Device
- Device::Initialize(required, optional) takes DeviceFeatures, the five
core feature structs vulkan10 to vulkan14. The library enables only what
its own shaders and code use. Device::enabledFeatures says what was
enabled, supportedFeatures what the GPU has, apiVersion the version in
use.
- shaderInt16, shaderFloat16, storageBuffer16BitAccess, scalarBlockLayout
and the uniform-buffer, storage-buffer and storage-image non-uniform
indexing bits are no longer enabled for everyone. An application whose
shaders take uint16_t spec constants passes
{.vulkan10 = {.shaderInt16 = VK_TRUE}}. scalarBlockLayout stays on with
the NVIDIA workaround, whose TLAS address may sit in a struct's tail
padding.
- Every GPU is weighed before one is chosen: Vulkan 1.3, the swapchain and,
below 1.4, maintenance5 extensions, the library's needs, the required
features. One that can't run the application is skipped, saying why when
it ranks higher. A CPU device runs it only when nothing else is listed,
and CRAFTER_GRAPHICS_DEVICE never falls back. A GPU two drivers both list
is tried through each.
- When no GPU qualifies, Initialize throws naming each GPU's gaps. It
destroys the instance it made, before any Wayland connection, so it can
be called again asking for less.
- maintenance5 is vulkan14's on a 1.4 GPU and VK_KHR_maintenance5's below.
CRAFTER_GRAPHICS_NO_VULKAN_1_4 runs as a 1.3 application, to exercise
that path on a 1.4 GPU.
- VK_KHR_spirv_1_4 and VK_KHR_shader_float_controls, core since 1.2, are no
longer enabled, nor VK_EXT_shader_atomic_float, which was enabled without
its feature struct. memoryDecompression's feature bit is queried before
it is enabled.
Shaders
- VulkanShader checks a module's capabilities, declared directly or
implicitly, against the enabled core features, the GPU's subgroup
operations and the optional groups, and throws naming the field to pass,
or saying the GPU lacks it. The tables are generated from vk.xml and
SPIR-V's grammar.
- WorkaroundNvidiaAS::Patch sized a row-major matrix push member by its
columns, so the TLAS address could land inside it.
Window
- The swapchain format is one whose own feature flags allow storage reads
and writes without a format, which since Vulkan 1.3 each format says for
itself; shaderStorageImageRead/WriteWithoutFormat are no longer required.
Tests
- DeviceFeatures: ResolveFeatures, ChooseDevice and CheckShaderCapabilities,
without a GPU.
- FeatureRequests: required and optional features end to end, the 1.3
path, and a retry after a refusal.
- PushConstantRewrite: a row-major mat3x4 push member.
- HeapASRead, HeapDynamicIndexHit, RTPassPushData and the ray-tracing
examples ask for the features their shaders use.
Co-Authored-By: Claude Opus 5.5 <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>
Adds tests/PushConstantRewrite, a host test that compiles representative
ray-generation shaders with glslang, runs the real WorkaroundNvidiaAS::Patch
over them, and asserts with spirv-val (the same invocation vkCreateShaderModule
uses) that the result is valid and contains exactly one push-constant block —
covering both the merge path (shaders that already declare a push constant,
including mat4/vec3/uint, a lone uint, and an array layout) and the synthesize
path, plus a no-op case (push constant but no AS read). It also checks the
published TLAS push offset for each layout.
The workaround namespace is exported so the test can drive Patch directly; both
go away with the rest of the workaround. project.cpp wires the test as an
executable that recompiles the module and requires glslang + spirv-val.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
