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From: pts@mendel.acc.Virginia.EDU (Paul T. Shannon)
Newsgroups: comp.sys.next
Subject: DPS buffer swapping animation
Message-ID: <1990Dec4.141356.6065@murdoch.acc.Virginia.EDU>
Date: 4 Dec 90 14:13:56 GMT
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Organization: University of Virginia
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Ireallyam: pts

I received such helpful responses to my last question about Display
Postscript that I now ask another.  

A common animation technique (used by SGI gl, for instance) is to draw
to a hidden buffer, and then to issue a 'swapbuffers' command which
displays the previously hidden buffer after the next vertical retrace.
This allows for an entire, possibly complex image to appear on the
screen at once, rather than serially as its parts on drawn.  

I've had some excellent suggestions about the NeXT's blit chip, and
the program /usr/bin/blit (used by /etc/rc at boot), and a promising
portable bit map program from William Lewis.  But before I dig into
these, does anyone know of buffer swapping techniques in DPS?  My
books and manuals didn't help.   Though it's a choice some may question,
I'm doing this work without the appkit, in order to get the greatest
possible control of timing during animation.

 - Paul Shannon
   pts@virginia.edu