Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site uvaee.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!mcnc!ncsu!uvacs!uvaee!nst 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. *** REPLACE THIS LINE WITH YOUR MESSAGE ***