(2019-03-12, 23:24)Lasse Deleuran Wrote: While I am not 100% sure about the root cause, I believe this problem is caused by inversions due to negative determinants.
Try to treat negative determinants of the rotation matrix as a switch for the winding.
This was the issue! The normals are all fixed now! I do think that the issue with 3001 is something with my matrix multiplications, since I now see that with more complicated bricks even more things get transformed incorrectly, but that seems unrelated so I won't go into it (at least not here not now). Thanks for the help.