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/*
* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/* All Rights Reserved */
/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
int del = 20;
void
step(int d)
{
del = d;
}
void
arc(int x, int y, int x0, int y0, int x1, int y1)
{
double pc;
double sqrt();
int flg,m,xc,yc,xs,ys,qs,qf;
float dx,dy,r;
char use;
dx = x-x0;
dy = y-y0;
r = dx*dx+dy*dy;
pc = r;
pc = pc > 0 ? sqrt(pc) : 0;
flg = pc/4;
if(flg == 0)step(1);
else if(flg < del)step(flg);
xc = xs = x0;
yc = ys = y0;
move(xs,ys);
if(x0 == x1 && y0 == y1)flg=0;
else flg=1;
qs = quad(x,y,x0,y0);
qf = quad(x,y,x1,y1);
if(abs(x-x1) < abs(y-y1)){
use = 'x';
if(qs == 2 || qs ==3)m = -1;
else m=1;
}
else {
use = 'y';
if(qs > 2)m= -1;
else m= 1;
}
while(1){
switch(use){
case 'x':
if(qs == 2 || qs == 3)yc -= del;
else yc += del;
dy = yc-y;
pc = r-dy*dy;
xc = m*(pc > 0 ? sqrt(pc) : 0)+x;
if((x < xs && x >= xc) || ( x > xs && x <= xc) ||
(y < ys && y >= yc) || ( y > ys && y <= yc) )
{
if(++qs > 4)qs=1;
if(qs == 2 || qs == 3)m= -1;
else m=1;
flg=1;
}
cont(xc,yc);
xs = xc;
ys = yc;
if(qs == qf && flg == 1)
switch(qf){
case 3:
case 4:
if(xs >= x1)return;
continue;
case 1:
case 2:
if(xs <= x1)return;
}
continue;
case 'y':
if(qs > 2)xc += del;
else xc -= del;
dx = xc-x;
pc = r-dx*dx;
yc = m*(pc > 0 ? sqrt(pc) : 0)+y;
if((x < xs && x >= xc) || ( x > xs && x <= xc ) ||
(y < ys && y >= yc) || (y > ys && y <= yc) )
{
if(++qs > 4)qs=1;
if(qs > 2)m = -1;
else m = 1;
flg=1;
}
cont(xc,yc);
xs = xc;
ys = yc;
if(qs == qf && flg == 1)
switch(qs){
case 1:
case 4:
if(ys >= y1)return;
continue;
case 2:
case 3:
if(ys <= y1)return;
}
}
}
}
int
quad(int x,int y,int xp,int yp)
{
if(x < xp)
if(y <= yp)return(1);
else return(4);
else if(x > xp)
if(y < yp)return(2);
else return(3);
else if(y < yp)return(2);
else return(4);
}
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