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From: cbdougla@uokmax.ecn.uoknor.edu (Collin Broad Douglas)
Newsgroups: comp.sys.atari.st
Subject: Re: TT graphics modes
Keywords: sample&hold
Message-ID: <1990Nov8.052824.16553@uokmax.ecn.uoknor.edu>
Date: 8 Nov 90 05:28:24 GMT
References: <1990Nov7.154503.9366@imada.dk> <2735@atari.UUCP>
Sender: cbdougla@uokmax.ecn.uoknor.edu
Organization: Engineering Computer Network, University of Oklahoma, Norman, OK
Lines: 63

In article <2735@atari.UUCP> apratt@atari.UUCP (Allan Pratt) writes:
>micro@imada.dk (Klaus Pedersen) writes:
>>Shifter mode called "Sample&Hold".
>>(the article said something about HAM and lotsa colors!).
>
>SAH mode has nothing to do with lots of colors.  What it lets you
>do is draw filled polygons really fast.  You can draw two dots
>on the screen and get a solid line between them, without having
>to write the color value to all the pixels in between in memory.
>Example below.
>
>EXAMPLE OF SAH MODE:
>
>In SAH mode, nonzero pixel values in memory appear as that color, and
>zero pixel values in memory mean "continue with previous color."  That's
>why it's also called "smear" mode: a colored dot will "smear" to the
>right until it reaches another nonzero pixel value.
>
>[munch munch]

>..****..
>...**...
>..****..
>........
>
>You can get it by drawing this:
>
>........
>..*...0.
>...*.0..
>..*...0.
>........
>
>This means you only had to write six pixels, not thirteen.  Of course,
>this is just a sample: the savings is much more dramatic for bigger pictures.
>
>
>============================================
>Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
>reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt

  
  You all will like this new feature.  We have in on the Apple IIGS (but we
call it fill mode).  It's really fun to have.  I believe the GS version of
Tunnels of Armagedon uses this mode.  I've also got a couple of animation
demos that use it.  I just with Rainbird would do ports of Carrier Command
and Mid Winter using fill mode  :).  then I'd be a happy camper!

       Collin Douglas

cbdougla@uokmax.ecn.uoknor.edu

P.S.  anyone know of a decent CAD for the Atari ST?  My roomate has an ST and
I'd like to get a CAD.  The only PD CADs for the GS are old and bad (old 
meaning they don't even use GS graphics  :(  CAD Apple is a little out of
my price range :( :(  ).

Thanks for any help.




even use h