A New Fast Clipping Algorithm for 2D-Polygon against Rectangular Windows

Abstract

Polygon clipping process often involves a lot of intersection calculations and comparison. One way for improving the efficiency of a polygon clipping algorithm is to save the unnecessary intersection calculations demanded by traditional algorithm by rejecting totally the edges lies outside the window. This paper presents a new 2D polygon clipping method, based on an extension to the Sutherland- Hodgman polygon clipping method in which the efficiency is improved either by rejecting the edges lies outside a boundary or by avoiding the comparison of clipping boundaries against the sides of a polygon which neither totally nor partially crossing a polygon. The proposed algorithm neither remembers so-called entry/exit intersection points and nor about union points. After discussing two basic polygon clipping algorithms, a different approach is proposed, explaining the principles of a new algorithm and presenting it step by step. An example implementation of the algorithm is given along with some results. A comparison between the proposed method, the Patrick-Gilles Maillot polygon clipping algorithm, and the Sutherland-Hodgman algorithm is also given, showing very less comparison of edge and clipping region boundary than the Sutherland-Hodgman algorithm, and the Patrick-Gilles Maillot proposed method.