Trim paneling shading issue.

Udjani

I am trying to use the trim workflow for sci fi stuff, but when I unwrap a panel line and make it straight the normals get broken. This is how this works or am I missing something?

Kanni3d

It could be possible the normals/tangents are influencing shading. How's the strip look without any material applied to it? Should be flat with no shading

If there is, try putting a hard edge/smoothing group at each polygon, and/or breaking off the uv strip at every angle change.

Udjani

@Kanni3d The plane normals are perfectly flat, so that can't be the problem. I also tried weighted normals and what not. 

It seems that skewing one side of the uv breaks the shading, but idk it feels wrong, I watched some videos about this workflow and they always just get a stripe make it straight and it works. 

Right side has the skewed uvs.

Kanni3d

I've used this workflow a bunch too, that's kinda strange. Could be the way it's being rendered in blenders viewport? How's it look in an engine, or marmoset? 

As a side note, you also wanna make sure that the strips uv's have no fall off/gradient on the edges of them, just so they can blend onto other planar surfaces more seamlessly. Idk if this was for demo purposes, but you can stretch/drag this edge out into where its neutral on the normal map.

icegodofhungary

What software are you doing this in? What software will it be presented in? Is this just a trim texture or is it deferred decals? What videos did you watch?

Udjani

@Kanni3d There is a little bit of gradient beteween the flat plane and the panel line when doing that, but is just a bit, and i don't think it is relate to that shading funckyness. I exported it to marmoset and unreal and they look just as bad. 

@icegodofhungary Blender, just a cut on a mesh, no special shaders. Here is one video for instance: https://youtu.be/3lEddXvb60k?t=4526. I noticed that the guy is beveling the edges in all corners, doing that reduced the shading errors for me but not removed completely.

poopipe

when you make a tangent space normal map flat like this you are assuming that everything is in a nice, flat, uniform space. 

Skewing the uvs means they are not uniform anymore and artefacts ensue. 
Unwrap the geometry so that the uvs have no distortion and it'll work fine. If that's not possible, adding more geometry to tame the distortion will help

icegodofhungary

I would say that stretching is some part of it. When I've done trims before I never straighten out the sides for angles like that. Even if you should be able to, it takes more time to do it than to just leave them at the angle you planar mapped them at. The vid you posted seems to be using curves instead of 45/90 degree corners. This may alleviate some of those issues.

If you think about it, when you have two pieces together at a right angle, that creates a 45 degree angle at the edges. This is if you have 0 stretching and just planar map it. If you have that curve like the guy in the video, the edges are way less than 45 degrees. Its like you're inserting more, straighter, rectangular pieces. This reduces distortion. Same for your pieces that meet at 45 degree angle, they too would have less distortion if you added curves there like the guy in the video.

But there's something a little off in your normal info too. I notice that the red channel is contributing to the surface right before your bevel happens (the pink gradient before blue/green bevel). You're getting a pucker right before a bevel in the opposite direction. So the flat area on your trim isn't actually flat. Make sure your plane you're baking on has the right vertex normals, just set them to match the face. Make sure the flat areas of your highpoly are actually flat.