Hi, I need help to write a solution determining the angle of intersection between surface of a sphere and the inner surface of a sphere segment. .. with the goal to let the sphere, that is moving towards the segment, be redirected as its outgoing angle as with the incoming angle.   If i am right I need to calculate the angle of the normals vectors of the intersection faces...   I need your help about the how to get the normals of the faces that are aligned to the in