Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!bu-cs!purdue!decwrl!sgi!miq@chromavac.SGI.COM
From: miq@chromavac.SGI.COM (Miq Millman)
Newsgroups: comp.sys.sgi
Subject: Re: 4Sight, X or NeWS?
Summary: XOR versus overlay planes
Message-ID: <20894@sgi.SGI.COM>
Date: 21 Oct 88 18:56:17 GMT
References: <8810202336.AA03068@ucbvax.Berkeley.EDU>
Sender: daemon@sgi.SGI.COM
Organization: Silicon Graphics, Inc., Mountain View, CA
Lines: 29

In article <8810202336.AA03068@ucbvax.Berkeley.EDU>, jim@THRUSH.STANFORD.EDU (Jim Helman) writes:
> 
> 
> I don't know if 4Sight's NeWS has better pixel performance, but
> normally I would expect X to be better than NeWS for raster image
> operations, since X is built around a raster imaging model.

The reason that X is so much slower on our machines is because of the way it
handles doing things like rubberbanding and highlighting.  X uses XOR to 
change colors on the screen which is just fine for a monochrome no grey scale
monitor, but it really sucks with color.  On the SGI workstations, overlay
planes are used for doing the same things that X tries to do with XOR.  The
graphics hardware is incredibly fast, so performace is not hurt.  On the 4D
series, pixel performance is about 8 million pixels per second.

Incidently, a new version of X for our machines is being worked on and it
should be released soon.

> 
> Jim Helman
> Department of Applied Physics
> Stanford University


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