/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include "map.h" static struct coord p0;		/* standard parallel */ int first; static doubletrigclamp(double x){	return x>1? 1: x<-1? -1: x;} static struct coord az;		/* azimuth of p0 seen from place */static struct coord rad;	/* angular dist from place to p0 */ static intazimuth(struct place *place){	if(place->nlat.c < FUZZ) {		az.l = PI/2 + place->nlat.l - place->wlon.l;		sincos(&az);		rad.l = fabs(place->nlat.l - p0.l);		if(rad.l > PI)			rad.l = 2*PI - rad.l;		sincos(&rad);		return 1;	}	rad.c = trigclamp(p0.s*place->nlat.s +	/* law of cosines */		p0.c*place->nlat.c*place->wlon.c);	rad.s = sqrt(1 - rad.c*rad.c);	if(fabs(rad.s) < .001) {		az.s = 0;		az.c = 1;	} else {		az.s = trigclamp(p0.c*place->wlon.s/rad.s); /* sines */		az.c = trigclamp((p0.s - rad.c*place->nlat.s)				/(rad.s*place->nlat.c));	}	rad.l = atan2(rad.s, rad.c);	return 1;} static intXmecca(struct place *place, double *x, double *y){	if(!azimuth(place))		return 0;	*x = -place->wlon.l;	*y = fabs(az.s)<.02? -az.c*rad.s/p0.c: *x*az.c/az.s;	return fabs(*y)>2? -1:	       rad.c<0? 0:	       1;} projmecca(double par){	first = 1;	if(fabs(par)>80.)		return(0);	deg2rad(par,&p0);	return(Xmecca);} static intXhoming(struct place *place, double *x, double *y){	if(!azimuth(place))		return 0;	*x = -rad.l*az.s;	*y = -rad.l*az.c;	return place->wlon.c<0? 0: 1;} projhoming(double par){	first = 1;	if(fabs(par)>80.)		return(0);	deg2rad(par,&p0);	return(Xhoming);} inthlimb(double *lat, double *lon, double res){	if(first) {		*lon = -90;		*lat = -90;		first = 0;		return 0;	}	*lat += res;	if(*lat <= 90) 		return 1;	if(*lon == 90)		return -1;	*lon = 90;	*lat = -90;	return 0;} intmlimb(double *lat, double *lon, double res){	int ret = !first;	if(fabs(p0.s) < .01)		return -1;	if(first) {		*lon = -180;		first = 0;	} else		*lon += res;	if(*lon > 180)		return -1;	*lat = atan(-cos(*lon*RAD)/p0.s*p0.c)/RAD;	return ret;}