Use flat arrays for BLAS traversal (fix Metal pointer-in-buffer issue)#13
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SimonDanisch merged 1 commit intoJuliaGeometry:sd/multitype-vecfrom Mar 2, 2026
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On Metal, device pointers (Core.LLVMPtr) stored inside GPU buffers cannot be reliably dereferenced by kernels. The inline data (root_aabb) reads correctly, but following embedded pointers to per-BLAS node/primitive arrays returns zeros. Replace the pointer-based BLAS architecture in StaticTLAS with: - BLASDescriptor: lightweight struct with nodes_offset, primitives_offset, root_aabb - Flat concatenated arrays (all_blas_nodes, all_blas_prims) built from per-BLAS GPU arrays - Offset-based indexing in closest_hit/any_hit traversal Management kernels (update_tlas_leaf_aabbs_kernel!, etc.) still use blas_array but only read root_aabb (inline, unaffected). Verified: CPU and Metal produce identical results (mean pixel ~0.327 on 3-sphere test scene). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
Core.LLVMPtr) stored inside GPU buffers cannot be reliably dereferenced by kernels — inline data reads correctly but following embedded pointers returns zerosStaticTLASwith flat concatenated arrays (all_blas_nodes,all_blas_prims) andBLASDescriptorstructs containing offsetsclosest_hitandany_hitnow use offset-based indexing instead of dereferencing per-BLAS pointer arraysblas_arraybut only readroot_aabb(inline data, unaffected)How these changes were tested
Created with the help of Claude Code