I’ve been experimenting with the matrix demo for a few weeks now, and I’m noticing some strange limitations and behaviors in regards to ray-tracing. Primarily, any translucent surfaces, and weirdly, the skydome, dissapear when the path-tracer is on. Ray-tracing is enabled in checkboxes in all the offending items, and even a custom glass material I made in the project had the same issue. Does anyone know why they just dissapear in RT mode entirely? Some project setting or optimization I’m unaware of?
Lumen is hybrid based Ray-Tracing. Meaning it uses RT and SSR at the same time.
This is true, lumen uses multiple light-transport techniques to get final image. But it doesn’t explain how certain materials are visible in some viewmodes and not in others, which is throwing me for a loop.
There’s plenty of information in the documentation about these limitations of the Path Tracer: Path Tracer in Unreal Engine | Unreal Engine Documentation
This is also true, yes. However, translucency is fully supported in the path-tracer, even more complex blend modes like thin translucent. It’s not a Nanite problem because translucency doesn’t work on nanite to begin with. It’s also not a culling problem because it still applies to meshes I’ve told it to not cull. I can’t figure out if it might be a CVar I can’t find, but I simply don’t know at the moment.
Read the section " Skylighting with the Path Tracer". Requirements for a material with “Is Sky” should be applied and the “Real-time capture” mode also needs to be enabled for the sky to appear in path tracing. This may also cure your glass issue. The CVar “r.PathTracing.VisibleLights 2” should help.
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I missed that, thanks for the advice. Visible lights made the cubemap lighting the scene visible to the path-tracer, but not the sky material itself (it might not be possible to have both at once given the path-tracer’s pipeline). It unfortunately didn’t clear the glass issue, they still remain invisible to the path-tracer and any RT effects in general. Working on it though.
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Hey sorry to hijack this thread but did anyone ever figure out how to get the glass working? Having the exact same issue!
Thanks
So far, no luck. I’ve tried a variety of CVars, other rendering settings and variables, and I haven’t gotten any luck. The last step may be to check out if there are any specific scripts/configs the matrix demo runs to change the renderer, but that’s all I can think of.
Yeah it’s super annoying just such a small little thing that makes rendering anything awkward!