update battle water

bump version

.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"

CHANGELOG.md

@@ -1,5 +1,228 @@
 # Changelog
 
+## 1.4.0
+
+### Added
+
+- **WATER, a new row on hotkey 9: water reflects the world, the sky, the sun
+  and the moon.** Every lake, sea and pond in Kanto was a flat animated
+  texture lying in a hole in the ground. It is now a surface, and it is
+  reflective.
+
+  What it reflects, in the order the shader resolves them:
+
+  - **The sky.** The reflected direction goes through the very matrix the
+    frame is drawn with, as a point at infinity, and the canvas row that
+    lands on is looked up on Sky's own band ramp -- the identical texture,
+    the identical checkerboard dither, the identical display-mode transform.
+    So the sky in the lake is the sky over it, and the two meet at the
+    waterline with no seam at any pitch, field of view, window shape or zoom.
+    Blue at noon, gold at dusk, navy under the moon; GRAY gets a grey lake
+    and CLASSIC a green one, for nothing.
+
+  - **The sun and the moon**, hung by ANGLE rather than by screen position,
+    because a reflected body is usually off the top of the frame entirely
+    and a projected point stops meaning anything out there. The angular
+    radius is the painted disc's own radius run back through the camera's
+    field of view, so the two are the same size -- craters, dithered rim,
+    the sunset's loom and all, off one shared list. This is also the
+    specular: a low sun lays a broken gold path across the water on its own,
+    out of the reflection rather than out of a highlight term nailed on
+    beside it.
+
+  - **The world, in screen space.** The reflected ray is walked forward in
+    world space, each step projected through the same matrix, looking for
+    where it passes behind what the depth buffer holds -- then binary-refined
+    onto the contact and read out of a copy of the frame as it stood before
+    the water went down. Shore trees, buildings, ledges and cliffs land in
+    the water because they are on screen; where the ray leaves the frame or
+    finds nothing, the sky above answers instead, which is what makes the far
+    half of a lake sky and the near half scenery with no seam between them.
+
+  Fresnel decides how much of it shows: almost nothing looked straight down
+  at, almost everything looked along -- so the 15-degree rung is a pond and
+  the 75-degree rung is a mirror, off the same surface.
+
+  Every rung gets one, though, which took a lean. A reflection off flat water
+  points as far above the horizon as the eye is above the water: 15 degrees
+  at the top rung -- grazing the sky's pale end, sweeping the sun's own path,
+  travelling far enough across the screen for the march to find the shoreline
+  -- and 75 degrees, straight up, at the steepest. Up there the bands are at
+  their darkest, the sun and moon sit at about 6 degrees of squashed
+  elevation and are nowhere near it, and the screen-space ray leaves the top
+  of the frame in two steps. All three are correct, and together they are a
+  lake with nothing in it.
+
+  So the reflection now LEANS toward the elevation the top rung reflects at,
+  by however far the camera is from having a horizon in frame -- **zero** at
+  the rung where the horizon IS in frame, so the one place the join can be
+  seen, the waterline, is still the exact reflection it was. Toward an
+  elevation rather than by a weight, because the ray it starts from differs
+  at every rung and a fixed fraction lands them all somewhere different: the
+  middle rungs came out further from the sun than the steepest one. And it
+  leans the LEVEL reflection with each column's own deflection added back on
+  top -- leaning the perturbed ray sets its elevation outright, which at full
+  lean gave every column on the lake the same one, flattened the sky to a
+  single band and removed the moon entirely.
+
+  Three rungs rather than a toggle. FULL is the whole thing; SKY drops the
+  ray march and keeps the sky, sun and moon, which is most of the look for a
+  handful of instructions; OFF is the flat water this mode always drew. The
+  FULL preset sets it to FULL.
+
+- **The water surface is a field of pixel-tall columns, and they are real.**
+  Not a normal map: a heightfield of one-world-pixel bars -- the same unit
+  every other voxel in this mode is built from, and exactly one texel of the
+  water tile -- each standing a WHOLE number of pixels high and rising and
+  falling on its own.
+
+  Three travelling wave trains, and one of them dominates: a wave has a
+  DIRECTION, and its crest is a line running across it for as far as the
+  water goes. Three trains of equal weight cancel and reinforce in patches
+  instead, and the surface comes out as round islands of raised pixels with
+  no travel to them -- blobs rather than waves. The dominant train's
+  wavelength is about forty world pixels, five tiles, so a crest is a long
+  run of columns at one height with a step down either side.
+
+  Drawn with no extra geometry at all: the mesh is still one flat quad per
+  tile, and the columns are found by walking the view ray down through the
+  slab in the pixel shader. That is what makes them read as solid -- a tall
+  bar hides the shorter ones behind it, you see the SIDE of the ones facing
+  you (wearing the mesh's own direction shading, so a crest is lit like every
+  other voxel in the world), and the whole field parallaxes against the plane
+  as the camera moves. The water's art is read at the column the ray landed
+  on rather than at the flat quad underneath, so the pixels travel with the
+  bars they are made of.
+
+  The columns are what you SEE; the normal they reflect with is read off the
+  smooth surface they are a quantisation of. That distinction is the whole
+  difference between a moon on the water and confetti: whole-pixel heights
+  have whole-pixel differences, so a normal built from them can only point in
+  about five directions, and a sun or moon barely two degrees across falls
+  between them. Still one normal per column, so the surface stays
+  pixel-quantised in space while the value it reflects with is continuous.
+
+  Crests stand up to five world pixels, well past the 2px recess water sits
+  in -- deliberately, because the columns are relief drawn inside the water
+  quad's own footprint, so a bar that reaches above the bank is clipped at
+  the water's edge rather than spilling over it. What it buys is a surface
+  with real swell in it instead of a two-rung terrace.
+
+  And it moves in STEPS, at **15 a second** -- the cadence hand-drawn pixel
+  art is animated at. A surface built out of whole pixels that crawls
+  smoothly between them gives away that the quantisation is only skin deep.
+  Each step advances the dominant wave by exactly one world pixel, derived
+  from that train's own wavelength rather than tuned beside it, so nothing
+  ever lands half-way between two pixels and changing a wavelength moves the
+  speed with it.
+
+
+### Changed
+
+- **The water surface is its own mesh, and its own pass.** A mirror cannot be
+  drawn until what it reflects exists, so water is lifted out of the terrain
+  mesh at build time and drawn between the world and the characters. The
+  shoreline faces around it are untouched -- they belong to the GROUND that
+  exposes them -- and the sun still sees the surface, so a tree at the water's
+  edge still throws its shadow onto the lake.
+
+- **The scene's depth buffer is a readable canvas.** It was an internal buffer
+  that could be written and tested and never sampled; it is now the same
+  buffer with a texture handle on it, at the same cost. Drivers that will not
+  make one fall straight back to the old buffer and lose the reflections and
+  nothing else.
+
+- **The cast is reflected too -- by being drawn twice.** Gen 1 draws people
+  over the world and water is world, so a surfing player has to composite
+  OVER the water they are sitting on, which puts them after it; and a
+  reflection can only hold what came before it. So the walkers, the NPCs and
+  the authored figures are painted into the reflection COPY alone, where they
+  are in the picture the water reflects and not yet in the picture the water
+  is drawn into. Both draws go through one function, so they cannot come out
+  different. The staged battle does the same with its two Pokemon.
+
+  The ray march finds them the honest way round: a sprite is not in the depth
+  buffer at that point, so a ray aimed at one passes through to the terrain
+  standing behind it and reads the copy there -- where the sprite is already
+  painted. The reflection lands a hair off the sprite's own depth and exactly
+  on its colour, which at a lake's worth of wave is the same picture.
+
+### Changed
+
+- **The waves arrive in sets now, and a little slower.** Three fixed trains
+  are an exactly periodic field -- every forty-odd pixels of sea wore the
+  same crest at the same height, which reads as wallpaper the moment a lake
+  is bigger than the repeat. Two long-wavelength fields now ride the
+  dominant train, four to five carrier wavelengths apiece so neither reads
+  as a wave itself: a SWELL that breathes its amplitude, so a few tall
+  crests march through and hand over to a lull that is itself moving, and a
+  BEND that bows its phase, so a crest line curves across the surface
+  instead of ruling itself over all of it. The two lesser trains stay
+  plain: they are texture rather than structure, and a third modulator is
+  the soup the train weights exist to avoid. The step beat comes down from
+  15 to 12 a second -- the crests were hurrying, and a big wave is slower
+  than a walk cycle -- still a clean divisor of the engine's 60, and still
+  exactly one world pixel of dominant-crest travel per step.
+
+- **Staged battles draw their water plain, whatever the WATER row says.**
+  The reflective pass is tuned for the overworld's ladder of cameras; a
+  battle's camera is PLACED -- low, tilted, framed like a picture -- and
+  under it the pass read wrong: Fresnel opened all the way up, the leaned
+  sky landed on bands the framing never shows, and a lake-sized arena came
+  out as murk wearing the tile art. The battle is a stage set, and stage
+  water is painted: the flat animated tiles the mode always drew, with the
+  mons compositing over them like everything else on the set.
+
+### Fixed
+
+- **On Android the water stayed flat, as if the row were off -- and once it
+  did draw, it came up in blocks with the haze showing through the holes.**
+  Three separate faults, every one of them invisible on desktop GL, run down
+  on a Galaxy Z Fold 7 with the driver's own compiler errors in logcat:
+
+  **The shader would not build.** Fragment floats default to **mediump** on
+  GLSL ES while the vertex stage's default is highp, and the water shader is
+  the mod's first to declare the same uniform -- the frame's `vp` matrix --
+  in BOTH stages, one on each default; GLSL ES refuses to link that, and the
+  pass fell back, quietly and by design, to the flat water the mode always
+  drew. The pixel stage now lifts its float default to highp (guarded, so a
+  GPU without fragment highp still compiles and falls back flat), which
+  settles the link and is also simply needed: the march works in world
+  coordinates that run to a few thousand, where fp16 has no fraction left.
+  The world-position varying is qualified highp for the same reason the
+  wireframe's always was, and the depth sampler too -- samplers default to
+  **lowp** whatever the floats are set to, and eight bits of depth is a
+  march with nothing to land on. One wrinkle inside the fix: LOVE's header
+  forward-declares `effect()` under ITS default, and Samsung's Xclipse
+  compiler treats a definition whose parameter precisions have drifted from
+  the prototype's as an illegal overload -- so effect()'s own float
+  parameters stay pinned to mediump, matching the declaration, and the
+  maths above them runs highp regardless.
+
+  **The depth test read the wrong texels.** The shader's own depth test
+  normalised LOVE's pixel coordinate by the `screen` uniform, which counts
+  canvas UNITS -- and on a highdpi phone (Android's density here is 2.625)
+  a canvas holds that many PIXELS per unit, so the lookup ran to 2.6,
+  clamped, and read edge texels across two thirds of the frame. Water
+  discarded itself in blocks wherever the mis-read depth landed in front,
+  and the haze backdrop showed through the holes. The coordinate is now
+  normalised by `love_ScreenSize.xy` -- the bound canvas's own pixel size,
+  measured in the same units on every display.
+
+  **And the readable depth canvas** -- the one hardware requirement the
+  rest of the mode does not already have -- now tries four formats before
+  giving up: depth24, depth24 riding a stencil (a pairing some mobile
+  drivers will texture when they refuse the bare format), depth32f, and
+  depth16 as the floor every GLES3 device can read. Refused all four, the
+  reflections are lost and nothing else, exactly as before.
+
+### Known
+
+- Screen-space reflections can only reflect what is in the frame. A tree just
+  off the top edge is not in the water below it, and a reflection whose ray
+  runs off the side of the screen fades into the sky rather than ending on a
+  hard line.
+
 ## 1.3.1
 
 ### Fixed

README.md

@@ -9,6 +9,22 @@ 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.
 
