I’ve got a normal map misbehaving, and it seems to be because I’ve got two different UV islands, each of which belongs to contiguous parts of the mesh, but which are rotated 90 degrees to each other. I’ve verified that if I make the rotation of the islands the same, I get the same normal map for both islands. (Note: one island is the front half of a cylinder, the other is the back half. I’ve divided them up this way so I can easily center decals when I’m texture painting).
Is it not safe to rotate islands like this? Most of the tutorials/books I’ve looked at show lots of rotations of islands.
(note: I tried to attach the blender file, but I got errors).
[edit: Marking this as “solved” since I cleared out all the normal maps in the project, deleted the nodes, and started from scratch. Everything seems fine now, but I don’t understand the problem.]