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 geodetic coordinate to a cartesian coordinat on the unit
35 * circle, scaled by the radius of the earth in meters. Ignores Altitude,
36 * since this is just for translating points around on the surface. */
37 struct fgCartesianPoint fgGeodetic2Cartesian(double lon, double lat);
39 /* Precalculate as much as possible so we can do a batch of transforms
40 * through the same angles, will rotates a cartesian point about the
41 * center of the earth by Theta (longitude axis) and Phi (latitude
44 /* Here are the unoptimized transformation equations
46 x' = cos(Phi) * cos(Theta) * x + cos(Phi) * sin(Theta) * y +
48 y' = -sin(Theta) * x + cos(Theta) * y
49 z' = -sin(Phi) * sin(Theta) * y - sin(Phi) * cos(Theta) * x +
53 void fgRotateBatchInit(double Theta, double Phi);
55 /* Rotates a cartesian point about the center of the earth by Theta
56 * (longitude axis) and Phi (latitude axis) */
57 struct fgCartesianPoint fgRotateCartesianPoint(struct fgCartesianPoint p);
64 /* Revision 1.2 1997/07/23 21:52:21 curt
65 /* Put comments around the text after an #endif for increased portability.
67 * Revision 1.1 1997/07/07 21:02:37 curt