/**
 * Get the position of a DisplayObject relative to another DisplayObject or the stage
 *
 * @param [parent] {DisplayObject} The DisplayObject to calculate the relative position to
 * @param [position] {Point} The position of the precedent DisplayObject in the recursive chain
 * @return {Point} A point object representing the position of this object relative a parent or the stage
 */
PIXI.DisplayObject.prototype.getRelativePosition = function(parent,position){
    var position = position || new PIXI.Point();
    var parent = parent || null;

    position.x += this.x;
    position.y += this.y;

    if(this.parent !== null && this.parent !== parent && this !== parent)
    {
        return this.parent.getRelativePosition(parent,position);
    }

    return position;
};