+Water is a surface rather than a texture lying in a hole. It is a field of
+one-pixel-wide voxel columns, each standing a whole number of pixels tall and
+rising and falling as waves — found by walking the view ray through them in
+the shader, so a crest hides what is behind it and shows you its lit side,
+with no extra geometry anywhere.
+
+And it reflects. The sky it stands under, in the same bands, the same dither
+and off the same clock, so the lake and the sky above it meet at the
+waterline with no seam. The sun or moon hanging in it, at the size the
+painted disc is drawn, craters and all. Whoever is standing beside it —
+walkers, NPCs, the two Pokémon in a staged battle. And on **FULL**, a
+screen-space ray march adds the rest of what is on screen: the shoreline, the
+trees behind it, the buildings across the bay. How much of it shows is
+Fresnel, so the top rung is a mirror and a looking-straight-down rung is a
+pond, off the same water.
+
 And battles fought on that world rather than on a white field. When
 something picks a fight the map's NPCs are culled, the engine's own wipe
 plays over the empty map, and the battle draws over the nearest patch of
@@ -34,6 +50,7 @@ menu.
 | `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 |
 | `8`, or the **3D-BTL** options row | ON / OFF — fight on the map instead of on a white field |
+| `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 **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 |
 

lib/BattleScene.lua

@@ -141,9 +141,10 @@ local function prefetchArena(state, host)
   for _, nb in ipairs(state.neighbors or {}) do live[nb.map.id] = true end
   ChunkMesher.setLive(live)
   TerrainAtlas.setLive(live)
-  local terrain = ChunkMesher.request(host, false, nil, true)
-                  or ChunkMesher.peek(host, true)
-  return terrain, {}
+  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
@@ -227,7 +228,8 @@ local function shadowSignature(state, arena, terrain, nbMesh, token)
 end
 
 local function castShadows(state, arena, terrain, nbMesh, cx, cy, vw, vh,
-                           atlasFor, cards, token, host, neighbors)
+                           atlasFor, cards, token, host, neighbors,
+                           water, nbWater)
   if not ShadowMap.available() then return end
   local sig = shadowSignature(state, arena, terrain, nbMesh, token)
   if not ShadowMap.stale(sig) then return end
@@ -237,6 +239,14 @@ local function castShadows(state, arena, terrain, nbMesh, cx, cy, vw, vh,
   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),
@@ -249,10 +259,15 @@ local function castShadows(state, arena, terrain, nbMesh, cx, cy, vw, vh,
   -- 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)
 
   ShadowMap.finish(sig)
 end
@@ -299,9 +314,36 @@ end
 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)
@@ -326,7 +368,7 @@ function BattleScene.render(state, arena, textures, token)
 
   -- 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 = prefetchArena(state, host)
+  local terrain, nbMesh, water, nbWater = prefetchArena(state, host)
   if not terrain then return nil end
 
   local lx, ly, s, pw, ph = BattleScene.letterbox()
@@ -356,7 +398,7 @@ function BattleScene.render(state, arena, textures, token)
   local cards = monCards(arena, groundY, textures)
   Voxel3D.camera = nil
   castShadows(state, arena, terrain, nbMesh, cx, cy, vw, vh, atlasFor,
-              cards, token, host, neighbors)
+              cards, token, host, neighbors, water, nbWater)
 
   -- 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
@@ -393,6 +435,22 @@ function BattleScene.render(state, arena, textures, token)
       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
     -- 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

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),
@@ -558,8 +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
@@ -764,18 +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)
@@ -858,8 +892,17 @@ 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
@@ -924,13 +967,17 @@ local function runJob(job)
     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
@@ -1032,12 +1079,14 @@ 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
@@ -1058,6 +1107,21 @@ 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

lib/ShadowMap.lua

@@ -130,17 +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
@@ -440,6 +446,9 @@ 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
@@ -448,6 +457,25 @@ 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

@@ -263,6 +263,27 @@ 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()
@@ -323,20 +344,51 @@ end
 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
-local MOON_CRATERS = { { -0.4, -0.2 }, { 0.2, 0.45 }, { 0.5, -0.4 },
-                       { -0.15, 0.7 }, { 0.05, 0.05 } }
+-- 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
 
 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 src = body.moon and DayNight.MOON_COLORS or DayNight.SUN_COLORS
-  local shades = PaletteFX.effectiveColors(src) or src
-  local twilight = (body.glowAmt or 0) > 0.25 and not body.moon
-  local r = math.max(Sky.DISC_MIN,
-                     math.floor(h * Sky.DISC_FRAC / cell + 0.5))
-  -- the low sun looms: the classic sunset exaggeration, and it reads
-  if twilight then r = r + math.max(1, math.floor(r * 0.4)) 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
@@ -429,7 +481,7 @@ function Sky.paint(w, h, sky, horizonY, cell, body)
       if glowAmt > 0 then
         local gc = body.glowColor or { 248, 224, 168 }
         sh:send("glowPos", { body.x, body.y })
-        sh:send("glowInvR", 1 / math.max(1, w * 0.55))
+        sh:send("glowInvR", 1 / math.max(1, w * Sky.GLOW_REACH))
         sh:send("glowColor", { gc[1] / 255, gc[2] / 255, gc[3] / 255 })
       end
     end)

lib/Voxel3D.lua

@@ -283,8 +283,66 @@ local activeShader = nil      -- the variant this pass bound
 -- resize, so the pair is stable for a session.
 local slots = {}
 local canvas, canvasW, canvasH = nil, 0, 0   -- the slot this pass bound
+local held = nil                             -- and the whole record for it
 local active = false
 
+-- A READABLE depth canvas, so a later pass in the same frame can ask the
+-- buffer questions rather than only write to it -- which is the whole of
+-- what makes screen-space reflections possible (see Water).
+--
+-- `depth = true` in the target list, which is what this used to bind,
+-- allocates an internal depth buffer that is written and tested and can
+-- never be sampled. An explicit canvas is the same buffer with a texture
+-- handle on it, and costs the same memory.
+--
+-- nil where the driver will not make one -- every depth format is optional
+-- in GLES and a canvas is the only honest test of any of them, so this asks
+-- for several in order of preference: 24 bits, the same 24 riding a stencil
+-- (a pairing some mobile drivers will texture when the bare format they
+-- refuse), 32-bit float, and 16 as the floor every GLES3 device can read.
+-- Refused all four, beginScene falls straight back to the internal buffer,
+-- which is exactly the old behaviour minus the reflections.
+local DEPTH_FORMATS = { "depth24", "depth24stencil8", "depth32f", "depth16" }
+
+local function newDepth(w, h)
+  if not (love.graphics and love.graphics.newCanvas) then return nil end
+  local c = nil
+  for _, format in ipairs(DEPTH_FORMATS) do
+    local ok, made = pcall(love.graphics.newCanvas, w, h,
+                           { format = format, readable = true })
+    if ok and made then c = made break end
+  end
+  if not c then return nil end
+  -- nearest: a depth is a distance, and a blend of two of them is a
+  -- distance to nothing. The march wants the texel it landed on.
+  pcall(c.setFilter, c, "nearest", "nearest")
+  pcall(c.setWrap, c, "clamp", "clamp")
+  -- and no compare mode: with one set, Texel returns a 0/1 shadow verdict
+  -- instead of the depth, which is not what any reader here wants
+  pcall(c.setDepthSampleMode, c)
+  return c
+end
+
+-- The bound target for the slot this pass holds: the colour canvas plus
+-- either the readable depth canvas or the internal buffer.
+local function depthTarget()
+  if held and held.depth then
+    return { held.canvas, depthstencil = held.depth }
+  end
+  return { canvas, depth = true }
+end
+
+-- Every GPU object one slot owns. The mirror is the copy of the frame the
+-- water pass reads (see beginWater); it is only ever made if something asks
+-- for one, so a session that never sees a lake never pays for it.
+local function releaseSlot(slotHeld)
+  for _, key in ipairs({ "canvas", "depth", "mirror" }) do
+    local obj = slotHeld[key]
+    if obj and obj.release then pcall(obj.release, obj) end
+    slotHeld[key] = nil
+  end
+end
+
 local IDENTITY = Mat4.identity()
 
 -- Whether the driver admits to supporting derivatives. Only a hint --
@@ -379,6 +437,41 @@ end
 -- way either way.
 Voxel3D.camera = nil
 
+-- ------- which way, and how steeply, this camera looks
+--
+-- Two facts about the view direction, set alongside the eye and the focus
+-- because they ARE the eye and the focus, and read by anything that has to
+-- reason about the camera's ATTITUDE rather than about a point in front of
+-- it:
+--
+--   lookFlat   the view direction flattened onto the ground plane and
+--              normalized -- "the way the horizon lies from here", which is
+--              what a reflection leans toward at the steeper rungs (Water).
+--   descent    how far below horizontal the view runs, as a sine: 0 looking
+--              level, 1 looking straight down. It is the number that says
+--              whether there is a horizon in frame at all, and it answers
+--              the same way for the orbit and for a placed battle camera --
+--              which is why this is derived from the two vectors rather than
+--              read off Voxel.angle, a rung the battle camera does not have.
+--
+-- A camera looking exactly straight down has no horizontal direction at all,
+-- and lookFlat then keeps whatever it last held rather than becoming a zero
+-- vector nothing downstream could normalize.
+Voxel3D.lookFlat = { 0, 0, -1 }
+Voxel3D.descent = 0
+
+local function setLook(eye, focus)
+  local dx = focus[1] - eye[1]
+  local dy = focus[2] - eye[2]
+  local dz = focus[3] - eye[3]
+  local len = math.sqrt(dx * dx + dy * dy + dz * dz)
+  if len < 1e-6 then return end
+  Voxel3D.descent = math.max(0, math.min(1, -dy / len))
+  local flat = math.sqrt(dx * dx + dz * dz)
+  if flat < 1e-6 then return end
+  Voxel3D.lookFlat = { dx / flat, 0, dz / flat }
+end
+
 -- View and projection for a `vw` x `vh` world-pixel view centred on
 -- (cx, cy) in world pixels. Returns the combined matrix.
 function Voxel3D.viewProjection(cx, cy, vw, vh)
@@ -389,10 +482,15 @@ function Voxel3D.viewProjection(cx, cy, vw, vh)
     -- kept beside the eye for horizonY: where the sky's pale end goes is a
     -- question about which way this camera looks, and only these two answer it
     Voxel3D.focus = focus
+    setLook(eye, focus)
     local dx = eye[1] - focus[1]
     local dy = eye[2] - focus[2]
     local dz = eye[3] - focus[3]
     local dist = math.max(1, math.sqrt(dx * dx + dy * dy + dz * dz))
+    -- kept for the passes that measure an ANGLE against this camera rather
+    -- than a position: the water's reflected sun is sized in radians, and
+    -- radians per canvas pixel is exactly this over the frame height
+    Voxel3D.fovY = cam.fov
     local proj = Mat4.perspective(cam.fov, vw / vh,
                                   math.max(1, dist * 0.05), dist * 4 + 4096)
     -- the same clip-space Y flip the orbit needs, for the same reason: we
@@ -409,12 +507,14 @@ function Voxel3D.viewProjection(cx, cy, vw, vh)
   -- the FOV that makes a straight-down camera at `dist` frame exactly `vh`
   -- world pixels, which is the framing the flat view already has
   local fov = 2 * math.atan(1 / (2 * focal))
+  Voxel3D.fovY = fov
 
