Merge pull request #139 from DramaticShape/stadium_fixes

1.7.1

lib/Diorama.lua

@@ -207,6 +207,11 @@ end
 
 local function volume(kind, x, y, z, r, fade)
   return { x = x, y = y, z = z, r = r,
+           -- The BOX kind is rectangular in the shader, because the flat
+           -- screen's box is the WINDOW's own footprint and a window is not
+           -- square (lib/ViewBox). A headset's model has no window to be
+           -- shaped like, so this one is: the same half-size twice.
+           rx = r, rz = r,
            -- a zero band is a hard edge: half a pixel of ramp, which is
            -- one pixel of antialiasing rather than a stair
            invFade = 1 / math.max(fade or 0, 0.5), kind = kind }

lib/ForestAtmos.lua

@@ -51,10 +51,11 @@ local floor, sqrt, min, max = math.floor, math.sqrt, math.min, math.max
 
 local ForestAtmos = {}
 
--- The diorama's viewport, as both shaders here take it (see Voxel3D.cull:
--- the field is set for a headset's diorama frame and nil for every other,
--- where kind 0 means "no cut"). Read through V.require rather than held as
--- an upvalue because this file loads before Voxel3D on some paths.
+-- The viewport, as both shaders here take it (see Voxel3D.cull: the field
+-- is set for a headset's diorama frame and for an orbit rung's window box,
+-- and nil for every other, where kind 0 means "no cut"). Read through
+-- V.require rather than held as an upvalue because this file loads before
+-- Voxel3D on some paths.
 local function cullAt()
   local c = V.require("Voxel3D").cull
   return c and { c.x, c.y, c.z } or { 0, 0, 0 }
@@ -65,6 +66,11 @@ local function cullShape()
   return c and { c.r, c.invFade, c.kind } or { 0, 0, 0 }
 end
 
+local function cullRect()
+  local c = V.require("Voxel3D").cull
+  return c and { c.rx or c.r, c.rz or c.r } or { 0, 0 }
+end
+
 -- FULL is the point; LOW halves the march and drops the particles, for
 -- hardware that minds a per-pixel loop under 4X supersampling.
 --
@@ -430,24 +436,25 @@ local RAY_SHADER = [[
   uniform vec3 sunward;      // unit, toward the unseen sun
   uniform vec2 wind;         // leaf-field drift, uv per second
   uniform float time;
-  // the diorama's viewport, as the scene shader takes it (see Voxel3D):
-  // air outside the model is not air, so a sample out there contributes
-  // nothing and the beams end with the world they fall through
+  // the viewport, as the scene shader takes it (see Voxel3D): air outside
+  // the model is not air, so a sample out there contributes nothing and
+  // the beams end with the world they fall through
   uniform vec3 cullAt;
   uniform vec3 cullShape;
+  uniform vec2 cullRect;     // the box's half-extents in x and z
 
   float dioramaCull(vec3 p) {
     if (cullShape.z <= 0.5) return 1.0;
     vec3 cd = p - cullAt;
-    float d;
-    if (cullShape.z < 1.5) {
-      d = max(abs(cd.x), abs(cd.z));      // the box
+    float inside;
+    if (cullShape.z < 1.5) {                 // the box
+      inside = min(cullRect.x - abs(cd.x), cullRect.y - abs(cd.z));
     } else if (cullShape.z < 2.5) {
-      d = length(cd);                     // the ball
+      inside = cullShape.x - length(cd);     // the ball
     } else {
-      d = length(cd.xz);                  // the fight's pillar
+      inside = cullShape.x - length(cd.xz);  // the fight's pillar
     }
-    return clamp((cullShape.x - d) * cullShape.y, 0.0, 1.0);
+    return clamp(inside * cullShape.y, 0.0, 1.0);
   }
 
