Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!ucsd!sdcc6!sdcc8!cs178abu
From: cs178abu@sdcc8.ucsd.EDU (John Schultz)
Newsgroups: comp.sys.amiga
Subject: Re: collision detection
Message-ID: <815@sdcc8.ucsd.EDU>
Date: 11 Mar 88 08:12:04 GMT
References: <893@astroatc.UUCP>
Reply-To: cs178abu@sdcc8.ucsd.edu.UUCP (John Schultz)
Organization: University of California, San Diego
Lines: 26
Keywords: does it work?




  The hardware collision registers work only for certain pairs of
hardware sprites.  I have written a few games for the Amiga, and
don't use the system animation routines; they are too slow.  In
"Libyans In Space" I used a simple "proximity" algorithm for
animation done using BltBitMap().  In "TacoRama!" (soon to be
released), I used hardware sprites and used the hardware collsion
registers.  TacoRama! was simple enough to allow me to choose the
pairs that would work for hardware collisions.  The runtime overhead
for algorithmic collision detection is quite small.  I would
recommend using that approach for anything sufficiently complex
(more than the hardware registers can handle).  Here is the simple
algorithm I use:

PROCEDURE proximity(targetx,targety,
                    missilex,missiley : INTEGER;
                    targetw,targeth   : CARDINAL): BOOLEAN;
BEGIN
  RETURN (ABS(targetx - missilex) < INTEGER(targetw)) 
     AND (ABS(targety - missiley) < INTEGER(targeth));
END proximity;



  John