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From: warwick@batserver.cs.uq.oz.au (Warwick Allison)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: Fast Raster Routines Needed.
Keywords: TT video modes
Message-ID: <7145@uqcspe.cs.uq.oz.au>
Date: 3 Feb 91 23:03:14 GMT
References: <1991Jan23.005852.28904@sbcs.sunysb.edu> <1991Jan31.183155.8948@ataritx.uucp> <7125@uqcspe.cs.uq.oz.au> <1991Feb1.032905.15481@ncsuvx.ncsu.edu>
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Reply-To: warwick@batserver.cs.uq.oz.au
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In <1991Feb1.032905.15481@ncsuvx.ncsu.edu> bmott@hobbes.ncsu.edu (Bradford Mott) writes:

>>                         Who wants 256 colour sprites????  Can you imagine
>>how SLOW it would be to draw up a sprite if you HAD to set all bitplanes?


>Actually, if 1 pixel = 1 byte it would be much faster to draw a 256
>color sprite.

	TRUE!  BUT IT IS TOTALLY UNREALISTIC TO WANT 256 COLOURS ON
	ONE SPRITE!!!!!

With only 4 colours, you often use all colours.  With 16, you MIGHT
consider optimising code that only draws on 3 bitplanes.  But with a 256
colour system, you would be crazy to use ALL bitplanes in EVERY sprite.
Take the following scheme as an example:

	1. Player 1: 8 colours, 0..7		3 bitplanes
	2. Player 2: 8 colours, 8..15		4 bitplanes
	3. Baddies : 48 colours, 16..63		6 bitplanes
	4. Scenery:  192 colours, 64..255	16 bitplanes

Now, if the players never overlap on the scenery, it's okay, you
don't have to worry about the other bitplanes.

If you want players over the scenery, the make it only on, say 16 of the
scenery colours - saving bitplanes.

If you try to use ALL bitplanes ALL the time with EVERYTHING on the screen,
then a machine running at 32 MHz (TT) will be as slow as a 8 MHz (ST)
machine for executing graphics operations.

Further discussion on this line should probably be in rec.games.programmer!

--
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    __    |\	warwick@batserver.cs.uq.oz.au:
  _/  |___/ \		Warwick Allison,	
 /           \		Computer Science Department,