1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
|
/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/* All Rights Reserved */
#ident "%Z%%M% %I% %E% SMI" /* SVr4.0 1.1 */
/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/
/*
* Copyright (c) 1983, 1984 1985, 1986, 1987, 1988, Sun Microsystems, Inc.
* All Rights Reserved.
*/
int del = 20;
step(d){
del = d;
}
arc(x,y,x0,y0,x1,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 = sqrt(pc);
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*sqrt(pc)+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*sqrt(pc)+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;
}
}
}
}
quad(x,y,xp,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);
}
abs(a){
if(a < 0)return(-a);
return(a);
}
|
