layout uses the face normal to find how to layout a given face. This means that face normals should be unified (unwrapping mobius strips might be problematic), and that the user should be aware of the orientation or select which side of the surface is "up"
layout uses the face normal to find how to layout a given face. This means that face normals should be unified (unwrapping mobius strips might be problematic), and that the user should be aware of the orientation or select which side of the surface is "up"