Title:	Generalized clipping of a polygon against a 2D arbitrary window and a 3D non-convex volume
Authors:	Tokuta, Alade Hua, Shuwei
Citation:	Journal of WSCG. 1996, vol. 4, no. 1-2, p. 257-266.
Issue Date:	1996
Publisher:	Václav Skala - UNION Agency
Document type:	článek article
URI:	http://wscg.zcu.cz/wscg1996/wscg96.htm#abs http://hdl.handle.net/11025/15986
ISSN:	1213-6972 (print) 1213-6980 (CD-ROM) 1213-6964 (online)
Keywords:	parametrická reprezentace;jednoduchý mnohoúhelník;nekonvexní objem
Keywords in different language:	parametric representation;simple polygon;non-convex volume
Abstract in different language:	Several clipping algorithms are in wide use. These are separated into broad classes. They include subdivision algorithms of which the best known is the midpoint subdivision algorithm; the Cohen-Sutherland algorithm which uses outcodes generators and line window intersection calculations to determine what portion(s) of line segments may be contained in the window. Outcode determination/redetermination for the stages of the algorithm can dominate the clipping process. There are algorithms that are based on parametric expressions for lines, and which are comparatively more efficient than the simple Cohen-Sutherland algorithm. The Skala 2D line clipping algorithms use a parameter value to determine the intersection of a line segment with a convex or non-convex polygon window. The Rappoport algorithm clips any subject polygon against a convex polygonal window. The work of Weiler and Atherton algorithm allows the clipping of any subject polygon against any clip polygon. However, it is base on some assuptions. This work presents an efficient method for clipping a polygon against an arbitrary two-dimensional polygonal windows and a modification of the algorithm can also be applied to clip a polygon against a non-convex volume on 3D. The basic idea based on geometry and parametric representation of the lines, determines if an edge of a subject polygon should be totally rejected, or is totally visible. On the other hand, if an edge of a polygon has intersections with the boundary of a simple polygon window, it is easy to decide which parts of the edge are visible after sorting these intersections.
Rights:	© Václav Skala - UNION Agency
Appears in Collections:	Volume 4, number 1-2 (1996)

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