fix(viewer): drive the frame loop with a timer when ?disable=draw#483
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With no real frames submitted, Chromium's no-damage scheduler throttles requestAnimationFrame to 1Hz on Linux — measured in the headless bake worker: every useFrame system ticked once per second, so a heavy scene needed 300+ seconds of wall time just to run ~300 frames of build work (and exceeded the capture deadline on the worker's slower cores). The empty-scene clear from #482 avoids this on macOS but not on Linux. When `draw` is disabled, drive advance() with setInterval instead of rAF — plain timers are never throttled on a visible page, so the loop pacing is deterministic (fps prop) regardless of compositor heuristics. Normal rendering paths are untouched. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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What does this PR do?
Follow-up to #482. On Linux (the headless bake worker), Chromium's no-damage scheduler throttles
requestAnimationFrameto 1Hz when the page never submits a real frame — measured in the prod-image container: main thread fully idle, rAF gaps exactly 1017ms, so everyuseFramesystem ticked once per second and a heavy scene needed 300+ seconds just to execute its ~300 frames of build work (and blew the capture deadline on the worker's slower cores). The #482 empty-scene clear prevents this on macOS but not on Linux.Fix: when
?disable=drawis active,FrameLimiterdrivesadvance()fromsetIntervalinstead of rAF. Foreground-page timers are never throttled, so loop pacing is deterministic (thefpsprop) regardless of compositor heuristics. The normal rendering path is unchanged (still rAF).How to test
bun dev, open/bake/demo_office?disable=postFx,draw—window.__BAKE__resolves in seconds (validated: 8.9s for a 200+-item scene, output in the normal byte range).draw— unchanged (verified demo_1 normal render byte-equal).project_2VqMH2p0YduKVd3i) should complete a headless CPU-only bake for the first time.Screenshots / screen recording
N/A — headless-only behavior.
Checklist
bun devbun checkto verify)mainbranch🤖 Generated with Claude Code
Note
Low Risk
Scoped to the ?disable=draw code path; normal viewer rendering still uses rAF unchanged.
Overview
When
?disable=drawis set (headless bakes that skip real drawing),FrameLimiternow advances the R3F loop withsetIntervalat the configuredfpsinstead ofrequestAnimationFrame.On Linux, Chromium throttles rAF to ~1Hz when no real frames are submitted, which made
useFramesystems crawl during bakes. Timers stay at full rate on a visible page, so build work can finish in seconds without changing the normal rAF path when drawing is enabled.Cleanup cancels the interval on unmount alongside the existing rAF teardown.
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