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From: nst@uvaee.UUCP
Newsgroups: net.graphics
Subject: Re: Re: Intersect line with polygon
Message-ID: <137@uvaee.UUCP>
Date: Sun, 16-Dec-84 20:54:01 EST
Article-I.D.: uvaee.137
Posted: Sun Dec 16 20:54:01 1984
Date-Received: Thu, 20-Dec-84 01:33:42 EST
References: <4663@utz, <148@gcc-opus.ARPA> <3122@utah-cs.UUCP>
Organization: EE Dept., U of Virginia, Charlottesville
Lines: 20

> You can substitute the line equation into the plane equation of the polygon
> (derived from its normal), to find where the line (or ray) intersects
> the plane.  (If you find yourself dividing by zero someplace, the line
> and plane are parallel).
> 
> Once you've found the intersection point, there is a nifty algorithm
> (for convex polygons) to determine if the point is inside the polygon.
> 
> This algorithm, along with an excellent discussion of the geometry involved,
> is given in:
> 
> 	Sutherland, I, Sproull, R., and Schumacker, R., "A Characterization
> 	of Ten Hidden-Surface Algorithms", Computer Surveys, 6(1):1,
> 	March, 1974.
> 
> This paper is a must-read for anybody doing 3D shaded graphics, whether it's
> ray-tracing or scanlines.  It has an amazing store of good information and
> handy tricks.

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