Subversion Repositories planix.SVN

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

static struct place gywhem, gyehem;
static struct coord gytwist;
static double gyconst, gykc, gyside;


static void
dosquare(double z1, double z2, double *x, double *y)
{
        double w1,w2;
        w1 = z1 -1;
        if(fabs(w1*w1+z2*z2)>.000001) {
                cdiv(z1+1,z2,w1,z2,&w1,&w2);
                w1 *= gyconst;
                w2 *= gyconst;
                if(w1<0)
                        w1 = 0;
                elco2(w1,w2,gykc,1.,1.,x,y);
        } else {
                *x = gyside;
                *y = 0;
        }
}

int
Xguyou(struct place *place, double *x, double *y)
{
        int ew;         /*which hemisphere*/
        double z1,z2;
        struct place pl;
        ew = place->wlon.l<0;
        copyplace(place,&pl);
        norm(&pl,ew?&gyehem:&gywhem,&gytwist);
        Xstereographic(&pl,&z1,&z2);
        dosquare(z1/2,z2/2,x,y);
        if(!ew)
                *x -= gyside;
        return(1);
}

proj
guyou(void)
{
        double junk;
        gykc = 1/(3+2*sqrt(2.));
        gyconst = -(1+sqrt(2.));
        elco2(-gyconst,0.,gykc,1.,1.,&gyside,&junk);
        gyside *= 2;
        latlon(0.,90.,&gywhem);
        latlon(0.,-90.,&gyehem);
        deg2rad(0.,&gytwist);
        return(Xguyou);
}

int
guycut(struct place *g, struct place *og, double *cutlon)
{
        int c;
        c = picut(g,og,cutlon);
        if(c!=1)
                return(c);
        *cutlon = 0.;
        if(g->nlat.c<.7071||og->nlat.c<.7071)
                return(ckcut(g,og,0.));
        return(1);
}

static int
Xsquare(struct place *place, double *x, double *y)
{
        double z1,z2;
        double r, theta;
        struct place p;
        copyplace(place,&p);
        if(place->nlat.l<0) {
                p.nlat.l = -p.nlat.l;
                p.nlat.s = -p.nlat.s;
        }
        if(p.nlat.l<FUZZ && fabs(p.wlon.l)>PI-FUZZ){
                *y = -gyside/2;
                *x = p.wlon.l>0?0:gyside;
                return(1);
        }
        Xstereographic(&p,&z1,&z2);
        r = sqrt(sqrt(hypot(z1,z2)/2));
        theta = atan2(z1,-z2)/4;
        dosquare(r*sin(theta),-r*cos(theta),x,y);
        if(place->nlat.l<0)
                *y = -gyside - *y;
        return(1);
}

proj
square(void)
{
        guyou();
        return(Xsquare);
}