Check if three vertices are linear - Java java.lang

Java examples for java.lang:Math Vector

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Description

Check if three vertices are linear

Demo Code

/**/*  w w w. j a va2s. com*/
 * Copyright 2010 JogAmp Community. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 *
 *    1. Redistributions of source code must retain the above copyright notice, this list of
 *       conditions and the following disclaimer.
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 *    2. Redistributions in binary form must reproduce the above copyright notice, this list
 *       of conditions and the following disclaimer in the documentation and/or other materials
 *       provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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 */
import java.util.ArrayList;

public class Main{
    /**
     * Check if three vertices are colliniear
     * @param v1 vertex 1
     * @param v2 vertex 2
     * @param v3 vertex 3
     * @return true if collinear, false otherwise
     */
    public static boolean isCollinearVec3(final float[] v1,
            final float[] v2, final float[] v3) {
        return FloatUtil.isZero(determinantVec3(v1, v2, v3),
                FloatUtil.EPSILON);
    }
    /**
     * Return true if all two vector components are zero, i.e. it's their absolute value < <code>epsilon</code>.
     * <p>
     * Implementation uses {@link FloatUtil#isZero(float, float)}, see API doc for details.
     * </p>
     */
    public static boolean isZero(final float x, final float y,
            final float epsilon) {
        return FloatUtil.isZero(x, epsilon) && FloatUtil.isZero(y, epsilon);
    }
    /**
     * Return true if all three vector components are zero, i.e. it's their absolute value < <code>epsilon</code>.
     * <p>
     * Implementation uses {@link FloatUtil#isZero(float, float)}, see API doc for details.
     * </p>
     */
    public static boolean isZero(final float x, final float y,
            final float z, final float epsilon) {
        return FloatUtil.isZero(x, epsilon) && FloatUtil.isZero(y, epsilon)
                && FloatUtil.isZero(z, epsilon);
    }
    /**
     * Return the determinant of 3 vectors
     * @param a vector 1
     * @param b vector 2
     * @param c vector 3
     * @return the determinant value
     */
    public static float determinantVec3(final float[] a, final float[] b,
            final float[] c) {
        return a[0] * b[1] * c[2] + a[1] * b[2] * c[0] + a[2] * b[0] * c[1]
                - a[0] * b[2] * c[1] - a[1] * b[0] * c[2] - a[2] * b[1]
                * c[0];
    }
}

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