wine-glcore-interpose

Two small fixes for OpenGL applications running under Wine on macOS (CrossOver, Sikarugir/Kegworks/Wineskin, Whisky, upstream Wine), delivered as one DYLD_INSERT_LIBRARIES dylib. No files inside Wine or the game are modified.

Written to get Project Reclaimer (Halo 3 custom games, a Rust/egui client that hosts the MCC Halo 3 engine) running on an Apple Silicon Mac. Both fixes are generic.

The two problems

1. "requires OpenGL 3.0 or later" — Wine hands out GL 2.1 on macOS. When a Windows program creates a default (non-attributed) WGL context, Windows and Linux drivers return their newest compatibility context (GL 4.x). Wine's Mac driver asks CoreGL for a legacy pixel format, and legacy on macOS means GL 2.1. glutin/egui and anything else that expects "default context ≥ 3.0" fails. The interposer hooks CGLChoosePixelFormat and, only for the request winemac.drv makes on behalf of the app (accelerated, minimum policy, no renderer id, no profile), adds kCGLPFAOpenGLProfile = GL4 core (or 3.2 core). Wine's own probes and renderer enumeration are left alone so its GL capability table stays correct. macOS core profiles reject #version 130/140, so glShaderSource is hooked to rewrite those to #version 150.

2. Beachball / frozen window — winemac.drv main-thread self-deadlock. When a window hosts both a Metal-backed surface (D3DMetal / MoltenVK swap chain) and an OpenGL context attached after the window is already visible, winemac.drv's viewWillDraw → macdrv_update_opengl_context ends up calling OnMainThread(^{ [context update]; }) on the main thread. OnMainThread queues the block for the main run loop and then waits on a dispatch semaphore forever — behind its own wait. The Cocoa main thread never services the window again (beachball), and every Wine thread that needs the main thread hangs behind it, while the Metal side keeps presenting at ~1 fps. The interposer hooks dispatch_semaphore_wait; if the call is on the main thread, uses DISPATCH_TIME_FOREVER, and the caller is inside winemac.so, it waits in 2 ms slices and runs the main run loop between them so the queued block executes and signals the semaphore. All other semaphore waits pass through untouched.

Relevant upstream code (Wine 10): dlls/winemac.drv/cocoa_window.m (viewWillDraw, addGLContext), cocoa_opengl.m (macdrv_update_opengl_context), cocoa_event.m (OnMainThread).

Build

make            # -> libglcore_interpose.dylib (x86_64; Wine on Apple Silicon runs under Rosetta)

Requires Xcode command line tools. Nothing else.

Use

./wine-glcore /path/to/wine 'C:\path\to\app.exe'
# or by hand:
DYLD_INSERT_LIBRARIES=/path/libglcore_interpose.dylib GLCORE_INTERPOSE=1 wine app.exe

The dylib does nothing unless GLCORE_INTERPOSE=1 is set, so it is safe to leave in a wrapper's environment.

Variable	Effect
GLCORE_INTERPOSE=1	enable (required)
GLCORE_INTERPOSE_PROFILE=41 | 32	core profile version requested (default 4.1)
GLCORE_INTERPOSE_PUMP=0	disable the main-thread deadlock workaround
GLCORE_INTERPOSE_LOG=1	log each converted pixel format, shader rewrite and caught deadlock to stderr

Caveat: macOS strips DYLD_* variables when launching protected system binaries (/usr/bin/python3, /bin/sh from /usr/bin/env, etc.). If you wrap the launch in such a tool, set DYLD_INSERT_LIBRARIES in the child's environment (see examples/reclaimer-sikarugir.sh).

Example: Project Reclaimer in a Sikarugir Steam bottle

1. Install Halo: MCC with Halo 3 (campaign + multiplayer) in the bottle's Windows Steam.
2. Copy project-reclaimer.exe to <bottle>/drive_c/ProjectReclaimer/.
3. examples/capture-sikarugir-env.sh ~/Applications/Sikarugir/Steam10.app (once; records the wrapper's Wine env).
4. make && examples/reclaimer-sikarugir.sh

The example launches detached from the terminal, logs to ~/Library/Logs/ProjectReclaimer/, and raises the game window (a process started from a terminal is not allowed to take focus, so it would otherwise open behind Steam).

Tested: macOS 26.2, M4 Max, Sikarugir 1.0.11, Wine 10.0 (CrossOver-derived "Sikarugir rev 4") + D3DMetal, Project Reclaimer 0.9.15. Menu, Spartan preview and music work; the Halo 3 engine renders through D3DMetal.

Scope

Intentionally not a Wine patch: the deadlock belongs in OnMainThread (run the block inline when already on the main thread) and the GL default-version behaviour is a design choice in winemac.drv; both are better fixed upstream. This dylib is the zero-rebuild workaround until then. It does nothing about anti-cheat, Easy Anti-Cheat, or any game's online services.

License

MIT.