webgpu demo

shaders/miss.wgsl

@@ -0,0 +1,14 @@
+// RTMultiShadow miss (runs in SHADE). Shadow miss → that light is visible
+// from the surface, so add its pending contribution; up to LIGHT_COUNT of
+// these resolve for the same pixel in one pass (atomic rtAccumulate, #30).
+// Primary miss → near-black night sky so the colored lighting carries the
+// frame.
+fn miss_main(ray: RayDesc, payload: ptr<function, Payload>) {
+    if ((*payload).shadowRay == 1u) {
+        rtAccumulate((*payload).color);
+        return;
+    }
+    let t = clamp(ray.direction.y * 0.5 + 0.5, 0.0, 1.0);
+    rtAccumulate(mix(vec3<f32>(0.010, 0.012, 0.022),
+                     vec3<f32>(0.030, 0.040, 0.075), t));
+}