subroutines perpec and lookat

[Gary Tarolli]

In article <38766 at sgi.SGI.COM>, thant at horus.sgi.com (Thant Tessman) writes:
> In article <8907250331.AA20644 at prism.gatech.edu>, ccsupos%prism at 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