/Proj4/PJ_imw_p.c
http://github.com/route-me/route-me · C · 154 lines · 148 code · 6 blank · 0 comment · 29 complexity · 2931594e2aeda4538c48b44525d88e5c MD5 · raw file
- #ifndef lint
- static const char SCCSID[]="@(#)PJ_imw_p.c 4.1 94/05/22 GIE REL";
- #endif
- #define PROJ_PARMS__ \
- double P, Pp, Q, Qp, R_1, R_2, sphi_1, sphi_2, C2; \
- double phi_1, phi_2, lam_1; \
- double *en; \
- int mode; /* = 0, phi_1 and phi_2 != 0, = 1, phi_1 = 0, = -1 phi_2 = 0 */
- #define PJ_LIB__
- #include "projects.h"
- PROJ_HEAD(imw_p, "International Map of the World Polyconic")
- "\n\tMod. Polyconic, Ell\n\tlat_1= and lat_2= [lon_1=]";
- #define TOL 1e-10
- #define EPS 1e-10
- static int
- phi12(PJ *P, double *del, double *sig) {
- int err = 0;
- if (!pj_param(P->params, "tlat_1").i ||
- !pj_param(P->params, "tlat_2").i) {
- err = -41;
- } else {
- P->phi_1 = pj_param(P->params, "rlat_1").f;
- P->phi_2 = pj_param(P->params, "rlat_2").f;
- *del = 0.5 * (P->phi_2 - P->phi_1);
- *sig = 0.5 * (P->phi_2 + P->phi_1);
- err = (fabs(*del) < EPS || fabs(*sig) < EPS) ? -42 : 0;
- }
- return err;
- }
- static XY
- loc_for(LP lp, PJ *P, double *yc) {
- XY xy;
- if (! lp.phi) {
- xy.x = lp.lam;
- xy.y = 0.;
- } else {
- double xa, ya, xb, yb, xc, yc, D, B, m, sp, t, R, C;
- sp = sin(lp.phi);
- m = pj_mlfn(lp.phi, sp, cos(lp.phi), P->en);
- xa = P->Pp + P->Qp * m;
- ya = P->P + P->Q * m;
- R = 1. / (tan(lp.phi) * sqrt(1. - P->es * sp * sp));
- C = sqrt(R * R - xa * xa);
- if (lp.phi < 0.) C = - C;
- C += ya - R;
- if (P->mode < 0) {
- xb = lp.lam;
- yb = P->C2;
- } else {
- t = lp.lam * P->sphi_2;
- xb = P->R_2 * sin(t);
- yb = P->C2 + P->R_2 * (1. - cos(t));
- }
- if (P->mode > 0) {
- xc = lp.lam;
- yc = 0.;
- } else {
- t = lp.lam * P->sphi_1;
- xc = P->R_1 * sin(t);
- yc = P->R_1 * (1. - cos(t));
- }
- D = (xb - xc)/(yb - yc);
- B = xc + D * (C + R - yc);
- xy.x = D * sqrt(R * R * (1 + D * D) - B * B);
- if (lp.phi > 0)
- xy.x = - xy.x;
- xy.x = (B + xy.x) / (1. + D * D);
- xy.y = sqrt(R * R - xy.x * xy.x);
- if (lp.phi > 0)
- xy.y = - xy.y;
- xy.y += C + R;
- }
- return (xy);
- }
- FORWARD(e_forward); /* ellipsoid */
- double yc;
- xy = loc_for(lp, P, &yc);
- return (xy);
- }
- INVERSE(e_inverse); /* ellipsoid */
- XY t;
- double yc;
- lp.phi = P->phi_2;
- lp.lam = xy.x / cos(lp.phi);
- do {
- t = loc_for(lp, P, &yc);
- lp.phi = ((lp.phi - P->phi_1) * (xy.y - yc) / (t.y - yc)) + P->phi_1;
- lp.lam = lp.lam * xy.x / t.x;
- } while (fabs(t.x - xy.x) > TOL || fabs(t.y - xy.y) > TOL);
- return (lp);
- }
- static void
- xy(PJ *P, double phi, double *x, double *y, double *sp, double *R) {
- double F;
- *sp = sin(phi);
- *R = 1./(tan(phi) * sqrt(1. - P->es * *sp * *sp ));
- F = P->lam_1 * *sp;
- *y = *R * (1 - cos(F));
- *x = *R * sin(F);
- }
- FREEUP; if (P) { if (P->en) pj_dalloc(P->en); pj_dalloc(P); } }
- ENTRY1(imw_p, en)
- double del, sig, s, t, x1, x2, T2, y1, m1, m2, y2;
- int i;
- if (!(P->en = pj_enfn(P->es))) E_ERROR_0;
- if( (i = phi12(P, &del, &sig)) != 0)
- E_ERROR(i);
- if (P->phi_2 < P->phi_1) { /* make sure P->phi_1 most southerly */
- del = P->phi_1;
- P->phi_1 = P->phi_2;
- P->phi_2 = del;
- }
- if (pj_param(P->params, "tlon_1").i)
- P->lam_1 = pj_param(P->params, "rlon_1").f;
- else { /* use predefined based upon latitude */
- sig = fabs(sig * RAD_TO_DEG);
- if (sig <= 60) sig = 2.;
- else if (sig <= 76) sig = 4.;
- else sig = 8.;
- P->lam_1 = sig * DEG_TO_RAD;
- }
- P->mode = 0;
- if (P->phi_1) xy(P, P->phi_1, &x1, &y1, &P->sphi_1, &P->R_1);
- else {
- P->mode = 1;
- y1 = 0.;
- x1 = P->lam_1;
- }
- if (P->phi_2) xy(P, P->phi_2, &x2, &T2, &P->sphi_2, &P->R_2);
- else {
- P->mode = -1;
- T2 = 0.;
- x2 = P->lam_1;
- }
- m1 = pj_mlfn(P->phi_1, P->sphi_1, cos(P->phi_1), P->en);
- m2 = pj_mlfn(P->phi_2, P->sphi_2, cos(P->phi_2), P->en);
- t = m2 - m1;
- s = x2 - x1;
- y2 = sqrt(t * t - s * s) + y1;
- P->C2 = y2 - T2;
- t = 1. / t;
- P->P = (m2 * y1 - m1 * y2) * t;
- P->Q = (y2 - y1) * t;
- P->Pp = (m2 * x1 - m1 * x2) * t;
- P->Qp = (x2 - x1) * t;
- P->fwd = e_forward;
- P->inv = e_inverse;
- ENDENTRY(P)