Abstract: A cross product calculator to multiply mathematical representations of a pair of vectors in order to calculate a resultant vector, which resultant vector is aligned normal to the plane in which the pair of vectors is located. The present cross product calculator has application to a real time computer generated imagery or graphics system having the capability to provide reliable color shading of a three dimensional object moving across the screen of a video display. The resultant normal vector provided by the cross product calculator is indicative of the orientation of the object relative to a source of supply of incident light. Storage apparatus and control hardware are included to provide accurate, normalized equivalents of the mathematical representations of the pair of vectors which are multiplied together to derive the cross product thereof.