   float sunDepth(vec2 uv) {
@@ -621,8 +628,9 @@ local PART_SHADER = [[
 #ifdef VERTEX
   uniform mat4 vp;
   uniform vec3 curve;
-  uniform vec3 cullAt;     // the diorama's viewport (see Voxel3D.cull):
-  uniform vec3 cullShape;  // a mote outside the model is not in the air
+  uniform vec3 cullAt;     // the viewport (see Voxel3D.cull): a mote
+  uniform vec3 cullShape;  // outside the model is not in the air
+  uniform vec2 cullRect;   // the box's half-extents in x and z
   uniform vec3 axisR;      // the camera's right, world space
   uniform vec3 axisU;      // and its up: the billboard's own frame
   uniform float time;
@@ -646,15 +654,15 @@ local PART_SHADER = [[
     // rather than having to cut one in half
     if (cullShape.z > 0.5) {
       vec3 cd = base - cullAt;
-      float cdd;
+      float inside;
       if (cullShape.z < 1.5) {
-        cdd = max(abs(cd.x), abs(cd.z));
+        inside = min(cullRect.x - abs(cd.x), cullRect.y - abs(cd.z));
       } else if (cullShape.z < 2.5) {
-        cdd = length(cd);
+        inside = cullShape.x - length(cd);
       } else {
-        cdd = length(cd.xz);
+        inside = cullShape.x - length(cd.xz);
       }
-      vGlow *= clamp((cullShape.x - cdd) * cullShape.y, 0.0, 1.0);
+      vGlow *= clamp(inside * cullShape.y, 0.0, 1.0);
     }
     vCorner = AtmosData.xy;
     vec4 w = vec4(base + axisR * (AtmosData.x * size)
@@ -815,6 +823,7 @@ function ForestAtmos.draw(map)
                 Voxel3D.curveK or 0 })
         pcall(sh.send, sh, "cullAt", cullAt())
         pcall(sh.send, sh, "cullShape", cullShape())
+        pcall(sh.send, sh, "cullRect", cullRect())
         pcall(sh.send, sh, "screen", { w, h })
         pcall(sh.send, sh, "fogW",
               { f.fog.density, f.fog.heightK,
@@ -847,6 +856,7 @@ function ForestAtmos.draw(map)
                 Voxel3D.curveK or 0 })
         pcall(psh.send, psh, "cullAt", cullAt())
         pcall(psh.send, psh, "cullShape", cullShape())
+        pcall(psh.send, psh, "cullRect", cullRect())
         pcall(psh.send, psh, "axisR", axisR)
         pcall(psh.send, psh, "axisU", axisU)
         pcall(psh.send, psh, "time", ForestAtmos.time)

lib/ViewBox.lua

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

lib/Voxel3D.lua

@@ -176,26 +176,35 @@ local SHADER = [[
   uniform vec3 cullAt;        // the viewport's centre, in world pixels
   uniform vec3 cullShape;     // half-size, 1/fade, kind: 1 box, 2 ball,
                               // 3 the staged fight's pillar
+  uniform vec2 cullRect;      // the BOX's half-extents in x and z, which
+                              // the round kinds have no use for. Two
+                              // numbers because the flat screen's box is
+                              // the WINDOW's own footprint and a window is
+                              // not square (lib/ViewBox); a headset's is,
+                              // and lib/Diorama sends the same half-size
+                              // twice.
 
   // 1 well inside the viewport, 0 outside it, and the rim in between --
   // which is a HARD edge for the box (its band is half a pixel wide, so
   // the ramp is just the antialiasing) and a dissolve for the other two.
   //
-  // The box and the pillar are unbounded upward and downward on purpose:
-  // what is wanted is a square (or round) piece cut OUT OF THE MAP, and a
-  // cut with a lid would take the tops off the trees standing in it.
+  // Every kind is unbounded upward and downward on purpose: what is wanted
+  // is a rectangular (or round) piece cut OUT OF THE MAP, and a cut with a
+  // lid would take the tops off the trees standing in it.
   float dioramaCull(vec3 p) {
     if (cullShape.z <= 0.5) return 1.0;
     vec3 cd = p - cullAt;
-    float d;
+    // how far INSIDE the cut this point is, in world pixels: the nearest
+    // side for the rectangle, the rim for the two round kinds
+    float inside;
     if (cullShape.z < 1.5) {
-      d = max(abs(cd.x), abs(cd.z));      // the box: a square of map
+      inside = min(cullRect.x - abs(cd.x), cullRect.y - abs(cd.z));
     } else if (cullShape.z < 2.5) {
-      d = length(cd);                     // the ball, under V-CURVE
+      inside = cullShape.x - length(cd);     // the ball, under V-CURVE
     } else {
-      d = length(cd.xz);                  // the fight's pillar
+      inside = cullShape.x - length(cd.xz);  // the fight's pillar
     }
-    return clamp((cullShape.x - d) * cullShape.y, 0.0, 1.0);
+    return clamp(inside * cullShape.y, 0.0, 1.0);
   }
 #endif
   uniform Image sunMap;
@@ -1068,13 +1077,16 @@ function Voxel3D.beginScene(w, h, cx, cy, vw, vh, sky, slot)
   pcall(sh.send, sh, "fogInfo", fog and
         { fog.density or 0, fog.start or 0, fog.heightK or 0, 0 }
         or { 0, 0, 0, 0 })
-  -- and the diorama's viewport (see Voxel3D.cull), kind 0 when there is
-  -- none -- which is every frame that is not a headset's diorama
+  -- and the viewport (see Voxel3D.cull), kind 0 when there is none --
+  -- which is every frame that neither a headset's diorama (lib/Diorama)
+  -- nor an orbit rung's window box (lib/ViewBox) has cut
   local cull = Voxel3D.cull
   pcall(sh.send, sh, "cullAt",
         cull and { cull.x, cull.y, cull.z } or { 0, 0, 0 })
   pcall(sh.send, sh, "cullShape",
         cull and { cull.r, cull.invFade, cull.kind } or { 0, 0, 0 })
+  pcall(sh.send, sh, "cullRect",
+        cull and { cull.rx or cull.r, cull.rz or cull.r } or { 0, 0 })
   -- the window glass: the tileset's mask (or the blank -- the sampler is
   -- declared either way, and unbound is a driver-dependent crash), how lit
   -- the panes are, and the movement-fed glint as the caller last set it

