Add instanced rendering for toping bevels: dedicated shaders
(voxelTopingVS/PS), PSO, GPU buffers (t4 vertices, t5 instances),
per-group DrawInstanced in a separate render pass with LoadOp::LOAD.
Fix inverted face winding (emitTri auto-winding condition flipped for
CW front-facing), slope normals (use inward direction not outward),
and PS lighting (negate sunDirection like voxelPS). Update CLAUDE.md
with Phase 4.1/4.2 documentation.
Compute shader fills indirect args buffer, replacing CPU cull loop.
Single DrawInstancedIndirectCount renders all visible face groups.
Key fixes:
- Compute shader: pack chunkIndex|(faceIndex<<16) in push constant,
startVertexLocation=0 (aligned with Phase 2.2 SV_VertexID fix)
- PushConstants must be called AFTER BindPipelineState, not before.
Wicked Engine dispatches to SetGraphicsRoot32BitConstants only when
active_pso is set; after BindComputeShader it targets compute instead.
- Barriers: UNDEFINED(COMMON)→UAV before compute, UAV→INDIRECT_ARGUMENT after
- Buffer decay: DX12 buffers always return to COMMON between frames,
no cross-frame state tracking needed
Replace per-chunk DrawInstanced loop with a single DrawInstancedIndirectCount.
CPU fills indirect args buffer with same frustum+backface cull logic as Phase 2.1.
Key discoveries:
- Wicked Engine command signature includes push constant (20-byte stride, not 16)
- SV_VertexID does not reliably include startVertexLocation with ExecuteIndirect
- Solution: pack chunkIndex|(faceIndex<<16) in push constant, VS reconstructs
quad offset from GPUChunkInfo lookup
- No explicit DX12 barriers needed (implicit promotion from COMMON suffices)
Also adds voxel_engine_spec.md and updates references from .docx to .md.
Mega-buffer architecture replacing per-chunk GPU buffers:
- Single StructuredBuffer<PackedQuad> for all chunks (2M quads, 16 MB)
- StructuredBuffer<GPUChunkInfo> with per-chunk metadata (position, quad offsets, face groups)
- VS reads chunk info via push constants (b999) for driver-safe chunk indexing
- CPU frustum culling with wi::primitive::Frustum + AABB per chunk
- Quads sorted by face direction in greedy mesher (faceOffsets/faceCounts)
- GPU frustum + backface cull compute shader (voxelCullCS.hlsl)
- GPU binary mesher compute shader baseline (voxelMeshCS.hlsl)
- Indirect draw buffers and timestamp query infrastructure
- README with build instructions and project architecture
