vector2f.java

java 3d game jme 工程开发源代码

/*
 * Copyright (c) 2003-2009 jMonkeyEngine
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * 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.
 *
 * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 THE COPYRIGHT OWNER 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.
 */

package com.jme.math;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.logging.Logger;

import com.jme.util.export.InputCapsule;
import com.jme.util.export.JMEExporter;
import com.jme.util.export.JMEImporter;
import com.jme.util.export.OutputCapsule;
import com.jme.util.export.Savable;

/**
 * <code>Vector2f</code> defines a Vector for a two float value vector.
 * 
 * @author Mark Powell
 * @author Joshua Slack
 */
public class Vector2f implements Externalizable, Savable, Cloneable {
    private static final Logger logger = Logger.getLogger(Vector2f.class.getName());

    private static final long serialVersionUID = 1L;
    /**
     * the x value of the vector.
     */
    public float x;
    /**
     * the y value of the vector.
     */
    public float y;

    /**
     * Creates a Vector2f with the given initial x and y values.
     * 
     * @param x
     *            The x value of this Vector2f.
     * @param y
     *            The y value of this Vector2f.
     */
    public Vector2f(float x, float y) {
        this.x = x;
        this.y = y;
    }

    /**
     * Creates a Vector2f with x and y set to 0. Equivalent to Vector2f(0,0).
     */
    public Vector2f() {
        x = y = 0;
    }

    /**
     * Creates a new Vector2f that contains the passed vector's information
     * 
     * @param vector2f
     *            The vector to copy
     */
    public Vector2f(Vector2f vector2f) {
        this.x = vector2f.x;
        this.y = vector2f.y;
    }

    /**
     * set the x and y values of the vector
     * 
     * @param x
     *            the x value of the vector.
     * @param y
     *            the y value of the vector.
     * @return this vector
     */
    public Vector2f set(float x, float y) {
        this.x = x;
        this.y = y;
        return this;
    }

    /**
     * set the x and y values of the vector from another vector
     * 
     * @param vec
     *            the vector to copy from
     * @return this vector
     */
    public Vector2f set(Vector2f vec) {
        this.x = vec.x;
        this.y = vec.y;
        return this;
    }

    /**
     * <code>add</code> adds a provided vector to this vector creating a
     * resultant vector which is returned. If the provided vector is null, null
     * is returned.
     * 
     * @param vec
     *            the vector to add to this.
     * @return the resultant vector.
     */
    public Vector2f add(Vector2f vec) {
        if (null == vec) {
            logger.warning("Provided vector is null, null returned.");
            return null;
        }
        return new Vector2f(x + vec.x, y + vec.y);
    }

    /**
     * <code>addLocal</code> adds a provided vector to this vector internally,
     * and returns a handle to this vector for easy chaining of calls. If the
     * provided vector is null, null is returned.
     * 
     * @param vec
     *            the vector to add to this vector.
     * @return this
     */
    public Vector2f addLocal(Vector2f vec) {
        if (null == vec) {
            logger.warning("Provided vector is null, null returned.");
            return null;
        }
        x += vec.x;
        y += vec.y;
        return this;
    }

    /**
     * <code>addLocal</code> adds the provided values to this vector
     * internally, and returns a handle to this vector for easy chaining of
     * calls.
     * 
     * @param addX
     *            value to add to x
     * @param addY
     *            value to add to y
     * @return this
     */
    public Vector2f addLocal(float addX, float addY) {
        x += addX;
        y += addY;
        return this;
    }

    /**
     * <code>add</code> adds this vector by <code>vec</code> and stores the
     * result in <code>result</code>.
     * 
     * @param vec
     *            The vector to add.
     * @param result
     *            The vector to store the result in.
     * @return The result vector, after adding.
     */
    public Vector2f add(Vector2f vec, Vector2f result) {
        if (null == vec) {
            logger.warning("Provided vector is null, null returned.");
            return null;
        }
        if (result == null)
            result = new Vector2f();
        result.x = x + vec.x;
        result.y = y + vec.y;
        return result;
    }

    /**
     * <code>dot</code> calculates the dot product of this vector with a
     * provided vector. If the provided vector is null, 0 is returned.
     * 
     * @param vec
     *            the vector to dot with this vector.
     * @return the resultant dot product of this vector and a given vector.
     */
    public float dot(Vector2f vec) {
        if (null == vec) {
            logger.warning("Provided vector is null, 0 returned.");
            return 0;
        }
        return x * vec.x + y * vec.y;
    }

