1 /**************************************************************************
2 * polar.c -- routines to deal with polar math and transformations
4 * Written by Curtis Olson, started June 1997.
6 * Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the
11 * License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 * (Log is kept at end of this file)
24 **************************************************************************/
30 #include <Include/fg_constants.h>
35 /* Convert a polar coordinate to a cartesian coordinate. Lon and Lat
36 * must be specified in radians. The FG convention is for distances
37 * to be specified in meters */
38 fgCartesianPoint3d fgPolarToCart3d(fgPolarPoint3d p) {
39 fgCartesianPoint3d pnew;
41 pnew.x = cos(p.lon) * cos(p.lat) * p.radius;
42 pnew.y = sin(p.lon) * cos(p.lat) * p.radius;
43 pnew.z = sin(p.lat) * p.radius;
49 /* Convert a cartesian coordinate to polar coordinates (lon/lat
50 * specified in radians. Distances are specified in meters. */
51 fgPolarPoint3d fgCartToPolar3d(fgCartesianPoint3d cp) {
54 pp.lon = atan2( cp.y, cp.x );
55 pp.lat = FG_PI_2 - atan2( sqrt(cp.x*cp.x + cp.y*cp.y), cp.z );
56 pp.radius = sqrt(cp.x*cp.x + cp.y*cp.y + cp.z*cp.z);
58 /* printf("lon = %.2f lat = %.2f radius = %.2f\n",
59 pp.lon, pp.lat, pp.radius); */
65 /* Revision 1.2 1998/05/03 00:45:49 curt
66 /* Commented out a debugging printf.
68 * Revision 1.1 1998/05/02 01:50:11 curt
69 * polar.[ch] renamed to polar3d.[ch]
71 * Revision 1.6 1998/04/25 22:06:23 curt
72 * Edited cvs log messages in source files ... bad bad bad!
74 * Revision 1.5 1998/01/27 00:48:00 curt
75 * Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
76 * system and commandline/config file processing code.
78 * Revision 1.4 1998/01/19 19:27:12 curt
79 * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
80 * This should simplify things tremendously.
82 * Revision 1.3 1997/12/15 23:54:54 curt
83 * Add xgl wrappers for debugging.
84 * Generate terrain normals on the fly.
86 * Revision 1.2 1997/07/31 22:52:27 curt
87 * Working on redoing internal coordinate systems & scenery transformations.
89 * Revision 1.1 1997/07/07 21:02:36 curt