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Regression test for the procedural BLAS path: the same 3x3x3 grid of unit-box AABBs runs through a PROCEDURAL_HIT_GROUP_KHR group whose GLSL intersection shader (reportIntersectionEXT) turns each box into a radius-1 sphere, the any-hit shader punches the spherical-checkerboard cut-out (visible proof non-opaque geometry runs any-hit), and the closest-hit shades per-instance tints — the WebGPU example behavior reproduced natively. Fixed camera in raygen.glsl; the WebGPU/DOM path is unchanged. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
36 lines
1.4 KiB
Markdown
36 lines
1.4 KiB
Markdown
# RTVolume
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Ray tracing of **procedural (AABB) geometry** with an **any-hit** cut-out
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on both backends — software WebGPU (issue #13) and native Vulkan hardware
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RT (issue #33).
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A 3×3×3 grid of unit boxes is registered as an AABB BLAS
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(`Mesh::BuildProcedural` — `VK_GEOMETRY_TYPE_AABBS_KHR` on Vulkan, the
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software AABB-leaf path on WebGPU). The hit group is procedural
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(`RTShaderGroupType::ProceduralHitGroup` /
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`VK_RAY_TRACING_SHADER_GROUP_TYPE_PROCEDURAL_HIT_GROUP_KHR`) carrying:
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- `intersection.wgsl` / `intersection.glsl` — analytic ray–sphere test that
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turns each box into a radius-1 sphere (runs once per box the ray enters);
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- `anyhit.wgsl` / `anyhit.glsl` — ignores the intersection for half the
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cells of a spherical checkerboard, so the ray passes through and the
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background / spheres behind show through (the visible proof any-hit runs);
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- `closesthit.wgsl` / `closesthit.glsl` — normal-based Lambert shading,
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tinted per instance.
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The geometry is registered **non-opaque** and the instances clear their
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force-opaque flag, which is what lets the any-hit shader run. Flip the
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instance flag to `kRTGeometryInstanceForceOpaque` (or build the mesh with
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`opaque = true`) to skip any-hit and see solid spheres.
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WebGPU/DOM (free camera, WASD + mouse):
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```
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crafter-build --target=wasm32-wasip1 -r
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```
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Native Vulkan (fixed camera in raygen.glsl):
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```
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crafter-build -r
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```
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