Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!decwrl!sgi!shinobu!odin!cashew.asd.sgi.com!kurt
From: kurt@cashew.asd.sgi.com (Kurt Akeley)
Newsgroups: comp.sys.sgi
Subject: Re: bitplane planeing
Message-ID: <1991Apr29.152647.6683@odin.corp.sgi.com>
Date: 29 Apr 91 15:26:47 GMT
References: <9104290717.AA16340@karron.med.nyu.edu>
Sender: news@odin.corp.sgi.com (Net News)
Reply-To: kurt@cashew.asd.sgi.com (Kurt Akeley)
Organization: sgi
Lines: 19

In article <9104290717.AA16340@karron.med.nyu.edu>, Dan Karron@UCBVAX.BERKELEY.EDU writes:
|> 
|> Is there any way to control the allocation of bit planes into OVERDRAW
|> mode ? I want to draw an intricate picture into the NORMALDRAW bitplanes, 
|> then draw various processed pixels from that image on top of it into the
|> OVERDRAW mode bitplanes. I need at least as many bitplanes as in the NORMALDRAW
|> bitplanes (24 bits for my application).
|> 
|> I want to be able to show how an image processing algorithm (a variant 
|> edge detection) draws line with respect to its base image.

No hardware platform currently shipped supports RGB mode in either overlay
or underlay bitplanes.  This probably won't help in your case, but it's
good to keep in mind that if RGB overlay is desired, it can be accomplished
by simply moving the base image to the underlay planes, then drawing "overlay"
images into the normal framebuffer.  If the base image is static, it can
sometimes be compressed into a carefully selected 8-bit colormap.

-- Kurt