147 lines
2.5 KiB
C
147 lines
2.5 KiB
C
/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
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/* All Rights Reserved */
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/* THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T */
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/* The copyright notice above does not evidence any */
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/* actual or intended publication of such source code. */
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#ident "$Revision: 1.2 $"
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#include <math.h>
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extern void move(int, int);
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extern void cont(int, int);
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int abs(int);
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int quad(int, int, int, int);
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int del = 20;
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void
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step(int d)
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{
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del = d;
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}
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void
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arc(int x, int y, int x0, int y0, int x1, int y1){
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double pc;
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int flg,m,xc,yc,xs,ys,qs,qf,qt,qtctr=0;
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int m0,m1;
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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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if(abs(x-x1) < abs(y-y1)){
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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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if(qs == qf) {
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m0=(y0-y)/(x0-x);
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m1=(y1-y)/(x1-x);
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if(m0 >= m1)qt = 4;
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else qt = 0;
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}
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else if((qt=qf-qs) < 0)qt += 4;
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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(++qtctr > qt)return;
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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(++qtctr > qt)return;
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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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int
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quad(int x, int y, int xp, int yp)
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{
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if(x < xp)
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if(y <= yp)return(1);
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else return(4);
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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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}
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int
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abs(int a)
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{
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if(a < 0)return(-a);
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return(a);
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}
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