Indexing a `layout(descriptor_heap)` array with a runtime (non-constant)
index inside a ray-tracing hit shader device-losts on NVIDIA 610.43.02,
for both SSBO and sampled-image descriptors. A constant/spec-constant
index is fine, and the same dynamic pattern works in fragment shaders, so
it's an RT-stage-specific driver fault — the same family as #7/#15
(descriptor-heap AS reads) and #21/#22 (RT recursion + compute TLAS push).
Unlike the AS-read fault, this cannot be worked around transparently: a
sampled image has no device-address escape hatch the way an acceleration
structure does (OpConvertUToAccelerationStructureKHR), and a buffer-only
buffer_reference rewrite would need a whole address-table architecture
while still leaving the texture half broken. So the resolution is the
documented-limitation path (the precedent set by #7).
Records the fault and its isolation in README's Native RT status and in
the Sponza example README (the textured-closest-hit example, which already
reads its albedo through a spec-constant slot for exactly this reason).
Documents the recommended consumer pattern: bind one resource and index
*within* it dynamically (single geometry SSBO / buffer_reference at a
spec-constant slot; one texture2DArray indexed by layer) rather than
selecting a descriptor dynamically — what the WebGPU path already does.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Restructure Sponza for the wavefront model: raygen emits the primary ray;
closesthit (in SHADE) gathers albedo/normal, accumulates ambient, and
emits a shadow ray carrying the pending direct term; miss adds the sky
(primary) or the direct term (shadow miss). resolve.wgsl applies the same
Reinhard+gamma the megakernel raygen did inline. User bindings moved to
group 3 (groups 0..2 reserved). RTPass maxDepth=2.
Renders the atrium correctly through the wavefront pipeline (textures,
two-sided shading, sun+ambient, shadows, tonemap).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
