Device::Initialize required twelve device extensions with no capability
check. Mesa Turnip (Adreno) lacks six of them: VK_EXT_descriptor_heap,
VK_KHR_shader_untyped_pointers, VK_EXT_device_fault and the three ray
tracing extensions. vkCreateDevice failed there, so not even a UI-only
program could start, although the UI path is compute-only and needs
nothing else that Turnip is missing.
The descriptor heap, ray tracing and device fault are now optional
groups, detected at start-up from the extension list and the feature
bits (Device::descriptorHeapSupported, rayTracingSupported,
deviceFaultSupported). Ray tracing needs the heap; on a device without
it the ray tracing entry points throw a message naming the cause.
Without the heap the same bindless slots live in one update-after-bind
descriptor set per frame, owned by DescriptorHeapVulkan: binding 0
storage images, 1 sampled images, 2 samplers, 3 storage buffers. Slot
allocation, the slot handles, UIDispatchHeader and the UIRenderer API
are unchanged; buffer slots simply stop being offset. Window::Render
binds that frame's set where it binds the heap, every compute pipeline
shares the heap object's pipeline layout, and push data travels as push
constants.
Each UI kernel is built twice from one source. ui-shared.glsl declares
its resources through UI_HEAP_* macros that expand to descriptor_heap
or, with CRAFTER_GRAPHICS_DESCRIPTOR_SETS defined, to set/binding.
<name>.comp.spv and <name>.comp.sets.spv ship side by side and
ComputeShader::Load picks one. The heap build of every shader is
byte-identical to before.
Breaking:
- ComputeShader::Load takes the heap as a second argument.
- DescriptorHeapVulkan is no longer copyable or movable.
- Custom UI shaders declare heap resources with the UI_HEAP_* macros
and are registered twice in project.cpp (see the README).
- project.cpp uses Shader::defines and Shader::variant, so it needs a
crafter-build that has them (Crafter.Build master, fe38cc1 or later).
Also:
- maintenance5 is enabled as a feature, not only as an extension:
every VulkanBuffer already relied on VkBufferUsageFlags2CreateInfo.
- Barrier stage masks drop RAY_TRACING_SHADER on devices without ray
tracing, and ImageVulkan::Create resolves its default consumer stage
to COMPUTE_SHADER there.
- Window refuses a swapchain whose image count is not numFrames
instead of writing past images[]. The limitation itself is #160.
- CRAFTER_GRAPHICS_NO_DESCRIPTOR_HEAP forces the fallback on a driver
that has the heap, so it can be exercised on a desktop GPU.
Verified on an RTX 4090 in both modes under the validation layer, and
on a Fairphone 6 (Turnip, Adreno 810, postmarketOS), where the fallback
is the only path.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Two gaps in the Vulkan RT path that fault the device on the NVIDIA
proprietary driver with a non-trivial pipeline (simple VulkanTriangle
never hit them):
1. maxPipelineRayRecursionDepth was hardcoded to 1, so any closest-hit
shader that traces a secondary ray (shadow ray — a very common
pattern) recursed past the pipeline limit (UB → device fault).
PipelineRTVulkan::Init now takes a maxRecursionDepth parameter
(default 1, clamped to the device's maxRayRecursionDepth).
2. The NVIDIA descriptor-heap AS-read workaround rewrites every shader
that reads an accelerationStructureEXT from the heap — including
compute shaders — to read the TLAS device address from a push
constant, but only RTPass pushed that address. A compute shader that
ray-queries the TLAS (rayQueryEXT) therefore ran against an unwritten
push slot → garbage AS handle → VK_ERROR_DEVICE_LOST.
WorkaroundNvidiaAS::Patch now returns a per-shader PatchResult
{patched, tlasPushOffset} instead of writing the clobber-prone global
Device::workaroundTlasPushOffset (removed). VulkanShader stores it;
ShaderBindingTableVulkan/PipelineRTVulkan carry it for RTPass, and
ComputeShader tracks its own offset and pushes the caller-supplied
TLAS address in Dispatch (new defaulted tlasAddress parameter),
mirroring RTPass::Record.
The PushConstantRewrite regression test now asserts Patch's returned
patched/offset and adds two ray-querying compute-shader cases, proving
the rewrite is stage-agnostic and the per-shader offset is correct.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The NVIDIA descriptor-heap AS-read workaround (#15) rewrote heap
acceleration-structure reads into a load of the TLAS device address from
a push-constant block. It always *synthesized a new* push-constant block,
so any ray-tracing shader that already declared one ended up with two —
which SPIR-V forbids ("at most one push constant block statically used per
entry point"), and vkCreateShaderModule's spirv-val check rejected:
Entry point id '4' uses more than one PushConstant interface.
WorkaroundNvidiaAS::Patch now detects an existing PushConstant variable and,
when present, appends a single ulong member (the TLAS address) to that
block instead of adding a second one, reading the address through the
shader's own push-constant variable. The append offset is the end of the
user's block, computed from the members' explicit Offset/ArrayStride/
MatrixStride decorations (correct under both scalar and std140 layout) and
rounded up to 8. Shaders with no push constant of their own keep getting a
freshly synthesized single-member block at offset 0, exactly as before.
That offset is published via Device::workaroundTlasPushOffset and RTPass
feeds it to vkCmdPushDataEXT so the address lands where the rewritten load
reads it (0 for the synthesized case, preserving prior behaviour).
Verified on the affected driver (NVIDIA 610.43.02, RTX 4090): VulkanTriangle
ray-traces correctly and validation-clean both with and without a
user-declared raygen push constant.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Reading an acceleration structure through VK_EXT_descriptor_heap aborts
with VK_ERROR_DEVICE_LOST on NVIDIA 610.43.02 — a brand-new-extension
driver fault isolated in #7 (engine setup is correct and validation-clean;
images/buffers through the same heap work, and both traceRayEXT and inline
rayQuery fault identically on the AS read).
An acceleration structure can equally be reached by its device address via
OpConvertUToAccelerationStructureKHR, which reads no descriptor and so never
touches the faulting heap path. glslang has no GLSL spelling for that
conversion, so VulkanShader rewrites the compiled SPIR-V at module-load
time: every `OpLoad %accelStruct <heap-ptr>` becomes a load of the TLAS
device address from a synthesized push-constant block followed by the
convert. RTPass pushes the active frame's TLAS address into that push
constant. User GLSL and example code are unchanged; acceleration structures
still bind into the heap normally.
The workaround is gated on Device::workaroundDescriptorHeapAS (true only on
the NVIDIA proprietary driver) and confined to one fenced block in
Crafter.Graphics-ShaderVulkan.cppm plus the RTPass push and the shaderInt64
feature toggle — delete those once a fixed NVIDIA driver ships and the heap
AS read becomes the direct path again.
Verified: VulkanTriangle ray-traces correctly on native NVIDIA (RTX 4090),
validation-layer-clean, no device loss. The SPIR-V rewrite was independently
validated with spirv-val on both the VulkanTriangle and Sponza raygen
modules.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