lib/VoxelScene.lua

@@ -28,6 +28,7 @@ local FirstPerson = V.require("FirstPerson")
 local BattleBillboard = V.require("BattleBillboard")
 local Pokedex = V.require("Pokedex")
 local Diorama = V.require("Diorama")
+local ViewBox = V.require("ViewBox")
 local PaletteFX = require("src.render.PaletteFX")
 local Map = require("src.world.Map")
 
@@ -623,10 +624,12 @@ local function drawCast(state, posed, atlasFor)
                  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)
+    if ViewBox.showsMap(nb) then
+      eachFigure(nb.map, nb.ox, nb.oy, function(mesh, model, caster)
+        Voxel3D.draw(mesh, atlasFor(nb.map), model, figPull,
+                     ShadowMap.snug(caster))
+      end)
+    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
@@ -770,6 +773,11 @@ local function shadowSignature(terrain, nbMesh, posed, cx, cy, vw, vh)
   -- and the sprite cards swap frames as it circles them, so a turn on the
   -- spot re-fits and redraws exactly like a camera move ("" outside 1ST)
   put(FirstPerson.signature())
+  -- and the window box, because WHICH neighbours went into the light is a
+  -- function of it (see ViewBox.signature): opening the row out brings a
+  -- map back inside the cut, and a sun map recorded without it would leave
+  -- that map standing in its own unlit shadow
+  put(ViewBox.signature())
   put(tostring(terrain))
   for i = 1, #nbMesh do put(tostring(nbMesh[i])) end
   for _, p in ipairs(posed) do
@@ -803,9 +811,16 @@ local function castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh,
   if not ShadowMap.begin(cx, cy, vw, vh) then return end
 
   ShadowMap.draw(terrain, atlasFor(state.map), nil)
+  -- The window box's coarse cut, here and at every neighbour loop below
+  -- (lib/ViewBox): a connected map lying entirely outside this frame's
+  -- viewport has nothing inside it that could reach the picture, so it is
+  -- not submitted at all. True for every map whenever there is no box,
+  -- which is every frame the row is OFF and every headset frame.
   for i, nb in ipairs(state.neighbors or {}) do
-    ShadowMap.draw(nbMesh[i], atlasFor(nb.map),
-                   Mat4.translate(nb.ox, 0, nb.oy))
+    if ViewBox.showsMap(nb) then
+      ShadowMap.draw(nbMesh[i], atlasFor(nb.map),
+                     Mat4.translate(nb.ox, 0, nb.oy))
+    end
   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
@@ -813,8 +828,10 @@ local function castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh,
   -- 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))
+    if ViewBox.showsMap(nb) then
+      ShadowMap.draw(nbWater and nbWater[i], atlasFor(nb.map),
+                     Mat4.translate(nb.ox, 0, nb.oy))
+    end
   end
   -- flower billboards live outside the terrain mesh (they draw after the
   -- characters, pulled -- see render), but the sun still sees them: a
@@ -825,8 +842,10 @@ local function castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh,
   ShadowMap.draw(ChunkMesher.flowers(state.map), atlasFor(state.map),
                  ShadowMap.snug(nil))
   for _, nb in ipairs(state.neighbors or {}) do
-    ShadowMap.draw(ChunkMesher.flowers(nb.map), atlasFor(nb.map),
-                   ShadowMap.snug(Mat4.translate(nb.ox, 0, nb.oy)))
+    if ViewBox.showsMap(nb) then
+      ShadowMap.draw(ChunkMesher.flowers(nb.map), atlasFor(nb.map),
+                     ShadowMap.snug(Mat4.translate(nb.ox, 0, nb.oy)))
+    end
   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
@@ -839,9 +858,11 @@ local function castShadows(state, terrain, nbMesh, posed, cx, cy, vw, vh,
     ShadowMap.draw(mesh, atlasFor(state.map), ShadowMap.snug(caster))
   end)
   for _, nb in ipairs(state.neighbors or {}) do
-    eachFigure(nb.map, nb.ox, nb.oy, function(mesh, _, caster)
-      ShadowMap.draw(mesh, atlasFor(nb.map), ShadowMap.snug(caster))
-    end)
+    if ViewBox.showsMap(nb) then
+      eachFigure(nb.map, nb.ox, nb.oy, function(mesh, _, caster)
+        ShadowMap.draw(mesh, atlasFor(nb.map), ShadowMap.snug(caster))
+      end)
+    end
   end
   for _, p in ipairs(posed) do
     local def = p.sprite.def
@@ -960,6 +981,25 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor, eyes)
     cx, cy = eyes.cx, eyes.cy
   end
 
