PJ_nsper.c
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#define PROJ_PARMS__ \
double height; \
double sinph0; \
double cosph0; \
double p; \
double rp; \
double pn1; \
double pfact; \
double h; \
double cg; \
double sg; \
double sw; \
double cw; \
int mode; \
int tilt;
#define PJ_LIB__
#include <projects.h>
PROJ_HEAD(nsper, "Near-sided perspective") "\n\tAzi, Sph\n\th=";
PROJ_HEAD(tpers, "Tilted perspective") "\n\tAzi, Sph\n\ttilt= azi= h=";
# define EPS10 1.e-10
# define N_POLE 0
# define S_POLE 1
# define EQUIT 2
# define OBLIQ 3
FORWARD(s_forward); /* spheroid */
double coslam, cosphi, sinphi;
sinphi = sin(lp.phi);
cosphi = cos(lp.phi);
coslam = cos(lp.lam);
switch (P->mode) {
case OBLIQ:
xy.y = P->sinph0 * sinphi + P->cosph0 * cosphi * coslam;
break;
case EQUIT:
xy.y = cosphi * coslam;
break;
case S_POLE:
xy.y = - sinphi;
break;
case N_POLE:
xy.y = sinphi;
break;
}
if (xy.y < P->rp) F_ERROR;
xy.y = P->pn1 / (P->p - xy.y);
xy.x = xy.y * cosphi * sin(lp.lam);
switch (P->mode) {
case OBLIQ:
xy.y *= (P->cosph0 * sinphi -
P->sinph0 * cosphi * coslam);
break;
case EQUIT:
xy.y *= sinphi;
break;
case N_POLE:
coslam = - coslam;
case S_POLE:
xy.y *= cosphi * coslam;
break;
}
if (P->tilt) {
double yt, ba;
yt = xy.y * P->cg + xy.x * P->sg;
ba = 1. / (yt * P->sw * P->h + P->cw);
xy.x = (xy.x * P->cg - xy.y * P->sg) * P->cw * ba;
xy.y = yt * ba;
}
return (xy);
}
INVERSE(s_inverse); /* spheroid */
double rh, cosz, sinz;
if (P->tilt) {
double bm, bq, yt;
yt = 1./(P->pn1 - xy.y * P->sw);
bm = P->pn1 * xy.x * yt;
bq = P->pn1 * xy.y * P->cw * yt;
xy.x = bm * P->cg + bq * P->sg;
xy.y = bq * P->cg - bm * P->sg;
}
rh = hypot(xy.x, xy.y);
if ((sinz = 1. - rh * rh * P->pfact) < 0.) I_ERROR;
sinz = (P->p - sqrt(sinz)) / (P->pn1 / rh + rh / P->pn1);
cosz = sqrt(1. - sinz * sinz);
if (fabs(rh) <= EPS10) {
lp.lam = 0.;
lp.phi = P->phi0;
} else {
switch (P->mode) {
case OBLIQ:
lp.phi = asin(cosz * P->sinph0 + xy.y * sinz * P->cosph0 / rh);
xy.y = (cosz - P->sinph0 * sin(lp.phi)) * rh;
xy.x *= sinz * P->cosph0;
break;
case EQUIT:
lp.phi = asin(xy.y * sinz / rh);
xy.y = cosz * rh;
xy.x *= sinz;
break;
case N_POLE:
lp.phi = asin(cosz);
xy.y = -xy.y;
break;
case S_POLE:
lp.phi = - asin(cosz);
break;
}
lp.lam = atan2(xy.x, xy.y);
}
return (lp);
}
FREEUP; if (P) pj_dalloc(P); }
static PJ *
setup(PJ *P) {
if ((P->height = pj_param(P->params, "dh").f) <= 0.) E_ERROR(-30);
if (fabs(fabs(P->phi0) - HALFPI) < EPS10)
P->mode = P->phi0 < 0. ? S_POLE : N_POLE;
else if (fabs(P->phi0) < EPS10)
P->mode = EQUIT;
else {
P->mode = OBLIQ;
P->sinph0 = sin(P->phi0);
P->cosph0 = cos(P->phi0);
}
P->pn1 = P->height / P->a; /* normalize by radius */
P->p = 1. + P->pn1;
P->rp = 1. / P->p;
P->h = 1. / P->pn1;
P->pfact = (P->p + 1.) * P->h;
P->inv = s_inverse;
P->fwd = s_forward;
P->es = 0.;
return P;
}
ENTRY0(nsper)
P->tilt = 0;
ENDENTRY(setup(P))
ENTRY0(tpers)
double omega, gamma;
omega = pj_param(P->params, "dtilt").f * DEG_TO_RAD;
gamma = pj_param(P->params, "dazi").f * DEG_TO_RAD;
P->tilt = 1;
P->cg = cos(gamma); P->sg = sin(gamma);
P->cw = cos(omega); P->sw = sin(omega);
ENDENTRY(setup(P))