Brandon ThomasandClaude Opus 5.5 2218ca5a4c Issue #78: GPU export: respect device limits, fall back to CPU on GPU errors ...

A GPU render no longer hands back an image it cannot vouch for:
- set the wgpu device-lost callback (wgpu never reports a lost device as an
  error, so a driver reset went unnoticed); readback waits with a timeout and
  checks the poll result and map callback instead of blocking forever
- each render runs in OutOfMemory/Validation/Internal error scopes; errors
  fail that render (OOM and limit failures for that render only, device
  errors for the process) and it is redone on the CPU
- every buffer is checked against the device limit when created (no
  validation error, no process-wide disable); LIGHTCRAFT_GPU_LIMITS=webgpu|<MiB>
  creates the device with lower limits to reproduce small adapters
- the output buffer is cleared and the per-pixel kernel writes alpha 255:
  any unwritten pixel (work silently dropped, the issue's all-black export)
  fails the render; an all-black result is re-rendered on the CPU
- renders submit per stage and every 16 M invocations, the per-pixel stage
  runs in ~4 MP bands: no long submission for a slow iGPU's watchdog to reset
- ui.inspect perf.gpuReason / perf.gpuFallback, app.gpu reason/lastFallback,
  System Info and Settings say why the GPU is off (e.g. llvmpipe skipped) and
  why the last render fell back

Tests: crates/gpu/tests/fallback.rs (limit, mid-render limit, validation
error, dropped work, black photo), engine export falls back to the CPU image,
banded 3000x2000 GPU/CPU equivalence.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-10-05 05:06:24 -04:00

..

src

Issue #78: GPU export: respect device limits, fall back to CPU on GPU errors

2026-10-05 05:06:24 -04:00

tests

Issue #78: GPU export: respect device limits, fall back to CPU on GPU errors

2026-10-05 05:06:24 -04:00

Cargo.toml

M5.2a: lightcraft-gpu crate (wgpu compute) with the per-pixel stage on the GPU

2026-10-01 02:29:54 -04:00