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WebSVN – planix.SVN – Blame – /os/branches/feature_tlsv12/sys/src/cmd/map/libmap/zcoord.c – Rev 2

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