I'm going to start keeping a list here of known barriers to implementing a 3D case.
GridTools::rotate only supports Triangulation<2>. We need to implement a Transformation that rotates in 3D (ideally with a rotation axis and a rotation angle rather than Euler angles), and pass this as the first argument to GridTools::transform.
I'm going to start keeping a list here of known barriers to implementing a 3D case.