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From: fdfishman@watcgl.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: Rapid Stimulus Displaying on the Amiga Help.  Solution
Message-ID: <916@watcgl.UUCP>
Date: Mon, 20-Apr-87 18:20:32 EST
Article-I.D.: watcgl.916
Posted: Mon Apr 20 18:20:32 1987
Date-Received: Tue, 21-Apr-87 00:14:19 EST
References: <8704200221.AA03819@cory.Berkeley.EDU>
Reply-To: fdfishman@watcgl.UUCP (Flynn D. Fishman)
Organization: U. of Waterloo, Ontario
Lines: 47

In article <8704200221.AA03819@cory.Berkeley.EDU> dillon@CORY.BERKELEY.EDU (Matt Dillon) writes:
>
>	Use a two plane screen, then render bitmap A into plane 1, and 
>	bitmap B into plane 2 .  The idea is that then all you need to
>	do to switch bitmaps is set the color registers:
>
>	plane:	2 1	color register
>		0 0	0	always background color
>		0 1	1	depends 
>		1 0	2	depends
>		1 1	3	doesn't matter
                ^^^^^^^ ^^^^^
colour 3 does matter, since it represents the intersection of the two stimulus, if you set this colour
to 0 then, where ever the two stimulus intersect you will see a missing hole.  As well if you set 3 to white
when you draw the stimulus, you see a white area before you want to display the object.  So want to know the
simple solution?  When you display a plane make sure you also enable colour 3.

This method of drawing into two planes is a very good one, but why stop at two planes, you have 5 to play
with, therefore you can display 5 stimulus, all you have to do when writing the stimulus is enable the
write mask so that only the desired plane is written to (i.e. RastPort.Mask = 1 << plane).

Then to display each plane you can use a simple routines like:

   DisplayPlane(view, plane)
   struct ViewPort *view;
   int plane;
      {
	  int loop;

	  for (loop = 0; loop < 2^NUMPLANES; loop++)
          {
		  if ( (loop & (1<<plane) ) == 0) SetRGB4(view, loop, 0, 0, 0);
		  else SetRGB4(view, loop, REDON, GREENON, BLUEON);
		  }
	  }

DisplayPlane enables all the colours that effect the displayed plane and turns all the other colours 0


>
>					-Matt
>		
-- 
FDFISHMAN (Flynn D. Fishman) @ WATCGL (but you can call me Flynn)
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