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#define PJ_LIB__
#include <errno.h>
#include <proj.h>
#include "projects.h"
PROJ_HEAD(oea, "Oblated Equal Area") "\n\tMisc Sph\n\tn= m= theta=";
struct pj_opaque {
double theta;
double m, n;
double two_r_m, two_r_n, rm, rn, hm, hn;
double cp0, sp0;
};
static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */
XY xy = {0.0,0.0};
struct pj_opaque *Q = P->opaque;
double Az, M, N, cp, sp, cl, shz;
cp = cos(lp.phi);
sp = sin(lp.phi);
cl = cos(lp.lam);
Az = aatan2(cp * sin(lp.lam), Q->cp0 * sp - Q->sp0 * cp * cl) + Q->theta;
shz = sin(0.5 * aacos(P->ctx, Q->sp0 * sp + Q->cp0 * cp * cl));
M = aasin(P->ctx, shz * sin(Az));
N = aasin(P->ctx, shz * cos(Az) * cos(M) / cos(M * Q->two_r_m));
xy.y = Q->n * sin(N * Q->two_r_n);
xy.x = Q->m * sin(M * Q->two_r_m) * cos(N) / cos(N * Q->two_r_n);
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 N, M, xp, yp, z, Az, cz, sz, cAz;
N = Q->hn * aasin(P->ctx,xy.y * Q->rn);
M = Q->hm * aasin(P->ctx,xy.x * Q->rm * cos(N * Q->two_r_n) / cos(N));
xp = 2. * sin(M);
yp = 2. * sin(N) * cos(M * Q->two_r_m) / cos(M);
cAz = cos(Az = aatan2(xp, yp) - Q->theta);
z = 2. * aasin(P->ctx, 0.5 * hypot(xp, yp));
sz = sin(z);
cz = cos(z);
lp.phi = aasin(P->ctx, Q->sp0 * cz + Q->cp0 * sz * cAz);
lp.lam = aatan2(sz * sin(Az),
Q->cp0 * cz - Q->sp0 * sz * cAz);
return lp;
}
PJ *PROJECTION(oea) {
struct pj_opaque *Q = pj_calloc (1, sizeof (struct pj_opaque));
if (0==Q)
return pj_default_destructor (P, ENOMEM);
P->opaque = Q;
if (((Q->n = pj_param(P->ctx, P->params, "dn").f) <= 0.) ||
((Q->m = pj_param(P->ctx, P->params, "dm").f) <= 0.)) {
return pj_default_destructor(P, PJD_ERR_INVALID_M_OR_N);
} else {
Q->theta = pj_param(P->ctx, P->params, "rtheta").f;
Q->sp0 = sin(P->phi0);
Q->cp0 = cos(P->phi0);
Q->rn = 1./ Q->n;
Q->rm = 1./ Q->m;
Q->two_r_n = 2. * Q->rn;
Q->two_r_m = 2. * Q->rm;
Q->hm = 0.5 * Q->m;
Q->hn = 0.5 * Q->n;
P->fwd = s_forward;
P->inv = s_inverse;
P->es = 0.;
}
return P;
}
#ifndef PJ_SELFTEST
int pj_oea_selftest (void) {return 0;}
#else
int pj_oea_selftest (void) {
double tolerance_lp = 1e-10;
double tolerance_xy = 1e-7;
char s_args[] = {"+proj=oea +a=6400000 +lat_1=0.5 +lat_2=2 +n=1 +m=2 +theta=3"};
LP fwd_in[] = {
{ 2, 1},
{ 2,-1},
{-2, 1},
{-2,-1}
};
XY s_fwd_expect[] = {
{ 228926.872097864107, 99870.4884300760023},
{ 217242.584036940476, -123247.885607474513},
{-217242.584036940476, 123247.885607474556},
{-228926.872097864078, -99870.4884300760168},
};
XY inv_in[] = {
{ 200, 100},
{ 200,-100},
{-200, 100},
{-200,-100}
};
LP s_inv_expect[] = {
{ 0.0017411857167771369, 0.000987726819566195693},
{ 0.00183489288577854998, -0.000800312481495174641},
{-0.00183489288577854954, 0.000800312481495174966},
{-0.00174118571677713712, -0.000987726819566195043},
};
return pj_generic_selftest (0, s_args, tolerance_xy, tolerance_lp, 4, 4, fwd_in, 0, s_fwd_expect, inv_in, 0, s_inv_expect);
}
#endif
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