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greg |
1.1 |
#ifndef lint
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schorsch |
1.3 |
static const char RCSid[] = "$Id: arc.c,v 1.2 2003/10/27 10:28:59 schorsch Exp $";
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greg |
1.1 |
#endif
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schorsch |
1.3 |
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#include "local4014.h"
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#include "lib4014.h"
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greg |
1.1 |
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int del = 20;
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schorsch |
1.3 |
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extern void
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step(int d)
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{
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greg |
1.1 |
del = d;
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}
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schorsch |
1.3 |
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extern void
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arc(
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int x,
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int y,
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int x0,
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int y0,
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int x1,
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int y1
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)
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{
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greg |
1.1 |
double pc;
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double sqrt();
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int flg,m,xc,yc,xs,ys,qs,qf;
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float dx,dy,r;
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char use;
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dx = x-x0;
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dy = y-y0;
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r = dx*dx+dy*dy;
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pc = r;
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pc = sqrt(pc);
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flg = pc/4;
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if(flg == 0)step(1);
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else if(flg < del)step(flg);
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xc = xs = x0;
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yc = ys = y0;
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move(xs,ys);
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if(x0 == x1 && y0 == y1)flg=0;
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else flg=1;
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qs = quad(x,y,x0,y0);
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qf = quad(x,y,x1,y1);
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schorsch |
1.2 |
if(abs_(x-x1) < abs_(y-y1)){
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greg |
1.1 |
use = 'x';
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if(qs == 2 || qs ==3)m = -1;
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else m=1;
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}
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else {
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use = 'y';
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if(qs > 2)m= -1;
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else m= 1;
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}
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while(1){
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switch(use){
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case 'x':
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if(qs == 2 || qs == 3)yc -= del;
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else yc += del;
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dy = yc-y;
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pc = r-dy*dy;
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xc = m*sqrt(pc)+x;
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if((x < xs && x >= xc) || ( x > xs && x <= xc) ||
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(y < ys && y >= yc) || ( y > ys && y <= yc) )
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{
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if(++qs > 4)qs=1;
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if(qs == 2 || qs == 3)m= -1;
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else m=1;
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flg=1;
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}
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cont(xc,yc);
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xs = xc;
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ys = yc;
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if(qs == qf && flg == 1)
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switch(qf){
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case 3:
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case 4:
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if(xs >= x1)return;
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continue;
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case 1:
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case 2:
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if(xs <= x1)return;
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}
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continue;
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case 'y':
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if(qs > 2)xc += del;
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else xc -= del;
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dx = xc-x;
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pc = r-dx*dx;
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yc = m*sqrt(pc)+y;
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if((x < xs && x >= xc) || ( x > xs && x <= xc ) ||
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(y < ys && y >= yc) || (y > ys && y <= yc) )
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{
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if(++qs > 4)qs=1;
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if(qs > 2)m = -1;
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else m = 1;
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flg=1;
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}
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cont(xc,yc);
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xs = xc;
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ys = yc;
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if(qs == qf && flg == 1)
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switch(qs){
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case 1:
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case 4:
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if(ys >= y1)return;
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continue;
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case 2:
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case 3:
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if(ys <= y1)return;
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}
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}
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}
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}
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| 116 |
schorsch |
1.3 |
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| 117 |
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extern int
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quad(
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| 119 |
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int x,
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| 120 |
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int y,
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| 121 |
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int xp,
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| 122 |
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int yp
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)
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{
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| 125 |
greg |
1.1 |
if(x < xp)
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| 126 |
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if(y <= yp)return(1);
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| 127 |
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else return(4);
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| 128 |
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else if(x > xp)
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if(y < yp)return(2);
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else return(3);
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else if(y < yp)return(2);
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else return(4);
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| 133 |
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}
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| 134 |
schorsch |
1.3 |
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| 135 |
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extern int
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| 136 |
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abs_( /* Windows complains that abs() is an "internal function" */
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| 137 |
|
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int a
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| 138 |
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)
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| 139 |
|
|
{
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| 140 |
greg |
1.1 |
if(a < 0)return(-a);
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| 141 |
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return(a);
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| 142 |
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}
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