From b84b36d885ef2f653837f5a380c1bc2802d4464a Mon Sep 17 00:00:00 2001 From: curt Date: Mon, 7 Jul 1997 21:02:36 +0000 Subject: [PATCH] Initial revision. --- Math/polar.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++ Math/polar.h | 67 ++++++++++++++++++++++++++++++++ 2 files changed, 173 insertions(+) create mode 100644 Math/polar.c create mode 100644 Math/polar.h diff --git a/Math/polar.c b/Math/polar.c new file mode 100644 index 000000000..cbbed7494 --- /dev/null +++ b/Math/polar.c @@ -0,0 +1,106 @@ +/************************************************************************** + * 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 +#include + +#include "polar.h" +#include "../constants.h" + + +/* we can save these values between calls for efficiency */ +static double st, ct, sp, cp; + + +/* Convert a geodetic coordinate to a cartesian coordinat on the unit + * circle, scaled by the radius of the earth in meters. Ignores Altitude, + * since this is just for translating points around on the surface. */ +struct fgCartesianPoint fgGeodetic2Cartesian(double lon, double lat) { + struct fgCartesianPoint pnew; + + pnew.x = cos(lon) * cos(lat) * EARTH_RAD; + pnew.y = sin(lon) * cos(lat) * EARTH_RAD; + pnew.z = sin(lat) * EARTH_RAD; + + 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 1997/07/07 21:02:36 curt +/* Initial revision. +/* */ diff --git a/Math/polar.h b/Math/polar.h new file mode 100644 index 000000000..4a164856f --- /dev/null +++ b/Math/polar.h @@ -0,0 +1,67 @@ +/************************************************************************** + * polar.h -- 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) + **************************************************************************/ + + +#ifndef POLAR_H +#define POLAR_H + + +#include "../types.h" + + +/* Convert a geodetic coordinate to a cartesian coordinat on the unit + * circle, scaled by the radius of the earth in meters. Ignores Altitude, + * since this is just for translating points around on the surface. */ +struct fgCartesianPoint fgGeodetic2Cartesian(double lon, double lat); + +/* 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); + +/* Rotates a cartesian point about the center of the earth by Theta + * (longitude axis) and Phi (latitude axis) */ +struct fgCartesianPoint fgRotateCartesianPoint(struct fgCartesianPoint p); + + +#endif POLAR_H + + +/* $Log$ +/* Revision 1.1 1997/07/07 21:02:37 curt +/* Initial revision. +/* + */