Path: utzoo!attcan!uunet!cs.utexas.edu!csd4.milw.wisc.edu!bionet!ames!sgi!tarolli@dragon.wpd.sgi.com
From: tarolli@dragon.wpd.sgi.com (Gary Tarolli)
Newsgroups: comp.sys.sgi
Subject: Re: subroutines perpec and lookat
Summary: y is up
Message-ID: <39135@sgi.SGI.COM>
Date: 28 Jul 89 18:57:05 GMT
References: <8907250331.AA20644@prism.gatech.edu> <38766@sgi.SGI.COM>
Sender: daemon@sgi.SGI.COM
Organization: Silicon Graphics, Inc., Mountain View, CA
Lines: 17

In article <38766@sgi.SGI.COM>, thant@horus.sgi.com (Thant Tessman) writes:
> In article <8907250331.AA20644@prism.gatech.edu>, ccsupos%prism@GATECH.EDU ("SCHREIBER, O. A.") writes:
> 
> 
> This is probably due you assuming that z is up (a perfectly reasonable
> assumption, one would think) but that the 'lookat' for historical reasons 
> thinks that y is up, not z.
> 
> 

I think it is perfectly reasonable for y to be the up axis.  Its not a 
historical reason, its a logical one.  If z was up, then zbuffers would
be called ybuffers wouldn't they?   Zbuffers are called zbuffers because
the z axis runs along the line of sight!  This implies x and y are 
therefore up/down  and right/left.
--
						Gary Tarolli