, chunk_off, 0
+    mask, bits = 0, 0
+    while pos < size:
+        if bits == 0:
+            mask = struct.unpack_from('>I', src, mask_p)[0]
+            mask_p += 4
+            bits = 32
+        if mask & 0x80000000:
+            out[pos] = src[chunk_p]
+            chunk_p += 1
+            pos += 1
+        else:
+            link = struct.unpack_from('>H', src, link_p)[0]
+            link_p += 2
+            dist = link & 0x0FFF
+            count = link >> 12
+            if count == 0:
+                count = src[chunk_p] + 0x12
+                chunk_p += 1
+            else:
+                count += 2
+            copy = pos - dist - 1
+            for _ in range(count):                  # overlapping runs are legal
+                out[pos] = out[copy]
+                pos += 1
+                copy += 1
+        mask = (mask << 1) & 0xFFFFFFFF
+        bits -= 1
+    return bytes(out)
+
+
+def decompress(blob):
+    """Unwrap whatever container an asset arrived in."""
+    if blob[:8] == b'PERS-SZP':
+        header = struct.unpack_from('>I', blob, 8)[0]
+        return yay0_decompress(blob[header:])
+    if blob[:4] == b'Yay0':
+        return yay0_decompress(blob)
+    return blob
+
+
+def pokemon_models(rom):
+    """Returns the decompressed model fragments, indexed by file number."""
+    return [decompress(b) for b in rom.archive(POKEMON_MODELS)]

oxr/OpenXR.Loader.nuspec

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<package xmlns="http://schemas.microsoft.com/packaging/2013/05/nuspec.xsd">
+  <metadata>
+    <id>OpenXR.Loader</id>
+    <version>1.0.10.2</version>
+    <authors>Khronos Group</authors>
+    <owners>Khronos Group</owners>
+    <requireLicenseAcceptance>false</requireLicenseAcceptance>
+    <license type="expression">Apache-2.0</license>
+    <licenseUrl>https://licenses.nuget.org/Apache-2.0</licenseUrl>
+    <projectUrl>https://github.com/KhronosGroup/OpenXR-SDK</projectUrl>
+    <description>Khronos OpenXR loader and headers required to build a Win32 or UWP OpenXR application</description>
+    <tags>native khronos openxr loader headers</tags>
+    <dependencies>
+      <dependency id="OpenXR.Headers" version="1.0.10.2" />
+    </dependencies>
+  </metadata>
+</package>

oxr/[Content_Types].xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">
+  <Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml" />
+  <Default Extension="psmdcp" ContentType="application/vnd.openxmlformats-package.core-properties+xml" />
+  <Default Extension="props" ContentType="application/octet" />
+  <Default Extension="targets" ContentType="application/octet" />
+  <Default Extension="dll" ContentType="application/octet" />
+  <Default Extension="lib" ContentType="application/octet" />
+  <Default Extension="nuspec" ContentType="application/octet" />
+</Types>

oxr/_rels/.rels

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
+  <Relationship Type="http://schemas.microsoft.com/packaging/2010/07/manifest" Target="/OpenXR.Loader.nuspec" Id="R0D169365D22F5E6F" />
+  <Relationship Type="http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties" Target="/package/services/metadata/core-properties/948f85fa57f345119150f5525085c62c.psmdcp" Id="R10D7CDDCA5670667" />
+</Relationships>

oxr/build/native/OpenXR.Loader.props

@@ -0,0 +1,5 @@
+<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <OpenXRLoaderPackageRoot>$(MSBuildThisFileDirectory)..\..\</OpenXRLoaderPackageRoot>
+  </PropertyGroup>
+</Project>

oxr/build/native/OpenXR.Loader.targets

@@ -0,0 +1,35 @@
+<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+
+    <Choose>
+        <When Condition="'$(ApplicationType)|$(ApplicationTypeRevision)' == 'Windows Store|10.0'">
+            <PropertyGroup>
+                <OpenXRLoaderBinaryRoot>$(OpenXRLoaderPackageRoot)native\$(Platform)_uwp\release</OpenXRLoaderBinaryRoot>
+            </PropertyGroup>
+        </When>
+        <Otherwise>
+            <PropertyGroup>
+                <OpenXRLoaderBinaryRoot>$(OpenXRLoaderPackageRoot)native\$(Platform)\release</OpenXRLoaderBinaryRoot>
+            </PropertyGroup>
+        </Otherwise>
+    </Choose>
+
+    <ItemDefinitionGroup>
+        <Link>
+            <AdditionalDependencies>%(AdditionalDependencies);$(OpenXRLoaderBinaryRoot)\lib\openxr_loader.lib</AdditionalDependencies>
+        </Link>
+    </ItemDefinitionGroup>
+
+    <!-- Copy the OpenXR loader DLL to the output directory and include in packaging -->
+    <ItemGroup Condition="'$(OpenXRSkipLoaderCopy)'!='true'">
+        <None Include="$(OpenXRLoaderBinaryRoot)\bin\openxr_loader.dll">
+            <Link>%(Filename)%(Extension)</Link>
+            <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+            <DeploymentContent>true</DeploymentContent>
+        </None>
+    </ItemGroup>
+
+    <Target Name="EnsurePropsImported" BeforeTargets="PrepareForBuild">
+        <Error Condition="'$(OpenXRLoaderPackageRoot)'==''" Text="OpenXRLoaderPackageRoot property missing. Project is malformed. Try removing and re-adding the NuGet reference." />
+    </Target>
+
+</Project>