/* 
 * Copyright (c) 2002 Light Weight Java Game Library Project
 * 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 'Light Weight Java Game Library' 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 org.lwjgl.vector;

import org.lwjgl.Math;

/**
 * $Id$
 *
 * Holds a 4-tuple vector.
 * 
 * @author cix_foo <cix_foo@users.sourceforge.net>
 * @version $Revision$
 */

public class Vector4f {

	public float x, y, z, w;

	/**
	 * Constructor for Vector4f.
	 */
	public Vector4f() {
		super();
	}
	
	/**
	 * Constructor
	 */
	public Vector4f(Vector4f src) {
		set(src);
	}
	
	/**
	 * Constructor
	 */
	public Vector4f(float x, float y, float z, float w) {
		set(x, y, z, w);
	}

	/**
	 * Set values
	 * @return this
	 */
	public Vector4f set(float x, float y, float z, float w) {
		this.x = x;
		this.y = y;
		this.z = z;
		this.w = w;
		return this;
	}

	/**
	 * Load from another Vector4f
	 * @param src The source vector
	 * @return this
	 */
	public Vector4f set(Vector4f src) {
		x = src.x;
		y = src.y;
		z = src.z;
		w = src.w;
		return this;
	}
	
	/**
	 * @return the length of the vector
	 */
	public float length() {
		return Math.sqrt(lengthSquared());
	}
	
	/**
	 * @return the length squared of the vector
	 */
	public float lengthSquared() {
		return x * x + y * y + z * z + w * w;
	}
	
	/**
	 * Translate a vector
	 * @param x The translation in x
	 * @param y the translation in y
	 * @return this
	 */
	public Vector4f translate(float x, float y, float z, float w) {
		this.x += x;
		this.y += y;
		this.z += z;
		this.w += w;
		return this;
	}
	
	/**
	 * Negate a vector
	 * @return this
	 */
	public Vector4f negate() {
		x = -x;
		y = -y;
		z = -z;
		w = -w;
		return this;
	}
	
	/**
	 * Normalise this vector
	 * @return this
	 */
	public Vector4f normalise() {
		float l = 1.0f / length();
		x *= l;
		y *= l;
		z *= l;
		w *= l;
		return this;
	}
	
	/**
	 * Normalise this vector and place the result in another vector.
	 * @param dest The destination vector, or null if a new vector is to be created
	 * @return the normalised vector
	 */
	public Vector4f normalise(Vector4f dest) {
		float l = length();
		
		if (dest == null)
			dest = new Vector4f(x / l, y / l, z / l, w / l);
		else
			dest.set(x / l, y / l, z / l, w / l);
		
		return dest;
	}
	
	/**
	 * The dot product of two vectors is calculated as
	 * v1.x * v2.x + v1.y * v2.y + v1.z * v2.z + v1.w * v2.w
	 * @param left The LHS vector
	 * @param right The RHS vector
	 * @return left dot right
	 */
	public static float dot(Vector4f left, Vector4f right) {
		return left.x * right.x + left.y * right.y + left.z * right.z + left.w * right.w;
	}
	
	/**
	 * Calculate the angle between two vectors, in degrees
	 * @param a A vector
	 * @param b The other vector
	 * @return the angle between the two vectors, in degrees
	 */
    public static float angle(Vector4f a, Vector4f b) {
        float dls = dot(a, b) / (a.length() * b.length());
        if (dls < -1f)
            dls = -1f;
        else if (dls > 1.0f)
            dls = 1.0f;
        return Math.acos(dls);
    }
	
}