+  -- and the ORBIT RUNGS' own viewport (lib/ViewBox): the flat screen's
+  -- answer to the same question the diorama's box asks -- the map cut to
+  -- the window that frames it, so a tilted world reads as a model with
+  -- sides rather than a map running off every edge. Flat frames only: a
+  -- headset's cut is Diorama's above, and the two must never both be live.
+  --
+  -- After the first-person block, so the box is centred on the camera
+  -- actually in charge and opens out with a dive into a head rather than
+  -- vanishing on the frame the rung changed.
+  --
+  -- Ahead of castShadows, deliberately: the sun draws the same neighbours
+  -- the eye does (both ask ViewBox.showsMap), so a map skipped out here is
+  -- skipped out there and nothing is left casting a shadow it cannot own.
+  if not eyes then
+    Voxel3D.cull = ViewBox.frame(cx, cy, vw, vh)
+  else
+    ViewBox.stop()
+  end
+
   -- A staged fight, seen by the VR eyes: the flat screen draws the battle
   -- SCREEN while one is up (this pass never runs), but the headset keeps
   -- looking at the world, so the world had better have the fight on it.
@@ -990,9 +1030,14 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor, eyes)
   local function drawScene()
 
   Voxel3D.draw(terrain, atlasFor(state.map), nil)
+  -- the window box's coarse cut, exactly as the sun pass took it: the same
+  -- test on the same maps, so the light and the eye can never disagree
+  -- about which neighbours are in this frame (see ViewBox.showsMap)
   for i, nb in ipairs(state.neighbors or {}) do
-    Voxel3D.draw(nbMesh[i], atlasFor(nb.map),
-                 Mat4.translate(nb.ox, 0, nb.oy))
+    if ViewBox.showsMap(nb) then
+      Voxel3D.draw(nbMesh[i], atlasFor(nb.map),
+                   Mat4.translate(nb.ox, 0, nb.oy))
+    end
   end
 
   -- Without a shadow map (headless, or a driver that could not make the
@@ -1024,7 +1069,7 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor, eyes)
     waterDraws[#waterDraws + 1] = { water, atlasFor(state.map), nil }
   end
   for i, nb in ipairs(state.neighbors or {}) do
-    if nbWater and nbWater[i] then
+    if nbWater and nbWater[i] and ViewBox.showsMap(nb) then
       waterDraws[#waterDraws + 1] = { nbWater[i], atlasFor(nb.map),
                                       Mat4.translate(nb.ox, 0, nb.oy) }
     end
@@ -1143,8 +1188,10 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor, eyes)
   local pull = VoxelScene.pull(lean)
   Voxel3D.draw(ChunkMesher.grass(state.map), atlasFor(state.map), nil, pull)
   for _, nb in ipairs(state.neighbors or {}) do
-    Voxel3D.draw(ChunkMesher.grass(nb.map), atlasFor(nb.map),
-                 Mat4.translate(nb.ox, 0, nb.oy), pull)
+    if ViewBox.showsMap(nb) then
+      Voxel3D.draw(ChunkMesher.grass(nb.map), atlasFor(nb.map),
+                   Mat4.translate(nb.ox, 0, nb.oy), pull)
+    end
   end
   -- flower billboards: pulled like the characters and the grass, MINUS
   -- the depth of 8 world pixels along the view (8 sin a -- the camera
@@ -1162,9 +1209,11 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor, eyes)
   Voxel3D.draw(ChunkMesher.flowers(state.map), atlasFor(state.map), nil,
                fpull, ShadowMap.snug(nil))
   for _, nb in ipairs(state.neighbors or {}) do
-    Voxel3D.draw(ChunkMesher.flowers(nb.map), atlasFor(nb.map),
-                 Mat4.translate(nb.ox, 0, nb.oy), fpull,
-                 ShadowMap.snug(Mat4.translate(nb.ox, 0, nb.oy)))
+    if ViewBox.showsMap(nb) then
+      Voxel3D.draw(ChunkMesher.flowers(nb.map), atlasFor(nb.map),
+                   Mat4.translate(nb.ox, 0, nb.oy), fpull,
+                   ShadowMap.snug(Mat4.translate(nb.ox, 0, nb.oy)))
+    end
   end
 
