/****************************************************************************
*
* Copyright (C) 2012 PX4 Development Team. All rights reserved.
* Author: Thomas Gubler <thomasgubler@student.ethz.ch>
* Julian Oes <joes@student.ethz.ch>
* Lorenz Meier <lm@inf.ethz.ch>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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*
****************************************************************************/
/**
* @file geo.c
*
* Geo / math functions to perform geodesic calculations
*
* @author Thomas Gubler <thomasgubler@student.ethz.ch>
* @author Julian Oes <joes@student.ethz.ch>
* @author Lorenz Meier <lm@inf.ethz.ch>
*/
#include <systemlib/geo/geo.h>
#include <math.h>
__EXPORT float get_distance_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next)
{
double lat_now_rad = lat_now / 180.0 * M_PI;
double lon_now_rad = lon_now / 180.0 * M_PI;
double lat_next_rad = lat_next / 180.0 * M_PI;
double lon_next_rad = lon_next / 180.0 * M_PI;
double d_lat = lat_next_rad - lat_now_rad;
double d_lon = lon_next_rad - lon_now_rad;
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);
double c = 2 * atan2(sqrt(a), sqrt(1 - a));
const double radius_earth = 6371000.0;
return radius_earth * c;
}
__EXPORT float get_bearing_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next)
{
double lat_now_rad = lat_now / 180.0 * M_PI;
double lon_now_rad = lon_now / 180.0 * M_PI;
double lat_next_rad = lat_next / 180.0 * M_PI;
double lon_next_rad = lon_next / 180.0 * M_PI;
double d_lat = lat_next_rad - lat_now_rad;
double d_lon = lon_next_rad - lon_now_rad;
/* conscious mix of double and float trig function to maximize speed and efficiency */
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));
// XXX wrapping check is incomplete
if (theta < 0.0f) {
theta = theta + 2.0f * M_PI_F;
}
return theta;
}
