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>
At kMaxShapedRuns (8192) UIRenderer::ShapeText did a full shapedRuns_.clear().
A stream of unique strings (FPS counters, timers) alongside many stable labels
periodically nuked every stable entry, forcing a full-UI reshape the next frame.
Track recency with an auxiliary std::list<const ShapedRunKey*> (front = most
recently used) holding pointers to the keys owned by the node-based map. A hit
splices its entry to the front; an overflow pops the least-recently-used entry
from the back and erases just that one — both O(1). The hot set of labels,
reshaped every frame, stays at the front and survives, so the churn of unique
strings only recycles the cold tail. Output is byte-identical either way.
InvalidateFont now drops matching entries from both the map and the LRU list.
Adds ShapedRunCacheSize()/IsShapedRunCached() introspection hooks (the policy
isn't observable through output or atlas.dirty) and a ShapeTextCache test that
asserts the cache plateaus at a fixed cap (evict-one, not clear-all), the hot
label survives a churn past the cap, and an untouched cold string is evicted.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
ShapeText built ShapedRunKey{..., std::string(utf8)} before find()
unconditionally — even on cache hits, on the per-frame onBuild path.
N labels meant N string copies + hashes (+ frees for non-SSO strings)
every frame, partially defeating the run cache.
Add is_transparent hash + equality functors on shapedRuns_ and probe
with a borrowing ShapedRunViewKey {const Font*, float, array<float,4>,
string_view}. The owning std::string is now materialised only on a
miss, for emplace. Cache hits copy and hash no string.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
uiResolveScreenPixel ran four float compares against hdr.clipRectPx for
every pixel of every UI dispatch, even though the clip rect is the
full-surface default {0,0,1e9,1e9} in the overwhelmingly common case.
Reserve the high bit of the header flags word (UI_FLAG_CLIP) and have
FillHeader set it only when the clip rect is narrower than the surface
(extracted into the unit-testable UIRenderer::ClipFlags). The shader
gates the compares on the bit; the branch is push-constant-uniform so it
never diverges. When the rect covers the surface the skipped compares
could never reject an in-surface pixel, so output is pixel-identical.
Mirrored on the WebGPU/WGSL path (dom-webgpu.js) for parity. Adds the
UIClipFlag CPU test covering the gate decision.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Per glyph, ShapeText did cache_.contains(key) (in Ensure) then
cache_.find(key) (in Lookup) — two independent hashes + node-chases of
the same key. Add EnsureAndGet returning const Glyph* with a single
find, insert-on-miss, returning &it->second. It returns nullptr only on
ShelfPlace failure, preserving the existing `if (g==nullptr) continue;`
behavior. Ensure now delegates to it.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
ShapeText re-decoded UTF-8, re-looked-up every glyph, and recomputed
layout every frame for static strings (DrawText / EmitCenteredLabel run
inside per-frame onBuild). DrawText and EmitCenteredLabel also did a
second full pass over the glyphs to apply alignment.
Memoize the shaped run, keyed by (Font*, pxSize, color, utf8), as an
origin-relative vector<GlyphItem>. A cache hit skips decode/lookup/layout
and just translates the cached run into the output buffer by
(x + alignShift, baselineY). The alignment shift (Center = -advance/2,
Right = -advance) is folded into ShapeText's single pass, dropping the
second loop in both callers. TextAlign moves to the :UI partition so
ShapeText can take it.
Pure CPU memoization — the glyph buffer is fully rewritten and re-flushed
every frame, so a hit is byte-equivalent. A miss still calls Ensure so new
glyphs rasterise and dirty the atlas; hits don't (atlas entries are never
evicted). InvalidateFont drops a font's runs before it is destroyed (the
cache, like FontAtlas's glyph cache, keys on the Font pointer). A soft cap
bounds memory against pathological per-frame-unique text.
Adds the ShapeTextCache test (15 checks): hit == miss byte-for-byte, hits
don't touch the atlas, translate/alignment/truncation/InvalidateFont.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
