package org.activityinfo.server.report.generator.map;
/*
* #%L
* ActivityInfo Server
* %%
* Copyright (C) 2009 - 2013 UNICEF
* %%
* This program 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 program 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/gpl-3.0.html>.
* #L%
*/
import org.activityinfo.legacy.shared.reports.content.Point;
public final class CircleMath {
private CircleMath() {
}
public static double area(double radius) {
return Math.PI * radius * radius;
}
/**
* Calculates the area of intersection of two circles.
*
* @param a The first point
* @param b The second point
* @param r0 The radius of the first point
* @param r1 The radius of the second point
* @return Area of the intersection
*/
public static double intersectionArea(Point a, Point b, double r0, double r1) {
double c = a.distance(b);
if (c >= r0 + r1) {
return 0; // no intersection
}
if (c < r0 && c + r1 < r0) {
return area(r1); // the first circle completely contains the second
}
if (c < r1 && c + r0 < r1) {
return area(r0); // the second circle completely contains the first
}
double cba = Math.acos(((r1 * r1) + (c * c) - (r0 * r0)) / (2.0 * r1 * c));
double cbd = cba * 2.0;
double cab = Math.acos(((r0 * r0) + (c * c) - (r1 * r1)) / (2.0 * r0 * c));
double cad = cab * 2.0;
return (0.5) * (cbd) * (r1 * r1) - (0.5) * (r1 * r1) * Math.sin(cbd) + (0.5) * (cad) * (r0 * r0) -
(0.5) * (r0 * r0 * Math.sin(cad));
}
}