diff options
Diffstat (limited to 'src/projections/poly.cpp')
| -rw-r--r-- | src/projections/poly.cpp | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/src/projections/poly.cpp b/src/projections/poly.cpp new file mode 100644 index 00000000..a970fdb1 --- /dev/null +++ b/src/projections/poly.cpp @@ -0,0 +1,171 @@ +#define PJ_LIB__ + +#include <errno.h> +#include <math.h> + +#include "proj.h" +#include "projects.h" + +PROJ_HEAD(poly, "Polyconic (American)") + "\n\tConic, Sph&Ell"; + +namespace { // anonymous namespace +struct pj_opaque { + double ml0; \ + double *en; +}; +} // anonymous namespace + +#define TOL 1e-10 +#define CONV 1e-10 +#define N_ITER 10 +#define I_ITER 20 +#define ITOL 1.e-12 + + +static XY e_forward (LP lp, PJ *P) { /* Ellipsoidal, forward */ + XY xy = {0.0,0.0}; + struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque); + double ms, sp, cp; + + if (fabs(lp.phi) <= TOL) { + xy.x = lp.lam; + xy.y = -Q->ml0; + } else { + sp = sin(lp.phi); + ms = fabs(cp = cos(lp.phi)) > TOL ? pj_msfn(sp, cp, P->es) / sp : 0.; + xy.x = ms * sin(lp.lam *= sp); + xy.y = (pj_mlfn(lp.phi, sp, cp, Q->en) - Q->ml0) + ms * (1. - cos(lp.lam)); + } + + return xy; +} + + +static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */ + XY xy = {0.0,0.0}; + struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque); + double cot, E; + + if (fabs(lp.phi) <= TOL) { + xy.x = lp.lam; + xy.y = Q->ml0; + } else { + cot = 1. / tan(lp.phi); + xy.x = sin(E = lp.lam * sin(lp.phi)) * cot; + xy.y = lp.phi - P->phi0 + cot * (1. - cos(E)); + } + + return xy; +} + + +static LP e_inverse (XY xy, PJ *P) { /* Ellipsoidal, inverse */ + LP lp = {0.0,0.0}; + struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque); + + xy.y += Q->ml0; + if (fabs(xy.y) <= TOL) { + lp.lam = xy.x; + lp.phi = 0.; + } else { + double r, c, sp, cp, s2ph, ml, mlb, mlp, dPhi; + int i; + + r = xy.y * xy.y + xy.x * xy.x; + lp.phi = xy.y; + for (i = I_ITER; i ; --i) { + sp = sin(lp.phi); + s2ph = sp * ( cp = cos(lp.phi)); + if (fabs(cp) < ITOL) { + proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION); + return lp; + } + c = sp * (mlp = sqrt(1. - P->es * sp * sp)) / cp; + ml = pj_mlfn(lp.phi, sp, cp, Q->en); + mlb = ml * ml + r; + mlp = P->one_es / (mlp * mlp * mlp); + lp.phi += ( dPhi = + ( ml + ml + c * mlb - 2. * xy.y * (c * ml + 1.) ) / ( + P->es * s2ph * (mlb - 2. * xy.y * ml) / c + + 2.* (xy.y - ml) * (c * mlp - 1. / s2ph) - mlp - mlp )); + if (fabs(dPhi) <= ITOL) + break; + } + if (!i) { + proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION); + return lp; + } + c = sin(lp.phi); + lp.lam = asin(xy.x * tan(lp.phi) * sqrt(1. - P->es * c * c)) / sin(lp.phi); + } + + return lp; +} + + +static LP s_inverse (XY xy, PJ *P) { /* Spheroidal, inverse */ + LP lp = {0.0,0.0}; + double B, dphi, tp; + int i; + + if (fabs(xy.y = P->phi0 + xy.y) <= TOL) { + lp.lam = xy.x; + lp.phi = 0.; + } else { + lp.phi = xy.y; + B = xy.x * xy.x + xy.y * xy.y; + i = N_ITER; + do { + tp = tan(lp.phi); + lp.phi -= (dphi = (xy.y * (lp.phi * tp + 1.) - lp.phi - + .5 * ( lp.phi * lp.phi + B) * tp) / + ((lp.phi - xy.y) / tp - 1.)); + } while (fabs(dphi) > CONV && --i); + if (! i) { + proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION); + return lp; + } + lp.lam = asin(xy.x * tan(lp.phi)) / sin(lp.phi); + } + + return lp; +} + + +static PJ *destructor(PJ *P, int errlev) { + if (nullptr==P) + return nullptr; + + if (nullptr==P->opaque) + return pj_default_destructor (P, errlev); + + if (static_cast<struct pj_opaque*>(P->opaque)->en) + pj_dealloc (static_cast<struct pj_opaque*>(P->opaque)->en); + + return pj_default_destructor(P, errlev); +} + + +PJ *PROJECTION(poly) { + struct pj_opaque *Q = static_cast<struct pj_opaque*>(pj_calloc (1, sizeof (struct pj_opaque))); + if (nullptr==Q) + return pj_default_destructor (P, ENOMEM); + + P->opaque = Q; + P->destructor = destructor; + + if (P->es != 0.0) { + if (!(Q->en = pj_enfn(P->es))) + return pj_default_destructor (P, ENOMEM); + Q->ml0 = pj_mlfn(P->phi0, sin(P->phi0), cos(P->phi0), Q->en); + P->inv = e_inverse; + P->fwd = e_forward; + } else { + Q->ml0 = -P->phi0; + P->inv = s_inverse; + P->fwd = s_forward; + } + + return P; +} |