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#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;
}
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;
}
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