area Of Triangle - Java java.lang

Java examples for java.lang:Math Geometry Shape

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Description

area Of Triangle

Demo Code

/**//  www  . j  a  va 2 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 double areaOfTriangle(Point3 a, Point3 b, Point3 c) {
        Vector3 ab = a.vectorTo(b);
        Vector3 bc = b.vectorTo(c);
        Vector3 ca = c.vectorTo(a);

        double abDOTbc = ab.dot(bc);
        double bcDOTca = bc.dot(ca);
        double caDOTab = ca.dot(ab);

        if (abDOTbc < bcDOTca && abDOTbc < caDOTab) {
            return 0.5 * ab.cross(bc).length();
        } else if (bcDOTca < caDOTab) {
            return 0.5 * bc.cross(ca).length();
        } else {
            return 0.5 * ca.cross(ab).length();
        }
    }
    public static double areaOfTriangle(Point2 a, Point2 b, Point2 c) {
        return Math.abs(0.5 * (a.x() * (b.y() - c.y()) + b.x()
                * (c.y() - a.y()) + c.x() * (a.y() - b.y())));
    }
}

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