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From: zyeh@caspian.usc.edu (zhenghao yeh)
Newsgroups: comp.graphics
Subject: Re: Need polygon splitting algo...
Date: 20 Apr 1993 12:06:59 -0700
Organization: University of Southern California, Los Angeles, CA
Lines: 25
Sender: zyeh@caspian.usc.edu (zhenghao yeh)
Distribution: world
Message-ID: <lt8iejINNbgl@caspian.usc.edu>
References: <1qvq4b$r4t@wampyr.cc.uow.edu.au>
NNTP-Posting-Host: caspian.usc.edu
Keywords: polygons, splitting, clipping


In article <1qvq4b$r4t@wampyr.cc.uow.edu.au>, g9134255@wampyr.cc.uow.edu.au (Coronado Emmanuel Abad) writes:
|> 
|> The idea is to clip one polygon using another polygon (not
|> necessarily rectangular) as a window.  My problem then is in
|> finding out all the new vertices of the resulting "subpolygons"
|> from the first one.  Is this simply a matter of extending the
|> usual algorithm whereby each of the edges of one polygon is checked
|> against another polygon???  Is there a simpler way??
|> 
|> Comments welcome.
|> 
|> Noel.

	It depends on what kind of the polygons. 
	Convex - simple, concave - trouble, concave with loop(s)
	inside - big trouble.

	Of cause, you can use the box test to avoid checking
	each edges. According to my experience, there is not
	a simple way to go. The headache stuff is to deal with
	the special cases, for example, the overlapped lines.

	Yeh
	USC
