Without this, BonsaiViewer.app launched on macOS would show a white
viewport for the same reason Windows did before d4d0c934b — the
`createSurface()` else branch fell through to "wgpu surface creation
not yet wired for this platform", `init()` returned false, and the
Qt window background was all the user saw.
Pieces:
- `WgpuMetalSurface_mac.{h,mm}`: tiny Objective-C++ bridge. Takes the
NSView pointer that Qt's `winId()` returns on macOS, attaches a
CAMetalLayer (using Qt's existing one when surfaceType is
MetalSurface, attaching one ourselves as a defensive fallback),
sets `contentsScale` from the window's backing scale factor so
retina drawables come out at native resolution, and returns the
layer as `void*`. The .mm keeps the Objective-C namespace pollution
out of WgpuViewportWindow.cpp.
- `WgpuViewportWindow` ctor: `setSurfaceType(QSurface::MetalSurface)`
on macOS so Qt backs the NSView with a CAMetalLayer at window
creation; OpenGLSurface elsewhere as before.
- `WgpuViewportWindow::createSurface()`: new `#elif defined(Q_OS_MAC)`
branch that fills a `WGPUSurfaceSourceMetalLayer` with the layer
pointer from the bridge and hands it to `wgpuInstanceCreateSurface`.
- `CMakeLists.txt`: `enable_language(OBJCXX)` + the .mm file added to
the source list on Apple, and links `-framework Cocoa` (NSView) +
`-framework QuartzCore` (CAMetalLayer).
`winId()` on macOS returns the backing NSView*, not the NSWindow* —
that's the layer-bearing host wgpu-native expects.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Dion Moult