Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>
#include "map.h"

struct coord center;

static int
Xelliptic(struct place *place, double *x, double *y)
{
        double r1,r2;
        r1 = acos(place->nlat.c*(place->wlon.c*center.c
                - place->wlon.s*center.s));
        r2 = acos(place->nlat.c*(place->wlon.c*center.c
                + place->wlon.s*center.s));
        *x = -(r1*r1 - r2*r2)/(4*center.l);
        *y = (r1*r1+r2*r2)/2 - (center.l*center.l+*x**x);
        if(*y < 0)
                *y = 0;
        *y = sqrt(*y);
        if(place->nlat.l<0)
                *y = -*y;
        return(1);
}

proj
elliptic(double l)
{
        l = fabs(l);
        if(l>89)
                return(0);
        if(l<1)
                return(Xazequidistant);
        deg2rad(l,&center);
        return(Xelliptic);
}