   local focus = { cx, 0, cy }
   local eye = { cx, dist * math.cos(a), cy + dist * math.sin(a) }
   -- exposed for camera-facing billboards (VoxelScene yaws sprites at it)
   Voxel3D.eye = eye
   Voxel3D.focus = focus
+  setLook(eye, focus)
   -- perpendicular to the view direction in the YZ plane: north is screen-up
   -- when looking straight down, +Y is screen-up when looking level. Never
   -- parallel to the view direction, so there is no degenerate a = 0 case.
@@ -538,22 +638,29 @@ function Voxel3D.beginScene(w, h, cx, cy, vw, vh, sky, slot)
   end
   if not sh then return false end
   local name = slot or "world"
-  local held = slots[name]
-  if not (held and held.w == w and held.h == h) then
+  local slotHeld = slots[name]
+  if not (slotHeld and slotHeld.w == w and slotHeld.h == h) then
     local ok, c = pcall(love.graphics.newCanvas, w, h)
     if not ok then return false end
     c:setFilter("nearest", "nearest")
-    if held and held.canvas and held.canvas.release then
-      pcall(held.canvas.release, held.canvas)
-    end
-    held = { canvas = c, w = w, h = h }
-    slots[name] = held
+    if slotHeld then releaseSlot(slotHeld) end
+    -- the depth canvas is sized with its colour, so a window resize
+    -- reallocates the pair together and they can never disagree
+    slotHeld = { canvas = c, w = w, h = h, depth = newDepth(w, h) }
+    slots[name] = slotHeld
   end
+  held = slotHeld
   canvas, canvasW, canvasH = held.canvas, w, h
   -- a depth buffer is what makes occlusion real: walk behind a building and
   -- the building wins, with no y-sorting anywhere
-  local ok = pcall(love.graphics.setCanvas,
-                   { canvas, depth = true })
+  local ok = pcall(love.graphics.setCanvas, depthTarget())
+  if not ok and held.depth then
+    -- the readable canvas would not bind; fall back to the internal buffer
+    -- for the rest of this session rather than losing the whole 3D pass
+    pcall(held.depth.release, held.depth)
+    held.depth = nil
+    ok = pcall(love.graphics.setCanvas, depthTarget())
+  end
   if not ok then
     pcall(love.graphics.setCanvas)
     return false
@@ -561,6 +668,14 @@ function Voxel3D.beginScene(w, h, cx, cy, vw, vh, sky, slot)
   -- Ahead of the clear, because the sky's bands are placed off the ground
   -- plane's vanishing line and that is a property of this matrix.
   Voxel3D.vp = Voxel3D.viewProjection(cx, cy, vw, vh)
+  -- This frame's pixels per WORLD pixel: the size a diorama pixel is on
+  -- screen. The sky's dither grid is cut to it, and so is the water's --
+  -- one number, so the two break up on the same checkerboard.
+  Voxel3D.cell = w / math.max(1, vw or w)
+  -- and where the sky's bottom edge lands, which is what the reflection
+  -- reads its bands against (see Water). nil when nothing painted bands.
+  Voxel3D.skyEdge = (sky and sky.bands)
+                    and Sky.region(h, Voxel3D.horizonY(h)) or nil
   if sky then
     love.graphics.clear(sky[1], sky[2], sky[3], sky[4] or 1, true, true)
     -- The sky goes down here, in the one window in this function where a
@@ -573,7 +688,7 @@ function Voxel3D.beginScene(w, h, cx, cy, vw, vh, sky, slot)
     -- are the same size as the world's own and follow every resize and zoom.
     -- The banded sky also hangs the hour's sun or moon (skyBody projects it
     -- through this very camera); a flat sky has no bands and hangs nothing.
-    Sky.paint(w, h, sky, Voxel3D.horizonY(h), w / math.max(1, vw or w),
+    Sky.paint(w, h, sky, Voxel3D.horizonY(h), Voxel3D.cell,
               sky.bands and Voxel3D.skyBody(w, h) or nil)
   else
     love.graphics.clear(0, 0, 0, 0, true, true)
@@ -720,6 +835,108 @@ function Voxel3D.flatten(color, amount)
   end
 end
 
+-- ------------------------------------------------------- the water pass --
+--
+-- A reflective surface has to READ the frame it is being drawn into: the
+-- colour of what is standing around it and the depth that says where. Both
+-- are attachments of the target this pass is bound to, and a texture cannot
+-- be sampled while it is one -- so for the length of the water draw the
+-- frame is taken apart:
+--
+--   the COLOUR is copied to a mirror canvas, which is a texture like any
+--   other and is what the reflection samples.
+--
+--   the DEPTH is simply detached. The water shader does the test itself
+--   against the texture (see Water), which is the same comparison the
+--   hardware would have made -- what it gives up is depth WRITES, and water
+--   is flat, never overlaps itself, and has nothing drawn under it later.
+--
+-- `paint`, when given, is called with the MIRROR bound and the scene shader
+-- set, to add things that must be REFLECTED without being composited yet.
+--
+-- The characters are the whole reason it exists. Gen 1 draws people over
+-- the world and water is world, so the cast has to composite AFTER the
+-- water -- but a reflection can only contain what was drawn BEFORE it, and
+-- a lake with everyone standing beside it and nobody in it reads as glass.
+-- Painting them into the mirror alone settles both: they are in the picture
+-- the water reflects and not yet in the picture the water is drawn into.
+--
+-- They go down depth-TESTED and depth-WRITE-FREE. Tested, so a figure behind
+-- a building is behind it in the reflection too; write-free because the very
+-- next thing to read that buffer is the water's own depth test, and a cast
+-- that had written to it would punch itself out of the water it is standing
+-- beside.
+--
+-- Returns the two textures, or nil when there is nothing to hand over: no
+-- readable depth canvas on this driver, or no pass open. A caller that gets
+-- nil draws its water like ordinary terrain, which is what this mode always
+-- did.
+--
+-- MUST be paired with endWater, which puts the frame back together.
+function Voxel3D.beginWater(paint)
+  if not (active and canvas and held and held.depth) then return nil end
+  if not held.mirror then
+    local ok, c = pcall(love.graphics.newCanvas, held.w, held.h)
+    if not (ok and c) then return nil end
+    pcall(c.setFilter, c, "nearest", "nearest")
+    pcall(c.setWrap, c, "clamp", "clamp")
+    held.mirror = c
+  end
+  love.graphics.setShader()
+  -- the frame's own depth rides along, so the paint below can test against
+  -- it; the copy underneath switches the test off rather than detaching it
+  local ok = pcall(love.graphics.setCanvas,
+                   { held.mirror, depthstencil = held.depth })
+  if not ok then
+    pcall(love.graphics.setCanvas, depthTarget())
+    return nil
+  end
+  love.graphics.setDepthMode("always", false)
+  -- COLOUR only. The last two arguments are what keep the depth buffer the
+  -- frame's rather than this canvas's: cleared here, the water's own depth
+  -- test a few lines later would find nothing in front of anything and every
+  -- lake would draw straight through the buildings standing in it.
+  love.graphics.clear(0, 0, 0, 0, false, false)
+  -- premultiplied over a cleared target is a straight copy: every channel
+  -- lands exactly as it stood, including the alpha, so the mirror is the
+  -- frame rather than the frame composited against something
+  love.graphics.setBlendMode("alpha", "premultiplied")
+  love.graphics.setColor(1, 1, 1, 1)
+  love.graphics.draw(canvas)
+  love.graphics.setBlendMode("alpha")
+  if paint and activeShader then
+    love.graphics.setDepthMode("lequal", false)
+    love.graphics.setShader(activeShader)
+    pcall(paint)
+    love.graphics.setShader()
+  end
+  love.graphics.setDepthMode()
+  -- and back to the scene canvas WITHOUT its depth: that texture is about
+  -- to be read
+  if not pcall(love.graphics.setCanvas, canvas) then
+    pcall(love.graphics.setCanvas, depthTarget())
+    return nil
+  end
+  return held.mirror, held.depth
+end
+
+-- Put the frame back: depth reattached, depth test and the scene shader as
+-- the pass had them. Safe to call after a beginWater that returned nil.
+function Voxel3D.endWater()
+  if not active then return end
+  pcall(love.graphics.setCanvas, depthTarget())
+  pcall(love.graphics.setDepthMode, "lequal", true)
+  love.graphics.setColor(1, 1, 1, 1)
+  if activeShader then love.graphics.setShader(activeShader) end
+end
+
+-- Whether a reflective water pass can run in this frame at all -- there is
+-- a depth texture to read. Callers use it to choose between the water
+-- shader and an ordinary terrain draw before they start moving canvases.
+function Voxel3D.depthReadable()
+  return (active and held and held.depth) and true or false
+end
+
 -- Whether what is drawn next carries the voxel wireframe. false for the
 -- length of a draw, true to put it back.
 --
@@ -931,18 +1148,25 @@ function Voxel3D.canvas()
   return canvas
 end
 
+-- The bound canvas's pixel size, for a pass that has to work in screen
+-- coordinates (the water's reflection marches in them).
+function Voxel3D.size()
+  return canvasW, canvasH
+end
+
 -- Drop the GPU objects (window resize, hot reload).
 function Voxel3D.invalidate()
-  for name, held in pairs(slots) do
-    if held.canvas and held.canvas.release then
-      pcall(held.canvas.release, held.canvas)
-    end
+  for name, slotHeld in pairs(slots) do
+    releaseSlot(slotHeld)
     slots[name] = nil
   end
   canvas, canvasW, canvasH = nil, 0, 0
+  held = nil
   ShadowMap.invalidate()
   -- the sky is part of this pass and holds a shader of its own
   Sky.invalidate()
+  -- and so does the water, for the same reason
+  V.require("Water").invalidate()
   -- and the glass masks are textures of this context too
   GlassMask.invalidate()
 end

lib/VoxelScene.lua

@@ -21,6 +21,8 @@ local TileShape = V.require("TileShape")
 local TerrainAtlas = V.require("TerrainAtlas")
 local Voxel = V.require("VoxelState")
 local Sky = V.require("Sky")
+local Water = V.require("Water")
+local VoxelGrid = V.require("VoxelGrid")
 local DayNight = V.require("DayNight")
 local PaletteFX = require("src.render.PaletteFX")
 local Map = require("src.world.Map")
@@ -404,17 +406,25 @@ function VoxelScene.prefetch(state)
   -- crossing demotes the map just left, and it must not vanish from
   -- behind the player while its body variant builds; its ring is
   -- already masked out under this map's body, so the stand-in is safe.
-  local terrain = ChunkMesher.request(state.map, false, masks, true)
+  -- The water surface rides along with whichever variant answers: it was
+  -- cut out of that build's own geometry (ChunkMesher.pair), so the two
+  -- always come from the same slot and a lake is never drawn twice or left
+  -- as a hole.
+  ChunkMesher.request(state.map, false, masks, true)
+  local terrain, water = ChunkMesher.pair(state.map, false)
   if not terrain then
-    terrain = ChunkMesher.peek(state.map, true)
+    terrain, water = ChunkMesher.pair(state.map, true)
   end
-  local nbMesh = {}
+  local nbMesh, nbWater = {}, {}
   for i, nb in ipairs(state.neighbors or {}) do
-    nbMesh[i] = ChunkMesher.request(nb.map, true)
-                or ChunkMesher.peek(nb.map, false)
+    ChunkMesher.request(nb.map, true)
+    nbMesh[i], nbWater[i] = ChunkMesher.pair(nb.map, true)
+    if not nbMesh[i] then
+      nbMesh[i], nbWater[i] = ChunkMesher.pair(nb.map, false)
+    end
   end
   Voxel.ready = terrain ~= nil
-  return terrain, nbMesh
+  return terrain, nbMesh, water, nbWater
 end
 
