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RTX Remix is a modding platform to remaster classic DirectX 8 and 9 games with path tracing, NVIDIA DLSS, AI-enhanced textures, and user-created assets. It leverages fixed-function rendering pipelines in these titles to properly capture and enhance these games. RTX Remix consists of the RTX Remix runtime (in this repository) and RTX Remix creator toolkit (available soon). The Runtime provides the rendering and asset replacement when placed alongside the game – but also allows for frame capture that is the basis for setting up replacements. Altogether, RTX Remix allows you to create path traced visual mods for some of your favorite classic games and share those mods with others.
You don’t have to be an expert in rendering to work with RTX Remix – the runtime and creator toolkit will take care of everything you need to create beautiful path traced mods. But understanding some of the key concepts and components and how they link together will make it easier to understand the workflow, and why the assets and captures are structured the way they are.
The RTX Remix runtime consists of two main parts: the Bridge, and the Renderer. The Bridge uses a d3d9.dll “interposer”, which when placed next to the game executable, captures the stream of rendering commands within the original 32-bit process of the game, and sends them to NvRemixBridge.exe, which is now a 64-bit process. This translation into a 64-bit instruction set gives you practically unlimited memory to play with, and better compatibility for modern ray tracing APIs.
The Bridge is only a pass-through however, feeding the d3d9 rendering commands as-is to another d3d9.dll, which contains the RTX Remix renderer. The Remix d3d9.dll is a fully-fledged path tracing rendering engine that takes the geometry, material and light information embedded in the d3d9 rendering commands and constructs a complete game scene with enhanced assets, materials and lights, and then proceeds to path trace it.
The renderer identifies replacement assets from a RTX Remix Mod that is placed in a special directory next to the runtime, and replaces the original game assets at playback. Original game assets are identified when a collection of triangles make up a distinct entity in subsequent frames—these assets are labeled with a hash ID to track them. RTX Mods produced by Remix contain new assets with corresponding hash IDs that match the old assets used in the original game. This is how the replacement’s directory can know which assets to replace on the fly. When the RTX Remix creator toolkit launches, users will easily be able to create and assign new assets, materials, and lights in the game scene. And with the RTX Remix creator toolkit being built on NVIDIA Omniverse, modders will be able to access a broad set of 3D creation tools to enhance their assets.