The atlas packed glyphs onto shelves and never gave a place back (#55).
Once its 1024x1024 image was full, EnsureAndGet returned nullptr for each
new glyph before caching anything, so every new string holding one
rasterised it again, and ShapeText dropped it together with its advance:
the rest of the line closed up over the gap, and stayed that way.
FontAtlas
- A glyph is measured, not rasterised, until it gets a cell. One that
finds no free room keeps its advance and box and draws blank for a
frame. EnsureAndGet always returns the glyph, now a reference;
Glyph::Resident() says whether it has a cell, Glyph::handle which one
(slot and generation).
- Evictions wait for the next frame: its first EnsureAndGet, Touch or
Update places the glyphs that waited, once every glyph the frame before
drew has been marked. Evicting while a frame is still asking for glyphs
took ones it drew further down, which then took others in turn: a page
switched back to could rasterise most of itself again rather than what
it was missing, and on the DOM backend an over-full view could do so
every frame.
- A glyph keeps its cell for framesInFlight + 1 frames after it was drawn.
The frame loop waits frame u's fence at the start of frame
u + framesInFlight, but Device::frameCounter reads that from the end of
the frame before, and input callbacks and onBeforeUpdate run in between.
- FontAtlas::Packer places glyphs. Until the rows run out it fills shelves
exactly as before. Then a glyph takes the same columns of one shelf at
least as tall, or of several in a row as tall together, the free rows
below the last shelf counting as one more: free texels, and, when the
frame begins, glyphs nothing in flight draws, the least recently drawn
first. A glyph spanning shelves lets in one taller than every shelf, and
a few glyphs drawn every frame pin only their columns. Merging whole
shelves instead, tried first, left a random workload without room for a
glyph while a median 43% of the atlas was in flight; spanning, at 65%.
- A box that found no room in a frame is remembered, with every box at
least as big, as a small set per mode, until the frame ends or (without
eviction) something is evicted: a saturated atlas no longer searches
every shelf for each of its missing glyphs.
- An evicted glyph is forgotten, and its texels are zeroed and uploaded
with the glyph that takes its place: a neighbour's filtering at its edge
must read padding or zero, not a stale glyph.
- Touch(handles) marks every glyph whose handle still holds its cell, and
says whether all did. InvalidateFont(font) forgets the font's glyphs and
those waiting for a cell, whose Font* the next frame would read. The
glyph index is looked up at rasterisation, so a Font replaced in place
never gets one past its glyphs. GlyphsRasterized() counts, for tests.
UIRenderer
- A shaped run keeps a handle per glyph it draws. A hit touches them all,
so the atlas keeps what is drawn every frame, and shapes the run again
when one was evicted or one had no room. A glyph without room draws
blank but advances the pen.
- InvalidateFont clears the atlas's glyphs of the font too, as its comment
and AGENTS.md always said it did.
- Record calls the atlas's Update before onBuild, every frame, so the
waiting glyphs are placed and uploaded first. Dispatch uploads the atlas
before any kernel, a Tier 1 one sampling FontAtlasImageSlot() included:
a glyph placed earlier in onBuild can sit in a cell another glyph had.
DispatchText and DispatchFused no longer do it themselves.
Device, Window (DOM)
- Device::frameCounter and Device::framesInFlight exist on the DOM backend
too, the counter bumped at the end of Window::Render, with one frame in
flight: a frame's writeTexture lands before that frame's submit but after
every earlier one.
HelloUI
- One set of item buffers and slots per frame in flight, by frameIdx. A
frame still on the GPU read the items the next frame's onBuild was
rewriting; with cells changing hands, those can name cells it drew other
glyphs in.
Tests
- FontAtlasPacker: the packer with made-up boxes and no device: the fill
order, least recently drawn first, framesInFlight + 1 frames held,
nothing without evict, wide glyphs, tall glyphs spanning shelves and the
free rows, Touch past a stale handle, stale handles, dirty spans, and the
invariants over a random workload placed the way the atlas places.
- FontAtlasEviction: fills the atlas through ShapeText frame by frame. The
line that no longer fits keeps its advance and its glyphs' places; its
missing glyphs aren't rasterised while nothing can go; when only line 0
is cold, only its glyphs give way; a frame's own misses evict nothing in
it; a frame later the line and twenty more are whole, pixel for pixel,
line 0 losing a larger share than the glyphs drawn after it; a stale
cached run is shaped again; no stale texel is left; InvalidateFont
reaches the atlas. Against master, with its two calls to the new API
stubbed out, an earlier version failed ten checks.
