Line Clipping Using Semi-Homogeneous Coordinates

Abstract

The dual intersection test is described. It is a new method for deciding whether a line intersects a window. The concept of semi-homogeneous coordinates is introduced. It allows us to define line segments in projective space, and to derive a generalized Cohen-Sutherland end-point test for such segments. When this is combined with the dual intersection test, we obtain new clipping algorithms for 2D and 3D projective space.