Hi! I’ve imported a mesh that I made in Blender into Unreal, applied a material I made, and I got this:
See how weird the shading is on the faces of the mesh? Is this a UV problem? A normals issue? Please enlighten me. I’ve not the slightest clue. 
(Notice the helmets of the minifigures, too!)
how you do the UVs in blender?
Usually weird lighting is a mesh normal issue, but if it only happens when the material is applied it must be related to that. If you post a picture of the material we may be able to guess. You can also unhook parts of the material to slowly debug it.
The visualization viewmodes are also very useful in these cases. For example, viewing the world normal buffer can help spot issues with normals.
Smart UV Unwrap
Perhaps you need to invert the normals there are problem areas.
That confirms normals are a problem. Flat objects facing the se direction should have the same normals, and thus the same color in the visualizer. It could be due to mesh normals or normal maps depending on if it occurs without the material or not.
I’m using a material that uses triplanar mapping, if that helps.
If you are using a normal map with a triplanar projection, you need to mathematically adjust them. Most tutorials on tri-planar projection will cover this part too. Failure to do this will definitely cause incorrect lighting so that could be what’s happening.
Could you point me in the right direction?
Oh, and one more thing. I imported the mesh that I imported into Unreal (the one that is messed up) into Blender, and the normals are correct. Does this mean that Unreal is incorrectly mapping the normals?
Guess not. Orginal mesh without my material looks like this:
So it is def a triplanar mapping normal issue.
Thank you SOOO much! I’ll test this out later. You are the best! 
Guess what? It was only a single node: I had a stray 1-minus node that one of my blended normals was running through. Removed that, and the issue was gone! Thanks again!
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Haha! well, that’s always fun to track down. Glad it’s working.
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