Mirrors are showing no translucency
closed
A
Adrian West
My problem appears to be an opacity issue where, I can't get opacity when using the path tracer. All I get are mirrors with no translucency. I'm running the current up to date version of Unreal Engine 5.1 and pretty much out of the box. The Kitbash kits were downloaded direct from the website before Cargo (Which I can't seem to get working either but not an issue for now). I will try in 5.2, but this is for production and 5.2 has bugs. Can you test in 5.1 and see if you get the same problem? Glass is transparent when using Lumen, but becomes fully opaque with path tracer.
Maxx Burman
closed
Phil Kuzmicz
Hi Adrian West!
I think the problem might be related to refraction on the glass material. Refraction requires an "exit plane" to calculate when pathtracing. The easiest solution is to set the refraction value to 1.
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Adrian West
Phil Kuzmicz: Thanks Phil. That worked a treat and the glass is now indeed transparent after reducing the IOR on the glass master material. The problem I am experiencing now though is, when inside the building the glass isn't letting the light in while path tracing. The glass is transparent, but light isn't getting in and the interior is black. Any idea how I can correct this? Many thanks. Adrian
Phil Kuzmicz
Adrian West: I just tried to replicate that issue, but I could not. Perhaps a hacky way to solve that problem would be to disable "Cast Shadow" on the material ID your glass is assigned to in your mesh. This does it on a per-LOD basis, but it might work in a pinch.
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Adrian West
After tinkering a bit more, I have found that if I reduce the Lerp in the "Refraction map used as mask" comment block to less than 1, glass lets light in/ is more opaque. I'll see if this affects or breaks anything elsewhere, but it looks OK so far. Many thanks