I build a two tetrahedron matrices, a To and From matrix, where I’m transforming a surface vertex from one space into the other. I’ve got that working. Now I’m trying to adjust the surface normal to be correct. The spaces are not just different in rotations but also in sheer. The to tetrahedron matrix has one of the ground vertices raised. When transforming between these two spaces any verts within the tetrahedron are correctly moved into their new relative position. So I need to modify the normal since the plane of the normal has changed. I was told that I can use the same matrix that transformed the vertex location to transform the surface normal. TranformVector does not seem to work. InverseTransformVector appears the closest but still does not work. When hovering over the method tranformVector() it says that if I want to transform a surface normal to use FPlane::TransformByUsingAdjointT. This takes a matrix, a determinant, and another matrix. I’m not exactly sure how to use it. Any ideas?