Article View: comp.lang.pascal.borland
Article #60Re: 3d programming
From: Tom Wheeley
Date: Thu, 15 Feb 1996 23:57
Date: Thu, 15 Feb 1996 23:57
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1957 bytes
In article <824147592snz@chrism.demon.co.uk>
chris@chrism.demon.co.uk "Chris Marriott" writes:
> In article <311E38D7.71BC@psu.edu> chc104@psu.edu "Christopher H. Clark" writes:>
> >Jonathan Cohen wrote:
> >>
> >> Sorry to quibble, but...
> >>
> >> A VECTOR IS NOT A POINT!!!!
> >>
> >> Now back to our regular program.
> >
> >Points are vectors.
>
> No they aren't. A vector has a DIRECTION in space, not merely a POSITION.
> It requires TWO points to define it.
>
Now that _is_ wrong.
A vector is just a way of describing a length with a certain direction.
Points may be referenced via POSITION VECTORS, and they are absolute within
your reference, being a Vector from point (0,0,0...)
You can define a vector using two points, but that vector can be moved anywhere
within your space and remain THE SAME VECTOR.
Thus two points can define a vector, but they are not the only two points to
do so.
--
* TQ 1.0 * The 'Just So Quotes'.
Jesus rose from the dead and the apostles came unto him saying "How's Elvis"
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Path: arc1-ca.pugleaf.net!mail2news.demon.co.uk!tsys.demon.co.uk From: Tom Wheeley <tomw@tsys.demon.co.uk> 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: Thu, 15 Feb 96 23:57:52 GMT Organization: City Zen FM Message-ID: <824428672snz@tsys.demon.co.uk> 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> <824147592snz@chrism.demon.co.uk> Reply-To: tomw@tsys.demon.co.uk X-NNTP-Posting-Host: tsys.demon.co.uk X-Newsreader: Demon Internet Simple News v1.30 X-Sig-By: Tomsystems Quote v1.2. (c)1996 Tom Wheeley, tomw@tsys.demon.co.uk X-Mail2News-Path: tsys.demon.co.uk