Black material when rotated


That’s the situation I’ve found today opening my project, till tonite was all perfect, now all the shadows are messed up, strange artifacts everywhere… Btw i’ll get to the hottest point, trying to be as clear as possible, my planks, the model was originally created with 4 planks together, one of them had the UV rotated of 180°, not scaled inward, rotated.
No overlapped UVs. (ah… was rotated to break the possible similarity of the textures during the repetition…) btw… I said, oook, so i re unwrapped the planks, now with all the UVs in the same direction… and that’s the result:
And i’ve got 4 planks black and 4 correct… XD Oooooook And I discovered that the black planks was the ones that i rotated after copying the orginal mesh. So I tried and… WTF…
The material was getting alternatively black and clear when rotated… GG The only explanation i’ve found it’s about the Normals… but it’s weird, never happened a thing like this, and it’s not the first time Im doing this kind of stuff O_o

PS. rebuild done and the lightmaps are perfect

Sorry for my english :slight_smile:

EDIT: Seems that everything has been messed up, seems that rotating UVs it’s a solution… But it’s crazy WTF, never happened before, always worked like this, in which crazy and Rainbow Unicorns populated world normals works only if oriented in ONE and only direction? O_o

Very strange. How many UV channels do you have? Most things use 1 for the textures and one for the lightmap, but if you have your normals applied to the 2nd (or 3rd) UV channel there can be problems. This is because Unreal bases its normal direction on the faces of the first set, so the UV set with the normals applied needs to have the faces in the same direction as the first set. I don’t think this is your problem, but it’s worth looking into. If you only have textures applied to your first UV set, then this isn’t your problem.