-/**************************************************************************
- * polar.cxx -- routines to deal with polar math and transformations
- *
- * Written by Curtis Olson, started June 1997.
- *
- * Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of the
- * License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- *
- * $Id$
- * (Log is kept at end of this file)
- **************************************************************************/
+// polar.cxx -- routines to deal with polar math and transformations
+//
+// Written by Curtis Olson, started June 1997.
+//
+// Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+// (Log is kept at end of this file)
#include <math.h>
#include "polar3d.hxx"
-/* Convert a polar coordinate to a cartesian coordinate. Lon and Lat
- * must be specified in radians. The FG convention is for distances
- * to be specified in meters */
-fgPoint3d fgPolarToCart3d(fgPoint3d p) {
- fgPoint3d pnew;
+// Convert a polar coordinate to a cartesian coordinate. Lon and Lat
+// must be specified in radians. The FG convention is for distances
+// to be specified in meters
+Point3D fgPolarToCart3d(const Point3D& p) {
+ Point3D pnew;
+ double tmp;
- pnew.x = cos(p.lon) * cos(p.lat) * p.radius;
- pnew.y = sin(p.lon) * cos(p.lat) * p.radius;
- pnew.z = sin(p.lat) * p.radius;
+ tmp = cos( p.lat() ) * p.radius();
- return(pnew);
+ pnew = Point3D ( cos( p.lon() ) * tmp,
+ sin( p.lon() ) * tmp,
+ sin( p.lat() ) * p.radius() );
+
+ return pnew;
+}
+
+
+// Convert a cartesian coordinate to polar coordinates (lon/lat
+// specified in radians. Distances are specified in meters.
+Point3D fgCartToPolar3d(const Point3D& cp) {
+ Point3D pp;
+
+ pp = Point3D( atan2( cp.y(), cp.x() ),
+ FG_PI_2 -
+ atan2( sqrt(cp.x()*cp.x() + cp.y()*cp.y()), cp.z() ),
+ sqrt(cp.x()*cp.x() + cp.y()*cp.y() + cp.z()*cp.z()) );
+
+ // printf("lon = %.2f lat = %.2f radius = %.2f\n",
+ // pp.lon, pp.lat, pp.radius);
+
+ return pp;
}
-/* Convert a cartesian coordinate to polar coordinates (lon/lat
- * specified in radians. Distances are specified in meters. */
-fgPoint3d fgCartToPolar3d(fgPoint3d cp) {
- fgPoint3d pp;
+// Find the Altitude above the Ellipsoid (WGS84) given the Earth
+// Centered Cartesian coordinate vector Distances are specified in
+// meters.
+double fgGeodAltFromCart(const Point3D& cp)
+{
+ double t_lat, x_alpha, mu_alpha;
+ double lat_geoc, radius;
+ double result;
- pp.lon = atan2( cp.y, cp.x );
- pp.lat = FG_PI_2 - atan2( sqrt(cp.x*cp.x + cp.y*cp.y), cp.z );
- pp.radius = sqrt(cp.x*cp.x + cp.y*cp.y + cp.z*cp.z);
+ lat_geoc = FG_PI_2 - atan2( sqrt(cp.x()*cp.x() + cp.y()*cp.y()), cp.z() );
+ radius = sqrt( cp.x()*cp.x() + cp.y()*cp.y() + cp.z()*cp.z() );
+
+ if( ( (FG_PI_2 - lat_geoc) < ONE_SECOND ) // near North pole
+ || ( (FG_PI_2 + lat_geoc) < ONE_SECOND ) ) // near South pole
+ {
+ result = radius - EQUATORIAL_RADIUS_M*E;
+ } else {
+ t_lat = tan(lat_geoc);
+ x_alpha = E*EQUATORIAL_RADIUS_M/sqrt(t_lat*t_lat + E*E);
+ mu_alpha = atan2(sqrt(RESQ_M - x_alpha*x_alpha),E*x_alpha);
+ if (lat_geoc < 0) {
+ mu_alpha = - mu_alpha;
+ }
+ result = (radius - x_alpha/cos(lat_geoc))*cos(mu_alpha - lat_geoc);
+ }
- /* printf("lon = %.2f lat = %.2f radius = %.2f\n",
- pp.lon, pp.lat, pp.radius); */
- return(pp);
+ return(result);
}
-/* $Log$
-/* Revision 1.1 1998/07/08 14:40:08 curt
-/* polar3d.[ch] renamed to polar3d.[ch]xx, vector.[ch] renamed to vector.[ch]xx
-/* Updated fg_geodesy comments to reflect that routines expect and produce
-/* meters.
-/*
- * Revision 1.2 1998/05/03 00:45:49 curt
- * Commented out a debugging printf.
- *
- * Revision 1.1 1998/05/02 01:50:11 curt
- * polar.[ch] renamed to polar3d.[ch]
- *
- * Revision 1.6 1998/04/25 22:06:23 curt
- * Edited cvs log messages in source files ... bad bad bad!
- *
- * Revision 1.5 1998/01/27 00:48:00 curt
- * Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
- * system and commandline/config file processing code.
- *
- * Revision 1.4 1998/01/19 19:27:12 curt
- * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
- * This should simplify things tremendously.
- *
- * Revision 1.3 1997/12/15 23:54:54 curt
- * Add xgl wrappers for debugging.
- * Generate terrain normals on the fly.
- *
- * Revision 1.2 1997/07/31 22:52:27 curt
- * Working on redoing internal coordinate systems & scenery transformations.
- *
- * Revision 1.1 1997/07/07 21:02:36 curt
- * Initial revision.
- * */
+// $Log$
+// Revision 1.5 1998/10/18 01:17:13 curt
+// Point3D tweaks.
+//
+// Revision 1.4 1998/10/16 19:30:09 curt
+// C++-ified the comments.
+//
+// Revision 1.3 1998/10/16 00:50:29 curt
+// Added point3d.hxx to replace cheezy fgPoint3d struct.
+//
+// Revision 1.2 1998/08/24 20:04:11 curt
+// Various "inline" code optimizations contributed by Norman Vine.
+//
+// Revision 1.1 1998/07/08 14:40:08 curt
+// polar3d.[ch] renamed to polar3d.[ch]xx, vector.[ch] renamed to vector.[ch]xx
+// Updated fg_geodesy comments to reflect that routines expect and produce
+// meters.
+//
+// Revision 1.2 1998/05/03 00:45:49 curt
+// Commented out a debugging printf.
+//
+// Revision 1.1 1998/05/02 01:50:11 curt
+// polar.[ch] renamed to polar3d.[ch]
+//
+// Revision 1.6 1998/04/25 22:06:23 curt
+// Edited cvs log messages in source files ... bad bad bad!
+//
+// Revision 1.5 1998/01/27 00:48:00 curt
+// Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
+// system and commandline/config file processing code.
+//
+// Revision 1.4 1998/01/19 19:27:12 curt
+// Merged in make system changes from Bob Kuehne <rpk@sgi.com>
+// This should simplify things tremendously.
+//
+// Revision 1.3 1997/12/15 23:54:54 curt
+// Add xgl wrappers for debugging.
+// Generate terrain normals on the fly.
+//
+// Revision 1.2 1997/07/31 22:52:27 curt
+// Working on redoing internal coordinate systems & scenery transformations.
+//
+// Revision 1.1 1997/07/07 21:02:36 curt
+// Initial revision.
+