Time based animation

/**
 * All scene graph nodes will be derived from this class.
 */
class ISceneGraphNode	:	public IMBase
{
protected:

	util::list<ISceneGraphNode*> m_childList;	///< Holds all the child nodes of this node
	scene::ISceneManager* m_sceneManager;		///< Pointer to the scene manager for rendering and other

public:

	/**
	 * Constructor
	 * \param smgr A pointer to the scene manager
	 */
	ISceneGraphNode(scene::ISceneManager* smgr)
		:	m_sceneManager(smgr)
	{
		// We are not calling smgr->get() because we want the graph to be destroyed when
		// smgr->drop() is called.
	}

	/**
	 * Copy constructor
	 * \param i A const reference to an object derived from ISceneGraphNode
	 */
	ISceneGraphNode(const ISceneGraphNode& i)
		:	m_sceneManager(i.m_sceneManager)
	{
		// We are not calling smgr->get() because we want the graph to be destroyed when
		// smgr->drop() is called.
	}

	/**
	 * Destructor
	 */
	virtual ~ISceneGraphNode()
	{
		util::list<ISceneGraphNode*>::iterator i = m_childList.begin();

		for( ; i != m_childList.end() ; i++)
			(*i)->drop();	// reduce the ref_count for all child nodes

		m_sceneManager->drop();
	}

	/**
	 * Add a node to the child list.
	 * \param n A pointer to a ISceneGraphNode derived object
	 */
	void addSceneGraphNode(scene::ISceneGraphNode* n)
	{
		m_childList.push_back( n );		// add n to the list
	}

	/**
	 * Render all the child nodes.
	 */
	virtual void render()
	{
		util::list<ISceneGraphNode*>::iterator i = m_childList.begin();

		for( ; i != m_childList.end(); i++)
			(*i)->render();	// render child node
	}

	/**
	 * Things to do before rendering, like updating.
	 * \param delta_time The time (in seconds) since the last rendering frame
	 */
	virtual void preRender(float delta_time)
	{
		util::list<ISceneGraphNode*>::iterator i = m_childList.begin();

		for( ; i != m_childList.end(); i++)
			(*i)->preRender(delta_time);	// render child node

	}

	/**
	 * Things to do after rendering.
	 * \param delta_time The time (in seconds) since the last rendering frame
	 */
	virtual void postRender(float delta_time)
	{
		util::list<ISceneGraphNode*>::iterator i = m_childList.begin();

		for( ; i != m_childList.end(); i++)
			(*i)->postRender(delta_time);	// render child node

	}

};

/**
 * Render all objects in the scene graph.
 */
void CSceneGraph::render()
{
	util::list<ISceneGraphNode*>::iterator i = m_nodeList.begin();

	for( ; i != m_nodeList.end(); i++){
		(*i)->preRender( m_hiResTimer.getElapsedSeconds() );
		(*i)->render();
		(*i)->postRender( m_hiResTimer.getElapsedSeconds() );
	}
}

/**
 * Update the animation.
 * \param delta_time The time since the last update.
 */
void update(float delta_time)
{
	m_modelTime += delta_time;
	if ( m_modelTime >= 1.0f / MD2AnimationList[m_animState].fps )
		m_modelTime = 0.0f;

	updateInterpolation( m_modelTime / ( 1.0f / MD2AnimationList[m_animState].fps ) );
}

/**
 * Pre-render things, like updating the animation.
 */
void preRender(float delta_time)
{
	update(delta_time);	// updates the animation

	ISceneGraphNode::preRender(delta_time);
}

/**
 * Render the model using indexed vertex arrays.
 */
void render()
{
	if(m_texture)
		m_texture->apply();	// apply the texture

	// draw the indexed triangle list
	m_sceneManager->getVideoDriver()->drawIndexedTriangleList(
				m_displayVertexList.getPtr(), m_displayVertexList.getSize(),
				m_displayIndexList.getPtr(), m_displayIndexList.getSize() );

	ISceneGraphNode::render();	// render all the children
}