I would like to point out a couple of weird behaviors with the Ray tracing Translucency. I don’t know if it is a problem of the actual stage of development or if is something I haven’t figure out yet.
I’m using a Threadripper 1950x with a Nvidia 2080ti, 64gb ram
The backface of single sheet meshes are being rendered as two-sided-translucent even if it has a simple opaque material
When the ray traced translucency is disabled the back faces disappear as it should. In the example above the squares are planes, one facing the camera the other away. The tree in this example has a simple masked material (no translucency or two sided foliage).
Two sided foliage:
Another problem is setting up a material with two sided foliage. I’ve tried a lot of things but it seems that when the raytracing shadows (on my skylight and directional light) is on there is no two-sided-translucency, when off it seems to work.
In the example above I have the same planes with a Two sided folliage simple material. The SSS color is ser to pink. As you can see, it only, kind of, works only without the raytrace shadows from the light source.
Most of the time, after turning ray tracing on (global, relfection and translucency), the viewport suddenly starts to flicker and the only way I could figure out to make it stop is turning raytrace off or closing and opening the unreal editor
In the example above you can see a couple screenshots from the flicker, it seems to be changing between buffer passes or something like that, it affects everything with raytrace and even the sky . Really annoying.
Max Refraction Rays:
Using max refraction rays above “2” will wash out other raytrace passes
I’m using in the example above a simple glass material with “o” in the specular and roughness, a fresnel in the opacity and almos white color. This was the only way I could make a single sheet glass to work with raytrace, but, it also has some weird behaviors like the one above. If I set the Max refraction rays to 3 or more it will simply occlude the other raytrace passes for everything behind the glass.
More images bellow from the Flicker effect.