- UIDispatchAtlasFlush: a custom ui.Dispatch after ShapeText leaves the
atlas uploaded. Needs a compositor.
- ShapeTextCache: a hit rasterises nothing; after InvalidateFont the
re-shaped run draws the same, from new cells.
Docs
- README and AGENTS.consumer.md: the atlas's eviction, the frame a glyph
waits, shaping text every frame into per-frame item buffers,
InvalidateFont, EnsureAndGet's signature and Lookup's lifetime, and that
the atlas, like the deletion queue, assumes one rendering window and
evicts nothing without one.
- AGENTS.md: FontAtlas::Packer among the pure-logic helpers, eviction
without a Window, and InvalidateFont.
Breaking: FontAtlas::EnsureAndGet returns const Glyph& and never fails;
check Glyph::Resident() before drawing from its UVs. FontAtlas::Touch is
no longer noexcept. A GlyphItem is good for the frame it was shaped for,
once the atlas has filled up, and item buffers must be per frame.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Window
- CreateSwapchain asked for exactly numFrames (3) images whatever the
surface said, read them into a three-element array, and keyed the
command buffers, the fences and the descriptor-heap copy holding "its"
swapchain image by the acquired image index. A swapchain of another
size fell back to FIFO (asked for MAILBOX or IMMEDIATE) or threw, and a
surface whose minimum is above three got a create info below it
(#160). Mesa's MAILBOX needs four images: Turnip on phoc, llvmpipe on
any Wayland compositor.
- The present mode is picked first, then the swapchain is sized by
SwapchainCapabilities: the surface's counts for that mode where the
instance has surface_maintenance1. With swapchain_maintenance1 the
swapchain names its mode (VkSwapchainPresentModesCreateInfoKHR), which
is what makes the mode's own count the one that applies, at creation and
to the forward progress of a UINT64_MAX acquire; without it the stricter
of the mode's and the surface's counts for all modes. It asks for
numFrames or that minimum where more, never past the maximum
(SwapchainMinImageCount). Turnip's FIFO keeps its three images and
MAILBOX gets four. The FIFO fallback and presentModeUnfit are gone.
- images, imageViewInfos (was imageViews: they are create-infos), the made
imageViews that descriptor sets take, imageInitialised and the
render-finished semaphores are per image, as many as the driver made.
The views are made once per swapchain. The semaphores only grow, since
a present of the old swapchain may still wait on one.
- Frames in flight stay numFrames, keyed by currentFrame, frameCounter %
numFrames: the command buffer, the fence, the acquire semaphore, the
heap copy (or set), RenderingElement3D::tlases, the frameIdx a pass is
recorded with. currentImage is the acquired image. currentBuffer is
gone, so code that used it stops compiling instead of picking the wrong
one; RenderPass::Record's frameIdx keeps its name and is now the frame
slot, as RenderPass.cppm says.
- The frame's fence is waited before the acquire. The acquire semaphores
need no spare then, and a frame waits for exactly the one numFrames
before it, which the deletion queue and the staging rings count on and
fences keyed by image did not promise once images come back out of
order. The swapchain slots are written before the fence is reset.
- From the acquire to the present the window is recording: a Resize or
SetPresentMode from a listener (a VSync key ticked in onUpdate) takes
effect after the present, through RebuildSwapchain, together with a
present that found the swapchain out of date. Rebuilding mid-frame used
to destroy the image the frame was drawing into; with images sized per
swapchain it would also index past the new one's end.
DescriptorHeapVulkan
- Frames and images pair up differently from frame to frame, so no heap
copy can keep one swapchain image. AddSwapchainSlot(slot, window) lists
an image slot as that window's swapchain image, and Window::Render
writes the image a frame acquired into its window's listed slots in that
frame's copy, or its set, before onUpdate, skipping a slot that holds it
already. A slot is one window's, so two windows can share a heap without
writing each other's slots under each other's frames in flight. A slot
listed during a frame its window records is written at once. A slot past
the heap's image slots, an empty ImageSlot's 0xFFFF among them, is
refused. Freeing a slot unlists it, as does initialising the heap in
either binding model. WriteImageSet, the one use of which this
replaces, is gone, and with it the per-frame dimension of setImageViews.
