Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!watmath!watcgl!jdchrist
From: jdchrist@watcgl.waterloo.edu (Dan Christensen)
Newsgroups: comp.graphics
Subject: Re: Z-Buffer Edge effects
Message-ID: <11370@watcgl.waterloo.edu>
Date: 2 Sep 89 18:40:38 GMT
References: <5270@tank.uchicago.edu>
Reply-To: jdchrist@watcgl.waterloo.edu (Dan Christensen)
Organization: Computer Graphics Lab, University of Waterloo
Lines: 17

In article <5270@tank.uchicago.edu> arch_ems@gsbacd.uchicago.edu writes:
|>Real systems get around this problem by using backface elimination
|>for all closed objects.  The strongest reason to use backface
|>elimination (in my opinion) is to get rid of the pixels that
|>occasionally show through, not for the speed advantage you get
|>through not having to draw all of the back facing polygons.
|
|Was this last point a smiley?  Isn't there a significant speed
|advantage to not having to draw all of the back facing polygons?

On our Iris 4D/120GTX drawing is slightly faster with backface removal
turned *off* if the polygons are small enough.  But for larger polygons
backface removal definitely speeds things up.

----
Dan Christensen, Computer Graphics Lab,	         jdchrist@watcgl.uwaterloo.ca
University of Waterloo, Waterloo, Ont.	         jdchrist@watcgl.waterloo.edu