 -- Capture every entity's pose for this frame. pose() advances the hop /
@@ -490,6 +500,124 @@ end
 
 local glint = {}
 
+-- ------- the cast
+--
+-- Everybody standing on the map: the walkers, and the authored FIGURES the
+-- tileset draws into its own furniture (they ARE characters as far as the
+-- artwork is concerned, just ones drawn by the tileset instead of by a
+-- sprite sheet, so they get the same lean and the same camera-ward pull).
+--
+-- One function because it is drawn TWICE and the two must be identical: once
+-- into the frame, and once into the water's reflection copy (see drawWater --
+-- Gen 1 draws people over the world, and water is world, so the cast cannot
+-- be composited before the water it has to appear in).
+--
+-- Characters carry no wireframe out here, whatever the V-GRID row says. The
+-- seams are what makes the WORLD read as built out of voxels, and the people
+-- walking around in it are the one thing that should read as drawn instead --
+-- a grid over a 16x16 sprite lands a line every couple of display pixels and
+-- turns a face into a mesh. (The battle pass makes the opposite call for its
+-- own combatants, deliberately -- see BattleBillboard.)
+--
+-- Sprite sheets until the figure pass: their texture coordinates mean
+-- nothing to the tileset-shaped glass mask, so the glass is off or the
+-- panes' atlas positions stripe the cast with lamplight at night.
+local function drawCast(state, posed, atlasFor)
+  Voxel3D.glass(false)
+  Voxel3D.seams(false)
+  -- Characters, normally depth-tested: the camera-ward pull inside
+  -- drawEntity resolves the lean-over-the-wall-in-front case, and a
+  -- character genuinely behind a building is far deeper and loses the
+  -- test, so buildings and trees really occlude.
+  for _, p in ipairs(posed) do
+    drawEntity(p.sprite, p.px, p.py, p.facing, p.phase, p.flip, p.gh,
+               p.colors, p.lift)
+  end
+  -- back on for everything textured from the atlas again -- figures, grass
+  -- and flowers all sample it, where the mask's coordinates are honest
+  Voxel3D.glass(true)
+  -- Figures after the walkers, so a player standing in front of the couch
+  -- wins the overlap -- the order the flat game draws them in.
+  local figPull = billboardPull()
+  eachFigure(state.map, 0, 0, function(mesh, model, caster)
+    Voxel3D.draw(mesh, atlasFor(state.map), model, figPull,
+                 ShadowMap.snug(caster))
+  end)
+  for _, nb in ipairs(state.neighbors or {}) do
+    eachFigure(nb.map, nb.ox, nb.oy, function(mesh, model, caster)
+      Voxel3D.draw(mesh, atlasFor(nb.map), model, figPull,
+                   ShadowMap.snug(caster))
+    end)
+  end
+  -- and the seams are back on for the terrain art that follows: grass and
+  -- flowers are the world's own drawing, not people
+  Voxel3D.seams(true)
+end
+
+-- ------- the water pass
+--
+-- Between the terrain and everything that stands on it, because water is a
+-- MIRROR and a mirror can only reflect what is already down: the ground, the
+-- shoreline, the trees and buildings behind it, and the sky the frame opened
+-- with.
+--
+-- THE CAST IS THE AWKWARD ONE, and it is settled by drawing it twice. Gen 1
+-- draws people over the world and water is world, so a surfing player has to
+-- composite OVER the water they are sitting on -- which puts them after it,
+-- and a reflection can only hold what came before it. So `cast` is painted
+-- into the reflection copy alone (Voxel3D.beginWater), where it is in the
+-- picture the water reflects and not yet in the picture the water is drawn
+-- into. Both draws go through drawCast, so they cannot come out different.
+--
+-- The ray march finds them the honest way round: a sprite is not in the
+-- DEPTH buffer at that point, so a ray aimed at one passes through to the
+-- terrain standing behind it and reads the copy there -- where the sprite is
+-- already painted. The reflection lands a hair off the sprite's own depth
+-- and exactly on its colour, which at a lake's worth of ripple is the same
+-- picture.
+--
+-- `draws` is a list of { mesh, texture, model }. Nothing is a special case:
+-- with the row OFF, no depth texture to read, or a shader that would not
+-- build, the same meshes go through the ordinary scene shader and come out
+-- as the flat animated water this mode always drew.
+-- The overworld's alone: the staged battle draws its water plain, always --
+-- its placed camera reads this pass wrong, and a stage set wants painted
+-- water anyway (see BattleScene, where the choice is argued).
+function VoxelScene.drawWater(draws, cast)
+  local plain = true
+  if Water.enabled() and Voxel3D.depthReadable() then
+    local mirror, depth = Voxel3D.beginWater(cast)
+    local w, h = Voxel3D.size()
+    local ok = mirror and depth and Water.begin({
+      reflect = mirror, depth = depth,
+      vp = Voxel3D.vp, eye = Voxel3D.eye, curve = { Voxel3D.curveX or 0,
+                                                    Voxel3D.curveZ or 0,
+                                                    Voxel3D.curveK or 0 },
+      screen = { w, h }, cell = Voxel3D.cell, fov = Voxel3D.fovY,
+      skyEdge = Voxel3D.skyEdge, grid = VoxelGrid.enabled(),
+      lookFlat = Voxel3D.lookFlat, descent = Voxel3D.descent,
+    })
+    if ok then
+      for _, d in ipairs(draws) do
+        Water.draw(d[1], d[2], d[3])
+      end
+      Water.finish()
+      plain = false
+    end
+    -- Unconditionally, and OUTSIDE the success branch: beginWater unbinds
+    -- the shader and the depth mode BEFORE it can discover it cannot go on,
+    -- so a frame that bails halfway through has to be put back together
+    -- exactly like one that succeeded -- otherwise the plain draw below (and
+    -- every pass after it) runs with no shader and no depth test.
+    Voxel3D.endWater()
+  end
+  if plain then
+    for _, d in ipairs(draws) do
+      Voxel3D.draw(d[1], d[2], d[3])
+    end
+  end
+end
+
 -- A stamp of everything the sun pass depends on. Nothing in it moving
 -- means the shadow map it produced last frame is still exactly right, and
 -- redrawing the whole world from the sun would buy nothing -- which is
@@ -540,7 +668,7 @@ end
 -- left out on purpose: thousands of tufts would cast a speckle no bigger
 -- than the pixels it lands on, at the cost of the mesh being drawn twice.
 local function castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh,
-                           atlasFor)
+                           atlasFor, water, nbWater)
   if not ShadowMap.available() then return end
   local sig = shadowSignature(terrain, nbMesh, posed, cx, cy, vw, vh)
   if not ShadowMap.stale(sig) then return end
@@ -551,6 +679,15 @@ local function castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh,
     ShadowMap.draw(nbMesh[i], atlasFor(nb.map),
                    Mat4.translate(nb.ox, 0, nb.oy))
   end
+  -- The water surface, which the terrain mesh no longer carries (it is its
+  -- own reflective pass now -- see Water). The sun still has to see it, or
+  -- the map the light records has a hole at every lake and the frustum's
+  -- far plane answers for the surface a shoreline tree's shadow falls on.
+  ShadowMap.draw(water, atlasFor(state.map), nil)
+  for i, nb in ipairs(state.neighbors or {}) do
+    ShadowMap.draw(nbWater and nbWater[i], atlasFor(nb.map),
+                   Mat4.translate(nb.ox, 0, nb.oy))
+  end
   -- flower billboards live outside the terrain mesh (they draw after the
   -- characters, pulled -- see render), but the sun still sees them: a
   -- handful of cutouts per meadow, unlike the grass left out below.
@@ -563,6 +700,11 @@ local function castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh,
     ShadowMap.draw(ChunkMesher.flowers(nb.map), atlasFor(nb.map),
                    ShadowMap.snug(Mat4.translate(nb.ox, 0, nb.oy)))
   end
+  -- From here down it is the CAST, marked as such in the map (see
+  -- ShadowMap.sprites) so water can decline them: everything the world casts
+  -- still shades a lake, a silhouette of somebody standing beside it does
+  -- not. Ground, roofs and the characters themselves take them as before.
+  ShadowMap.sprites(true)
   -- authored figures cast too, for the same reason the flowers do: a
   -- handful of cards per map, and a person with no shadow reads as pasted on
   eachFigure(state.map, 0, 0, function(mesh, _, caster)
@@ -584,6 +726,7 @@ local function castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh,
                                             mirror)))
     end
   end
+  ShadowMap.sprites(false)
 
   ShadowMap.finish(sig)
 end
@@ -593,7 +736,7 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor)
   -- return nil: the engine keeps the 2D path for the frame and
   -- Voxel.ready holds the camera tween at flat, so the switch waits
   -- invisibly instead of freezing or tilting an empty stage.
-  local terrain, nbMesh = VoxelScene.prefetch(state)
+  local terrain, nbMesh, water, nbWater = VoxelScene.prefetch(state)
   if not terrain then return nil end
 
   local cam = state.camera
@@ -630,7 +773,8 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor)
   end
 
   local posed, me = posesOf(state, spriteColors)
-  castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh, atlasFor)
+  castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh, atlasFor,
+              water, nbWater)
 
   if not Voxel3D.beginScene(w, h, cx, cy, vw, vh, skyFor(state.map)) then
     return nil
@@ -658,6 +802,34 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor)
     Voxel3D.endShadows()
   end
 
+  -- and the water over the top of it, reflecting everything just drawn plus
+  -- the sky the frame opened with (see drawWater).
+  --
+  -- After the fallback decals deliberately: those are the stand-in drop
+  -- shadows for a frame with no shadow map, they write no depth, and a
+  -- lake would otherwise wear one as a black smear. Water covers them,
+  -- which is the same answer the shadow map's own pass gives (see
+  -- ShadowMap.sprites) -- people do not shadow water either way.
+  local waterDraws = {}
+  if water then
+    waterDraws[#waterDraws + 1] = { water, atlasFor(state.map), nil }
+  end
+  for i, nb in ipairs(state.neighbors or {}) do
+    if nbWater and nbWater[i] then
+      waterDraws[#waterDraws + 1] = { nbWater[i], atlasFor(nb.map),
+                                      Mat4.translate(nb.ox, 0, nb.oy) }
+    end
+  end
+  -- the cast goes into the reflection copy only -- see drawWater for why it
+  -- cannot be composited yet and why it is drawn through the same function
+  -- the real pass below uses
+  if #waterDraws > 0 then
+    VoxelScene.drawWater(waterDraws, function()
+      drawCast(state, posed, atlasFor)
+    end)
+  end
+
+
   -- Sprite sheets from here to the figure pass: their texture coordinates
   -- mean nothing to the tileset-shaped glass mask, so the glass is off or
   -- the panes' atlas positions stripe the cast with lamplight at night
@@ -689,33 +861,7 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor)
   -- drawEntity resolves the lean-over-the-wall-in-front case, and a
   -- character genuinely behind a building is far deeper and loses the
   -- test, so buildings and trees really occlude.
-  Voxel3D.seams(false)
-  for _, p in ipairs(posed) do
-    drawEntity(p.sprite, p.px, p.py, p.facing, p.phase, p.flip, p.gh,
-               p.colors, p.lift)
-  end
-  -- back on for everything textured from the atlas again -- figures, grass
-  -- and flowers all sample it, where the mask's coordinates are honest
-  Voxel3D.glass(true)
-  -- Authored figures, alongside the characters and with the same lean and
-  -- the same camera-ward pull -- they ARE characters as far as the artwork
-  -- is concerned, just ones the tileset draws instead of a sprite sheet.
-  -- Drawn after the walkers so a player standing in front of the couch
-  -- wins the overlap, which is the order the flat game draws them in.
-  local figPull = billboardPull()
-  eachFigure(state.map, 0, 0, function(mesh, model, caster)
-    Voxel3D.draw(mesh, atlasFor(state.map), model, figPull,
-                 ShadowMap.snug(caster))
-  end)
-  for _, nb in ipairs(state.neighbors or {}) do
-    eachFigure(nb.map, nb.ox, nb.oy, function(mesh, model, caster)
-      Voxel3D.draw(mesh, atlasFor(nb.map), model, figPull,
-                   ShadowMap.snug(caster))
-    end)
-  end
-  -- and the seams are back on for the terrain art that follows: grass and
-  -- flowers are the world's own drawing, not people
-  Voxel3D.seams(true)
+  drawCast(state, posed, atlasFor)
   -- tall grass last, pulled camera-ward exactly as far as the characters
   -- were (same per-vertex shader bias, so grass never drifts either):
   -- relative depth between a walker and the tuft row south of their feet

main.lua

@@ -81,6 +81,7 @@ local OverworldBattle = V.require("OverworldBattle")
 local BattleExit = V.require("BattleExit")
 local DayNight = V.require("DayNight")
 local DayTint = V.require("DayTint")
+local Water = V.require("Water")
 
