diff options
Diffstat (limited to 'src/projections/bacon.cpp')
| -rw-r--r-- | src/projections/bacon.cpp | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/src/projections/bacon.cpp b/src/projections/bacon.cpp new file mode 100644 index 00000000..6c6350fe --- /dev/null +++ b/src/projections/bacon.cpp @@ -0,0 +1,81 @@ +# define HLFPI2 2.46740110027233965467 /* (pi/2)^2 */ +# define EPS 1e-10 +#define PJ_LIB__ +#include <errno.h> +#include <math.h> + +#include "projects.h" + + +namespace { // anonymous namespace +struct pj_opaque { + int bacn; + int ortl; +}; +} // anonymous namespace + +PROJ_HEAD(apian, "Apian Globular I") "\n\tMisc Sph, no inv"; +PROJ_HEAD(ortel, "Ortelius Oval") "\n\tMisc Sph, no inv"; +PROJ_HEAD(bacon, "Bacon Globular") "\n\tMisc Sph, no inv"; + + +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 ax, f; + + xy.y = Q->bacn ? M_HALFPI * sin(lp.phi) : lp.phi; + if ((ax = fabs(lp.lam)) >= EPS) { + if (Q->ortl && ax >= M_HALFPI) + xy.x = sqrt(HLFPI2 - lp.phi * lp.phi + EPS) + ax - M_HALFPI; + else { + f = 0.5 * (HLFPI2 / ax + ax); + xy.x = ax - f + sqrt(f * f - xy.y * xy.y); + } + if (lp.lam < 0.) xy.x = - xy.x; + } else + xy.x = 0.; + return (xy); +} + + + +PJ *PROJECTION(bacon) { + 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; + + Q->bacn = 1; + Q->ortl = 0; + P->es = 0.; + P->fwd = s_forward; + return P; +} + + +PJ *PROJECTION(apian) { + 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; + + Q->bacn = Q->ortl = 0; + P->es = 0.; + P->fwd = s_forward; + return P; +} + + +PJ *PROJECTION(ortel) { + 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; + + Q->bacn = 0; + Q->ortl = 1; + P->es = 0.; + P->fwd = s_forward; + return P; +} |
