125 lines
3.8 KiB
C
125 lines
3.8 KiB
C
|
/**************************************************************************
|
||
|
|
* polar.c -- 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 <stdio.h>
|
||
|
|
|
||
|
|
#include <Math/polar.h>
|
||
|
|
#include <Include/fg_constants.h>
|
||
|
|
|
||
|
|
|
||
|
|
/* we can save these values between calls for efficiency */
|
||
|
|
static double st, ct, sp, cp;
|
||
|
|
|
||
|
|
|
||
|
|
/* 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 */
|
||
|
|
struct fgCartesianPoint fgPolarToCart(double lon, double lat, double radius) {
|
||
|
|
struct fgCartesianPoint pnew;
|
||
|
|
|
||
|
|
pnew.x = cos(lon) * cos(lat) * radius;
|
||
|
|
pnew.y = sin(lon) * cos(lat) * radius;
|
||
|
|
pnew.z = sin(lat) * radius;
|
||
|
|
|
||
|
|
return(pnew);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/* Precalculate as much as possible so we can do a batch of transforms
|
||
|
|
* through the same angles, will rotates a cartesian point about the
|
||
|
|
* center of the earth by Theta (longitude axis) and Phi (latitude
|
||
|
|
* axis) */
|
||
|
|
|
||
|
|
/* Here are the unoptimized transformation equations
|
||
|
|
|
||
|
|
x' = cos(Phi) * cos(Theta) * x + cos(Phi) * sin(Theta) * y +
|
||
|
|
sin(Phi) * z
|
||
|
|
y' = -sin(Theta) * x + cos(Theta) * y
|
||
|
|
z' = -sin(Phi) * sin(Theta) * y - sin(Phi) * cos(Theta) * x +
|
||
|
|
cos(Phi) * z;
|
||
|
|
|
||
|
|
*/
|
||
|
|
void fgRotateBatchInit(double Theta, double Phi) {
|
||
|
|
printf("Theta = %.3f, Phi = %.3f\n", Theta, Phi);
|
||
|
|
|
||
|
|
st = sin(Theta);
|
||
|
|
ct = cos(Theta);
|
||
|
|
sp = sin(-Phi);
|
||
|
|
cp = cos(-Phi);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Rotates a cartesian point about the center of the earth by Theta
|
||
|
|
* (longitude axis) and Phi (latitude axis) */
|
||
|
|
struct fgCartesianPoint fgRotateCartesianPoint(struct fgCartesianPoint p) {
|
||
|
|
struct fgCartesianPoint p1, p2;
|
||
|
|
|
||
|
|
/* printf("start = %.3f %.3f %.3f\n", p.x, p.y, p.z); */
|
||
|
|
|
||
|
|
/* rotate about the z axis */
|
||
|
|
p1.x = ct * p.x - st * p.y;
|
||
|
|
p1.y = st * p.x + ct * p.y;
|
||
|
|
p1.z = p.z;
|
||
|
|
|
||
|
|
/* printf("step 1 = %.3f %.3f %.3f\n", p1.x, p1.y, p1.z); */
|
||
|
|
|
||
|
|
/* rotate new point about y axis */
|
||
|
|
p2.x = cp * p1.x + sp * p1.z;
|
||
|
|
p2.y = p1.y;
|
||
|
|
p2.z = cp * p1.z - sp * p1.x;
|
||
|
|
|
||
|
|
/* printf("cp = %.5f, sp = %.5f\n", cp, sp); */
|
||
|
|
/* printf("(1) = %.5f, (2) = %.5f\n", cp * p1.z, sp * p1.x); */
|
||
|
|
|
||
|
|
/* printf("step 2 = %.3f %.3f %.3f\n", p2.x, p2.y, p2.z); */
|
||
|
|
|
||
|
|
return(p2);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/* $Log$
|
||
|
|
/* Revision 1.1 1998/04/08 23:22:16 curt
|
||
|
|
/* Adopted Gnu automake/autoconf system.
|
||
|
|
/*
|
||
|
|
* Revision 1.5 1998/01/27 00:48:00 curt
|
||
|
|
* Incorporated Paul Bleisch's <bleisch@chromatic.com> 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.
|
||
|
|
* */
|