931500ddc3
WebGPUBuffer::EnqueueReadback / PollReadback always copied the full buffer `size` GPU→staging→wasm. Over-provisioned event-queue buffers (e.g. Forts3D's GPU physics event drain) paid the full-capacity copy every drain even when only a small live prefix held data. Add an optional `byteCount` parameter (default 0 = whole buffer, so the existing full-buffer callers are unchanged) bounding the readback to the live prefix. Pass the same byteCount to the paired PollReadback so the matching number of bytes lands in `.value`. JS bridge: the staging buffer is now sized to the full device-buffer capacity (not the first call's byteSize) so a varying prefix length never overflows it, while the copyBufferToBuffer + mapAsync/getMappedRange are bounded to the requested prefix — that's where the copy saving lands. Verified end-to-end in the browser via RayQueryPick: the full readback still resolves correctly, and a follow-up 8-byte prefix read copies only hit+customIndex while primitiveIndex keeps its poison sentinel, proving the copy was bounded. Native `crafter-build test` suite: 24 passed. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> |
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|---|---|---|
| .. | ||
| closesthit.wgsl | ||
| main.cpp | ||
| miss.wgsl | ||
| project.cpp | ||
| raygen.wgsl | ||
| rayquery_pick.wgsl | ||
| README.md | ||
| resolve.wgsl | ||
RayQueryPick
Regression test for the WebGPU software ray-query shim
(additional/dom-webgpu.js, _rqTraverseTlas).
Builds an 8³ = 512-instance TLAS and shoots one fully-determined ray
through a rayQuery=true PlainComputeShader. The committed hit is read
back to the host and checked against the analytically-known answer
(instance customIndex = 484, t = 40.75). On success the console prints:
[RayQueryPick] result: hit=1 customIndex=484 prim=6 t=40.75
[RayQueryPick] PASS — rayQuery TLAS traversal hit the expected instance
Why 512 instances
The TLAS sweep tree is padded to next_pow2(instanceCount) leaves. The
rayQuery shim used to detect BVH leaves with a hardcoded 16384 - 1 leaf
start, so for any scene with fewer than 8193 instances no node index
ever reached a leaf and every pick missed (issue #25). 512 sits squarely
in that broken regime, so this example fails fast if the shim regresses to
a static leaf start. The shim now derives the leaf start from a per-build
RqTlasMeta.nPadded uniform, matching the megakernel _rtwTraverseTlas.
The scene also renders through the wavefront RT pipeline (same as RTStress) so the run produces a visible frame, but the pass/fail signal is the console line above.
cd examples/RayQueryPick
crafter-build -r --target=wasm32-wasip1
WebGPU/DOM only — the native path uses hardware ray queries.