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#define PJ_LIB__
#include <errno.h>
#include <proj.h>
#include "projects.h"
PROJ_HEAD(ortho, "Orthographic") "\n\tAzi, Sph.";
enum Mode {
N_POLE = 0,
S_POLE = 1,
EQUIT = 2,
OBLIQ = 3
};
struct pj_opaque {
double sinph0;
double cosph0;
enum Mode mode;
};
#define EPS10 1.e-10
static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */
XY xy = {0.0,0.0};
struct pj_opaque *Q = P->opaque;
double coslam, cosphi, sinphi;
cosphi = cos(lp.phi);
coslam = cos(lp.lam);
switch (Q->mode) {
case EQUIT:
if (cosphi * coslam < - EPS10) {
proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
return xy;
}
xy.y = sin(lp.phi);
break;
case OBLIQ:
if (Q->sinph0 * (sinphi = sin(lp.phi)) + Q->cosph0 * cosphi * coslam < - EPS10) {
proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
return xy;
}
xy.y = Q->cosph0 * sinphi - Q->sinph0 * cosphi * coslam;
break;
case N_POLE:
coslam = - coslam;
/*-fallthrough*/
case S_POLE:
if (fabs(lp.phi - P->phi0) - EPS10 > M_HALFPI) {
proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
return xy;
}
xy.y = cosphi * coslam;
break;
}
xy.x = cosphi * sin(lp.lam);
return xy;
}
static LP s_inverse (XY xy, PJ *P) { /* Spheroidal, inverse */
LP lp = {0.0,0.0};
struct pj_opaque *Q = P->opaque;
double rh, cosc, sinc;
if ((sinc = (rh = hypot(xy.x, xy.y))) > 1.) {
if ((sinc - 1.) > EPS10) {
proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
return lp;
}
sinc = 1.;
}
cosc = sqrt(1. - sinc * sinc); /* in this range OK */
if (fabs(rh) <= EPS10) {
lp.phi = P->phi0;
lp.lam = 0.0;
} else {
switch (Q->mode) {
case N_POLE:
xy.y = -xy.y;
lp.phi = acos(sinc);
break;
case S_POLE:
lp.phi = - acos(sinc);
break;
case EQUIT:
lp.phi = xy.y * sinc / rh;
xy.x *= sinc;
xy.y = cosc * rh;
goto sinchk;
case OBLIQ:
lp.phi = cosc * Q->sinph0 + xy.y * sinc * Q->cosph0 /rh;
xy.y = (cosc - Q->sinph0 * lp.phi) * rh;
xy.x *= sinc * Q->cosph0;
sinchk:
if (fabs(lp.phi) >= 1.)
lp.phi = lp.phi < 0. ? -M_HALFPI : M_HALFPI;
else
lp.phi = asin(lp.phi);
break;
}
lp.lam = (xy.y == 0. && (Q->mode == OBLIQ || Q->mode == EQUIT))
? (xy.x == 0. ? 0. : xy.x < 0. ? -M_HALFPI : M_HALFPI)
: atan2(xy.x, xy.y);
}
return lp;
}
PJ *PROJECTION(ortho) {
struct pj_opaque *Q = pj_calloc (1, sizeof (struct pj_opaque));
if (0==Q)
return pj_default_destructor(P, ENOMEM);
P->opaque = Q;
if (fabs(fabs(P->phi0) - M_HALFPI) <= EPS10)
Q->mode = P->phi0 < 0. ? S_POLE : N_POLE;
else if (fabs(P->phi0) > EPS10) {
Q->mode = OBLIQ;
Q->sinph0 = sin(P->phi0);
Q->cosph0 = cos(P->phi0);
} else
Q->mode = EQUIT;
P->inv = s_inverse;
P->fwd = s_forward;
P->es = 0.;
return P;
}
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