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Diffstat (limited to 'src/PJ_airy.cpp')
| -rw-r--r-- | src/PJ_airy.cpp | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/src/PJ_airy.cpp b/src/PJ_airy.cpp new file mode 100644 index 00000000..037362b3 --- /dev/null +++ b/src/PJ_airy.cpp @@ -0,0 +1,151 @@ +/****************************************************************************** + * Project: PROJ.4 + * Purpose: Implementation of the airy (Airy) projection. + * Author: Gerald Evenden (1995) + * Thomas Knudsen (2016) - revise/add regression tests + * + ****************************************************************************** + * Copyright (c) 1995, Gerald Evenden + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included + * in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS + * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER + * DEALINGS IN THE SOFTWARE. + *****************************************************************************/ + +#define PJ_LIB__ +#include "proj.h" +#include <errno.h> +#include "projects.h" + +PROJ_HEAD(airy, "Airy") "\n\tMisc Sph, no inv\n\tno_cut lat_b="; + + +enum Mode { + N_POLE = 0, + S_POLE = 1, + EQUIT = 2, + OBLIQ = 3 +}; + +struct pj_opaque { + double p_halfpi; + double sinph0; + double cosph0; + double Cb; + enum Mode mode; + int no_cut; /* do not cut at hemisphere limit */ +}; + + +# define EPS 1.e-10 + + +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 sinlam, coslam, cosphi, sinphi, t, s, Krho, cosz; + + sinlam = sin(lp.lam); + coslam = cos(lp.lam); + switch (Q->mode) { + case EQUIT: + case OBLIQ: + sinphi = sin(lp.phi); + cosphi = cos(lp.phi); + cosz = cosphi * coslam; + if (Q->mode == OBLIQ) + cosz = Q->sinph0 * sinphi + Q->cosph0 * cosz; + if (!Q->no_cut && cosz < -EPS) { + proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION); + return xy; + } + if (fabs(s = 1. - cosz) > EPS) { + t = 0.5 * (1. + cosz); + Krho = -log(t)/s - Q->Cb / t; + } else + Krho = 0.5 - Q->Cb; + xy.x = Krho * cosphi * sinlam; + if (Q->mode == OBLIQ) + xy.y = Krho * (Q->cosph0 * sinphi - + Q->sinph0 * cosphi * coslam); + else + xy.y = Krho * sinphi; + break; + case S_POLE: + case N_POLE: + lp.phi = fabs(Q->p_halfpi - lp.phi); + if (!Q->no_cut && (lp.phi - EPS) > M_HALFPI) { + proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION); + return xy; + } + if ((lp.phi *= 0.5) > EPS) { + t = tan(lp.phi); + Krho = -2.*(log(cos(lp.phi)) / t + t * Q->Cb); + xy.x = Krho * sinlam; + xy.y = Krho * coslam; + if (Q->mode == N_POLE) + xy.y = -xy.y; + } else + xy.x = xy.y = 0.; + } + return xy; +} + + + + +PJ *PROJECTION(airy) { + double beta; + + struct pj_opaque *Q = static_cast<struct pj_opaque*>(pj_calloc (1, sizeof (struct pj_opaque))); + if (0==Q) + return pj_default_destructor (P, ENOMEM); + + P->opaque = Q; + + Q->no_cut = pj_param(P->ctx, P->params, "bno_cut").i; + beta = 0.5 * (M_HALFPI - pj_param(P->ctx, P->params, "rlat_b").f); + if (fabs(beta) < EPS) + Q->Cb = -0.5; + else { + Q->Cb = 1./tan(beta); + Q->Cb *= Q->Cb * log(cos(beta)); + } + + if (fabs(fabs(P->phi0) - M_HALFPI) < EPS) + if (P->phi0 < 0.) { + Q->p_halfpi = -M_HALFPI; + Q->mode = S_POLE; + } else { + Q->p_halfpi = M_HALFPI; + Q->mode = N_POLE; + } + else { + if (fabs(P->phi0) < EPS) + Q->mode = EQUIT; + else { + Q->mode = OBLIQ; + Q->sinph0 = sin(P->phi0); + Q->cosph0 = cos(P->phi0); + } + } + P->fwd = s_forward; + P->es = 0.; + return P; +} + + |