#ifndef _OcclusionCullingSceneManager_H__
#define _OcclusionCullingSceneManager_H__

#include "OgreSceneNode.h"
#include "OgreSceneManager.h"
#include "OgrePrerequisites.h"
#include <queue>

using namespace std;

namespace Ogre {
	/**
		This class implements the compare operator for the priority queue.
		a lower distance has a higher value in the queue
	*/
	template <typename T> class myless
	{
	public:
		myless(Camera *cam) { mCamera = cam; }
		//bool operator() (HierarchyNode *v1, HierarchyNode *v2) const
		bool operator() (T v1, T v2) const
		{
			return v1->getSquaredViewDepth(mCamera) > v2->getSquaredViewDepth(mCamera);
		}
	private:
		Camera *mCamera;
	};

	typedef priority_queue<SceneNode *, vector<SceneNode *>, myless<vector<SceneNode *>::value_type> > PriorityQueue;

	/**
		Class which implements a scene mangager which uses occlusion queries for culling occluded objects
	*/
	class OcclusionCullingSceneManager : public SceneManager
	{
	public:
		enum {RENDER_CULL_FRUSTUM, RENDER_STOP_AND_WAIT, RENDER_COHERENT, NUM_RENDERMODES};

		OcclusionCullingSceneManager();
	
		/** Overriden from SceneManager. */
		void _renderVisibleObjects(void);
		void _findVisibleObjects(Camera* cam, bool onlyShadowCasters);
	
	protected:

		void renderZPass();
		void traverseNode(SceneNode *node);
		void renderSceneNode(SceneNode *node);
		/** renders the scene with view frustum culling only */
		void renderCullFrustum();

		/** we use a priority queue rather than a renderstack */
		PriorityQueue *mDistanceQueue; 
		// RenderQueue* mDistanceQueue;

		int mFrameID;	
	};

}
#endif // OCCLUSIONCULLINGSCENEMANAGER_H