samhocevar / d3d4linux

Expose D3DCompiler to Linux programs (early PoC)

Description

The d3d4linux project allows to compile HLSL shaders on Linux using the Microsoft DirectX compiler DLL. It works by launching a Windows program in the background using Wine and diverting calls to that server on the fly.

Note: this is not for porting games to Linux. The goal of this project is to use Linux machines to build and package Windows games (because Linux build machines are cheaper and more reliable). You could see it as “shader cross-compilation”. In the end you still get HLSL bytecode which is of little use on Linux.

Only four functions are implemented for now. They are the ones required by the Unreal Engine shader compiler:

• D3DCompile
• D3DReflect
• D3DStripShader
• D3DDisassemble

d3d4linux is work in progress and not ready for production but is being successfully used at Dontnod Entertainment to package Windows versions of Unreal Engine 4 games.

Build

Prerequisites:

apt install g++-mingw-w64

Build d3d4linux:

make

Test

Prerequisites:

apt install wine64

Launch the test:

make check

Unreal Engine integration

Patch and build:

• copy d3d4linux.Build.cs and the include directory to Engine/Sources/ThirdParty/d3d4linux.
• copy d3d4linux.exe and the d3dcompiler DLLs to Engine/Binaries/ThirdParty/d3d4linux.
• apply one of the patches found in the extras directory to the Unreal source tree.
• verify and optionally tweak the D3D4LINUX_ macros in Engine/Source/Developer/Windows/ShaderFormatD3D/Private/D3D11ShaderCompiler.cpp so that they match your desired setup (note that these can also be overridden at runtime using the similarly named environment variables)
• make sure to rebuild UE4Editor and ShaderCompileWorker.

Cook:

• with AutomationTool: run BuildCookRun as usual with the -targetplatform=Win64 argument.
• with UE4Editor: run with the -run=Cook -TargetPlatform=WindowsNoEditor arguments.

Debug:

• set the D3D4LINUX_VERBOSE environment variable to 1 for some debugging information.