Device
- VK_KHR_surface_maintenance1 (or EXT) and VK_KHR_get_surface_capabilities2
are enabled where the loader has them (surfaceMaintenance1Supported,
vkGetPhysicalDeviceSurfaceCapabilities2KHR), and the matching
swapchain_maintenance1 with its feature where the device has it
(swapchainMaintenance1Supported).
- DistinctGpus groups the physical devices by GPU as CRAFTER_GRAPHICS_DEVICE
numbers them, for ChooseGpu and tests.
UI
- UIRenderer lists its output slot instead of writing every copy itself,
and again on every resize; the resize listener is gone on both
backends. The headers' frameIdx is currentFrame.
Examples
- VulkanTriangle, Sponza, SponzaBench and RTVolume list their output slot
and write only the per-frame TLASes. They wrote imageViews[f] into copy
f once, which a resize left pointing at destroyed images.
Tests
- SwapchainImageCount: SwapchainMinImageCount on the numbers drivers
report; every offered mode keeps its mode and gets what the window asks
for; every frame presents the colour it drew, read back a texel per
frame; a switch and a resize asked for during a frame wait for its
present; a slot listed during a frame holds its image at once; two
windows on one heap draw their own colours. The frame checks run again
in child processes, through CRAFTER_GRAPHICS_DEVICE, on a GPU whose
swapchains have more images than frames (this one, else llvmpipe), in
each binding model the parent didn't cover; a child skips only for a GPU
that can't run the library, and checks it runs the model it was asked
for.
- FrameLoopSync checks the frame slot follows the frame counter and counts
the swapchain's own images. HeapASRead, HeapDynamicIndexHit and
RTPassPushData list their swapchain slot and drop their resize rewrites.
Docs
- README, AGENTS.md and AGENTS.consumer.md: frames and images, the
swapchain slots, rebuilds held to the present, the new optional groups.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
DescriptorHeapVulkan
- The buffer region started at images * imageDescriptorSize /
bufferDescriptorSize, rounded down. A descriptor_heap array indexes
the heap from byte 0 in strides of its descriptor size, so buffer slot
0 has to sit on a whole buffer descriptor past the images. Where the
image descriptors were not a whole number of buffer descriptors, the
first buffer descriptors overwrote the last image descriptors. Where
they were less than one, the start was bumped to descriptor 1, but the
heap was still sized as if the buffers began right after the images,
so the last buffer descriptors went into the implementation's reserved
range. Every descriptor size is a power of two, so both cases need
image descriptors smaller than buffer descriptors, which NVIDIA (32
and 16 bytes) and llvmpipe (64 and 16) do not have. The start now
rounds up and the heap is sized from it (#163).
- The reserved range sat at a multiple of imageDescriptorAlignment only,
where vkCmdBindResourceHeapEXT also wants bufferDescriptorAlignment
(VUID-vkCmdBindResourceHeapEXT-pBindInfo-11435 and -11436). It now
starts on a multiple of the larger. The buffer descriptors need no more
than the rounding: each alignment is at most its descriptor size, so a
whole number of descriptors is aligned.
- bufferStartElement is 16 bits and took the division unchecked, so an
image region past 65535 buffer descriptors (16384 images on llvmpipe)
wrapped the buffer region around onto the images. Slot counts whose
buffer indices do not fit 16 bits, 0xFFFF being the empty slot, now
throw, naming the counts. A heap without buffer slots has no buffer
region, which starts at 0 as in descriptor-set mode, so image-only
heaps have no index to fit.
- On a driver that reserves nothing (llvmpipe), a heap without sampler
slots was a zero-size buffer, which every Initialize(1, 1, 0) made,
and Window::Render bound its address each frame. Each heap now holds at
least one descriptor, as each binding does in descriptor-set mode. That
grows NVIDIA's sampler heap by one descriptor when no sampler slots are
asked for; the resource heaps of the slot counts in the tree keep their
layouts byte for byte.
- ComputeLayout holds the arithmetic, pure over the descriptor-heap
properties, and Initialize goes through it. GetBufferOffset and
GetBufferOffsetElement, which had their own copies of the old
arithmetic and never had a caller, are gone.
