public Rectangle4i flatten() {
Transformation t = Rotation.sideOrientation(side, 0).inverse().with(new Scale(-1, 0, -1));
Vector3 vmin = verts[0].vec.copy().apply(t);
Vector3 vmax = verts[2].vec.copy().apply(t);
return new Rectangle4i((int) vmin.x, (int) vmin.z, (int) (vmax.x - vmin.x), (int) (vmax.z - vmin.z));
}