1 /**************************************************************************
2 * polar.h -- 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 **************************************************************************/
34 /* Convert a polar coordinate to a cartesian coordinate. Lon and Lat
35 * must be specified in radians. The FG convention is for distances
36 * to be specified in meters */
37 struct fgCartesianPoint fgPolarToCart(double lon, double lat, double radius);
40 /* Precalculate as much as possible so we can do a batch of transforms
41 * through the same angles, will rotates a cartesian point about the
42 * center of the earth by Theta (longitude axis) and Phi (latitude
45 /* Here are the unoptimized transformation equations
47 x' = cos(Phi) * cos(Theta) * x + cos(Phi) * sin(Theta) * y +
49 y' = -sin(Theta) * x + cos(Theta) * y
50 z' = -sin(Phi) * sin(Theta) * y - sin(Phi) * cos(Theta) * x +
54 void fgRotateBatchInit(double Theta, double Phi);
57 /* Rotates a cartesian point about the center of the earth by Theta
58 * (longitude axis) and Phi (latitude axis) */
59 struct fgCartesianPoint fgRotateCartesianPoint(struct fgCartesianPoint p);
66 /* Revision 1.3 1997/07/31 22:52:28 curt
67 /* Working on redoing internal coordinate systems & scenery transformations.
69 * Revision 1.2 1997/07/23 21:52:21 curt
70 * Put comments around the text after an #endif for increased portability.
72 * Revision 1.1 1997/07/07 21:02:37 curt