- Bind(cmd, frame) binds a frame's heaps with the reserved ranges
Initialize stored, or in descriptor-set mode the frame's descriptor
set. Window::Render and the RTVolume example worked the reserved-range
offset out from the heap's size with the image-alignment mask, and
call Bind now. The window's per-heap cache of bind structs goes with
it: keyed on the heap pointer, it kept binding the old buffers after a
re-Initialize that reallocated them. The heap still ends with its
reserved range, so code that derives the offset from the size keeps
getting the right one.
Tests
- DescriptorHeapLayout: the issue's two layouts, the reserved range where
buffer descriptors are aligned more strictly than image ones, every
legal combination of descriptor sizes and alignments up to 256 bytes,
no heap empty, the NVIDIA and llvmpipe layouts, the 16-bit limit and
image-only heaps. Pure CPU, no device. Against the old arithmetic it
fails 12 of its 18 checks.
Docs
- README.md's heap bullet and AGENTS.consumer.md say how to bind the
heap outside the frame loop, and the consumer notes that Initialize
throws when buffer indices would pass 16 bits. AGENTS.md lists
ComputeLayout among the functions the pure-logic tests drive.
Closes#163.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Window
- The constructor made a fractional scale, a toplevel decoration and a
viewport from Device::fractionalScaleManager, Device::manager and
Device::wpViewporter without looking at them. Device::handle_global
binds those globals only when the compositor advertises them, and
Initialize requires only wl_shm, wl_compositor and xdg_wm_base, so on a
compositor without one of the three (GNOME's Mutter has no
xdg-decoration) the constructor handed libwayland a null proxy and
crashed before the window existed (#162). Each object is now made only
when its global is there, which Resize and the destructor already
assumed.
- The fractional scale needs the viewporter too: the preferred scale is
applied through the viewport, which shows the buffer's physical pixels at
width/scale x height/scale. A surface without a viewport is as large as
its buffer, so there the scale stays 1, which keeps pointer and touch
positions, configure sizes and the text-input caret, all converted by
it, in physical pixels; the compositor scales the window up on a HiDPI
output. A scale that changes after the constructor is still applied only
by the next resize, which is #165.
- Without xdg-decoration the window has no title bar, since the library
draws no client-side decorations.
Device
- The optional globals say they are optional, and that a request on a
null proxy crashes.
Tests
- WindowOptionalGlobals: hides xdg-decoration, wp_viewporter and
wp_fractional_scale_v1 from the Window one at a time and all at once,
by nulling the Device statics after Initialize, and renders, resizes
and closes a window each time without a protocol error. Before the fix
it crashed on the window without xdg-decoration. A global the compositor
does not offer is reported as a SKIP line, since the path that uses it
goes untested there.
README
- Which Wayland protocols the window needs, and what it does without the
optional ones.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
examples/Sponza no longer built natively (#164). Its closest-hit declared a
descriptor_heap sampler2D, which glslang has rejected since c8253623
("Reject descriptor_heap combined image samplers"), and main.cpp wrote it
through VkResourceDescriptorDataEXT::pCombinedImageSampler, which that union
no longer has: the descriptor heap has no combined image samplers. Both went
unnoticed because nothing builds the examples.
Sponza
- closesthit.glsl declares texture2D and sampler heap arrays and joins them
where it samples, as ui-shared.glsl and HeapDynamicIndexHit do. The
sampler slot is a second spec constant beside the image slot, so the
shader assumes nothing about where the host put it, and a constant index
keeps the example running on NVIDIA 610.43.02 (see its README). The
comment no longer says the image slot is offset by bufferStartElement;
only buffer slots are.
- main.cpp gives the heap a sampler slot, writes the albedo as a
SAMPLED_IMAGE from a view create-info, and writes the sampler into the
sampler heap from a VkSamplerCreateInfo with vkWriteSamplerDescriptorsEXT,
as UIRenderer::RegisterSampler does. SamplerVulkan's VkSampler had no use
left. The sampler keeps its linear filtering and repeat addressing and
drops anisotropy, which a hit shader cannot use: it samples at LOD 0,
without derivatives.
Docs
- README.md and examples/Sponza/README.md quote the new declarations, and
the Sponza README says why the texture and the sampler are two
descriptors. Its texture2DArray materials pattern declared a
descriptor_heap sampler2DArray, which glslang rejects as well; it now
joins a texture2DArray and a sampler.
