Seam visible when using a material with BumpOffset on a Nanite mesh

Development Rendering
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1

When having a material that uses BumpOffset that is fed into the Emissive Color of Surface Opaque Default Lit material that is then applied to a nanite mesh, a visible seam can be seen along edges and the intersections with other geometry.

Disabling nanite (r.nanite 0) will remove the seam.

2

Steps to Reproduce
Open the project in the editor. The level Nanite_BumpOffset_Seam should load.

3

Hi Henning,

Thanks for reaching out. At first glance, those artifacts look like either your analytical or hardware derivatives for your material are incorrect. We fixed all those bugs with our improvements with the switch to Nanite compute shader materials, but maybe something has slipped through. While I investigate this issue further, what is your use case for this material setup? That way, I can ensure we have not missed a use case.

4

We use it to setup a fake skylight and add some parallax effect to it

5

Hi Henning,

I tried investigating this issue further, but could not reach a definite conclusion about why you see this artifact. I created a Jira with the dev team to investigate this issue further:

Unreal Engine Issues and Bug Tracker (UE\-328940\). If you still have any other questions, please get in touch with us again.