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/smoke_sky.frag

@@ -0,0 +1,30 @@
+#version 460
+// Smoke in front of the sky (Vulkan): the sky pass has no fog (its photo has its own haze), so
+// smoke against open sky is laid over it here, from the fog grid's smoke-only column totals
+// (froxel_main.glsl: light, and how much of what's behind gets through). Drawn on the far plane
+// after the sky, where nothing else is: colour × through + light.
+#include "backend.glsl"
+#define KEEL_FRAME_ONLY
+#include "model.glsl"
+layout(buffer_reference, std430) readonly buffer SmokeSky { uvec2 f[]; };
+PUSH_BLOCK {
+    FrameData frame;
+    SmokeSky sky; // 160 × 90 (the fog grid's columns)
+} pc;
+#define FRAME pc.frame
+layout(location = 0) in vec2 v_ndc;
+layout(location = 0) out vec4 o_color;
+
+const ivec2 kCols = ivec2(160, 90);
+vec4 column(ivec2 c) {
+    uvec2 v = pc.sky.f[clamp(c.y, 0, kCols.y - 1) * kCols.x + clamp(c.x, 0, kCols.x - 1)];
+    return vec4(unpackHalf2x16(v.x), unpackHalf2x16(v.y));
+}
+
+void main() {
+    vec2 g = gl_FragCoord.xy / FRAME.screen.xy * vec2(kCols) - 0.5;
+    ivec2 b = ivec2(floor(g));
+    vec2 f = g - vec2(b);
+    vec4 s = mix(mix(column(b), column(b + ivec2(1, 0)), f.x), mix(column(b + ivec2(0, 1)), column(b + ivec2(1, 1)), f.x), f.y);
+    o_color = vec4(s.rgb, s.a); // (blended: src + dst × src.a)
+}