mirror of https://github.com/ArduPilot/ardupilot
97 lines
3.1 KiB
C++
97 lines
3.1 KiB
C++
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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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* location.cpp
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* Copyright (C) Andrew Tridgell 2011
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*
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* This file is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This file is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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this module deals with calculations involving struct Location
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*/
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#include <FastSerial.h>
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#include "AP_Math.h"
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static float longitude_scale(const struct Location *loc)
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{
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static uint32_t last_lat;
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static float scale = 1.0;
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if (abs(last_lat - loc->lat) < 100000) {
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// we are within 0.01 degrees (about 1km) of the
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// same latitude. We can avoid the cos() and return
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// the same scale factor.
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return scale;
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}
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scale = cos((fabs((float)loc->lat)/1.0e7) * 0.0174532925);
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return scale;
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}
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// return distance in meters to between two locations, or -1
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// if one of the locations is invalid
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int32_t get_distance(const struct Location *loc1, const struct Location *loc2)
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{
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if (loc1->lat == 0 || loc1->lng == 0)
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return -1;
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if(loc2->lat == 0 || loc2->lng == 0)
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return -1;
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float dlat = (float)(loc2->lat - loc1->lat);
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float dlong = ((float)(loc2->lng - loc1->lng)) * longitude_scale(loc2);
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return sqrt(sq(dlat) + sq(dlong)) * .01113195;
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}
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// return bearing in centi-degrees between two locations
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int32_t get_bearing(const struct Location *loc1, const struct Location *loc2)
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{
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int32_t off_x = loc2->lng - loc1->lng;
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int32_t off_y = (loc2->lat - loc1->lat) / longitude_scale(loc2);
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int32_t bearing = 9000 + atan2(-off_y, off_x) * 5729.57795;
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if (bearing < 0) bearing += 36000;
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return bearing;
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}
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// see if location is past a line perpendicular to
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// the line between point1 and point2. If point1 is
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// our previous waypoint and point2 is our target waypoint
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// then this function returns true if we have flown past
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// the target waypoint
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bool location_passed_point(struct Location &location,
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struct Location &point1,
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struct Location &point2)
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{
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// the 3 points form a triangle. If the angle between lines
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// point1->point2 and location->point2 is greater than 90
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// degrees then we have passed the waypoint
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Vector2f loc1(location.lat, location.lng);
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Vector2f pt1(point1.lat, point1.lng);
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Vector2f pt2(point2.lat, point2.lng);
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float angle = (loc1 - pt2).angle(pt1 - pt2);
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if (angle == 0) {
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// if we are exactly on the line between point1 and
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// point2 then we are past the waypoint if the
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// distance from location to point1 is greater then
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// the distance from point2 to point1
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return get_distance(&location, &point1) >
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get_distance(&point2, &point1);
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}
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if (degrees(angle) > 90) {
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return true;
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}
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return false;
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}
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