PGR4: ReGPU

PGR4:ReGPU

A native PC port of Project Gotham Racing 4 (Bizarre Creations, 2007, Xbox 360). It is not an emulator: nothing interprets the console's code or runs it in a virtual machine.

• The game code is native x64. XenonRecomp translates the game's PowerPC code ahead of time into C++, which is compiled into pgr4.exe. The console's kernel and system calls are reimplemented as ordinary Windows code.
• The graphics are native Direct3D 12. ReGPU, the renderer in thirdparty/ReGPU, turns the game's GPU commands into Direct3D 12 draws, and its shaders (Xenos microcode) into HLSL compiled for your GPU. Pipelines are cached, so a shader compiles once.

No game files are included: you need your own copy of the disc (and, optionally, Title Update #2 and DLC).

ReGPU

ReGPU gives the port a PC renderer instead of a GPU emulator. The game draws exactly as it did on the console, writing command packets and calling the Vd* video functions, and ReGPU builds Direct3D 12 work from them:

• Shaders: each Xenos shader is translated once to HLSL and compiled to a D3D12 pipeline, cached on disk between runs.
• Render targets: the console's 10 MB EDRAM tiles and resolves become D3D12 render targets and copies, with real MSAA.
• Textures: the console's tiled, big-endian formats are converted to D3D12 textures as the game uploads them.
• PC features the console never had: any resolution, FSR 1 upscaling and sharpening, anisotropic filtering, an uncapped or custom frame rate.

It started in the Forza Motorsport 2 port and was proven on this one; fixes made for PGR4 go back into it.

What's here

Folder	What it is
src/	The port's runtime: the console kernel and XAM, memory, threads, file system, audio (XMA, WMA via XMP), saves and profiles, settings, and the game-specific hooks (src/hooks/)
thirdparty/ReGPU/	The renderer: command processor, Xenos shader microcode to HLSL, EDRAM, resolves, MSAA, texture formats, upscaling (FSR 1) and the debug server. Was a submodule of zer0ducksgiven/ReGPU; it now lives in this repository
config/pgr4.toml	XenonRecomp's function boundaries and jump tables for default.xex with Title Update #2
tools/	Disc and package extraction (xiso.py, stfs.py), recompile (recomp.sh), import and stub generators
launcher/PGR4Launcher/	The launcher (C#, Photino): install, graphics settings, DLC and mods, profiles and 360 save import, title update import, photos, updates
installer/	The Inno Setup installer and first-boot setup

Building

Windows 10/11, a Direct3D 12 GPU, clang-cl, CMake 3.25+, Ninja, Python 3, and the .NET SDK for the launcher.

py -3 tools/xiso.py extract "<PGR4 disc>.iso" game
py -3 tools/stfs.py update "<TU_16L61VP_...>" out/tu2
sh tools/recomp.sh                 # XenonRecomp: game/default.xex + TU2 -> out/ppc
cmake --build build/rel            # pgr4.exe
dotnet build launcher/PGR4Launcher -c Release

play.cmd starts the game from the repository root (logs to out/play.log).

DLC

360 DLC packages install through the launcher's Add DLC. The Kellogg's Typhon promo, whose 360 package is lost, installs from its zip of rebuilt files (PGR4-Kelloggs-Typhon-DLC.zip) through the same button.

Contributors

• Scott (zer0ducksgiven): the port and ReGPU.

ReGPU contributors:

• Aiden-Piercee: ring buffer replacement without racing the command processor, depth-only alpha test and clear fixes for fixed-point targets, pixel-shader kills in depth-only passes, regpuctl whole-frame capture and draw counts.
• tankyx: explicit-LOD sampling in vertex shaders; skipping microcode that cannot be a shader.
• ReGPU also carries fixes from the Forza Motorsport 2, Forza Motorsport 4 and Glue2GPU ports.

Credits

• XenonRecomp (MIT).
• Xenia's research into the Xenos GPU and the Xbox 360 kernel informed this work. No Xenia code is included.
• AMD FidelityFX SDK (MIT); Microsoft's d3dcompiler_47.dll (Windows SDK redistributable); Photino.NET for the launcher.

Project Gotham Racing 4 is © Microsoft. This project contains none of its code or data.