Hi all,
Stability is our main priority for 4.22 hotfixes and for 4.23. The ray tracing technology is built on top of other components that are also brand new, or less tested than the classic UE4 path:
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It is build on top of the DX12 layer, which was not the default mode in UE4. Many of the issues found when using ray tracing actually were DX12 issues. We have fixed many of them in 4.22.1 and 4.22.2, and we have just fixed another one that will be released in 4.22.3 (no fixed ETA there but very soon)
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It is also built on top of the major refactoring we did in the rendering pipeline. It is quite stable now, but it took time to get there.
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It is also built on top of DXR, a brand new tech developed by a 3rd party (Microsoft) and using a drivers layer developed by another 3rd party (Nvidia)
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And of course, on top of these potential sources of instabilities we could have ray tracing specific issues.
That is why ray tracing was tagged as Early Access, and that is why our focus in the next months is stability and performance (although we are also working on new features and things that were not supported in ray tracing in 4.22 such as landscape, which I hope you like!). We are quite happy with how things are going so far and we are doing our best to make it even better in 4.22.3 and 4.23.
We have just found a problem with complex materials that have tessellation enabled. We have a potential fix that we are evaluating right now, hopefully it will be included in 4.23. You can try disabling tessellation for the material and seeing if that avoids the crash. It is actually not a ray tracing bug, even not a DX12 bug but it manifests as a crash in DX12 mode, while in DX11 it just fails silently (despite the shader network might generate an invalid output).
Thanks,