- examples/SponzaBench/README.md drops its caveat that Sponza does not
compile.
Tests
- ExampleShaders compiles every GLSL shader under examples/ with glslang as
crafter-build does for the example (Vulkan rules, SPIR-V 1.4, shaders/ on
the include path, and the descriptor-set build where the example
registers one), so a glslang that starts rejecting one fails a test
rather than an example build nobody runs. It fails on Sponza's old
closest-hit and needs glslang only.
Closes#164.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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>
The heap acceleration-structure read still needs the rewrite on
615.78.08; the READMEs say so and point at HeapASRead --no-workaround
for checking a newer driver. Dynamic descriptor indexing in hit shaders
is fixed there, which the README and the Sponza and SponzaBench notes
now say, and the VulkanTriangle investigation no longer contradicts
itself about llvmpipe, which advertises VK_EXT_descriptor_heap now.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The Linux gamepad backend included <libevdev/libevdev.h> from
/usr/include/libevdev-1.0 and linked the system libevdev, but the
Flatpak SDK crafter-build runs in (org.freedesktop.Sdk 26.08) ships no
libevdev headers, so Crafter.Graphics stopped building there.
lib/libevdev now carries libevdev 1.14.0 (MIT), built once as its own
static library that Crafter.Graphics depends on. As part of cfg it would
be compiled again in every test configuration, since they copy
cfg.cFiles.
libevdev's generated event-names.h names every input code by its macro,
so the library compiles against the kernel input headers that table was
generated from (lib/libevdev/kernel-headers), not the target's. That
directory is deliberately not called include: Crafter.Build puts every
include directory of a dependency on its consumers' include path, where
those headers would shadow each consumer's own <linux/input.h>. The
paths are absolute because Crafter.Build only resolves the returned
configuration's paths against the project root.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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>
wfAccum becomes array<atomic<u32>> (4 slots/pixel, f32 bit patterns — same
16 B/pixel footprint) and rtAccumulate CASes each channel, so N rays for one
pixel may resolve in the same SHADE pass without the read-modify-write
racing. GENERATE clears with atomicStore (bitcast(0.0) == 0u); RESOLVE
atomicLoads + bitcasts the vec4 it hands runResolve.
Capacity half: RTPass::raysPerPixel (default 1) scales the wavefront
ray/hit/payload buffers to raysPerPixel·W·H rays per bounce so the
per-light emits actually fit instead of being dropped by rtEmitRay's
capacity guard. The accumulator stays per-pixel.
No flag-gating: uncontended the CAS succeeds first try — RTStress SHADE
stays at its documented ~1.0 ms and master-vs-branch renders are
byte-identical, so single-ray consumers pay nothing.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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>
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>
A 3x3x3 grid of AABB-geometry spheres rendered through an analytic
ray-sphere intersection shader, with an any-hit spherical-checkerboard
cut-out so the background shows through. Exercises both features end to
end on the WebGPU wavefront tracer.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Investigated the VK_ERROR_DEVICE_LOST on the native VulkanTriangle (#7).
Verified the engine side is correct and validation-clean: the BLAS/TLAS
build finishes before render (FinishInit waits), the built instance is
well-formed (identity transform, mask=0xFF, correct BLAS ref), and
vkWriteResourceDescriptorsEXT stores the TLAS device address at the
expected heap offset (confirmed by dumping the heap bytes). Khronos
validation 1.4.350 reports zero errors.
The fault is isolated to reading the acceleration structure through
VK_EXT_descriptor_heap:
- images/buffers via the same heap render fine (trace disabled -> the
raygen imageStore path renders a full gradient);
- both traceRayEXT and inline rayQueryEXT (no SBT) fault identically on
the AS read;
- reproduces with the AS descriptor at heap byte 0 / shader index 0 (no
offset/stride ambiguity) and regardless of pAddressRange size.
NVIDIA 610.43.02 is the only descriptor_heap implementation available
(llvmpipe lacks the extension), so there is no second implementation to
cross-check. Conclusion: driver-side fault in NVIDIA's brand-new
VK_EXT_descriptor_heap acceleration-structure path; should be reported to
NVIDIA. The traceRayEXT call is left active so the example stays a
faithful reproducer. Documented in both READMEs.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
