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Amiga ACS 1998 #6
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amigaacscoverdisc1998-061998.iso
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descent
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2d
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circle.c
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1998-06-08
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/*
THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
SOFTWARE CORPORATION ("PARALLAX"). PARALLAX, IN DISTRIBUTING THE CODE TO
END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
IN USING, DISPLAYING, AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
FREE PURPOSES. IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES. THE END-USER UNDERSTANDS
AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED.
*/
/*
* $Source: f:/miner/source/2d/rcs/circle.c $
* $Revision: 1.3 $
* $Author: john $
* $Date: 1994/11/18 22:51:01 $
*
* .
*
* $Log: circle.c $
* Revision 1.3 1994/11/18 22:51:01 john
* Changed a bunch of shorts to ints in calls.
*
* Revision 1.2 1994/05/12 17:33:18 john
* Added circle code.
*
* Revision 1.1 1994/05/12 17:21:49 john
* Initial revision
*
*
*/
#pragma off (unreferenced)
static char rcsid[] = "$Id: circle.c 1.3 1994/11/18 22:51:01 john Exp $";
#pragma on (unreferenced)
#include "mem.h"
#include "gr.h"
#include "grdef.h"
int gr_circle(fix xc1,fix yc1,fix r1)
{
int p,x, y, xc, yc, r;
r = f2i(r1);
xc = f2i(xc1);
yc = f2i(yc1);
p=3-(r*2);
x=0;
y=r;
// Big clip
if ( (xc+r) < 0 ) return 1;
if ( (xc-r) > WIDTH ) return 1;
if ( (yc+r) < 0 ) return 1;
if ( (yc-r) > HEIGHT ) return 1;
while(x<y)
{
// Draw the first octant
gr_pixel( xc-y, yc-x );
gr_pixel( xc+y, yc-x );
gr_pixel( xc-y, yc+x );
gr_pixel( xc+y, yc+x );
if (p<0)
p=p+(x<<2)+6;
else {
// Draw the second octant
gr_pixel( xc-x, yc-y );
gr_pixel( xc+x, yc-y );
gr_pixel( xc-x, yc+y );
gr_pixel( xc+x, yc+y );
p=p+((x-y)<<2)+10;
y--;
}
x++;
}
if(x==y) {
gr_pixel( xc-x, yc-y );
gr_pixel( xc+x, yc-y );
gr_pixel( xc-x, yc+y );
gr_pixel( xc+x, yc+y );
}
return 0;
}
int gr_ucircle(fix xc1,fix yc1,fix r1)
{
int p,x, y, xc, yc, r;
r = f2i(r1);
xc = f2i(xc1);
yc = f2i(yc1);
p=3-(r*2);
x=0;
y=r;
while(x<y)
{
// Draw the first octant
gr_upixel( xc-y, yc-x );
gr_upixel( xc+y, yc-x );
gr_upixel( xc-y, yc+x );
gr_upixel( xc+y, yc+x );
if (p<0)
p=p+(x<<2)+6;
else {
// Draw the second octant
gr_upixel( xc-x, yc-y );
gr_upixel( xc+x, yc-y );
gr_upixel( xc-x, yc+y );
gr_upixel( xc+x, yc+y );
p=p+((x-y)<<2)+10;
y--;
}
x++;
}
if(x==y) {
gr_upixel( xc-x, yc-y );
gr_upixel( xc+x, yc-y );
gr_upixel( xc-x, yc+y );
gr_upixel( xc+x, yc+y );
}
return 0;
}