get Normal Vector - Java java.lang

Java examples for java.lang:Math Vector

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Description

get Normal Vector

Demo Code

/**//from w w w .  j av  a  2s. co m
 * 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.
 *
 *    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
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * 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
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 * The views and conclusions contained in the software and documentation are those of the
 * authors and should not be interpreted as representing official policies, either expressed
 * or implied, of JogAmp Community.
 */
import java.util.ArrayList;

public class Main{
    /**
     * @param result vec2 result for normal
     * @param v1 vec2
     * @param v2 vec2
     * @return result for chaining
     */
    public static float[] getNormalVec2(final float[] result,
            final float[] v1, final float[] v2) {
        subVec2(result, v2, v1);
        final float tmp = result[0];
        result[0] = -result[1];
        result[1] = tmp;
        return normalizeVec2(result);
    }
    /**
     * Subtracts two vectors, result = v1 - v2
     * @param result float[2] result vector, may be either v1 or v2 (in-place)
     * @param v1 vector 1
     * @param v2 vector 2
     * @return result vector for chaining
     */
    public static float[] subVec2(final float[] result, final float[] v1,
            final float[] v2) {
        result[0] = v1[0] - v2[0];
        result[1] = v1[1] - v2[1];
        return result;
    }
    /**
     * Normalize a vector
     * @param result output vector, may be vector (in-place)
     * @param vector input vector
     * @return normalized output vector
     * @return result vector for chaining
     */
    public static float[] normalizeVec2(final float[] result,
            final float[] vector) {
        final float lengthSq = normSquareVec2(vector);
        if (FloatUtil.isZero(lengthSq, FloatUtil.EPSILON)) {
            result[0] = 0f;
            result[1] = 0f;
        } else {
            final float invSqr = 1f / FloatUtil.sqrt(lengthSq);
            result[0] = vector[0] * invSqr;
            result[1] = vector[1] * invSqr;
        }
        return result;
    }
    /**
     * Normalize a vector in place
     * @param vector input vector
     * @return normalized output vector
     */
    public static float[] normalizeVec2(final float[] vector) {
        final float lengthSq = normSquareVec2(vector);
        if (FloatUtil.isZero(lengthSq, FloatUtil.EPSILON)) {
            vector[0] = 0f;
            vector[1] = 0f;
        } else {
            final float invSqr = 1f / FloatUtil.sqrt(lengthSq);
            vector[0] *= invSqr;
            vector[1] *= invSqr;
        }
        return vector;
    }
    /**
     * Return the squared length of a vector, a.k.a the squared <i>norm</i> or squared <i>magnitude</i>
     */
    public static float normSquareVec2(final float[] vec) {
        return vec[0] * vec[0] + vec[1] * vec[1];
    }
    /**
     * Return the squared length of a vector, a.k.a the squared <i>norm</i> or squared <i>magnitude</i>
     */
    public static float normSquareVec2(final float[] vec, final int offset) {
        float v = vec[0 + offset];
        final float r = v * v;
        v = vec[1 + offset];
        return r + v * v;
    }
    /**
     * 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);
    }
}

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