Tessellation and Transparency

Hey community!

I am running into weird rendering artifacts when I enable tessellation in a transparent material. I wanted to use it to render a “3D Minimap” but I can’t explain where the artifacts are coming from.

I have already tried

  • Using another mesh which is pre-tesselated
  • Switching from UE 4.21 to 4.22
  • Messing around with depth test settings
  • A few others which I probably have already forgotten about

I cannot find any solution and it’s frustrating me a lot.
Below are some screenshots so you know what I am referring to along with one of the node setup.


Does anyone know what might be causing this?
Thanks a lot for your help! (:

  • Khazzy

I guess since noone’s got an idea what this is it might as well be a bug? I’ll probably file a bug report then since I really can’t figure out what is causing this behavior and it happens even if I set the opacity to 1.0

you could try using a masked material and dither the opacity.

Hey there, sorry for the super late reply, I’ve been busy with some unexpected rl issues.

An EPIC engineer is currently looking into the matter but from what I can tell so far, dithering might really be an alternative to translucency.

One way or the other thanks a lot for the hint! (:

was a bug report ever made on this?
I’m getting very similar issues. it’s not reflections and going to base color the mesh doesn’t crack. the transparency view shows the artifacts however. I really though it was one of the crack free/adaptive settings until I started messing with the number of tris in the base mesh.
The more tris I have the more this effect is visible…

Yes and their reply was

After looking into this through several versions of the editor, and consulting with developers, the translucent material domain has always rendered in manner you are seeing
This is not a bug. If you run into any other issues that you believe is a bug please feel free to create another report for us to take a look at.

So I don’t know… might help if more people report this issue? I am still not satisfied but if they think it’s not a bug I think arguing against it won’t help much.

I filed my own report for a similar issue here.

In my case I’m almost 100% it is a bug, since it’s both reproducible and it can be overcome by changing the shader type to a non translucent material.