Trying to bring RTXGI to 5.7

Given that Arc Raiders apparently uses RTXGI, I started with the noble intention of bringing RTXGI to Unreal Engine 5.7 and sharing it with the community.

Unfortunately, I ran into a major roadblock: enabling ray tracing in the latest version of UE5 requires SM6. To make the plugin compatible with SM6, I tried to copy as much as I could from Lumen. The plugin now runs, but the shaders are outdated and likely need to be rewritten to match the ray tracing shader model.

I don’t have much experience with shaders, so if anyone else is interested in this effort, feel free to try updating them. I made a few attempts to follow Lumen’s shader patterns, but without success, and I haven’t pushed those changes.

The repo wasn’t intended to be shared in this broken state, but I’m not making any progress so apologies for that.

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RTXGI is no longer the latest version that matches, RTXDI yes New,you should refer to the NVRTX 5.6 branch,https://developer.nvidia.com/game-engines/unreal-engine/rtx-branch,https://github.com/NvRTX/UnrealEngine/tree/NvRTX_Caustics-5.6.

great work man. maybe you should create some issues on github on your repo so people wanting to contribute can know where to start. as detailed as possible would be ideal.

I’ll do it later, thanks for the tip. I wanted to release a base version that at least replicates the previous behavior, since I believe there’s room to optimize by reducing the number of permutations.

Basically, the volume is spawnable and the probes are visible, but the engine keeps logging a mismatch between the expected shader and the actual one. The shader has a hash of 0 and isn’t properly initialized.

The log says:

[205]LogD3D12RHI: Warning: Raytracing shader with entry point ProbeUpdateRGS, name , and ShaderBindingLayout hash 0 doesn’t match the RTPSO ShaderBindingLayout hash 3892743247.

Despite this, I think it’s close to working, the engine and the map start up properly.

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Lumen GI and Reflections feedback thread - #2387 by WayAway - there is a mention of official implementation of something similar in UE 5.8.

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I have been looking into doing the same thing. I’m wondering where you got the source from, if it was from the ProjectBorealis Github then I’m not sure the plugin is actually functional. Check out these 2 issues from that Github:

The official Nvidia Github only has the UE4 version of the plugin, but the final UE5.0 version of the plugin including source and binaries can still be downloaded on the web archive here:

https://web.archive.org/web/20240601123846/https://developer.download.nvidia.com/rtx/rtxgi/RTXGI_UE5_Binary_Plugin_v1.1.50.zip

I took it from there and modified the incompatible parts of the code, as I mentioned earlier. The plugin is running, but the shaders still need to be updated.

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NvRTX/UnrealEngine at nvrtx-5.7 Branch is presently in Preview