Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!gatech!mcnc!thorin!unc!cullip
From: cullip@unc.cs.unc.edu (Timothy Cullip)
Newsgroups: comp.sys.amiga
Subject: Re: 4096 colors in HIRES
Message-ID: <8721@thorin.cs.unc.edu>
Date: 5 Jul 89 12:09:13 GMT
References: <20069@cup.portal.com> <409@xdos.UUCP> <20112@cup.portal.com> <412@xdos.UUCP> <1166@atanasoff.cs.iastate.edu>
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Reply-To: cullip@unc.cs.unc.edu (Timothy Cullip)
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Organization: University Of North Carolina, Chapel Hill
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Actually the 4096 color mode in HIRES can be quite useful.  I have recently
modified a ray tracer I wrote that used to use 320x400 HAM to now also use
640x400 HIRES with the ability to change the color registers every scanline.
I have found that with 4 bitplanes the bus is too busy during the scanline
to get any color registers changed through copper instruction, but during
horizontal blank I can easily change 13 of the 16 registers.  You end up
with one very long copper list, but it works just fine.  I even have it
behaving quite well under Intuition (but screen drags are very slow!).  
The limit of 16 colors per scan line can be somewhat of a problem in a ray
tracer, but for the most part my pictures turn out much nicer looking than
the old 320x400 HAM pictures I was generating.  I would be very interested
in an IFF standard that incorporated this mode since right now I use a crude
double file format that kept the color info separate from the IFF picture.

   T. J. Cullip