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Comment by mastax | Hacker News Reader

https://github.com/apple/homebrew-apple/tree/main

This isn't the DX12 emulator itself, right? It's just a patch to crossover which makes it use the emulator which is proprietary and bundled with the OS (or Xcode)?

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From a quick look, the patch doesn't seem to contain references to Metal, but just a lot of random updates—backports from upstream Wine to the CrossOver thing?—including an AMD ADL implementation that is clearly for Linux (using /sys/class/… stuff). Maybe the whole toolkit is… literally just CrossOver?

Nope. The Game Porting Toolkit itself contains a large `D3DMetal` framework that directly translates Direct3D calls into Metal. The Homebrew repo is only part of the toolkit. To actually use it, you have to move the Direct3D -> Metal translation layer into installed Homebrew prefix. From Apple's README:

The graphics bridge libraries need to be placed inside your Wine prefix in order to finalize your game evaluation environment. These instructions assume you have mounted the Game Porting Toolkit at /Volumes/Game Porting Toolkit-1.0. • Copy the Game Porting Toolkit library directory into Wine’s library directory.

    ditto /Volumes/Game\ Porting\ Toolkit-1.0/lib/ `brew --prefix game-porting-toolkit`/lib/

They literally made a new Direct3D implementation on top of Metal.

The actual interesting bit is at the end of the patch, in `static void init_non_native_support` where they dlopen a proprietary MetalD3D dylib.

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