Polygon Rectangle Clipping

From CGAFaq

To clip a polygon against an axis-aligned rectangle, use the Sutherland-Hodgman algorithm, an old favorite that should be covered in any basic graphics textbook.

According to Vatti (q.v.) "This [algorithm] produces degenerate edges in certain concave / self intersecting polygons that need to be removed as a special extension to the main algorithm" (though this is not a problem if all you are doing with the results is scan converting them.)

It should be noted that the Sutherland-Hodgman algorithm may be used to clip a polygon against any convex polygon. Cf. also Subject 5.04.