I have an object that has been mirrored in Blender with the mirror modifier. UV’s have been correctly mirrored as normal, but applying a normal map to the object in Unity causes only one half of the object to be bump mapped. So after doing some research on the topic I noticed it had something to do incorrect tangents. However, after disabling Unity’s tangent importer, I was left with an unshaded objects. (No tangents had been imported)
I thought the problem was that .blend files didn’t contain tangents, so I exported an FBX with “tangent space” checked. And sure enough, there was bump mapping on both halves of the object. But something is still not right, there is an obvious seam and the bump mapping on one half looks opposite to the other half:
On the left is the original .blend (with only half bump mapped) and the right is the .fbx with imported tangents (noticeable seam with inverted bump maps). What is going on here?
Side note: previously when I ran into this problem I would just apply the mirror and recalculate UV’s. This worked when I had tiled textures (as I could just scale up UV mapping to compensate for the extra UV coordinates) but now I’m using a non-tileable texture, which means I can’t just dump the current UVs! The mapping is now dependent on the texture being correct in mirrored mode. Thanks in advance!