Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!uwm.edu!spool.mu.edu!munnari.oz.au!metro!cs.uow.edu.au!u9050728
From: u9050728@cs.uow.edu.au (Shane Kelvin Richards)
Newsgroups: comp.sys.apple2
Subject: Animation
Keywords: Animation
Message-ID: <1991Apr17.061057.22357@cs.uow.edu.au>
Date: 17 Apr 91 06:10:57 GMT
Organization: Dept of Computer Science, Wollongong University
Lines: 33


	Hello. I am hoping someone can help me. I am developing a set of
animation routines for the //GS. So far its okay, BUT things are becoming
a tad slow when many objects are on the screen. Heres how I am doing it..

	If I want to put a shape on the screen, I go through a loop pulling
off each background byte (that the shape will be using) anding it with the
shapes mask (using a mask makes it really easy to have "see-through" holes
in the shapes and so that the background moves around the shape if the 
background and shape happen to fall in the same byte) then I ora the shape
byte and place this calculated byte back on the screening (and yes I am
using the shadow screen in bank $01 for faster reads). So this is the 
basic process. It slows down quite considerably but I can't think of any
other way of doing what  am trying to do. This is the place the shape
down on top of the background nicely (so that it doesn't get jaggies if
I had for instance just Stored the shape directly on the screen.

       My question is, is my basic ideas/techniquie correct? Am I using
the wrong method for fast shape manipulation. OR am I using the correct
method and I should just try to improve upon my code and optimise where
I can?

      For simplicity I only let shapes move by 2 pixels so that they 
always fall on a byte boundary. Also, I am usin the 320x200 resolution.

	Any ideas, what other techniques are there?


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Shane Richards
u9050728@cs.uow.edu.au
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