Article View: comp.lang.pascal.borland
Article #29Re: 3d programming
From: David Matiskella
Date: Mon, 12 Feb 1996 20:50
Date: Mon, 12 Feb 1996 20:50
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2083 bytes
On Mon, 12 Feb 1996, Paul Rowntree wrote: > Christopher H. Clark 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. > > ^^^^^^^^^^^^^^^^^^ > > Sorry, but I must take offense here. A point in Cartesian space has three > aspects [X,Y,Z]. A vector requires a direction, and depending on how sticky you > are, probably a length. This implies 6 independent aspects. Result; A plane > requires 3 points. Always. > > Cheers > A vector has a direction and magnitude. That is 4 parameters. YOu can consider a point to be a vector from (0,0,0) to (x,y,z). However a vector (x,y,z) could be a vector from (x1,y1,z2) to (x2,y2,z3). The point has a fixed location with respect to the coordinate axes while the vector has no fixed location with respect to the coordinate axes. 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: Mon, 12 Feb 1996 12:50:39 -0800 Organization: University of Washington Message-ID: <Pine.OSF.3.91.960212124550.12811A-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> <311F9C84.3B26@structure.chimie.usherb.ca> NNTP-Posting-Host: curtis.aa.washington.edu Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII In-Reply-To: <311F9C84.3B26@structure.chimie.usherb.ca>