Path: utzoo!news-server.csri.toronto.edu!rutgers!usc!elroy.jpl.nasa.gov!swrinde!zaphod.mps.ohio-state.edu!wuarchive!waikato.ac.nz!aukuni.ac.nz!groc1 From: groc1@cs.aukuni.ac.nz (GuyonAlanEdward Roche ) Newsgroups: comp.graphics Subject: Re: newell plane equation Keywords: graphics, plane eqation Message-ID: Date: 12 Mar 91 02:11:58 GMT References: <9283@exodus.Eng.Sun.COM> Sender: news@ccu1.aukuni.ac.nz (News Owner) Organization: University of Auckland, New Zealand. Lines: 28 In <9283@exodus.Eng.Sun.COM> stephenj@deblil.Eng.Sun.COM (Stephen Johnson) writes: >and I discovered that the plane defined by the following points is >computing incorrectly: >(2,2,0), (12,2,0), (2,2,3), (12, 2, 3) [ stuff deleted here ] >Oops, by inspection we can see that the equation for this plane is >y = -2. So, what's wrong? Has someone noticed this before and fixed >it. What is in fact wrong here is that the points have to be entered in in a clockwise or counter-clockwise direction making a simple closed polygon. If you were to rearange the points like this .. (2,2,0), (12,2,0),(12, 2, 3), (2,2,3) it should work. ======================================================================== | Guyon Roche : Don't buy a used car from Caveat Emptor's used cars! | ========================================================================