    /**
     * <code>cross</code> calculates the cross product of this vector with a
     * parameter vector v.
     * 
     * @param v
     *            the vector to take the cross product of with this.
     * @return the cross product vector.
     */
    public Vector3f cross(Vector2f v) {
        return new Vector3f(0, 0, determinant(v));
    }

    public float determinant(Vector2f v) {
        return (x * v.y) - (y * v.x);
    }
    
    /**
     * Sets this vector to the interpolation by changeAmnt from this to the
     * finalVec this=(1-changeAmnt)*this + changeAmnt * finalVec
     * 
     * @param finalVec
     *            The final vector to interpolate towards
     * @param changeAmnt
     *            An amount between 0.0 - 1.0 representing a percentage change
     *            from this towards finalVec
     */
    public void interpolate(Vector2f finalVec, float changeAmnt) {
        this.x = (1 - changeAmnt) * this.x + changeAmnt * finalVec.x;
        this.y = (1 - changeAmnt) * this.y + changeAmnt * finalVec.y;
    }

    /**
     * Sets this vector to the interpolation by changeAmnt from beginVec to
     * finalVec this=(1-changeAmnt)*beginVec + changeAmnt * finalVec
     * 
     * @param beginVec
     *            The begining vector (delta=0)
     * @param finalVec
     *            The final vector to interpolate towards (delta=1)
     * @param changeAmnt
     *            An amount between 0.0 - 1.0 representing a precentage change
     *            from beginVec towards finalVec
     */
    public void interpolate(Vector2f beginVec, Vector2f finalVec,
            float changeAmnt) {
        this.x = (1 - changeAmnt) * beginVec.x + changeAmnt * finalVec.x;
        this.y = (1 - changeAmnt) * beginVec.y + changeAmnt * finalVec.y;
    }

    /**
     * Check a vector... if it is null or its floats are NaN or infinite, return
     * false. Else return true.
     * 
     * @param vector
     *            the vector to check
     * @return true or false as stated above.
     */
    public static boolean isValidVector(Vector2f vector) {
      if (vector == null) return false;
      if (Float.isNaN(vector.x) ||
          Float.isNaN(vector.y)) return false;
      if (Float.isInfinite(vector.x) ||
          Float.isInfinite(vector.y)) return false;
      return true;
    }

    /**
     * <code>length</code> calculates the magnitude of this vector.
     * 
     * @return the length or magnitude of the vector.
     */
    public float length() {
        return FastMath.sqrt(lengthSquared());
    }

    /**
     * <code>lengthSquared</code> calculates the squared value of the
     * magnitude of the vector.
     * 
     * @return the magnitude squared of the vector.
     */
    public float lengthSquared() {
        return x * x + y * y;
    }

    /**
     * <code>distanceSquared</code> calculates the distance squared between
     * this vector and vector v.
     *
     * @param v the second vector to determine the distance squared.
     * @return the distance squared between the two vectors.
     */
    public float distanceSquared(Vector2f v) {
        double dx = x - v.x;
        double dy = y - v.y;
        return (float) (dx * dx + dy * dy);
    }

    /**
     * <code>distanceSquared</code> calculates the distance squared between
     * this vector and vector v.
     *
     * @param v the second vector to determine the distance squared.
     * @return the distance squared between the two vectors.
     */
    public float distanceSquared(float otherX, float otherY) {
        double dx = x - otherX;
        double dy = y - otherY;
        return (float) (dx * dx + dy * dy);
    }

    /**
     * <code>distance</code> calculates the distance between this vector and
     * vector v.
     *
     * @param v the second vector to determine the distance.
     * @return the distance between the two vectors.
     */
    public float distance(Vector2f v) {
        return FastMath.sqrt(distanceSquared(v));
    }

    /**
     * <code>mult</code> multiplies this vector by a scalar. The resultant
     * vector is returned.
     * 
     * @param scalar
     *            the value to multiply this vector by.
     * @return the new vector.
     */
    public Vector2f mult(float scalar) {
        return new Vector2f(x * scalar, y * scalar);
    }

    /**
     * <code>multLocal</code> multiplies this vector by a scalar internally,
     * and returns a handle to this vector for easy chaining of calls.
     * 
     * @param scalar
     *            the value to multiply this vector by.
     * @return this
     */
    public Vector2f multLocal(float scalar) {
        x *= scalar;
        y *= scalar;
        return this;
    }

    /**
     * <code>multLocal</code> multiplies a provided vector to this vector
     * internally, and returns a handle to this vector for easy chaining of
     * calls. If the provided vector is null, null is returned.
     * 
     * @param vec
     *            the vector to mult to this vector.
     * @return this
     */
    public Vector2f multLocal(Vector2f vec) {
        if (null == vec) {
            logger.warning("Provided vector is null, null returned.");
            return null;
        }
        x *= vec.x;
        y *= vec.y;