 -- Forward declaration: the voxel pipeline's update hook (registered below)
 -- calls this, and it is defined further down with the settings it drives.
@@ -282,6 +283,10 @@ applyFull = function(level)
   -- the horizon flat. The curve bends the world away from a walking player,
   -- which fights a fixed diorama framing
   WorldCurve.setting:setIndex(1, Game)
+  -- and the water reflecting everything it can: FULL is the diorama at its
+  -- most photographed, and a lake with the sky and the shoreline in it is
+  -- most of what makes the model read as being outdoors
+  Water.setting:setIndex(1, Game)
   -- and the view fitted to the window
   opts.zoom = 0
   Zoom.applyOptions(opts)
@@ -332,6 +337,11 @@ local SETTINGS = {
   { VoxelGrid.setting, "One-pixel wireframe along every voxel edge." },
   { WorldCurve.setting,
     "Bend the world down over the horizon, Animal Crossing style." },
+  { Water.setting,
+    "Reflections on water. FULL adds screen-space reflections of the "
+    .. "shoreline, the trees and the buildings behind it; SKY is the sky, "
+    .. "the sun and the moon alone, which is most of the look for a "
+    .. "fraction of the cost." },
   -- `full` marks a row FULL does not take away. FULL owns the diorama's own
   -- knobs; what a battle is drawn over, and how it is framed, are not that.
   { OverworldBattle.setting,
@@ -366,6 +376,7 @@ mod.options:define(schema)
 --   6  T-SHIFT  cycle the blur ladder        (was 9)
 --   7  V-CURVE  cycle the horizon bend       (new)
 --   8  3D-BTL   toggle overworld battles     (new)
+--   9  WATER    cycle the water reflections  (new; 9 was T-SHIFT's old key)
 --
 -- Only 6 arrives by the documented route. Game:keypressed answers the
 -- engine's own display keys FIRST and returns -- 2 COLORS, 3 TILT, 4 ZOOM,
@@ -398,6 +409,7 @@ local HOTKEYS = {
   ["5"] = VoxelGrid.setting,
   ["7"] = WorldCurve.setting,
   ["8"] = OverworldBattle.setting,
+  ["9"] = Water.setting,
 }
 
 do
@@ -447,19 +459,19 @@ do
           return
         end
       elseif Pipelines.canToggle("voxel", top, self.overworld) then
-        -- All three answer to the voxel pass's own free-roam gate --
+        -- All four answer to the voxel pass's own free-roam gate --
         -- borrowed from the registry rather than restated, so a press
         -- mid-warp or mid-cutscene is refused for the wireframe exactly when
-        -- it would be for the mode itself. Two of them parameterise that
-        -- pass; the third (3D-BTL) decides what a battle is drawn over, and
+        -- it would be for the mode itself. Three of them parameterise that
+        -- pass; the fourth (3D-BTL) decides what a battle is drawn over, and
         -- wants the same gate for a different reason: the answer is read
         -- when the fight starts, so flipping it from inside one would be a
         -- switch that appeared to do nothing.
         claim:cycle(self)
         -- 8 is one of the two ways staged battles get switched on, and they
-        -- pin BATTLE LAYOUT to OG (see the rows hook). The other two keys
+        -- pin BATTLE LAYOUT to OG (see the rows hook). The other keys
         -- parameterise the pass and leave the layout alone; the guard answers
-        -- for all three, so nothing here has to know which key it was.
+        -- for all of them, so nothing here has to know which key it was.
         if stagedBattles() then OverworldBattle.forceOG(self) end
         return
       end
@@ -848,7 +860,7 @@ mod.hooks:wrap("world.tod", function(next, tod, ctx)
   return DayNight.tod()
 end)
 
-mod.exports.version = "1.3.1"
+mod.exports.version = "1.4.0"
 -- exposed so a companion mod can pin its own tiles' shapes or read the
 -- camera without reaching into this mod's file layout
 mod.exports.lib = V

manifest.json

@@ -1,7 +1,7 @@
 {
   "id": "DRAMATIC_SHAPE",
   "name": "Dramatic Shape Voxel Mod",
-  "version": "1.3.1",
+  "version": "1.4.0",
   "api": 2,
   "entry": "main.lua",
   "profile": "content",
@@ -15,5 +15,6 @@
     "engine_internals"
   ],
   "affects_link": false,
-  "description": "A full 3D diorama overworld: extruded terrain, depth-buffered occlusion, voxel characters and a tilt-shift miniature pass -- and battles fought on the map itself, shot over the shoulder at the nearest clear ground with a slow parallax drift and a depth-of-field pass. Registers two render pipelines and claims hotkeys 3, 5, 6, 7 and 8 -- 3 and 5 displace the engine's TILT and GBC FX keys, both still reachable on the OPTIONS menu. Presentational only: it changes what a battle is drawn over, never where anybody stands."
+  "description": "A full 3D diorama overworld: extruded terrain, depth-buffered occlusion, voxel characters and a tilt-shift miniature pass -- and battles fought on the map itself, shot over the shoulder at the nearest clear ground with a slow parallax drift and a depth-of-field pass. Water reflects the sky, the sun, the moon and -- through a screen-space ray march -- the shoreline standing behind it. Registers two render pipelines and claims hotkeys 3, 5, 6, 7, 8 and 9 -- 3 and 5 displace the engine's TILT and GBC FX keys, both still reachable on the OPTIONS menu. Presentational only: it changes what a battle is drawn over, never where anybody stands.",
+  "github": "DramaticShape/DramaticShapeVoxelMod"
 }

mod.card

@@ -21,6 +21,7 @@ return {
       "VOXEL options row and hotkey 3 (OFF / 15 / 35 / 50 / 75 degrees)",
       "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",
+      "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 (ON / OFF, on by default), battles fought on the world map",
       "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",
       "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",
@@ -30,6 +31,9 @@ return {
     },
     known = {
       "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 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",

tests/dramatic_shape_test.lua

@@ -298,7 +298,7 @@ local order = {}
 for i, row in ipairs(grouped) do order[row.id] = i end
 T.check(order["pipeline:tiltshift"] < order["DRAMATIC_SHAPE:grid"],
   "the mode's settings follow its pipeline rows")
-T.eq(order["DRAMATIC_SHAPE:battles"] - order["pipeline:tiltshift"], 3,
+T.eq(order["DRAMATIC_SHAPE:battles"] - order["pipeline:tiltshift"], 4,
   "and sit in one unbroken block, not scattered to the end of the list")
 T.check(order["void_fill"] > order["DRAMATIC_SHAPE:battles"],
   "with the engine's own later rows still after them")
@@ -379,9 +379,15 @@ end
 Pipelines.setLevel("voxel", 2)
 local hookedRows = Runtime.call("ui.options.rows", function(_, r) return r end,
                                { data = Data }, { { id = "text_speed" } })
-T.eq(#hookedRows, 6, "the options hook added a row per setting")
-local grid, curve, battles = hookedRows[2], hookedRows[3], hookedRows[4]
-local backRow, daytime = hookedRows[5], hookedRows[6]
+T.eq(#hookedRows, 7, "the options hook added a row per setting")
+local grid, curve, water = hookedRows[2], hookedRows[3], hookedRows[4]
+local battles, backRow, daytime = hookedRows[5], hookedRows[6], hookedRows[7]
+T.eq(water.label, "WATER", "the water row carries its label")
+T.eq(water.value(), "FULL",
+  "and defaults to FULL -- reflections are the point of having the row")
+water.step({ save = { options = {} }, mods = { modOptions = {} } }, 1)
+T.eq(water.value(), "SKY",
+  "stepping down drops the screen-space march and keeps the sky, sun and moon")
 T.eq(daytime.label, "DAYTIME", "the day/night row carries its label")
 T.eq(daytime.value(), "SYNC",
   "and defaults to SYNC -- no value set follows the clock on the wall")
@@ -1482,6 +1488,440 @@ T.eq(Sky.paint(320, 0, skyGrad, 40, 7), false,
   "and a frame with no height paints nothing at all")
 end
 
