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From: faber@clown.cs.wisc.edu (Ted Faber)
Newsgroups: comp.graphics
Subject: Re: clipping polygons to a viewport
Summary: Paper reference
Keywords: polygons,clipping
Message-ID: <8660@spool.cs.wisc.edu>
Date: 3 Oct 89 04:30:49 GMT
References: <120@csinc.UUCP>
Sender: news@spool.cs.wisc.edu
Reply-To: faber@clown.cs.wisc.edu (Ted Faber)
Organization: U of Wisconsin CS Dept
Lines: 25

In article <120@csinc.UUCP> shal@csinc.UUCP (Shal Jain x848) writes:
>Am looking for a very robust algorithm/code for clipping polygons to a 
>rectangular viewport. The polygons can be concave,convex or bow-tied.
>The only reference I have is Newman-Sproull "Principals of Interactive
>Computer Graphics". Any pointers,references etc. will be appreciated


	OK. I'll take a stab at this.  No I'm not going to send code, but I do
have a reference for you.

	Sutherland and Hodgman's "Reentrant Polygon Clipping" in Communications
	of the ACM, Vol 17, No. 1 Jan 1974

	This is a good place to start, but I believe that their method will 
result in an unusual case for your case, namely that their algorithm will 
leave you with the two triangles in the viewport connected by two edges on the 
right edge of the VP.  The two edges will be the same line.  At the end of the
paper they do go into detail about how to deal with this, as I recall, but it's
been a while since I read it, so caveat emptor.  The algorithm is an interesting
approach and educational to implement.

		Good luck,

			Ted Faber
No sig yet, but I can be reached at faber@cs.wisc.edu