#ifndef _OcclusionCullingOctreeSceneTraverser_H__
#define _OcclusionCullingOctreeSceneTraverser_H__

#include "OgreOctree.h"
#include "OgreOcclusionCullingSceneTraverser.h"

using namespace std;

namespace Ogre {
	/**
		This class implements the compare operator for the priority queue
		especially for octree hierarchies using getCullBounds for bounding
		box computation. A lower distance has a higher value in the queue.
	*/
	template <typename T> class octreeless 
	{
	public:
		octreeless(Camera *cam) { mCamera = cam; }
		
		bool operator() (T v1, T v2) const
		{
			AxisAlignedBox box1, box2;
			v1->_getCullBounds(&box1);
			v2->_getCullBounds(&box2);

			return getSquaredViewDepth(mCamera, &box1) > getSquaredViewDepth(mCamera, &box2);
		}

	private:
		Real getSquaredViewDepth(const Ogre::Camera* cam, const Ogre::AxisAlignedBox* box) const
		{
			Vector3 mid  = ((box->getMinimum() - box->getMaximum()) * 0.5) + box->getMinimum();
			return (cam->getDerivedPosition() - mid).squaredLength();                                                                   
		}

		Camera *mCamera;
		//AxisAlignedBox mBox1, mBox2;
		//Ogre::Vector3 min, max, mid, dist;
	};

	typedef pair<Octree *, HardwareOcclusionQuery *> OctreeQueryPair;
	typedef priority_queue<Octree *, vector<Octree *>, octreeless<vector<Octree *>::value_type> > OctreePriorityQueue;
	typedef queue<OctreeQueryPair> OctreeQueryQueue;

	class OcclusionCullingOctreeSceneTraverser: public OcclusionCullingSceneTraverser
	{
	public:
		OcclusionCullingOctreeSceneTraverser(SceneManager *sm, RenderSystem *rsys);
		~OcclusionCullingOctreeSceneTraverser();
		//void renderScene( Camera *cam );
		void setSceneRoot(Octree *root);
		/** Sets the number of nodes in this octree 
		@remark do not confuse this with the OctreeNode class 
		which is derived from SceneNode
		@param num number of nodes in the octree
		*/
		void setNumOctreeNodes( unsigned int num );
	
		/** Gets the given option for the scene traverser.
	        @remarks
		    See setOption
		*/
		bool getOption( const String &, void * );
		bool getOptionKeys( StringVector &refKeys );
		
	protected:
		/** Renders the scene with view frustum culling only. */
		void renderCullFrustum( Camera *cam );
		/** Renders the scene with the hierarchical stop and wait algorithm. */
		void renderStopAndWait( Camera *cam );
		/** Renders the scene with the coherent hierarchical algorithm and the query queye. */
		void renderCoherentWithQueue( Camera *cam );
		/** Issue a occlusion query for this node. */
		
		void initDistanceQueue(Camera *cam);
		void pullUpVisibility(Octree *octree);
		void traverseOctant(Camera *cam, Octree *octant);
		void renderOctant(Camera *cam, Octree *octant);
		bool isLeaf(Octree *octant);

	private:
		OctreePriorityQueue *mOctreeDistanceQueue;
		// the octree root
		Octree *mOctreeSceneRoot;

		unsigned int mNumOctreeNodes;
	};

}
#endif // OcclusionCullingOctreeSceneTraverser_H