Trim sheet normal inverted

Udjani

This wall is mirrored so i'ts using the same uvs position for both sides, but for some reason in one side the trim normals are inverted. I have the same setup inside blender and the normals look fine there. Any tips on what i can try to fix this? 




Some update, the problem seems to be happening because i have the trimsheet on the second UV channel, still no fix tho. I first thought that the normals were broken only on one side, but even the ''not broken'' side have some weird behavior with light.





-------
Attached both walls and normals if you want to test it, check ''combine meshes'' when importing.

Udjani

An update, apparently using trimsheet/decal on the second uv set is not possible, even unwrapping and exporting both sides of the wall separately didn't work. But for whatever reason if i use the trim on the first uv set and the tiling normal on the second it works fine, the tilling normal reacts correctly to lighting.

However now i am having another problem, i can't make the trim/decal blend correctly with the tiling normal, it end up having a seam where the decal/trim cut is. 




This one is from Obscura on another thread, the material setup is basically the same but he is not getting the nasty seam, i don't get it. 

Obscura

That looks more like an uv compression issue but the image is not very sharp so I could be wrong. Open up he static mesh, and enable "use full precision uvs".

Anyways, the reason for why you are getting broken shading when the normal map uses uv channel 1 is that unreal only generates tangents for uv0. You can try using "generate tangent basis" node, but it doesn't always work perfectly. And whats the problem with mesh decals? That post of mine was before they added that feature and now you could do this in a much easier way.

Udjani

Just tried the full precision uvs but dosen't seem to be the problem, I might be missing one step or something.



I decide to go with 2 uv's because this way I am able to do all the decal materials without affecting the borders(insets). Also with mesh decals the decal normal override the the tilling normals, so on a mesh like this wall at the bottom where i want both off them to blend i would have some seams problems.

Obscura

What if you do the detail normal map in world space, and you include it in the decal material?

Udjani

Obscura said:

What if you do the detail normal map in world space, and you include it in the decal material?

Will try this latter.

For now i found this post on UE4 forum and the seam is gone, but it increases the shader complexity quite a bit.





Though if i use the detail normal with proper scale it's almost not possible to see the seam.