Simple rotation procedure for a graphical display system
J.B. Gosling, R.M. Ingham · Electronics Letters · 1976
Rotation of graphical objects consisting of nested subpictures by multiples of 90° can be achieved by adding or subtracting the rotational parameters. This is much simpler than the matrix multiplication usually assumed. The technique is particularly useful in integrated-circuit design, since ‘objects’ are only rotated by multiples of 90°.