On some Windows machines FXC fails to compile egui's own shaders on DX12
("The parameter is incorrect. (0x80070057)" in egui_pipeline) and wgpu's
default error handler panicked. Each renderer (DX12, Vulkan, GL, glow) is
now probed with error scopes and a logging error handler before the window
opens; the one that works is remembered; a start that dies leaves a marker
and relaunches with the next renderer. LIGHTCRAFT_GPU_BACKEND=glow added.
Sources: own design.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
On a 2015 MacBook Pro (Intel Iris/Metal), 0.5.0 never opened its window, even with
LIGHTCRAFT_GPU=0: wgpu's indirect-call validation builds an internal compute pipeline when the
window's device is created, Metal's compiler fails on it ("Compiler encountered an internal
error"), the device is lost and eframe exits. That validation only guards indirect draws and
dispatches, which neither LightCraft nor egui issue.
backend::instance_flags clears InstanceFlags::VALIDATION_INDIRECT_CALL for every instance
LightCraft creates (the window's, Gpu::new and the denoise device), unless
WGPU_VALIDATION_INDIRECT_CALL asks for it. Tests: the flag rule, and that the window's instance
descriptor goes without it.
wgpu's default DX12 compiler (Auto) loads whichever dxcompiler.dll the DLL
search path finds first. LightCraft ships none, so it picked up another
program's copy; one without dxil.dll beside it (e.g. DXC 1.7) warns that
the DXIL is unsigned, wgpu treats that as a compile error, its
indirect-validation pipelines fail, the device is lost and the window
never opens ("Parent device is lost", exit code 1).
Every wgpu instance (window and both compute devices) now uses
lightcraft_gpu::backend::backend_options(): wgpu's env options with the
DX12 compiler pinned to FXC (d3dcompiler_47.dll, part of Windows), unless
WGPU_DX12_COMPILER asks for another.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
`--help`, the module doc and the README promise that a `--memory` session
"writes nothing", and the desktop app broke that in two places:
- `PrefsWriter` saved `ui.json` whenever the UI state changed (issue #164),
so a throwaway session's `thumbSize`, window layout or language replaced
the user's saved settings — the README showcase script does exactly that.
- The GPU crash sentinel from #136 armed itself in every session except
`LIGHTCRAFT_NO_PREFS` (issue #169); `with_init_marker` creates the
settings folder to hold `gpu-init.marker`, removes the marker and leaves
the folder, so a `--memory` run on a fresh home left an empty
`Library/Application Support/LightCraft` behind.
Now `PrefsWriter` carries its target path (`None` for `--memory`,
`LIGHTCRAFT_NO_PREFS` or no home folder) and writes nothing without one; it
also writes nothing while the session is the one offered when the library
can't be opened (the question window and Continue Without Saving, which
`docs/control-protocol.md` already describes as writing nothing) and
resumes when `app.openLibrary` ends it. `gpu_crash_check(in_memory)` neither
arms the sentinel nor removes a marker in a `--memory` session; it still
reads one (new `read_init_marker`), so GPU rendering starts off there too
and the next ordinary launch reports and clears it. A `--memory` session
still reads `ui.json`, but a damaged one is reported and left in place
rather than set aside. Normal launches are unchanged.
Tests: `prefs_writer_writes_nothing_in_a_memory_or_temporary_session`,
`memory_session_leaves_the_gpu_marker_and_folder_alone`,
`memory_session_leaves_a_damaged_ui_json_alone` (apps/lightcraft), and
`read_init_marker` coverage in the gpu crate's marker test.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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 <noreply@anthropic.com>
MarekSpodBiedry