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
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
#include <u.h>
#include <libc.h>
#include <stdio.h>
#include "map.h"
static double cirmod(double);
static struct place pole; /* map pole is tilted to here */
static struct coord twist; /* then twisted this much */
static struct place ipole; /* inverse transfrom */
static struct coord itwist;
void
orient(double lat, double lon, double theta)
{
lat = cirmod(lat);
if(lat>90.) {
lat = 180. - lat;
lon -= 180.;
theta -= 180.;
} else if(lat < -90.) {
lat = -180. - lat;
lon -= 180.;
theta -= 180;
}
latlon(lat,lon,&pole);
deg2rad(theta, &twist);
latlon(lat,180.-theta,&ipole);
deg2rad(180.-lon, &itwist);
}
void
latlon(double lat, double lon, struct place *p)
{
lat = cirmod(lat);
if(lat>90.) {
lat = 180. - lat;
lon -= 180.;
} else if(lat < -90.) {
lat = -180. - lat;
lon -= 180.;
}
deg2rad(lat,&p->nlat);
deg2rad(lon,&p->wlon);
}
void
deg2rad(double theta, struct coord *coord)
{
theta = cirmod(theta);
coord->l = theta*RAD;
if(theta==90) {
coord->s = 1;
coord->c = 0;
} else if(theta== -90) {
coord->s = -1;
coord->c = 0;
} else
sincos(coord);
}
static double
cirmod(double theta)
{
while(theta >= 180.)
theta -= 360;
while(theta<-180.)
theta += 360.;
return(theta);
}
void
sincos(struct coord *coord)
{
coord->s = sin(coord->l);
coord->c = cos(coord->l);
}
void
normalize(struct place *gg)
{
norm(gg,&pole,&twist);
}
void
invert(struct place *g)
{
norm(g,&ipole,&itwist);
}
void
norm(struct place *gg, struct place *pp, struct coord *tw)
{
register struct place *g; /*geographic coords */
register struct place *p; /* new pole in old coords*/
struct place m; /* standard map coords*/
g = gg;
p = pp;
if(p->nlat.s == 1.) {
if(p->wlon.l+tw->l == 0.)
return;
g->wlon.l -= p->wlon.l+tw->l;
} else {
if(p->wlon.l != 0) {
g->wlon.l -= p->wlon.l;
sincos(&g->wlon);
}
m.nlat.s = p->nlat.s * g->nlat.s
+ p->nlat.c * g->nlat.c * g->wlon.c;
m.nlat.c = sqrt(1. - m.nlat.s * m.nlat.s);
m.nlat.l = atan2(m.nlat.s, m.nlat.c);
m.wlon.s = g->nlat.c * g->wlon.s;
m.wlon.c = p->nlat.c * g->nlat.s
- p->nlat.s * g->nlat.c * g->wlon.c;
m.wlon.l = atan2(m.wlon.s, - m.wlon.c)
- tw->l;
*g = m;
}
sincos(&g->wlon);
if(g->wlon.l>PI)
g->wlon.l -= 2*PI;
else if(g->wlon.l<-PI)
g->wlon.l += 2*PI;
}
double
tan(double x)
{
return(sin(x)/cos(x));
}
void
printp(struct place *g)
{
printf("%.3f %.3f %.3f %.3f %.3f %.3f\n",
g->nlat.l,g->nlat.s,g->nlat.c,g->wlon.l,g->wlon.s,g->wlon.c);
}
void
copyplace(struct place *g1, struct place *g2)
{
*g2 = *g1;
}
|