int _localZOrder;               ///< Local order (relative to its siblings) used to sort the node
float _globalZOrder;            ///< Global order used to sort the node

/**
     LocalZOrder is the ‘key‘ used to sort the node relative to its siblings.

     The Node‘s parent will sort all its children based ont the LocalZOrder value.
     If two nodes have the same LocalZOrder, then the node that was added first to the children‘s array will be in front of the other node in the array.
     
     Also, the Scene Graph is traversed using the "In-Order" tree traversal algorithm ( http://en.wikipedia.org/wiki/Tree_traversal#In-order )
     And Nodes that have LocalZOder values < 0 are the "left" subtree
     While Nodes with LocalZOder >=0 are the "right" subtree.
     
     @see `setGlobalZOrder`
     @see `setVertexZ`
     */
    virtual void setLocalZOrder(int localZOrder);

    CC_DEPRECATED_ATTRIBUTE virtual void setZOrder(int localZOrder) { setLocalZOrder(localZOrder); }
    
    /* Helper function used by `setLocalZOrder`. Don‘t use it unless you know what you are doing.
     */
    CC_DEPRECATED_ATTRIBUTE virtual void _setLocalZOrder(int z);

    /**
     * Gets the local Z order of this node.
     *
     * @see `setLocalZOrder(int)`
     *
     * @return The local (relative to its siblings) Z order.
     */
    virtual int getLocalZOrder() const { return _localZOrder; }
    CC_DEPRECATED_ATTRIBUTE virtual int getZOrder() const { return getLocalZOrder(); }

void Node::setLocalZOrder(int z)
{
    if (_localZOrder == z)
        return;
    
    _localZOrder = z;
    if (_parent)
    {
        _parent->reorderChild(this, z);
    }

    _eventDispatcher->setDirtyForNode(this);
}