/* 
 * 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"

int
Xpolyconic(struct place *place, double *x, double *y)
{
	double r, alpha;
	double lat2, lon2;
	if(fabs(place->nlat.l) > .01) {
		r = place->nlat.c / place->nlat.s;
		alpha = place->wlon.l * place->nlat.s;
		*y = place->nlat.l + r*(1 - cos(alpha));
		*x = - r*sin(alpha);
	} else {
		lon2 = place->wlon.l * place->wlon.l;
		lat2 = place->nlat.l * place->nlat.l;
		*y = place->nlat.l * (1+(lon2/2)*(1-(8+lon2)*lat2/12));
		*x = - place->wlon.l * (1-lat2*(3+lon2)/6);
	}
	return(1);
}

proj
polyconic(void)
{
	return(Xpolyconic);
}