#ifndef __CHCPLUSPLUSTRAVERSER_H
#define __CHCPLUSPLUSTRAVERSER_H

#include "RenderTraverser.h"


namespace CHCDemoEngine
{

class OcclusionQuery;


/** Class predicting the visiblity of nodes.
*/
class VisibilityPredictor
{
public:
	/** Predicts the probability of a node to stay visible / invisible.
	    The probability could be taken from a measured or analytic function.
	*/
	float GetProbability(BvhNode *node) const 
	{ 
		return 0.98f - 0.68f * exp(-(float)node->GetTimesTestedInvisible()); 
	}
};


/** Class implementing traversal using the CHC++ algorithm.
*/
class CHCPlusPlusTraverser: public RenderTraverser
{
public:
	
	CHCPlusPlusTraverser();

	virtual int GetType() const { return CHCPLUSPLUS;}


protected:
	/** Traverses and renders the scene with the specified method
	*/
	virtual void Traverse();
	/** Queries nodes nodes tested invisible in previous frames.
	*/
	void QueryPreviouslyInvisibleNodes(BvhNode *node);
	/** Computes the next multiquery.
	*/
	OcclusionQuery *GetNextMultiQuery(BvhNodeContainer &iqueue);
	/** Issues batched multiqueries.
	*/
	void IssueMultiQueries();
	/** Handles the result of an occlusion query.
	*/
	void HandleQueryResult(OcclusionQuery *query);


	//////////////

	/// the query queue
	QueryQueue mQueryQueue;

	BvhNodeQueue mVQueue;
	BvhNodeContainer mIQueue;

	VisibilityPredictor mVisibilityPredictor;
};

}



#endif // __CHCPLUSPLUSTRAVERSER_H