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/****************************************************************************
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*
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* Copyright (C) 2012 PX4 Development Team. All rights reserved.
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* Author: Thomas Gubler <thomasgubler@student.ethz.ch>
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* Julian Oes <joes@student.ethz.ch>
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* Lorenz Meier <lm@inf.ethz.ch>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name PX4 nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/**
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* @file geo.c
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*
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* Geo / math functions to perform geodesic calculations
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*
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* @author Thomas Gubler <thomasgubler@student.ethz.ch>
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* @author Julian Oes <joes@student.ethz.ch>
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* @author Lorenz Meier <lm@inf.ethz.ch>
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*/
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#include <systemlib/geo/geo.h>
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#include <math.h>
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__EXPORT float get_distance_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next)
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{
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double lat_now_rad = lat_now / 180.0 * M_PI;
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double lon_now_rad = lon_now / 180.0 * M_PI;
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double lat_next_rad = lat_next / 180.0 * M_PI;
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double lon_next_rad = lon_next / 180.0 * M_PI;
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double d_lat = lat_next_rad - lat_now_rad;
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double d_lon = lon_next_rad - lon_now_rad;
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double a = sin(d_lat / 2.0) * sin(d_lat / 2.0) + sin(d_lon / 2.0) * sin(d_lon / 2.0) * cos(lat_now_rad) * cos(lat_next_rad);
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double c = 2 * atan2(sqrt(a), sqrt(1 - a));
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const double radius_earth = 6371000.0;
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return radius_earth * c;
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}
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__EXPORT float get_bearing_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next)
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{
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double lat_now_rad = lat_now / 180.0 * M_PI;
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double lon_now_rad = lon_now / 180.0 * M_PI;
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double lat_next_rad = lat_next / 180.0 * M_PI;
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double lon_next_rad = lon_next / 180.0 * M_PI;
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double d_lat = lat_next_rad - lat_now_rad;
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double d_lon = lon_next_rad - lon_now_rad;
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/* conscious mix of double and float trig function to maximize speed and efficiency */
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float theta = atan2f(sin(d_lon) * cos(lat_next_rad) , cos(lat_now_rad) * sin(lat_next_rad) - sin(lat_now_rad) * cos(lat_next_rad) * cos(d_lon));
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if (theta < M_PI_F) {
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theta += 2.0f * M_PI_F;
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}
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if (theta > M_PI_F) {
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theta -= 2.0f * M_PI_F;
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}
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return theta;
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}
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