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#ifndef _PagingLandScapeOcclusionSorterH

#define _PagingLandScapeOcclusionSorterH

 

#include "OgrePagingLandScapePrerequisites.h"

#include "OgrePagingLandScapeOcclusionElement.h"

 

namespace Ogre

{

   

    //comparator for priority queue

    class FrontToBackNodeSorterOperator 

    {

 

            public:

                        FrontToBackNodeSorterOperator(const Vector3& position) :   pos(position) {};

                        //-----------------------------------------------------------------------

                    inline bool operator()(OcclusionElement*& a, OcclusionElement*& b) const 

            {

                // could check if both distance == 0 then order visible first// ?

                        return vectorToBoxDistance (*a, pos) > vectorToBoxDistance (*b, pos);

                        }       

                        //-----------------------------------------------------------------------

                        inline bool operator()(const OcclusionElement*& a, const OcclusionElement*& b) const 

                        {

                                // could check if both distance == 0 then order visible first ?

                                return vectorToBoxDistance (*a, pos) > vectorToBoxDistance (*b, pos);

                        }       

                        //-----------------------------------------------------------------------

            Real vectorToBoxDistance(const OcclusionElement &a, const Vector3& point)  const

                {

                const Vector3 &boxMin = a.getCullBoundingBox ().getMinimum ();

                const Vector3 halfSize ((a.getCullBoundingBox ().getMaximum () - boxMin) * 0.5);

                // work in the box's coordinate system

                const Vector3 kDiff (point - (halfSize + boxMin));

                // compute squared distance and closest point on box

                Real fSqrDistance (0.0);

                for (unsigned int i = 0; i < 3; i++)

                {

                    const Real kClosest = kDiff[i];

                    const Real khalfSize = halfSize[i];

                    if (kClosest < -khalfSize)

                    {

                        const Real fDelta = kClosest + khalfSize;

                        fSqrDistance += fDelta * fDelta;

                    }

                    else if (kClosest > khalfSize)

                    {

                        const Real fDelta = kClosest - khalfSize;

                        fSqrDistance += fDelta * fDelta;

                    }

                }

                return fSqrDistance;

            }

 

        private:

                    const Vector3 pos;

    };

}//namespace Ogre

 

#endif //_PagingLandScapeOcclusionSorterH