webgpu triangle

interfaces/Crafter.Graphics-Mesh.cppm

@@ -60,3 +60,54 @@ export namespace Crafter {
     };
 }
 #endif // !CRAFTER_GRAPHICS_WINDOW_DOM
+
+#ifdef CRAFTER_GRAPHICS_WINDOW_DOM
+import std;
+import Crafter.Math;
+import :WebGPU;
+
+export namespace Crafter {
+    // Software-RT BLAS node, packed to 32 bytes. Matches the WGSL
+    // `BVHNode` struct in the RT WGSL prelude (additional/dom-webgpu.js,
+    // rtWgslPrelude) byte-for-byte.
+    //
+    //   primCount == 0          → inner node, children at indices
+    //                             firstChildOrPrim and firstChildOrPrim+1.
+    //   primCount  > 0          → leaf, `primCount` primitives starting at
+    //                             primIndex `firstChildOrPrim` in the
+    //                             global primRemap heap.
+    //
+    // SAH-built BVH2; constructed CPU-side at Build() time, never refit.
+    struct BVHNode {
+        float         aabbMin[3];
+        std::uint32_t firstChildOrPrim;
+        float         aabbMax[3];
+        std::uint32_t primCount;
+    };
+    static_assert(sizeof(BVHNode) == 32);
+
+    class Mesh {
+        public:
+        // BLAS "handle": opaque identity that goes into
+        // RTInstance::accelerationStructureReference. Set by Build() to a
+        // stable u32 (widened to u64 for Vulkan-struct layout parity), used
+        // by the WebGPU TLAS-build compute shader to look up the BLAS root
+        // AABB and per-mesh heap offsets. Handle 0 is the unassigned
+        // sentinel; never returned by Build().
+        std::uint64_t blasAddr = 0;
+        std::uint32_t triangleCount = 0;
+
+        bool opaque = true;
+
+        // Build BLAS from raw triangle data. Runs the CPU SAH BVH2 builder
+        // and forwards vertex/index/BVH/remap arrays to the JS-side mesh
+        // heap (additional/dom-webgpu.js), which queue.writeBuffers them
+        // into the global heaps and records the per-mesh offsets keyed by
+        // the returned handle. The `cmd` parameter is unused on WebGPU —
+        // kept for API symmetry with the Vulkan signature.
+        void Build(std::span<Crafter::Vector<float, 3, 3>> vertices,
+                   std::span<std::uint32_t>                indices,
+                   WebGPUCommandEncoderRef                  cmd = 0);
+    };
+}
+#endif // CRAFTER_GRAPHICS_WINDOW_DOM