Thin Translucent Material Artifacts

Hi there!

Whenever I apply a Thin Translucent Material to my curtain model, these artifacts start to appear.

Two-sided is enabled and it does not happen on a plane, it happens on meshes with faces that overlap for example a box which makes it show the plane underneath the one im looking at

Does anyone know what is causing this and how I can solve this?

These are translucency sorting errors, you shouldn’t be using translucent materials on a surface like this; Use Opaque or Masked.

What should I use them on?

I’m trying to achieve this look:

Ahh… sheer fabric… yeah thats a difficult one.

You can use masked with dithered opacity, you may find the result is smeared when moving the camera though.

Another option you could try is to brute force it using sorted translucency. In the actor settings there should be a sort triangles option:

image

You can try enabling that on your mesh with the translucent material. It may be unreliable though, and sorting is per-triangle so you may still get some overlap

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In addition to these options, there is also a project level setting to enable “Order Independent Transparency” in newer versions. This is much more reliable at solving sorting issues, but it will make all translucent materials more expensive. Maybe not a big deal if your goal is arch vis, but for real time use it’s much better practice to:

  1. not use transparency at all.
  2. not let transparent triangles overlap.
  3. keep their size in screen to a minimum.

Not only does this cause the aforementioned sorting issues, but it also causes overdraw, as the background, and multiple layers of the expensive translucent material need to be rendered on the same pixel multiple times, significantly increasing the time needed to draw those pixels.

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