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From: djh@neuromancer.metaphor.com (Dallas J. Hodgson)
Newsgroups: rec.games.programmer,comp.sys.amiga.tech
Subject: Animation Speed & Redraw
Message-ID: <1401@metaphor.Metaphor.COM>
Date: 4 Sep 90 19:27:53 GMT
Sender: news@metaphor.Metaphor.COM
Reply-To: djh@neuromancer.metaphor.com (Dallas J. Hodgson)
Organization: Metaphor Computer Systems, Mountain View, CA
Lines: 23


You know, I've never seen this mentioned anywhere but the question is always
in the back of my mind. If you're working on a real-time game that commonly
has high numbers of animated objects moving around at all times (using a
double-buffered screen) is it faster to clear out the undisplayed screen
completely and redraw all the objects vs. restoring the background behind
each object and then redrawing?

There's a lot of overhead associated with clipping & storing the background
behind every object just so it can be restored later. However, even with
blitter assist clearing out 32-40K worth of video memory each frame is
real-time significant. Not that I'm working on any games currently, but I've
always wondered about this. How do you approach bitmap animation when speed
is a prime consideration? Games like Datastorm are technological wonders
in my book.
+----------------------------------------------------------------------------+
| Dallas J. Hodgson               |     "This here's the wattle,             |
| Metaphor Computer Systems       |      It's the emblem of our land.        |
| Mountain View, Ca.              |      You can put it in a bottle,         |
| USENET : djh@metaphor.com       |      You can hold it in your hand."      |
+============================================================================+
| "The views I express are my own, and not necessarily those of my employer" |
+----------------------------------------------------------------------------+