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From: jdresser@altair.uucp (Jay Dresser)
Newsgroups: rec.games.programmer,comp.sys.amiga.tech
Subject: Re: Animation Speed & Redraw
Message-ID: <3776@tymix.UUCP>
Date: 6 Sep 90 22:23:21 GMT
References: <1401@metaphor.Metaphor.COM>
Sender: usenet@tymix.UUCP
Reply-To: jdresser@altair.Tymnet.com (Jay Dresser)
Organization: BT Tymnet, Inc. / San Jose, CA
Lines: 19

I can tell you from my experience that it is definately faster to erase
each object than to erase the whole screen; blitter or not.  The method
I use has three screen buffers.  Two for double buffering, and the
third I call the "pristene screen".  The pristene screen contains the
background without any objects and is never written to.  When I prepare
the object to be blitted, I save some of the information (that
pertaining to the rectangle that encompasses the object) in a structure
for erasing (actually, 2 structures because of double buffering).  Then
when I erase, I simply copy the reactangle from the pristene screen to
the rendering buffer.  When I was given the task of speeding up Dark
Castle/Atari, it was just this kind of change that brought it from 2
frames/sec to 15f/s, and that was using the CPU.  It's a tradeoff of
memory for speed.  If you can afford the third buffer, this is the way
to go.

Jay

Disclaimer: so, if I didn't have a disclaimer here, would anybody
seriously think I was speaking for my company???  yeah, right!