PX4-Autopilot/src/platforms/ros/geo.cpp

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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>
 * @author Anton Babushkin <anton.babushkin@me.com>
 */

#include <geo/geo.h>
#include <px4.h>
#include <unistd.h>
#include <pthread.h>
#include <stdio.h>
#include <math.h>
#include <stdbool.h>
#include <string.h>
#include <float.h>

__EXPORT float _wrap_pi(float bearing)
{
	/* value is inf or NaN */
	if (!PX4_ISFINITE(bearing)) {
		return bearing;
	}

	int c = 0;

	while (bearing >= M_PI_F) {
		bearing -= M_TWOPI_F;

		if (c++ > 3) {
			return NAN;
		}
	}

	c = 0;

	while (bearing < -M_PI_F) {
		bearing += M_TWOPI_F;

		if (c++ > 3) {
			return NAN;
		}
	}

	return bearing;
}

__EXPORT float _wrap_2pi(float bearing)
{
	/* value is inf or NaN */
	if (!PX4_ISFINITE(bearing)) {
		return bearing;
	}

	int c = 0;

	while (bearing >= M_TWOPI_F) {
		bearing -= M_TWOPI_F;

		if (c++ > 3) {
			return NAN;
		}
	}

	c = 0;

	while (bearing < 0.0f) {
		bearing += M_TWOPI_F;

		if (c++ > 3) {
			return NAN;
		}
	}

	return bearing;
}

__EXPORT float _wrap_180(float bearing)
{
	/* value is inf or NaN */
	if (!PX4_ISFINITE(bearing)) {
		return bearing;
	}

	int c = 0;

	while (bearing >= 180.0f) {
		bearing -= 360.0f;

		if (c++ > 3) {
			return NAN;
		}
	}

	c = 0;

	while (bearing < -180.0f) {
		bearing += 360.0f;

		if (c++ > 3) {
			return NAN;
		}
	}

	return bearing;
}

__EXPORT float _wrap_360(float bearing)
{
	/* value is inf or NaN */
	if (!PX4_ISFINITE(bearing)) {
		return bearing;
	}

	int c = 0;

	while (bearing >= 360.0f) {
		bearing -= 360.0f;

		if (c++ > 3) {
			return NAN;
		}
	}

	c = 0;

	while (bearing < 0.0f) {
		bearing += 360.0f;

		if (c++ > 3) {
			return NAN;
		}
	}

	return bearing;
}

__EXPORT bool map_projection_initialized(const struct map_projection_reference_s *ref)
{
	return ref->init_done;
}

__EXPORT uint64_t map_projection_timestamp(const struct map_projection_reference_s *ref)
{
	return ref->timestamp;
}

__EXPORT int map_projection_init_timestamped(struct map_projection_reference_s *ref, double lat_0, double lon_0,
		uint64_t timestamp) //lat_0, lon_0 are expected to be in correct format: -> 47.1234567 and not 471234567
{

	ref->lat_rad = lat_0 * M_DEG_TO_RAD;
	ref->lon_rad = lon_0 * M_DEG_TO_RAD;
	ref->sin_lat = sin(ref->lat_rad);
	ref->cos_lat = cos(ref->lat_rad);

	ref->timestamp = timestamp;
	ref->init_done = true;

	return 0;
}

__EXPORT int map_projection_init(struct map_projection_reference_s *ref, double lat_0,
				 double lon_0) //lat_0, lon_0 are expected to be in correct format: -> 47.1234567 and not 471234567
{
	return map_projection_init_timestamped(ref, lat_0, lon_0, px4::get_time_micros());
}

__EXPORT int map_projection_reference(const struct map_projection_reference_s *ref, double *ref_lat_rad,
				      double *ref_lon_rad)
{
	if (!map_projection_initialized(ref)) {
		return -1;
	}

	*ref_lat_rad = ref->lat_rad;
	*ref_lon_rad = ref->lon_rad;

	return 0;
}

__EXPORT int map_projection_project(const struct map_projection_reference_s *ref, double lat, double lon, float *x,
				    float *y)
{
	if (!map_projection_initialized(ref)) {
		return -1;
	}

	double lat_rad = lat * M_DEG_TO_RAD;
	double lon_rad = lon * M_DEG_TO_RAD;

	double sin_lat = sin(lat_rad);
	double cos_lat = cos(lat_rad);
	double cos_d_lon = cos(lon_rad - ref->lon_rad);

	double c = acos(ref->sin_lat * sin_lat + ref->cos_lat * cos_lat * cos_d_lon);
	double k = (fabs(c) < DBL_EPSILON) ? 1.0 : (c / sin(c));

	*x = k * (ref->cos_lat * sin_lat - ref->sin_lat * cos_lat * cos_d_lon) * CONSTANTS_RADIUS_OF_EARTH;
	*y = k * cos_lat * sin(lon_rad - ref->lon_rad) * CONSTANTS_RADIUS_OF_EARTH;

	return 0;
}

__EXPORT int map_projection_reproject(const struct map_projection_reference_s *ref, float x, float y, double *lat,
				      double *lon)
{
	if (!map_projection_initialized(ref)) {
		return -1;
	}

	double x_rad = x / CONSTANTS_RADIUS_OF_EARTH;
	double y_rad = y / CONSTANTS_RADIUS_OF_EARTH;
	double c = sqrtf(x_rad * x_rad + y_rad * y_rad);
	double sin_c = sin(c);
	double cos_c = cos(c);

	double lat_rad;
	double lon_rad;

	if (fabs(c) > DBL_EPSILON) {
		lat_rad = asin(cos_c * ref->sin_lat + (x_rad * sin_c * ref->cos_lat) / c);
		lon_rad = (ref->lon_rad + atan2(y_rad * sin_c, c * ref->cos_lat * cos_c - x_rad * ref->sin_lat * sin_c));

	} else {
		lat_rad = ref->lat_rad;
		lon_rad = ref->lon_rad;
	}

	*lat = lat_rad * 180.0 / M_PI;
	*lon = lon_rad * 180.0 / M_PI;

	return 0;
}