unsigned Polygon Area - Java 2D Graphics

Java examples for 2D Graphics:Polygon

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Description

unsigned Polygon Area

Demo Code

/*//from   www.  j a  v a 2  s  . c  o m
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 * 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 com.java2s;
import java.awt.*;
import java.awt.geom.Point2D;

public class Main {
    public static double unsignedPolygonArea(Point2D.Double[] polygon) {
        double area = signedPolygonArea(polygon);
        return (area < 0 ? -area : area);
    }

    /**
     * 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
    }
}

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