   -- The map's atmosphere -- god rays down from the invisible canopy, and
@@ -1208,10 +1257,11 @@ function VoxelScene.render(state, w, h, vw, vh, paletteFor, eyes)
 
   end   -- drawScene
 
-  -- the two diorama fields are this function's for the length of this
+  -- the viewport fields are this function's for the length of this
   -- function, whichever way it leaves (see where they are set)
   local function done(result)
     Voxel3D.cull, Voxel3D.keyColor = nil, nil
+    ViewBox.stop()
     return result
   end
 

lib/Water.lua

@@ -463,26 +463,27 @@ uniform float pxAngle;       // radians of view one screen pixel subtends
 // sample to get back to the screen. Declared in both stages, like `vp`, and
 // both are highp here.
 uniform vec3 curve;          // xy = the focus in world XZ, z = k; 0 = off
-// The diorama's viewport, exactly as the scene shader takes it: centre in
-// world pixels, then half-size / one-over-fade / kind (0 off, 1 box, 2
-// ball, 3 the staged fight's pillar). Water is world like anything else,
-// and a lake left lying outside the model would be the one thing floating
-// in the sky.
+// The viewport, exactly as the scene shader takes it: centre in world
+// pixels, then half-size / one-over-fade / kind (0 off, 1 box, 2 ball, 3
+// the staged fight's pillar), plus the box's two half-extents. Water is
+// world like anything else, and a lake left lying outside the model would
+// be the one thing floating in the sky.
 uniform vec3 cullAt;
 uniform vec3 cullShape;
+uniform vec2 cullRect;
 
 float dioramaCull(vec3 p) {
   if (cullShape.z <= 0.5) return 1.0;
   vec3 cd = p - cullAt;
-  float d;
+  float inside;
   if (cullShape.z < 1.5) {
-    d = max(abs(cd.x), abs(cd.z));
+    inside = min(cullRect.x - abs(cd.x), cullRect.y - abs(cd.z));
   } else if (cullShape.z < 2.5) {
-    d = length(cd);
+    inside = cullShape.x - length(cd);
   } else {
-    d = length(cd.xz);
+    inside = cullShape.x - length(cd.xz);
   }
-  return clamp((cullShape.x - d) * cullShape.y, 0.0, 1.0);
+  return clamp(inside * cullShape.y, 0.0, 1.0);
 }
 
 // How far the bend has pushed the world down at world XZ `q` -- the vertex
@@ -1274,12 +1275,15 @@ function Water.begin(ctx)
   send("vp", "row", ctx.vp)
   send("eye", ctx.eye)
   send("curve", ctx.curve)
-  -- the diorama's viewport, as beginScene sent it to the scene shader;
-  -- kind 0 -- every frame that is not a headset's diorama -- is "no cut"
+  -- the viewport, as beginScene sent it to the scene shader; kind 0 --
+  -- every frame neither the diorama nor the orbit's box has cut -- is
+  -- "no cut"
   local cull = V.require("Voxel3D").cull
   send("cullAt", cull and { cull.x, cull.y, cull.z } or { 0, 0, 0 })
   send("cullShape", cull and { cull.r, cull.invFade, cull.kind }
                     or { 0, 0, 0 })
+  send("cullRect", cull and { cull.rx or cull.r, cull.rz or cull.r }
+                   or { 0, 0 })
   send("screen", { ctx.screen[1], ctx.screen[2] })
   send("cell", math.max(1, ctx.cell or 1))
   -- how much of the view one screen pixel is worth: what sets the relief