+-- ------- reflections on water
+--
+-- Water is the one surface in this mode that cannot be drawn with the rest
+-- of the world: it is a mirror, and a mirror needs what it reflects to
+-- already be down. So it is lifted out of the terrain mesh at BUILD time and
+-- drawn as its own pass. That lift is the load-bearing part -- get it wrong
+-- and a lake is either a hole in the world or is drawn twice -- and it is
+-- pure geometry, so it is driven here against a hand-drawn map.
+do
+local Water = run.loader.exports.DRAMATIC_SHAPE.lib.require("Water")
+local Sky = run.loader.exports.DRAMATIC_SHAPE.lib.require("Sky")
+local ChunkMesher = run.loader.exports.DRAMATIC_SHAPE.lib.require("ChunkMesher")
+local Structures = run.loader.exports.DRAMATIC_SHAPE.lib.require("Structures")
+local Shapes = run.loader.exports.DRAMATIC_SHAPE.lib.require("TileShape")
+local TileShapeHeights = Shapes.heights()
+
+-- ------- the ladder
+--
+-- Three rungs, not a toggle: the sky half of this costs a handful of
+-- instructions and the screen-space half costs a ray march, so a machine
+-- that wants the sunset on the lake but not the march has somewhere to sit.
+T.eq(Water.setting.values[1], "full",
+  "FULL is the default -- reflections are the point of having the row")
+Water.setting:sync("full")            -- the row test above stepped it
+T.eq(Water.level(), 2, "and it reads back as the full pass")
+T.eq(Water.enabled(), true, "which is on")
+Water.setting:sync("sky")
+T.eq(Water.level(), 1, "SKY keeps the pass but drops the screen-space march")
+T.eq(Water.enabled(), true, "and is still a reflection")
+Water.setting:sync("off")
+T.eq(Water.level(), 0, "OFF is no pass at all")
+T.eq(Water.enabled(), false,
+  "which is what puts the water back in the ordinary scene shader")
+Water.setting:sync("full")
+
+-- ------- the waves are geometry, not shading -- and they step at 15fps
+--
+-- The surface is a heightfield of one-world-pixel columns, each standing a
+-- WHOLE number of pixels tall -- a voxel like every other voxel in this
+-- mode -- and it advances in STEPS rather than sliding: 15 a second, the
+-- cadence hand-drawn pixel art is animated at. A surface built out of whole
+-- pixels that crawls smoothly between them gives away that the quantisation
+-- is only skin deep.
+do
+local TerrainAtlas = run.loader.exports.DRAMATIC_SHAPE.lib.require("TerrainAtlas")
+local realClock = TerrainAtlas._animFrame
+local frame = 0
+TerrainAtlas._animFrame = function() return frame end
+local function at(f)
+  frame = f
+  return Water._waveTime()
+end
+
+local period = 60 / Water.WAVE_FPS
+T.eq(period, 5, "12 steps a second is one every five engine frames")
+T.eq(math.floor(period), period,
+  "and the beat divides the engine's 60 exactly, so every step spans the "
+  .. "same whole number of frames")
+-- inside one step nothing moves; crossing one, it does
+T.eq(at(0), at(period - 1),
+  "every frame inside one wave step gets the same phase -- the surface "
+  .. "steps rather than crawling between its own pixels")
+T.neq(at(0), at(period), "and the step boundary is where it moves")
+
+local steps = {}
+for f = 0, 59 do steps[at(f)] = true end
+local n = 0
+for _ in pairs(steps) do n = n + 1 end
+T.eq(n, Water.WAVE_FPS, "which is WAVE_FPS distinct positions in a second")
+TerrainAtlas._animFrame = realClock
+
+-- and the step is worth taking: one world pixel of the dominant train per
+-- step, DERIVED from that train rather than tuned beside it, so a change of
+-- wavelength moves the speed with it. A step the surface cannot resolve is
+-- a smooth crawl wearing a quantised clock.
+local t = Water.WAVE_TRAINS[1]
+local freq = math.sqrt(t[1] * t[1] + t[2] * t[2])
+local travel = (Water.waveRate() / Water.WAVE_FPS) * math.abs(t[3]) / freq
+T.check(math.abs(travel - Water.WAVE_PIXELS_PER_STEP) < 1e-9,
+  "each step advances the dominant crest by exactly WAVE_PIXELS_PER_STEP "
+  .. "world pixels, so nothing ever lands half-way between two")
+
+-- the trains reach the shader as source, off the same table the rate above
+-- is derived from -- one list, so the two cannot drift
+local trains = Water._trainSource()
+T.eq(select(2, trains:gsub("h %+= sin", "")), #Water.WAVE_TRAINS,
+  "every train in the table is summed by the shader")
+T.check(trains:find(("%.4f"):format(t[1]), 1, true) ~= nil,
+  "at the frequency the table states")
+
+-- the variation that keeps three periodic trains from reading as wallpaper:
+-- the dominant train's amplitude breathes with the swell and its crests bow
+-- with the bend, both pasted from their own tables like the trains are
+T.check(trains:find(("%.4f"):format(Water.WAVE_SWELL[1]), 1, true) ~= nil
+        and trains:find(("%.4f"):format(Water.WAVE_BEND[1]), 1, true) ~= nil,
+  "the swell and the bend reach the shader off the tables that document "
+  .. "them, not off copies kept in step by hand")
+T.check(Water.WAVE_SWELL[4] > 0 and Water.WAVE_SWELL[4] < 1,
+  "the swell's deepest lull thins the dominant train without deleting or "
+  .. "inverting it -- a sea with sets in it, not a sea that turns off")
+for _, mod in ipairs({ Water.WAVE_SWELL, Water.WAVE_BEND }) do
+  local mf = math.sqrt(mod[1] * mod[1] + mod[2] * mod[2])
+  T.check(mf * 3.5 < freq,
+    "a modulator's wavelength sits several times the carrier's, far enough "
+    .. "apart that it reads as weather over the waves rather than as a "
+    .. "fourth wave -- which would be the soup the weights exist to avoid")
+end
+
+T.check(Water.WAVE_HEIGHT > -TileShapeHeights.water,
+  "the crests stand taller than the recess TileShape sinks water into -- "
+  .. "they are RELIEF inside the quad's own footprint, so a bar that reaches "
+  .. "above the bank is clipped at the water's edge rather than spilling")
+end
+
+-- ------- the moon on the water is the moon in the sky
+--
+-- The reflected disc is drawn by a shader and the painted one by rectangles,
+-- so nothing but shared DATA can keep them the same moon. The crater list is
+-- pasted into the shader source from Sky's own table, which is the seam that
+-- makes "they cannot drift" true rather than merely intended.
+local craters = Water._craterSource()
+local craterLines = select(2, craters:gsub("crater%(", ""))
+T.eq(craterLines, #Sky.MOON_CRATERS,
+  "the shader gets one crater per crater the painted moon has")
+for _, c in ipairs(Sky.MOON_CRATERS) do
+  T.check(craters:find(("%.4f"):format(c[1]), 1, true) ~= nil,
+    "and each one at the offset the painted moon puts it at")
+end
+T.check(craters:find(("%.4f"):format(Sky.CRATER_FRAC), 1, true) ~= nil,
+  "at the same fraction of the disc's radius")
+
+-- and the disc is the same SIZE, which is the other half of being the same
+-- moon: one function answers for the painted radius and for the angle the
+-- reflection subtends it at
+local px, cells = Sky.discRadius(288, 7, { moon = true })
+T.eq(cells, Sky.DISC_MIN,
+  "a small frame floors the disc at its minimum radius in cells")
+T.eq(px, Sky.DISC_MIN * 7, "reported in canvas pixels on that cell grid")
+T.eq(select(2, Sky.discRadius(288, 7, { glowAmt = 0.9 })), Sky.DISC_MIN + 1,
+  "and the low sun looms, exactly as the painted one does")
+T.eq(select(2, Sky.discRadius(288, 7, { glowAmt = 0.9, moon = true })),
+  Sky.DISC_MIN, "which is a SUNSET exaggeration -- the moon never looms")
+
+-- the same band ramp, too: one texture, so the sky on the lake cannot be a
+-- different palette from the sky over it
+local rampImg, rampCount = Sky.ramp()
+T.check(rampImg == nil or rampCount == #Sky.bands(),
+  "the reflection reads the sky off the very ramp the sky is painted from")
+
+-- ------- the horizon lean: the reflection has to have something IN it at
+-- every rung, not just the one whose horizon is in frame
+--
+-- The rungs are named for the camera's tilt off VERTICAL, so at 15 the eye
+-- meets the water nearly head-on and the mirror ray points 75 degrees UP --
+-- where the sky's bands are darkest, the sun and moon (squashed to about 6
+-- degrees) are nowhere near, and a screen-space ray leaves the frame in two
+-- steps. All three are correct and together they are an empty lake. The lean
+-- tips the reflection toward the way the camera looks by however far that
+-- camera is from having a horizon in frame.
+do
+local Voxel3D = run.loader.exports.DRAMATIC_SHAPE.lib.require("Voxel3D")
+local VoxelState = run.loader.exports.DRAMATIC_SHAPE.lib.require("VoxelState")
+local wasAngle, wasCam = VoxelState.angle, Voxel3D.camera
+Voxel3D.camera = nil
+
+local lean = {}
+for _, deg in ipairs({ 15, 35, 50, 75 }) do
+  VoxelState.angle = math.rad(deg)
+  Voxel3D.viewProjection(256, 256, 320, 288)
+  lean[deg] = { Water.lean(Voxel3D.descent), Voxel3D.descent }
+  -- the orbit looks NORTH, so the flattened view direction is -Z and level
+  T.check(math.abs(Voxel3D.lookFlat[3] + 1) < 1e-6,
+    ("the %d rung looks north along the ground plane"):format(deg))
+  T.eq(Voxel3D.lookFlat[2], 0,
+    "flattened onto it, so the lean can never tip a reflection underground")
+end
+
+-- descent is the SINE of how far below horizontal the view runs, and the
+-- rungs are the camera's tilt off vertical -- so the two are complements
+for _, deg in ipairs({ 15, 35, 50, 75 }) do
+  T.check(math.abs(lean[deg][2] - math.cos(math.rad(deg))) < 1e-6,
+    ("the %d rung descends by cos(%d)"):format(deg, deg))
+end
+
+T.eq(lean[75][1], 0,
+  "at the rung whose horizon is in frame there is NO lean -- the one place "
+  .. "the join can be seen (the waterline, where the lake meets the painted "
+  .. "sky) is still the exact reflection it always was")
+T.check(lean[50][1] > 0, "and it comes in as the camera tips over")
+T.check(lean[35][1] >= lean[50][1] and lean[15][1] >= lean[35][1],
+  "growing with every rung further from the horizon")
+T.eq(lean[15][1], 1,
+  "and complete well before the steepest rung, so every rung under the top "
+  .. "one aims its reflection where the top one's already lands")
+
+-- a camera looking dead level has nothing to lean
+T.eq(Water.lean(0), 0, "a level camera leans not at all")
+T.eq(Water.lean(1), 1, "and one looking straight down leans all the way")
+T.eq(Water.lean(Water.LEAN_FROM), 0,
+  "the ramp starts exactly where the top rung sits, so that rung is the one "
+  .. "the lean never touches")
+T.check(math.abs(math.sin(Water.LEAN_ELEV) - Water.LEAN_FROM) < 1e-12,
+  "and the elevation it aims at IS that rung's own, stated as the same "
+  .. "number rather than beside it")
+
+VoxelState.angle, Voxel3D.camera = wasAngle, wasCam
+end
+
+-- ------- people do not shadow water
+--
+-- The sun pass is ONE map, so a surface cannot ask what threw a shadow
+-- unless the map says -- and it does, in the blue channel, which was zero
+-- anyway. Water is the only surface that asks: a character standing at a
+-- lake's edge laid a hard cut-out of its own sprite across a surface already
+-- showing the sky and the shoreline, which reads as a sticker rather than as
+-- a shadow. Everything the world casts still shades it.
+do
+local ShadowMap = run.loader.exports.DRAMATIC_SHAPE.lib.require("ShadowMap")
+T.check(type(ShadowMap.sprites) == "function",
+  "the sun pass can be told it is drawing the cast rather than the world")
