// namespaces
var dwv = dwv || {};
dwv.math = dwv.math || {};

/**
 * Immutable 3D vector.
 * @constructor
 * @param {Number} x The X component of the vector.
 * @param {Number} y The Y component of the vector.
 * @param {Number} z The Z component of the vector.
 */
dwv.math.Vector3D = function (x,y,z)
{
    /**
     * Get the X component of the vector.
     * @return {Number} The X component of the vector.
     */
    this.getX = function () { return x; };
    /**
     * Get the Y component of the vector.
     * @return {Number} The Y component of the vector.
     */
    this.getY = function () { return y; };
    /**
     * Get the Z component of the vector.
     * @return {Number} The Z component of the vector.
     */
    this.getZ = function () { return z; };
}; // Vector3D class

/**
 * Check for Vector3D equality.
 * @param {Object} rhs The other vector to compare to.
 * @return {Boolean} True if both vectors are equal.
 */
dwv.math.Vector3D.prototype.equals = function (rhs) {
    return rhs !== null &&
        this.getX() === rhs.getX() &&
        this.getY() === rhs.getY() &&
        this.getZ() === rhs.getZ();
};

/**
 * Get a string representation of the Vector3D.
 * @return {String} The vector as a string.
 */
dwv.math.Vector3D.prototype.toString = function () {
    return "(" + this.getX() +
        ", " + this.getY() +
        ", " + this.getZ() + ")";
};

/**
 * Get the norm of the vector.
  * @return {Number} The norm.
 */
dwv.math.Vector3D.prototype.norm = function () {
    return Math.sqrt( (this.getX() * this.getX()) +
        (this.getY() * this.getY()) +
        (this.getZ() * this.getZ()) );
};

/**
 * Get the cross product with another Vector3D, ie the
 * vector that is perpendicular to both a and b.
 * If both vectors are parallel, the cross product is a zero vector.
 * @param {Object} vector3D The input vector.
  * @return {Object} The result vector.
 */
dwv.math.Vector3D.prototype.crossProduct = function (vector3D) {
    return new dwv.math.Vector3D(
        (this.getY() * vector3D.getZ()) - (vector3D.getY() * this.getZ()),
        (this.getZ() * vector3D.getX()) - (vector3D.getZ() * this.getX()),
        (this.getX() * vector3D.getY()) - (vector3D.getX() * this.getY()) );
};

/**
 * Get the dot product with another Vector3D.
 * @param {Object} vector3D The input vector.
 * @return {Number} The dot product.
 */
dwv.math.Vector3D.prototype.dotProduct = function (vector3D) {
    return (this.getX() * vector3D.getX()) +
        (this.getY() * vector3D.getY()) +
        (this.getZ() * vector3D.getZ());
};