Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!rice!uw-beaver!fluke!ssc-vax!coy
From: coy@ssc-vax.UUCP (Stephen B Coy)
Newsgroups: comp.graphics
Subject: Re: A-Buffer source (and plotting lots of triangles)?
Message-ID: <3452@ssc-vax.UUCP>
Date: 23 Jul 90 18:03:35 GMT
References: <1990Jul16.225553.2623@maths.tcd.ie> <1264@idunno.Princeton.EDU> <104 <10673@odin.corp.sgi.com>
Organization: Boeing Aerospace & Electronics, Seattle WA
Lines: 22

In article <10673@odin.corp.sgi.com>, robert@texas.esd.sgi.com (Robert Skinner) writes:
> 	A:  render objects back-to-front
> 	B:  save more information at each pixel
> 	C:  oops, I could have sworn I thought of a third 8^)
> 
> Doing A eliminates the render-any-number-of-primitives-in-any-order
> advantage of the Z buffer.  Doing B to save just one value doubles the
> amount of memory the Z buffer takes, which is already considerable.
> If you save much more information, it starts to look like the alpha
> buffer.

A compromise can be reached by rendering all the opaque objects as
you get them but saving the transparent objects for last.  The
transparent objects can then be sorted and rendered back to front.
This works best with scenes that have relatively few transparent
objects.

> Robert Skinner
> robert@sgi.com

Stephen Coy
uw-beaver!ssc-vax!coy