+-- inert outside a pass, like every other toggle on it -- a caller that
+-- brackets a draw it never made must not send to a shader that is not bound
+T.check(pcall(ShadowMap.sprites, true) and pcall(ShadowMap.sprites, false),
+  "and saying so outside one is harmless")
+
+local shadowSrc = ShadowMap._source and ShadowMap._source() or nil
+if shadowSrc then
+  T.check(shadowSrc:find("fract(d), sprite", 1, true) ~= nil,
+    "the marker rides the channel the depth pack left free, so it costs "
+    .. "nothing: the map is still two channels of depth")
+end
+end
+
+-- ------- the compiled variants
+local plain = Water._source(false)
+local gridded = Water._source(true)
+T.check(plain:find("#define WAVE_STEPS " .. Water.WAVE_STEPS, 1, true) ~= nil,
+  "the relief march's step count is compiled in too")
+-- the whole surface is answered per COLUMN: the ray picks one, and the art,
+-- the shading, the reflection and the dither all read that one rather than
+-- the fragment's own place on the flat quad. A smoothly-shaded reflection
+-- over hard-edged 8-bit water is two pictures stacked.
+T.check(plain:find("floor(waveRaw(q) * waveHeight + 0.5)", 1, true) ~= nil,
+  "column heights are floored to WHOLE world pixels -- a fractional step is "
+  .. "a smooth wave with extra arithmetic, not a bar")
+-- and the normal is read off the SMOOTH field underneath, which is the
+-- difference between a moon on the water and confetti: integer heights give
+-- integer differences, so a normal built from them can only point in about
+-- five directions and a two-degree disc falls between them
+T.check(plain:find("float h = waveRaw(q);", 1, true) ~= nil,
+  "but the reflection's normal comes off the smooth surface the columns are "
+  .. "a quantisation of, so the ray sweeps instead of jumping")
+T.check(plain:find("waveNormal(vec2 q, float tilt)", 1, true) ~= nil
+        and plain:find("waveNormal(col,", 1, true) ~= nil,
+  "still one answer per column, so the surface stays pixel-quantised in "
+  .. "space while the value it reflects with is continuous")
+T.check(plain:find("relief(vBent, view, hit, col, face, axis)", 1, true) ~= nil,
+  "and the visible column is found by walking the view ray through the "
+  .. "slab, which is what makes a tall bar hide the short ones behind it")
+-- the march's reach grows as one over the ray's descent, so a grazing camera
+-- asks for hundreds of world pixels of it from a fixed number of samples --
+-- which stepped over whole crests and smeared the surface into streaks
+-- a sample is worth a SCREEN pixel of surface, so that is the stride: held
+-- at a world pixel up close (finer buys nothing and skipping costs the
+-- pepper) and opened out with distance (holding it there just runs the march
+-- out of samples part-way down the slab, which flattened the lowest rung's
+-- whole middle distance)
+T.check(plain:find("#define WAVE_STRIDE", 1, true) ~= nil
+        and plain:find("max(WAVE_STRIDE, dist * pxAngle / dy)", 1, true) ~= nil,
+  "the relief stride is a screen pixel's worth of surface, floored at a "
+  .. "world pixel")
+T.check(Water.WAVE_STRIDE <= 1,
+  "and that floor is at most ONE world pixel, because a column is one world "
+  .. "pixel wide -- a longer one steps over columns, and which ones it "
+  .. "misses changes fragment to fragment, which is the peppery noise")
+-- and the art is read off the COLUMN rather than by offsetting the
+-- fragment's own uv by however far the march happened to travel: one world
+-- pixel is one texel, so a column's texel follows from where it stands and
+-- two fragments landing on the same column cannot disagree about it
+T.check(plain:find("org + (mod(col, 8.0) + 0.5) * texel", 1, true) ~= nil,
+  "a column's art follows from its own world position, so it cannot swim "
+  .. "with the camera or speckle between neighbouring fragments")
+T.check(plain:find("waveUV(tc, col)", 1, true) ~= nil,
+  "and the column is what is handed to it")
+
+-- the wireframe is ruled on the COLUMNS, not on the flat sheet they stand on
+T.check(gridded:find("columnSeam(hit, vBent, axis)", 1, true) ~= nil,
+  "with V-GRID on, the seams outline the column the ray landed on -- every "
+  .. "voxel of water its own block -- rather than ruling a grid across the "
+  .. "flat quad underneath and ignoring the bars entirely")
+T.check(gridded:find("vec3 w = fwidth(base);", 1, true) ~= nil,
+  "measured off the smooth plane, because the hit jumps a whole column "
+  .. "between neighbouring fragments and its own derivative is a step")
+T.check(plain:find("march(surf, r)", 1, true) ~= nil,
+  "the reflection marches from that column, not from the raw fragment")
+T.check(plain:find("mod(col.x + col.y, 2.0)", 1, true) ~= nil,
+  "and the dither's checkerboard is cut from the columns too, so a camera "
+  .. "pan slides the world through nothing")
+T.check(plain:find("#define RAY_STEPS " .. Water.RAY_STEPS, 1, true) ~= nil,
+  "the march's step count is compiled in -- GLSL wants a constant bound")
+T.check(plain:find("VOXEL_GRID", 1, true) ~= nil,
+  "the wireframe is guarded in the source")
+T.check(plain:find("#define VOXEL_GRID", 1, true) == nil,
+  "and off in the plain variant")
+T.check(gridded:find("#define VOXEL_GRID", 1, true) ~= nil,
+  "so a frame with the seams on gets its own compilation, like the scene "
+  .. "shader -- a driver that refuses derivatives loses the seams and not "
+  .. "the water")
+T.check(plain:find("//@CRATERS", 1, true) == nil,
+  "and the crater placeholder is gone by the time a driver sees the source")
+
+-- ANDROID. GLSL ES defaults fragment floats to mediump and samplers to
+-- lowp, and this shader is the one place in the mod where both defaults
+-- are fatal: world coordinates run past fp16's fraction, the depth read
+-- rounds to steps the march falls straight through, and -- the sharp edge
+-- -- `vp` is declared by BOTH stages, whose defaults disagree, which GLSL
+-- ES answers by refusing to LINK the shader at all. Flat lakes, empty log.
+-- The sky's band ramp is this same lesson learned once already.
+T.check(plain:find("precision highp float;", 1, true) ~= nil,
+  "the pixel stage lifts GLSL ES's mediump default to highp, so the march "
+  .. "keeps its fraction and the dual-declared vp links at one precision")
+T.check(plain:find("GL_FRAGMENT_PRECISION_HIGH", 1, true) ~= nil,
+  "guarded, so the odd GPU without fragment highp still compiles and "
+  .. "falls back flat instead of failing loudly")
+T.check(plain:find("LOVE_HIGHP_OR_MEDIUMP vec3 vBent", 1, true) ~= nil,
+  "the world-position varying is qualified like the scene shader's vGrid "
+  .. "rather than left to the fragment default")
+T.check(plain:find("LOVE_HIGHP_OR_MEDIUMP Image depthTex", 1, true) ~= nil,
+  "and the depth sampler is lifted off lowp, which is eight bits of depth")
+T.check(plain:find(
+    "effect(mediump vec4 color, Image tex, mediump vec2 tc, mediump vec2 sc)",
+    1, true) ~= nil,
+  "effect()'s own floats stay pinned to LOVE's prototype precision -- the "
+  .. "Xclipse compiler reads a definition that drifted from the forward "
+  .. "declaration as an illegal overload and refuses the whole shader")
+T.check(plain:find("sc / love_ScreenSize.xy", 1, true) ~= nil,
+  "the depth test normalises the pixel coord by the canvas's own pixel "
+  .. "size -- `screen` counts canvas UNITS, and on a highdpi phone the two "
+  .. "differ by the density, which clamped the lookup and cut the water "
+  .. "into blocks")
+
+-- ------- the lift itself
+--
+-- A pond in a field: four water cells recessed below flat ground. The
+-- shipped maps are the real thing but a picture states the invariant
+-- exactly, and this one needs no atlas, no GPU and no fixture.
+local WATER_TILE, GRASS_TILE = 20, 3
+local pond = {
+  { GRASS_TILE, GRASS_TILE, GRASS_TILE, GRASS_TILE },
+  { GRASS_TILE, WATER_TILE, WATER_TILE, GRASS_TILE },
+  { GRASS_TILE, WATER_TILE, WATER_TILE, GRASS_TILE },
+  { GRASS_TILE, GRASS_TILE, GRASS_TILE, GRASS_TILE },
+}
+local pondMap = {
+  id = "DS_TEST_POND",
+  tileset = { id = "DS_TEST_SET", image = "gfx/tilesets/ds_test.png",
+              tilesPerRow = 16, imageWidth = 128, imageHeight = 48,
+              blocks = {}, grassTile = -1 },
+  def = { width = 1, height = 1, tileset = "DS_TEST_SET" },
+  walkable = { [GRASS_TILE] = true },
+  waterTiles = { [WATER_TILE] = true },
+  doorTiles = {},
+  tileAt = function(_, tx, ty)
+    return pond[(ty % 4) + 1][(tx % 4) + 1]
+  end,
+  cellTile = function(self, cx, cy) return self:tileAt(cx * 2, cy * 2 + 1) end,
+  isWaterCell = function(self, cx, cy)
+    return self:cellTile(cx, cy) == WATER_TILE
+  end,
+  isWalkableCell = function(self, cx, cy)
+    return self:cellTile(cx, cy) == GRASS_TILE
+  end,
+  inBounds = function(_, cx, cy)
+    return cx >= 0 and cy >= 0 and cx < 2 and cy < 2
+  end,
+}
+
+-- body-only, so the border ring is out of it and the count is the picture
+local _, _, whole = ChunkMesher.geometry(pondMap, true, nil)
+Structures.invalidate(pondMap.id)
+local landVerts, _, land, waterVerts, _, wet =
+  ChunkMesher.geometry(pondMap, true, nil, true)
+
+T.check(wet > 0, "the pond's surface comes out as water quads")
+T.eq(land + wet, whole,
+  "and the split is a MOVE, not a copy: every quad the one-sink build "
+  .. "emitted is in exactly one of the two")
+T.eq(#waterVerts, wet * 4, "the water sink holds whole quads")
+
+-- every water vertex sits on the recessed plane, which is what says the
+-- surface and only the surface was lifted -- the shoreline faces that drop
+-- from the ground down to it belong to the GROUND that exposes them, and
+-- must stay in the terrain mesh or a lake is ringed by a slit into the sky
+local heights = Shapes.heights()
+for _, v in ipairs(waterVerts) do
+  T.check(v[2] == heights.water,
+    "a water vertex stands on the water plane, not on a shoreline face")
+end
+local shore = 0
+for _, v in ipairs(landVerts) do
+  if v[2] < 0 then shore = shore + 1 end
+end
+T.check(shore > 0,
+  "and the shoreline bands below ground level stayed with the terrain")
+
+-- a map with no water at all splits into everything and nothing, rather
+-- than into an empty terrain mesh
+Structures.invalidate(pondMap.id)
+local dry = {}
+for y = 1, 4 do
+  dry[y] = {}
+  for x = 1, 4 do dry[y][x] = GRASS_TILE end
+end
+pond = dry
+local _, _, dryLand, _, _, dryWet = ChunkMesher.geometry(pondMap, true, nil,
+                                                         true)
+T.check(dryLand > 0, "a map with no water still meshes its ground")
+T.eq(dryWet, 0, "and hands back no water surface at all")
+
+-- ------- and the pairing
+--
+-- The terrain mesh and the water lifted out of it are ONE answer: they came
+-- from the same build, so a caller must never end up holding a full mesh
+-- beside a body build's water (the ring's ponds twice, the body's as holes).
+-- pair() is the only way to ask, which is what makes that unpairable.
+local mesh, wetMesh = ChunkMesher.pair({ id = "DS_NOT_A_MAP" }, false)
+T.eq(mesh, nil, "an unbuilt map pairs to nothing")
+T.eq(wetMesh, nil, "on both halves, so a caller cannot half-draw one")
+
+Structures.invalidate(pondMap.id)
+ChunkMesher.invalidate(pondMap.id)
+Shapes.invalidate()
+end
+
 Voxel.angle = 0
 
