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/* set ellipsoid parameters a and es */
#include <string.h>
#include "proj_internal.h"
#include "projects.h"
#define SIXTH .1666666666666666667 /* 1/6 */
#define RA4 .04722222222222222222 /* 17/360 */
#define RA6 .02215608465608465608 /* 67/3024 */
#define RV4 .06944444444444444444 /* 5/72 */
#define RV6 .04243827160493827160 /* 55/1296 */
/* copy ellipsoidal parameters from src to dst */
void pj_inherit_ellipsoid_defs(const PJ *src, PJ *dst) {
/* The linear parameters */
dst->a = src->a;
dst->b = src->b;
dst->ra = src->ra;
dst->rb = src->rb;
/* The eccentricities */
dst->alpha = src->alpha;
dst->e = src->e;
dst->es = src->es;
dst->e2 = src->e2;
dst->e2s = src->e2s;
dst->e3 = src->e3;
dst->e3s = src->e3s;
dst->one_es = src->one_es;
dst->rone_es = src->rone_es;
/* The flattenings */
dst->f = src->f;
dst->f2 = src->f2;
dst->n = src->n;
dst->rf = src->rf;
dst->rf2 = src->rf2;
dst->rn = src->rn;
/* This one's for GRS80 */
dst->J = src->J;
/* es and a before any +proj related adjustment */
dst->es_orig = src->es_orig;
dst->a_orig = src->a_orig;
}
int pj_calc_ellps_params(PJ *P, double a, double es) {
P->a = a;
P->es = es;
/* Compute some ancillary ellipsoidal parameters */
P->e = sqrt(P->es); /* eccentricity */
P->alpha = asin (P->e); /* angular eccentricity */
/* second eccentricity */
P->e2 = tan (P->alpha);
P->e2s = P->e2 * P->e2;
/* third eccentricity */
P->e3 = (0!=P->alpha)? sin (P->alpha) / sqrt(2 - sin (P->alpha)*sin (P->alpha)): 0;
P->e3s = P->e3 * P->e3;
/* flattening */
P->f = 1 - cos (P->alpha); /* = 1 - sqrt (1 - PIN->es); */
P->rf = P->f != 0.0 ? 1.0/P->f: HUGE_VAL;
/* second flattening */
P->f2 = (cos(P->alpha)!=0)? 1/cos (P->alpha) - 1: 0;
P->rf2 = P->f2 != 0.0 ? 1/P->f2: HUGE_VAL;
/* third flattening */
P->n = pow (tan (P->alpha/2), 2);
P->rn = P->n != 0.0 ? 1/P->n: HUGE_VAL;
/* ...and a few more */
P->b = (1 - P->f)*P->a;
P->rb = 1. / P->b;
P->ra = 1. / P->a;
P->one_es = 1. - P->es;
if (P->one_es == 0.) {
pj_ctx_set_errno( P->ctx, PJD_ERR_ECCENTRICITY_IS_ONE);
return PJD_ERR_ECCENTRICITY_IS_ONE;
}
P->rone_es = 1./P->one_es;
return 0;
}
/* initialize geographic shape parameters */
int pj_ell_set(projCtx ctx, paralist *pl, double *a, double *es) {
int i;
double b=0.0, e;
char *name;
paralist *start = 0;
/* clear any previous error */
pj_ctx_set_errno(ctx,0);
/* check for varying forms of ellipsoid input */
*a = *es = 0.;
/* R takes precedence */
if (pj_param(ctx, pl, "tR").i)
*a = pj_param(ctx,pl, "dR").f;
/* probable elliptical figure */
else {
/* check if ellps present and temporarily append its values to pl */
if ((name = pj_param(ctx,pl, "sellps").s) != NULL) {
char *s;
for (start = pl; start && start->next ; start = start->next) ;
for (i = 0; (s = pj_ellps[i].id) && strcmp(name, s) ; ++i) ;
if (!s) { pj_ctx_set_errno( ctx, -9); return 1; }
start->next = pj_mkparam(pj_ellps[i].major);
start->next->next = pj_mkparam(pj_ellps[i].ell);
}
*a = pj_param(ctx,pl, "da").f;
if (pj_param(ctx,pl, "tes").i) /* eccentricity squared */
*es = pj_param(ctx,pl, "des").f;
else if (pj_param(ctx,pl, "te").i) { /* eccentricity */
e = pj_param(ctx,pl, "de").f;
*es = e * e;
} else if (pj_param(ctx,pl, "trf").i) { /* recip flattening */
*es = pj_param(ctx,pl, "drf").f;
if (*es == 0.0) {
pj_ctx_set_errno( ctx, -10);
goto bomb;
}
*es = 1./ *es;
*es = *es * (2. - *es);
} else if (pj_param(ctx,pl, "tf").i) { /* flattening */
*es = pj_param(ctx,pl, "df").f;
*es = *es * (2. - *es);
} else if (pj_param(ctx,pl, "tb").i) { /* minor axis */
b = pj_param(ctx,pl, "db").f;
*es = 1. - (b * b) / (*a * *a);
} /* else *es == 0. and sphere of radius *a */
if (b == 0.0)
b = *a * sqrt(1. - *es);
/* following options turn ellipsoid into equivalent sphere */
if (pj_param(ctx,pl, "bR_A").i) { /* sphere--area of ellipsoid */
*a *= 1. - *es * (SIXTH + *es * (RA4 + *es * RA6));
*es = 0.;
} else if (pj_param(ctx,pl, "bR_V").i) { /* sphere--vol. of ellipsoid */
*a *= 1. - *es * (SIXTH + *es * (RV4 + *es * RV6));
*es = 0.;
} else if (pj_param(ctx,pl, "bR_a").i) { /* sphere--arithmetic mean */
*a = .5 * (*a + b);
*es = 0.;
} else if (pj_param(ctx,pl, "bR_g").i) { /* sphere--geometric mean */
*a = sqrt(*a * b);
*es = 0.;
} else if (pj_param(ctx,pl, "bR_h").i) { /* sphere--harmonic mean */
if ( (*a + b) == 0.0) {
pj_ctx_set_errno(ctx, -20);
goto bomb;
}
*a = 2. * *a * b / (*a + b);
*es = 0.;
} else if ((i = pj_param(ctx,pl, "tR_lat_a").i) || /* sphere--arith. */
pj_param(ctx,pl, "tR_lat_g").i) { /* or geom. mean at latitude */
double tmp;
tmp = sin(pj_param(ctx,pl, i ? "rR_lat_a" : "rR_lat_g").f);
if (fabs(tmp) > M_HALFPI) {
pj_ctx_set_errno(ctx,-11);
goto bomb;
}
tmp = 1. - *es * tmp * tmp;
*a *= i ? .5 * (1. - *es + tmp) / ( tmp * sqrt(tmp)) :
sqrt(1. - *es) / tmp;
*es = 0.;
}
bomb:
if (start) { /* clean up temporary extension of list */
pj_dalloc(start->next->next);
pj_dalloc(start->next);
start->next = 0;
}
if (ctx->last_errno)
return 1;
}
/* some remaining checks */
if (*es < 0.)
{ pj_ctx_set_errno( ctx, -12); return 1; }
if (*a <= 0.)
{ pj_ctx_set_errno( ctx, -13); return 1; }
return 0;
}
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