Article View: comp.lang.pascal.borland
Article #65Re: 3d programming
From: David Matiskella
Date: Wed, 14 Feb 1996 22:35
Date: Wed, 14 Feb 1996 22:35
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On Wed, 14 Feb 1996 TheAnalyst@Nfo.Org wrote: > "Christopher H. Clark" <chc104@psu.edu> wrote: > > >Jonathan Cohen wrote: > >> > >> In article <3118310E.52F@psu.edu>, Christopher H. Clark <chc104@psu.edu> wrote: > >> >Actually, you only need 2 points to define a plane: a point on the plane and > >> >a normal vector. > >> > >> Sorry to quibble, but... > >> > >> A VECTOR IS NOT A POINT!!!! > >> > >> Now back to our regular program. > > >Points are vectors. > > I may not be a 3d programmer but I do know that a point is NOT a vector. > > Definition of Vector from my Physics book: > VECTOR: Quantity having both magnitude (size [meaning speed]) and direction. > > In other words a point is not a vector and a vector is not a point. Also, two > points do not necessarily make a vector. A vector is a point that *points* > somewhere But a point has a magnitude and direction. Point x,y,z has a magnitude of sqrt(x^2+y^2+z^2) and a direction of ( x i y j z k)/magnitude where i,j,k are the unit vectors. Remember when you define a point in space you are referencing it to some reference point. David Matiskella matiskel@aa.washington.edu
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Path: arc1-ca.pugleaf.net!curtis.aa.washington.edu!matiskel From: David Matiskella <matiskel@aa.washington.edu> Newsgroups: comp.lang.pascal.borland,comp.lang.pascal.mac,comp.lang.pascal.ansi-iso,comp.lang.pascal.misc,comp.sys.amiga.programmer,comp.graphics.algorithms,comp.os.ms-windows.programmer.graphics,comp.sys.amiga.graphics Subject: Re: 3d programming Date: Wed, 14 Feb 1996 14:35:34 -0800 Organization: University of Washington Message-ID: <Pine.OSF.3.91.960214142740.20349A-100000@curtis.aa.washington.edu> References: <4f3od9$2jg@zeus.tcp.co.uk> <jderrick-0502961551360001@slip037.csc.cuhk.hk> <3118310E.52F@psu.edu> <4fiuh2$qrj@fulton.cs.unc.edu> <311E38D7.71BC@psu.edu> <4frlln$lp5@dfw.nkn.net> NNTP-Posting-Host: curtis.aa.washington.edu Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII In-Reply-To: <4frlln$lp5@dfw.nkn.net>