Draw the scattering plane
Draw the intersections with the faces of the unit cell (one unit cell? many unit cells?)
Dynamic selection of the intersections: so that A, B, Q, Ki, Kf are in the set of faces
Draw the intersections with the faces of the unit cell (one unit cell? many unit cells?)
Dynamic selection of the intersections: so that A, B, Q, Ki, Kf are in the set of faces