/*
* This file is part of the LIRE project: http://www.semanticmetadata.net/lire
* LIRE 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 2 of the License, or
* (at your option) any later version.
*
* LIRE 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 LIRE; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* We kindly ask you to refer the any or one of the following publications in
* any publication mentioning or employing Lire:
*
* Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval –
* An Extensible Java CBIR Library. In proceedings of the 16th ACM International
* Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008
* URL: http://doi.acm.org/10.1145/1459359.1459577
*
* Lux Mathias. Content Based Image Retrieval with LIRE. In proceedings of the
* 19th ACM International Conference on Multimedia, pp. 735-738, Scottsdale,
* Arizona, USA, 2011
* URL: http://dl.acm.org/citation.cfm?id=2072432
*
* Mathias Lux, Oge Marques. Visual Information Retrieval using Java and LIRE
* Morgan & Claypool, 2013
* URL: http://www.morganclaypool.com/doi/abs/10.2200/S00468ED1V01Y201301ICR025
*
* Copyright statement:
* --------------------
* (c) 2002-2013 by Mathias Lux (mathias@juggle.at)
* http://www.semanticmetadata.net/lire, http://www.lire-project.net
*/
package net.semanticmetadata.lire.imageanalysis.mser.fourier.utils;
import java.awt.*;
import java.awt.geom.Point2D;
/**
* Created by IntelliJ IDEA.
* User: Shotty
* Date: 10.01.11
* Time: 04:11
* To change this template use File | Settings | File Templates.
*/
public class PolygonUtils {
/**
* METHODS TO CALCULATE THE AREA AND CENTROID OF A POLYGON
* INSERT THEM INTO THE CORRESPONDING CLASS *
*/
public static double signedPolygonArea(Point2D.Double[] polygon) {
int N = polygon.length;
Polygon P;
int i, j;
double area = 0;
for (i = 0; i < N; i++) {
j = (i + 1) % N;
area += polygon[i].x * polygon[j].y;
area -= polygon[i].y * polygon[j].x;
}
area /= 2.0;
return (area);
//return(area < 0 ? -area : area); for unsigned
}
public static double unsignedPolygonArea(Point2D.Double[] polygon) {
double area = signedPolygonArea(polygon);
return (area < 0 ? -area : area);
}
/* CENTROID */
public static Point2D.Double polygonCenterOfMass(Point2D.Double[] polygon) {
int N = polygon.length - 1;
double cx = 0, cy = 0;
// double A = signedPolygonArea(polygon);
Point2D.Double res = new Point2D.Double();
int i, j;
double sumDet = 0;
double factor = 0;
for (i = 0; i < N; i++) {
j = i + 1;
factor = (polygon[i].x * polygon[j].y - polygon[j].x * polygon[i].y);
cx += (polygon[i].x + polygon[j].x) * factor;
cy += (polygon[i].y + polygon[j].y) * factor;
sumDet += factor;
}
factor = 1 / (3 * sumDet);
// A*=6.0;
// factor=1/A;
cx *= factor;
cy *= factor;
res.x = cx;
res.y = cy;
return res;
}
public static void applyCoG(Point2D.Double[] points, Point2D.Double cog) {
for (int i = 0; i < points.length; i++) {
points[i].setLocation(points[i].x - cog.x, points[i].y - cog.y);
}
}
public static void main(String[] args) {
Point2D.Double[] test =
{
new Point2D.Double(-1, -4),
new Point2D.Double(-4, 2),
new Point2D.Double(-1, 5),
new Point2D.Double(2, 2)
};
Point2D cog = polygonCenterOfMass(test);
System.out.println(cog.getX() + "/" + cog.getY());
Point.Double[] test2 =
{
new Point2D.Double(1, 2),
new Point2D.Double(4, 2),
new Point2D.Double(5, 3),
new Point2D.Double(2, 3)
};
cog = polygonCenterOfMass(test2);
System.out.println(cog.getX() + "/" + cog.getY());
}
}