关键词: Cohen-Sutherland裁剪算法, 直线分类, 辅助线, 符号

Abstract: Cohen-Sutherland clipping algorithm is lower efficiency because of four intersection operations of line segment and window edge lines. In this paper, a modified Sutherland-Cohen line clipping algorithm is proposed. The line in the window or out the window completely is judged. The auxiliary line is decided according by the coding of a line endpoint, and one of edges of the window is deduced to compute the point of intersection with the line by the relation of three points on a plane. The modified algorithm makes intersection operation be twice at most, avoiding to compute the slope and distance, can improve the efficiency of the algorithm greatly. The thought is simple, the operation is convenient, hardware implementation is easy, and is important practical value for graphics applications.

Key words: Cohen-Sutherland clipping algorithm, line classification, auxiliary line, sign