point In Triangle - Java java.lang

Java examples for java.lang:Math Geometry Shape

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Description

point In Triangle

Demo Code

/**//from   w  w  w. j  a  v a2 s .  c  om
 * Java Modular Image Synthesis Toolkit (JMIST)
 * Copyright (C) 2008-2013 Bradley W. Kimmel
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

public class Main{
    public static boolean pointInTriangle(Point2 p, Point2 a, Point2 b,
            Point2 c) {
        Vector2 ab = a.vectorTo(b);
        Vector2 ac = a.vectorTo(c);
        Vector2 ap = a.vectorTo(p);

        double dot00 = ab.dot(ab);
        double dot01 = ab.dot(ac);
        double dot02 = ab.dot(ap);
        double dot11 = ac.dot(ac);
        double dot12 = ac.dot(ap);

        // Compute barycentric coordinates
        double invDenom = 1 / (dot00 * dot11 - dot01 * dot01);
        double u = (dot11 * dot02 - dot01 * dot12) * invDenom;
        double v = (dot00 * dot12 - dot01 * dot02) * invDenom;

        // Check if point is in triangle
        return (u > 0) && (v > 0) && (u + v < 1);
    }
}

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