GTA rendering hook

GTA rendering hook

Implements DirectX11 and Vulkan rendering API to GTA 3, GTA VC and GTA SA.

Currently there are 2 versions, one of which is broken(can't really build it anymore):

• Old one which implemented only DirectX11 and had a few features(only GTA SA)
• New one which at the moment runs only on RTX hardware and uses vk_nv_ray_tracing extension(to be replaced with KHR one once it is implemented in release drivers)

We have discord server, come and help to improve it!

How it works?

TL;DR: Currently we have incomplete RW rendering backend implementation that communicates via shared memory to incomplete rendering engine instance running rendering loop based on Vulkan API.

Long version:

• Game rendering engine code is partially redirected to shared memory task queue
• Task queue loads game assets to GPU memory, processes various requests like retrieving supported resolutions etc.
• One of the tasks prepares a frame to framebuffer based on uploaded scene data, each frame draw calls is uploaded to 64bit process via task queue.
• Separation between rendering and game code is done for several reasons:
  • It allows to use newer drivers, and support raytracing extensions
  • It allows to use more memory if needed
  • Surprisingly it works faster!
• Rendering right now is basic, and very hacky:
  • BLAS is built for each model instance being loaded by the game. For GTA 3 we load some sectors around the player using original lod system.
  • Animations are prepared by compute shaders and rebuilt every frame
  • TLAS is rebuilt every frame
  • Scene is loaded to GPU, contains all materials, textures, vertex/index buffers and transform data
  • Lights are prepared using very basic tiled culling implementation
  • Primary rays are traced to compute G-Buffers: Albedo, Normals, LinearDepth, Motion vectors and Material params
  • AO rays are traced, temporally accumulated and blurred via bilateral blur with varying kernel(based on temporal variance)
  • Shading for sunlight and each point light inside a tile is generated, then temporally accumulated and blurred via bilateral blur(based on temporal luminance variance)
  • Reflections are traced with one shadow ray per-pixel and blurred via same filter that is used for shading
  • Everything is combined based on material properties etc.
  • Immediate 3D objects are drawn on top(with depth from G-Buffer)
  • Immediate 2D objects are drawn on top

Current requirements to build development source code

1. VCPkg
2. Cmake
3. Visual Studio/CLion
4. C++ compiler with c++20

Build instructions

1. Setup libraries via vcpkg(all dependencies are listed in response_file.txt)
2. Prepare environment:
   • GTA_3_FOLDER, GTA_VC_FOLDER and GTA_SA_FOLDER should be set to some places where you want resulting executables to be.
   • When building 32bit binaries use only BUILD_32BIT_LIBS
   • When building 64bit binaries use BUILD_32BIT_LIBS and ARCH_64BIT
   • Loading mod requires Ultimate ASI Loader installed.
   • For GTA 3 it'll work only on steam, v1.1 and v1.0 at the moment.
3. Build x86 and x64 libraries/executables in release or debug configuration using configured CMake.
4. Run, test and report bugs and incompatibilities!

Tips

1. If you encounter bug please report it, and attach .log files and crash dumps and build/game version if possible to bugreport
2. It's buggy and code is bad at the moment, sorry in advance :)