#ifndef _DistanceQueue_H__
#define _DistanceQueue_H__

#include "OcclusionQuery.h"

#include <queue>

namespace GtpVisibility {

/*  We define HierarchyNode as void * because
	there is no common ancestor for hierarchy nodes in Ogre
*/
typedef void HierarchyNode;

class HierarchyInterface;
/** This class implements the less operator for the priority queue, i.e.,
	a greater distance has a lower priority in the queue.
*/
template <typename T> class GtDistance
{
public:
	GtDistance(HierarchyInterface *hierarchyInterface): mHierarchyInterface(hierarchyInterface)
	{}
	
	bool operator() (const T v1, const T v2) const
	{
		//return false;
		return mHierarchyInterface->GetSquaredDistance(v1) > mHierarchyInterface->GetSquaredDistance(v2);
	}
		
private:
	HierarchyInterface *mHierarchyInterface;
};

/** A priority queue where closer hierarchy nodes are given a higher priority.
*/
typedef std::priority_queue<HierarchyNode *, std::vector<HierarchyNode *>, GtDistance<std::vector<HierarchyNode *>::value_type> > DistanceQueue;

} // namespace GtpVisibility

#endif // DistanceQueue_H