Fry3DX 0.4: an easy 3D modeller

Shapes with live settings, shape editing, knife and hole tools, drawing
shapes onto other objects, combining objects (add / subtract / overlap),
copies, thickness, painting with stickers and layers, a Layout tab, a
Print tab with checks, packed .fry files with autosave, export to GLB,
glTF, FBX, OBJ, 3MF, STL and PLY, folders in Layers, its own crash
screen, and a website for GitHub Pages in docs/.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NMSrd5oe1GpUD7E6d825KP

engine/shaders/froxel.glsl

@@ -0,0 +1,30 @@
+// The fog grid ("froxels", as in Frostbite / id Tech): kFroxels cells over the screen and along
+// the view, slices spaced exponentially from FRAME.froxel.y to .z. froxel.comp fills it; entry k
+// of a column holds the light the fog adds (rgb) and how much of what's behind gets through (a)
+// from the eye to the far side of slice k.
+const uvec3 kFroxels = uvec3(160, 90, 64);
+uint froxelIndex(uvec3 c) { return (c.z * kFroxels.y + c.y) * kFroxels.x + c.x; }
+// Where slice boundary j lies (view depth); slice k spans boundaries k and k + 1.
+float froxelBoundary(float j) { return FRAME.froxel.y * pow(FRAME.froxel.z / FRAME.froxel.y, j / float(kFroxels.z)); }
+float froxelSlice(float depth) { return log(max(depth, 1e-3) / FRAME.froxel.y) / log(FRAME.froxel.z / FRAME.froxel.y) * float(kFroxels.z); }
+
+#ifndef KEEL_FROXEL_WRITER
+vec4 froxelEntry(ivec2 xy, int z) {
+    uvec2 v = FRAME.froxels.f[froxelIndex(uvec3(clamp(xy, ivec2(0), ivec2(kFroxels.xy) - 1), clamp(z, 0, int(kFroxels.z) - 1)))];
+    return vec4(unpackHalf2x16(v.x), unpackHalf2x16(v.y));
+}
+vec4 froxelColumn(ivec2 xy, float c) { // c: entry index, fractional
+    if (c < 0.0) return mix(vec4(0.0, 0.0, 0.0, 1.0), froxelEntry(xy, 0), clamp(c + 1.0, 0.0, 1.0));
+    int z = int(c);
+    return mix(froxelEntry(xy, z), froxelEntry(xy, z + 1), c >= float(kFroxels.z - 1) ? 0.0 : fract(c));
+}
+// The fog between the eye and a point at uv on screen, depth along the view: (light, transmittance).
+vec4 froxelFog(vec2 uv, float depth) {
+    vec2 g = uv * vec2(kFroxels.xy) - 0.5;
+    ivec2 b = ivec2(floor(g));
+    vec2 f = g - vec2(b);
+    // Entry k ends at boundary k + 1; nearer than the first slice's far side fades in from nothing.
+    float c = max(froxelSlice(depth) - 1.0, -1.0);
+    return mix(mix(froxelColumn(b, c), froxelColumn(b + ivec2(1, 0), c), f.x), mix(froxelColumn(b + ivec2(0, 1), c), froxelColumn(b + ivec2(1, 1), c), f.x), f.y);
+}
+#endif