1 /*
2 ** libproj -- library of cartographic projections
3 **
4 ** Copyright (c) 2003, 2006 Gerald I. Evenden
5 */
6 static const char
7 LIBPROJ_ID[] = "Id";
8 /*
9 ** Permission is hereby granted, free of charge, to any person obtaining
10 ** a copy of this software and associated documentation files (the
11 ** "Software"), to deal in the Software without restriction, including
12 ** without limitation the rights to use, copy, modify, merge, publish,
13 ** distribute, sublicense, and/or sell copies of the Software, and to
14 ** permit persons to whom the Software is furnished to do so, subject to
15 ** the following conditions:
16 **
17 ** The above copyright notice and this permission notice shall be
18 ** included in all copies or substantial portions of the Software.
19 **
20 ** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 ** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 ** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
23 ** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
24 ** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
25 ** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
26 ** SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
27 */
28 #define DEFAULT_LAT 5.*DEG_TO_RAD
29 #define PROJ_LIB__
30 #define PROJ_PARMS__ \
31 double cp1, sp1;
32 # include <lib_proj.h>
33 PROJ_HEAD(gilbert, "Gilbert Two World Perspective") "\n\tPCyl., Sph., NoInv.\n\tlat_1=";
34 static double
phiprime(double phi)35 phiprime(double phi) { return (proj_asin(tan(0.5 * phi))); }
36 FORWARD(s_forward); /* spheroid */
37 double sp, cp, cl;
38
39 lp.phi = phiprime(lp.phi);
40 sp = sin(lp.phi);
41 cp = cos(lp.phi);
42 cl = cos(lp.lam *= 0.5);
43 if ((P->sp1*sp + P->cp1*cp*cl) >= 0.) {
44 xy.x = cp * sin(lp.lam);
45 xy.y = P->cp1*sp - P->sp1 * cp * cl;
46 } else
47 F_ERROR;
48 return (xy);
49 }
50 FREEUP; if (P) free(P); }
51 ENTRY0(gilbert)
52 P->cp1 = phiprime((proj_param(P->params, "tlat_1").i) ?
53 proj_param(P->params, "rlat_1").f : DEFAULT_LAT );
54 P->sp1 = sin(P->cp1);
55 P->cp1 = cos(P->cp1);
56 P->es = 0.;
57 P->fwd = s_forward;
58 ENDENTRY(P)
59 /*
60 ** Log: proj_gilbert.c
61 ** Revision 3.1 2006/01/11 01:38:18 gie
62 ** Initial
63 **
64 */
65