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Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!ihnp4!qantel!lll-crg!well!perry
From: perry@well.UUCP (Perry S. Kivolowitz)
Newsgroups: net.micro.amiga
Subject: balls (2 of 2)
Message-ID: <302@well.UUCP>
Date: Wed, 27-Nov-85 08:01:11 EST
Article-I.D.: well.302
Posted: Wed Nov 27 08:01:11 1985
Date-Received: Fri, 29-Nov-85 21:27:19 EST
Organization: Whole Earth Lectronic Link, Sausalito, CA
Lines: 42
Keywords: source code, bresenham's circle algorithm

This is file two of two. To be loaded with balls.c
Thanks to Captain Crunch for getting this off my amiga
and onto a VAX.
	Perry S. Kivolowitz
-----------------------------------------------------
/*
** b r e s . c
**
** perry s. kivolowitz - ihnp4!ptsfa!well!perry
**
** not to be distritbuted for commercial use. any distribution
** must included this notice, please.
**
** generate radial  displacements according to bresenham's circle
** algorithm. suitable for running twice, giving a fast spherical
** surface.
**
*/
 
bres(r , array)
register short *array;
register r;
{
   register x , y , d;
 
   x = 0;
   y = r;
   d = 3 - 2 * r;
   while (x < y) {
      *(array + r - y) = x;
      *(array + r - x) = y;
      *(array + r + y - 1) = x;
      *(array + r + x - 1) = y;
      if (d < 0) d += 4 * x + 6;
      else d += 4 * (x - y--) + 10;
      x++;
   }
   if (x == y) {
      *(array + r - y) = x;
      *(array + r + y - 1) = x;
   }
}