Skyrim modded with path-traced lighting – and all DX9+ games could follow

Enterprising developer Pascal Gilcher, best known for creating a ReShade add-on for ray-traced global illumination (RTGI), has unveiled his work on a path-traced version of Skyrim Special Edition. Even more excitingly, this new ReShade add-on operates on similar principles to Nvidia’s RTX Remix, with the potential to add world-space (rather than screen-space) path-traced lighting to thousands of games based on DirectX 9 or later.

This new PTGI upgrade is significantly easier to implement than RTX Remix, which requires a good amount of coding to implement. Pascal, in contrast, promises “a little bit of clicking around in the [interface]” that works in pretty much any DX9+ game that the ReShade plugin can operate in.

Behind the scenes, Pascal says that the add-on works by grabbing pretty much all calls to the graphics card no matter their parameters, in a similar manner to debugging tools like NSight or RenderDoc. From here, you can pass the data to the shaders and do your own things with it; getting the special world-space path tracing shader to work just requires sending it the appropriate input data for the game it’s running in, a process that can take anywhere from 10 minutes to two hours.

The actual path tracing works using voxels, generated by a sparse pointer-based solution in a volume of 2048x2048x1024 units – similar to SEUS PTGI for Minecraft.

The project is still in an early stage, but the idea is that eventually each game should have a tweakable ENB file that determines how the path-tracing operates in that title, making it easy for people to enable path tracing in a wide range of games after someone has done the tweaking and configuration needed to produce a good result.

At present, the goal is to make the add-on functional for a wide range of games, rather than specialising it for Skyrim specifically. It has the advantage of being patch-stable (ie it’s operating at such a low level that game or driver updates aren’t likely to affect its efficacy), so once it is ready for release it should continue to improve over time without any significant regressions as you’d expect from more game-specific mods.