mirror of https://github.com/ArduPilot/ardupilot
77 lines
2.4 KiB
C++
77 lines
2.4 KiB
C++
/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
|
|
/*
|
|
* polygon.cpp
|
|
* Copyright (C) Andrew Tridgell 2011
|
|
*
|
|
* This file is free software: you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License as published by the
|
|
* Free Software Foundation, either version 3 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This file is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
|
* See the GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License along
|
|
* with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include "AP_Math.h"
|
|
|
|
/*
|
|
The point in polygon algorithm is based on:
|
|
http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
|
|
*/
|
|
|
|
|
|
/*
|
|
Polygon_outside(): test for a point in a polygon
|
|
Input: P = a point,
|
|
V[] = vertex points of a polygon V[n+1] with V[n]=V[0]
|
|
Return: true if P is outside the polygon
|
|
|
|
This does not take account of the curvature of the earth, but we
|
|
expect that to be very small over the distances involved in the
|
|
fence boundary
|
|
*/
|
|
bool Polygon_outside(const Vector2l &P, const Vector2l *V, unsigned n)
|
|
{
|
|
unsigned i, j;
|
|
bool outside = true;
|
|
for (i = 0, j = n-1; i < n; j = i++) {
|
|
if ((V[i].y > P.y) == (V[j].y > P.y)) {
|
|
continue;
|
|
}
|
|
float dx1, dx2, dy1, dy2;
|
|
// use floating point to cope with possible integer overflow
|
|
// this still results in precision of better than 1m
|
|
dx1 = P.x - V[i].x;
|
|
dx2 = V[j].x - V[i].x;
|
|
dy1 = P.y - V[i].y;
|
|
dy2 = V[j].y - V[i].y;
|
|
if (dy2 < 0) {
|
|
if ( dx1 * dy2 > dx2 * dy1 ) {
|
|
outside = !outside;
|
|
}
|
|
} else {
|
|
if ( dx1 * dy2 < dx2 * dy1 ) {
|
|
outside = !outside;
|
|
}
|
|
}
|
|
}
|
|
return outside;
|
|
}
|
|
|
|
/*
|
|
check if a polygon is complete.
|
|
|
|
We consider a polygon to be complete if we have at least 4 points,
|
|
and the first point is the same as the last point. That is the
|
|
minimum requirement for the Polygon_outside function to work
|
|
*/
|
|
bool Polygon_complete(const Vector2l *V, unsigned n)
|
|
{
|
|
return (n >= 4 && V[n-1].x == V[0].x && V[n-1].y == V[0].y);
|
|
}
|