Application: gvSIG desktop

#ifndef lint

static const char SCCSID[]="@(#)PJ_ocea.c        4.1        94/02/15        GIE        REL";

#endif

#define PROJ_PARMS__ \

        double        rok; \

        double        rtk; \

        double        sinphi; \

        double        cosphi; \

        double        singam; \

        double        cosgam;

#define PJ_LIB__

#include        <projects.h>

PROJ_HEAD(ocea, "Oblique Cylindrical Equal Area") "\n\tCyl, Sph"

        "lonc= alpha= or\n\tlat_1= lat_2= lon_1= lon_2=";

FORWARD(s_forward); /* spheroid */

        double t;

        xy.y = sin(lp.lam);

/*

        xy.x = atan2((tan(lp.phi) * P->cosphi + P->sinphi * xy.y) , cos(lp.lam));

*/

        t = cos(lp.lam);

        xy.x = atan((tan(lp.phi) * P->cosphi + P->sinphi * xy.y) / t);

        if (t < 0.)

                xy.x += PI;

        xy.x *= P->rtk;

        xy.y = P->rok * (P->sinphi * sin(lp.phi) - P->cosphi * cos(lp.phi) * xy.y);

        return (xy);

}

INVERSE(s_inverse); /* spheroid */

        double t, s;

        xy.y /= P->rok;

        xy.x /= P->rtk;

        t = sqrt(1. - xy.y * xy.y);

        lp.phi = asin(xy.y * P->sinphi + t * P->cosphi * (s = sin(xy.x)));

        lp.lam = atan2(t * P->sinphi * s - xy.y * P->cosphi,

                t * cos(xy.x));

        return (lp);

}

FREEUP; if (P) pj_dalloc(P); }

ENTRY0(ocea)

        double phi_0=0.0, phi_1, phi_2, lam_1, lam_2, lonz, alpha;

        P->rok = P->a / P->k0;

        P->rtk = P->a * P->k0;

        if ( pj_param(P->params, "talpha").i) {

                alpha        = pj_param(P->params, "ralpha").f;

                lonz = pj_param(P->params, "rlonc").f;

                P->singam = atan(-cos(alpha)/(-sin(phi_0) * sin(alpha))) + lonz;

                P->sinphi = asin(cos(phi_0) * sin(alpha));

        } else {

                phi_1 = pj_param(P->params, "rlat_1").f;

                phi_2 = pj_param(P->params, "rlat_2").f;

                lam_1 = pj_param(P->params, "rlon_1").f;

                lam_2 = pj_param(P->params, "rlon_2").f;

                P->singam = atan2(cos(phi_1) * sin(phi_2) * cos(lam_1) -

                        sin(phi_1) * cos(phi_2) * cos(lam_2),

                        sin(phi_1) * cos(phi_2) * sin(lam_2) -

                        cos(phi_1) * sin(phi_2) * sin(lam_1) );

                P->sinphi = atan(-cos(P->singam - lam_1) / tan(phi_1));

        }

        P->lam0 = P->singam + HALFPI;

        P->cosphi = cos(P->sinphi);

        P->sinphi = sin(P->sinphi);

        P->cosgam = cos(P->singam);

        P->singam = sin(P->singam);

        P->inv = s_inverse;

        P->fwd = s_forward;

        P->es = 0.;

ENDENTRY(P)