* Desktop: pick the graphics backend before the window exists; DirectX 12 on Windows
On an AMD hybrid-graphics laptop (Radeon RX 6800M beside an integrated
Radeon, with two versions of amdvlk64.dll loaded into one process) the
app died a few seconds after launch with an access violation inside
AMD's Vulkan driver at the first swapchain present. Nothing reached the
log: a fault inside a driver is a native crash the engine's panic guard
never sees. wgpu's default backend set (PRIMARY | GL) enumerates Vulkan
first, so every start on that machine went down the same path, while
WGPU_BACKEND=dx12 and WGPU_BACKEND=gl ran fine and the headless CPU
renderer was never affected.
The desktop app now chooses the backend before creating the window
(apps/designcraft/src/gpu.rs): DirectX 12 first on Windows, then Vulkan,
then OpenGL; Vulkan then OpenGL on Linux; Metal on macOS. OpenGL stays
in the set as the in-process fallback when the chosen backend has no
adapter. WGPU_BACKEND still overrides everything and turns the fallback
off.
Start-up fallback: gpu.json in the settings directory records the
backend being tried until the third frame begins (the first has been
presented by then) or the app exits normally. A record left behind means
that backend never showed a frame, so the next start skips it, tries the
next candidate and says so in the status bar. The list starts over when
every candidate has failed or the app version changes;
DESIGNCRAFT_NO_PREFS records nothing. The adapter, backend and driver
version are logged at start-up for bug reports.
Verified on the affected machine: a default start runs on DirectX 12; a
simulated crashed DX12 start moved to Vulkan, which faulted for real,
and the start after that came up on OpenGL with the status line. Nine
unit tests cover the chooser and the record; cargo xtask ci passes.
Co-Authored-By: Claude Fable 5.1 <[email protected]>
* Merge origin/main; on Windows OpenGL isn't added to the DX12 or Vulkan instance (#167)
Co-Authored-By: Claude Opus 5.5 <[email protected]>
---------
Co-authored-by: Claude Fable 5.1 <[email protected]>
Co-authored-by: Brandon Thomas <[email protected]>