 -- ------- overworld battles: where the fight is staged

tests/mon_shots.lua

@@ -0,0 +1,71 @@
+-- Driver: one overworld-battle screenshot per species, the mon fighting
+-- ITSELF -- its back pic on the player's mark and its front pic on the
+-- enemy's, so a single frame shows both sprites the 3D mode draws for it.
+--
+-- The point is a visual sweep for pic glitches (holes the paper-fill missed,
+-- a silhouette cut wrong, a pin that leaves the mon floating), so every shot
+-- is staged identically: same map, same cells, same beat -- the battle menu,
+-- both HUD panels up. Whatever differs between two shots is the mon.
+--
+--   SHOT_DIR=.scratchpad/mon_shots \
+--   POKEPORT_DRIVER=mods/DramaticShapeVoxelMod/tests/mon_shots.lua love .
+--
+-- Files land as NNN_species.png in dex order.
+return function(game)
+  local U = dofile("tests/drivers/util.lua")
+  local DIR = os.getenv("SHOT_DIR") or ".scratchpad/mon_shots"
+  local Pokemon = require("src.pokemon.Pokemon")
+  local BattleState = require("src.battle.BattleState")
+
+  -- every real species the merged data carries, walked in dex order
+  local species = {}
+  for id, def in pairs(game.data.pokemon) do
+    if type(id) == "string" and type(def) == "table"
+       and def.dex and def.dex >= 1 and def.dex <= 151 then
+      species[#species + 1] = { id = id, dex = def.dex }
+    end
+  end
+  table.sort(species, function(a, b) return a.dex < b.dex end)
+  U.log(("%d species"):format(#species))
+
+  game.save.player.name = "RED"
+
+  for _, s in ipairs(species) do
+    -- level 50 both sides: high enough that nothing about the staging is
+    -- species-specific, and a wild battle never awards exp off a menu shot
+    game.save.party = { Pokemon.new(game.data, s.id, 50) }
+
+    U.teleport(game, "ROUTE_1", 5, 8, "down")
+    -- let the neighbourhood's meshes land so the first battle frame is the
+    -- real arena rather than the flat fallback
+    U.wait(60)
+
+    local battle = BattleState.newWild(game, s.id, 50)
+    battle.onFinish = function() end
+    game.overworld:pushBattle(battle)
+
+    -- the wipe, then tap through "Wild X appeared!" and the send-out until
+    -- the battle MENU is actually up -- a fixed tap count lands on whatever
+    -- beat the intro happened to be on, which is how a shot ends up with the
+    -- trainer still standing where the mon should be
+    U.wait(70)
+    for _ = 1, 200 do
+      if battle.phase == "menu" then break end
+      U.tap(game, "a")
+      U.wait(6)
+    end
+    if battle.phase ~= "menu" then
+      U.log(("STUCK before menu: %s (phase %s)"):format(s.id, tostring(battle.phase)))
+    end
+    -- let the send-out slide/ball beat finish so the mon is standing still
+    U.wait(40)
+    U.shot(game, ("%s/%03d_%s.png"):format(DIR, s.dex, s.id:lower()))
+
+    while game.stack:top() and game.stack:top() ~= game.overworld do
+      game.stack:pop()
+    end
+    U.wait(10)
+  end
+
+  U.log("done -- " .. DIR)
+end

tests/pic_dump.lua

@@ -0,0 +1,63 @@
+-- Driver: dump the exact pic textures a live 3D battle draws, per stage --
+-- the sprite as loaded (raw) and what picImage hands the billboard after the
+-- palette bake and BattlePics' paper fill (final). Diagnostic for pics that
+-- render with holes: whichever stage the transparency first appears in is
+-- the stage that made it.
+--
+--   SHOT_DIR=.scratchpad/pic_dump \
+--   POKEPORT_DRIVER=mods/DramaticShapeVoxelMod/tests/pic_dump.lua love .
+return function(game)
+  local U = dofile("tests/drivers/util.lua")
+  local DIR = os.getenv("SHOT_DIR") or ".scratchpad/pic_dump"
+  local Pokemon = require("src.pokemon.Pokemon")
+  local BattleState = require("src.battle.BattleState")
+
+  local function save(img, path)
+    if not img then U.log("NIL image for " .. path) return end
+    local w, h = img:getDimensions()
+    local g = love.graphics
+    local prev = g.getCanvas()
+    local canvas = g.newCanvas(w, h, { dpiscale = 1 })
+    g.setCanvas(canvas)
+    g.clear(0, 0, 0, 0)
+    g.setBlendMode("replace", "premultiplied")
+    g.setColor(1, 1, 1, 1)
+    g.draw(img, 0, 0)
+    g.setCanvas(prev)
+    g.setBlendMode("alpha")
+    local f = assert(io.open(path, "wb"))
+    f:write(canvas:newImageData():encode("png"):getString())
+    f:close()
+  end
+
+  local SPECIES = os.getenv("PIC_SPECIES")
+  local list = {}
+  if SPECIES then
+    for id in SPECIES:gmatch("[^,%s]+") do list[#list + 1] = id:upper() end
+  else
+    list = { "PIKACHU", "SEEL", "BULBASAUR", "MEWTWO" }
+  end
+
+  for _, id in ipairs(list) do
+    game.save.party = { Pokemon.new(game.data, id, 50) }
+    U.teleport(game, "ROUTE_1", 5, 8, "down")
+    U.wait(30)
+    local battle = BattleState.newWild(game, id, 50)
+    battle.onFinish = function() end
+    game.overworld:pushBattle(battle)
+    U.wait(80)
+    local lo = id:lower()
+    save(battle.enemy.sprite, ("%s/%s_front_raw.png"):format(DIR, lo))
+    save(battle:picImage(battle.enemy.sprite), ("%s/%s_front_final.png"):format(DIR, lo))
+    save(battle.player.sprite, ("%s/%s_back_raw.png"):format(DIR, lo))
+    save(battle:picImage(battle.player.sprite), ("%s/%s_back_final.png"):format(DIR, lo))
+    U.log("dumped " .. id)
+    while game.stack:top() and game.stack:top() ~= game.overworld do
+      game.stack:pop()
+    end
+    U.wait(5)
+  end
+
+  U.log("done -- " .. DIR)
+  love.event.quit()
+end

tests/water_reflect_probe.lua

@@ -0,0 +1,128 @@
+-- Driver: WHY is the water not reflecting anything?
+--
+-- The reflective pass has several links and every one of them fails quietly
+-- back to flat water, which looks exactly like the row being off. This walks
+-- the chain in the LIVE game and prints where it stops.
+--
+--   POKEPORT_DRIVER=mods/DRAMATIC_SHAPE/tests/water_reflect_probe.lua lovec .
+--
+-- knobs (env):
+--   REFL_MAP    map id                       (default PALLET_TOWN)
+--   REFL_SPOT   "x,y[,facing]"               (default 5,6,down)
+--   REFL_LEVEL  voxel rung                   (default 5, the 75-degree camera,
+--                                             which is where a reflection is
+--                                             most of what you can see)
+--   REFL_TIME   daytime pin (day/dusk/...)   (default: leave as-is)
+return function(game)
+  local U = dofile("tests/drivers/util.lua")
+  local Pipelines = require("src.render.Pipelines")
+
+  local mapId = os.getenv("REFL_MAP") or "PALLET_TOWN"
+  local level = math.floor(tonumber(os.getenv("REFL_LEVEL")) or 5)
+  local sx, sy, facing = (os.getenv("REFL_SPOT") or "5,6,down")
+    :match("^%s*(%d+)%s*,%s*(%d+)%s*,?%s*(%a*)")
+  facing = (facing ~= "" and facing) or "down"
+
+  local function say(...) print("[water-ssr] " .. string.format(...)) end
+
+  U.teleport(game, mapId, tonumber(sx), tonumber(sy), facing)
+  U.wait(20)
+  Pipelines.setLevel("voxel", level)
+  U.wait(40)                       -- outlast the camera tween and the build
+
+  local V = game.mods.exports["DRAMATIC_SHAPE"]
+  V = V and V.lib
+  if not V then return say("mod exports unreachable -- is it enabled?") end
+
+  local Water = V.require("Water")
+  local Voxel3D = V.require("Voxel3D")
+  local ChunkMesher = V.require("ChunkMesher")
+  local Sky = V.require("Sky")
+  local DayNight = V.require("DayNight")
+
+  if os.getenv("REFL_TIME") then
+    DayNight.setting:sync(os.getenv("REFL_TIME"))
+    U.wait(5)
+  end
+
+  local ow = game.overworld
+  local map = ow and ow.map
+  if not map then return say("no live map") end
+
+  -- 1. is the row on at all?
+  say("row=%s level=%d", tostring(Water.setting:get()), Water.level())
+  if not Water.enabled() then
+    return say("STOP: WATER is OFF -- press 9, or set the row")
+  end
+
+  -- 2. is there any water on this map to reflect in?
+  local terrain, water = ChunkMesher.pair(map, false)
+  if not terrain then terrain, water = ChunkMesher.pair(map, true) end
+  say("terrain mesh=%s water mesh=%s", tostring(terrain ~= nil),
+      tostring(water ~= nil))
+  if not terrain then
+    return say("STOP: no terrain mesh yet -- the build is still cooking")
+  end
+  if not water then
+    say("STOP: this map has no water surface. That is not a fault unless")
+    say("      you can see a lake: check the tileset's water tiles reach")
+    say("      TileShape (run voxel_survey.lua for the shape breakdown).")
+    return
+  end
+
+  -- 3. did the driver give us a depth texture to read? This is the one
+  --    hardware requirement the rest of the mode does not already have.
+  say("depth canvas readable: %s", tostring(Voxel3D.depthReadable()))
+  if not Voxel3D.depthReadable() then
+    say("STOP: no readable depth canvas on this driver (tried depth24, ")
+    say("      depth24stencil8, depth32f and depth16).")
+    say("      The water falls back to the flat scene shader, which is")
+    say("      exactly what it looked like before this feature existed.")
+    return
+  end
+
+  -- 4. did the shader build? Both variants -- the wireframe one needs
+  --    derivatives, which a driver may refuse on its own.
+  say("shader plain=%s grid=%s",
+      tostring(Water.shader(false) ~= nil), tostring(Water.shader(true) ~= nil))
+  if not Water.shader(false) then
+    return say("STOP: the water shader did not compile -- the mod log has "
+               .. "the driver's own message")
+  end
+
+  -- 5. is there a sky to reflect, and something hanging in it?
+  local ramp, count = Sky.ramp()
+  say("sky ramp=%s bands=%s edge=%s", tostring(ramp ~= nil), tostring(count),
+      tostring(Voxel3D.skyEdge))
+  local body = DayNight.body()
+  if body then
+    local amt = DayNight.glow()
+    local w, h = Voxel3D.size()
+    local rpx = Sky.discRadius(h, Voxel3D.cell or 1,
+                               { moon = body.moon, glowAmt = amt })
+    local ang = rpx / ((h or 1) / math.max(1e-4, Voxel3D.fovY or 1))
+    say("body=%s dir=(%.2f, %.2f, %.2f) disc=%.1fpx (%.2f deg)",
+        body.moon and "moon" or "sun", body.dx, body.dy, body.dz, rpx,
+        math.deg(ang))
+  else
+    say("body: none in the sky right now (set REFL_TIME=day or =night)")
+  end
+  if not ramp then
+    say("NOTE: no band ramp -- indoors, or the ramp could not be built. The")
+    say("      sky half of the reflection is off; the ray march still runs.")
+  end
+
+  -- 6. how much reflection this camera is actually asking for. Both numbers
+  --    fall out of the rung, and between them they explain every "it only
+  --    works at 75" report: Fresnel decides how much shows, and the lean
+  --    decides whether what shows has anything in it.
+  local f = Water.FRESNEL_FLOOR + (Water.FRESNEL_CEIL - Water.FRESNEL_FLOOR)
+            * (1 - Voxel3D.descent) ^ Water.FRESNEL_POWER
+  say("camera: descent %.3f -> fresnel about %.2f, horizon lean %.2f",
+      Voxel3D.descent, f, Water.lean(Voxel3D.descent))
+  say("waves: %d px columns, phase %.2f", Water.WAVE_HEIGHT, Water._waveTime())
+
+  say("OK: every link is live. The effect is strongest at REFL_LEVEL=5 (the")
+  say("    75-degree rung, where Fresnel is highest and the reflection is")
+  say("    exact) and with a low sun (REFL_TIME=dusk).")
+end