ardupilot/ArduSub/position_vector.cpp

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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#include "Sub.h"
// position_vector.pde related utility functions
// position vectors are Vector3f
// .x = latitude from home in cm
// .y = longitude from home in cm
// .z = altitude above home in cm
// pv_location_to_vector - convert lat/lon coordinates to a position vector
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Vector3f Sub::pv_location_to_vector(const Location& loc)
{
const struct Location &origin = inertial_nav.get_origin();
float alt_above_origin = pv_alt_above_origin(loc.alt); // convert alt-relative-to-home to alt-relative-to-origin
return Vector3f((loc.lat-origin.lat) * LATLON_TO_CM, (loc.lng-origin.lng) * LATLON_TO_CM * scaleLongDown, alt_above_origin);
}
// pv_alt_above_origin - convert altitude above home to altitude above EKF origin
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float Sub::pv_alt_above_origin(float alt_above_home_cm)
{
const struct Location &origin = inertial_nav.get_origin();
return alt_above_home_cm + (ahrs.get_home().alt - origin.alt);
}
// pv_alt_above_home - convert altitude above EKF origin to altitude above home
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float Sub::pv_alt_above_home(float alt_above_origin_cm)
{
const struct Location &origin = inertial_nav.get_origin();
return alt_above_origin_cm + (origin.alt - ahrs.get_home().alt);
}
// pv_get_bearing_cd - return bearing in centi-degrees between two positions
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float Sub::pv_get_bearing_cd(const Vector3f &origin, const Vector3f &destination)
{
float bearing = atan2f(destination.y-origin.y, destination.x-origin.x) * DEGX100;
if (bearing < 0) {
bearing += 36000;
}
return bearing;
}
// pv_get_horizontal_distance_cm - return distance between two positions in cm
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float Sub::pv_get_horizontal_distance_cm(const Vector3f &origin, const Vector3f &destination)
{
return pythagorous2(destination.x-origin.x,destination.y-origin.y);
}
// returns distance between a destination and home in cm
float Sub::pv_distance_to_home_cm(const Vector3f &destination)
{
Vector3f home = pv_location_to_vector(ahrs.get_home());
return pv_get_horizontal_distance_cm(home, destination);
}