Brandon ThomasandClaude Opus 5.5 b66cdb23a3 Issue #136: Windows: use DX12 by default, honour WGPU_BACKEND, never let GPU init block startup ...

wgpu loads the driver of every backend in an instance's set while it
enumerates adapters. The compute device (crates/gpu) hard-coded
Backends::PRIMARY (Vulkan + DX12 + Metal) and ignored WGPU_BACKEND, and
was created from LightcraftApp::new on a background thread at launch, so
a crashing Vulkan driver (Intel UHD 630, igvk64.dll) killed the process
before the window appeared; the window (egui-wgpu) also listed Vulkan.

- lightcraft_gpu::backend: DX12 only on Windows (Metal on macOS, as before
  on Linux) for both the compute device and the window;
  LIGHTCRAFT_GPU_BACKEND=dx12|vulkan|metal|gl|auto|off, else WGPU_BACKEND;
  backends missing from the build fall back to the default.
- The device is created only when GPU rendering is enabled, after the
  first frame; the preference is applied before the window opens.
- Crash sentinel: gpu-init.marker in the settings folder around device
  creation; if left behind, the next launch starts with GPU rendering off
  and a notice saying how to turn it back on.
- Tests: backend parsing/selection, sentinel, window defaults, headless
  snapshot with LIGHTCRAFT_GPU=0 / LIGHTCRAFT_GPU_BACKEND=off.
- Docs: gpu-pipeline.md (backends, env vars, troubleshooting), whats-new,
  parity LR-BEHAV-GPU.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

2026-10-06 10:16:05 -04:00

..

src

Merge main into fix/issue-99-library-lock

2026-10-05 18:54:56 -04:00

tests

Issue #136: Windows: use DX12 by default, honour WGPU_BACKEND, never let GPU init block startup

2026-10-06 10:16:05 -04:00

Cargo.toml

Never crash: move the one unsafe FFI call into crates/sysmem

2026-10-05 02:06:08 -04:00