source: GTP/trunk/Lib/Vis/Preprocessing/src/ViewCellsManager.h @ 1121

#ifndef _ViewCellsManager_H__
#define _ViewCellsManager_H__

#include "Ray.h"
#include "VssRay.h"
#include "Containers.h"
#include "ViewCell.h"
#include "ViewCellBsp.h"

namespace GtpVisibilityPreprocessor {

class ViewCell;
class Intersectable;
class RenderSimulator;
class Renderer;
class Mesh;
struct Triangle3;
class SimulationStatistics;
class BspTree;
class KdTree;
class VspOspTree;
class VspBspTree;
class KdNode;
class KdLeaf;
class AxisAlignedBox3;
class BspLeaf;
class ViewCellsStatistics;
class Exporter;
class Beam;
class Preprocessor;
class ViewCellsTree;
class MergeCandidate;
class BoundingBoxConverter;
class VspTree;
class OspTree;
class VspNode;
class HierarchyManager;
struct AxisAlignedPlane;

struct BspRay;


/** Probably Visible Set */
class PrVs 
{
public:
  /// root of view cells tree
  ViewCell *mViewCell;

  // input parameter is the render budget for the PrVs
  float mRenderBudget;

  /// some characteristic values could be here
  
};


/**     Manages different higher order operations on the view cells.
*/
class ViewCellsManager
{
public:
        struct PvsStatistics 
        {
                int minPvs;
                int maxPvs;
                float avgPvs;
                int viewcells;
  };

        /// view cell container types
        enum {BSP, KD, VSP_KD, VSP_BSP, VSP_OSP};
  
        /// render cost evaluation type
        enum {PER_OBJECT, PER_TRIANGLE};

        /** Default constructor.
        */
        ViewCellsManager();

        virtual ~ViewCellsManager();

        /** Constructs view cells container taking a preprocessor
                @returns the output rays (if not null)
        */ 
        int Construct(Preprocessor *preprocessor, VssRayContainer *outRays = NULL);

        /** Constructs view cell container with a given number of samples.
        */
        virtual int ConstructSubdivision(const ObjectContainer &objects, 
                                                  const VssRayContainer &rays) = 0;

        /** Computes sample contributions of the rays to the view cells PVS.
        
                @param rays bundle of rays used to find intersections with view cells and 
                adding the contribution
                @param addRays true if rays should be added to the PVSs of the viewcells they
                intersect 
                @param storeViewCells true if view cells should be stored in the ray
        */
        float ComputeSampleContributions(const VssRayContainer &rays,
                                                                   const bool addContributions,
                                                                   const bool storeViewCells);

        /** Add sample contributions to the viewcells they intersect */
        void AddSampleContributions(const VssRayContainer &rays);
  

        /** Computes sample contribution of a simgle ray to the view cells PVS.
                @param ray finds intersections with view cells and holds the contribution
                @param castRay true if ray should be cast to gain the information, false if ray
                is already holding the information and need not be recast.
          
                @returns number of sample contributions
        */
        virtual float ComputeSampleContributions(VssRay &ray, 
                                                                                         const bool addRays, 
                                                                                         const bool storeViewCells);

        virtual void AddSampleContributions(VssRay &ray);

        /** Prints out statistics of the view cells.
        */
        virtual void PrintStatistics(ostream &s) const;

        /** Post processes view cells givemŽa number of rays.
        */
        virtual int PostProcess(const ObjectContainer &objects, 
                                                        const VssRayContainer &rays) = 0;

        /** Show visualization of the view cells.
        */
        virtual void Visualize(const ObjectContainer &objects,
                                                   const VssRayContainer &sampleRays) = 0;

        /** type of the view cell container.
        */
        virtual int GetType() const = 0;

        /** Load the input viewcells. The input viewcells should be given as a collection
                of meshes. Each mesh is assume to form a bounded polyhedron defining the interior of
                the viewcell. The method then builds a BSP tree of these view cells.
                
                @param filename file to load
                @return true on success
    */
    virtual bool LoadViewCellsGeometry(const string filename);

        
        /** Constructs view cell from base triangle. The ViewCell is extruded along the normal vector.
                @param the base triangle
                @param the height of the newly created view cell
        */
        ViewCell *ExtrudeViewCell(const Triangle3 &baseTri, const float height) const;

        /** Merges two view cells.
                @note the piercing rays of the front and back will be ordered   
                @returns new view cell based on the merging.
        */
        ViewCellInterior *MergeViewCells(ViewCell *front, ViewCell *back) const;

        /** Merges a container of view cells.
                @returns new view cell based on the merging.
        */
        ViewCellInterior *MergeViewCells(ViewCellContainer &children) const;
        
        /** Generates view cell of type specified by this manager
        */
        virtual ViewCell *GenerateViewCell(Mesh *mesh = NULL) const = 0;

        /** Adds a new view cell to the list of predefined view cells.
        */
        void AddViewCell(ViewCell *viewCell);

        /** Derive view cells from scene objects. The view ells are created by taking the object
                geometry into account.
        */
        void DeriveViewCellsFromObjects(const ObjectContainer &objects, 
                                                                        ViewCellContainer &viewCells, 
                                                                        const int maxViewCells) const;

        /** Sets maximal number of samples used for the 
                construction of the view cells.
        */
        void SetVisualizationSamples(const int visSamples);

        /** Sets maximal number of samples used for the construction of the view cells.
        */
        void SetConstructionSamples(const int constructionSamples);

        /** Sets maximal number of samples used for the visualization of the view cells.
        */
        void SetInitialSamples(const int initialSamples);

        /** Sets maximal number of samples used for the post processing of the view cells.
        */
        void SetPostProcessSamples(const int postProcessingSamples);

        /** See set.
        */
        int GetVisualizationSamples() const;

        /** See set.
        */
        int GetConstructionSamples() const;

        /** See set.
        */
        int GetPostProcessSamples() const;

        /** Returns true if view cells are already constructed.
        */
        virtual bool ViewCellsConstructed() const = 0;

        /** cast line segment to get a list of unique viewcells which are intersected
                by this line segment 
        */
  
        virtual int CastLineSegment(const Vector3 &origin,
                                                          const Vector3 &termination,
                                                          ViewCellContainer &viewcells
                                                          ) = 0;

        virtual void GetPvsStatistics(PvsStatistics &stat);

        virtual void GetPrVS(const Vector3 &viewPoint, PrVs &prvs, const float filterWidth);
  
        /** Get a viewcell containing the specified point 
                @param active if the active or elementary view cell should be returned.
        */
        virtual ViewCell *GetViewCell(const Vector3 &point, const bool active = false) const = 0;
  
        virtual void PrintPvsStatistics(ostream &s);

        /** Updates pvs of the view cell hierarchy if necessary.
        */
        void UpdatePvs();

        /** Returns probability that view point lies in one view cell.
        */
        virtual float GetProbability(ViewCell *viewCell) = 0;

        /** Returns render cost of a single view cell given the render cost of an object.
        */
        float GetRendercost(ViewCell *viewCell) const;

        /** Returns reference to container of loaded / generated view cells.
        */
        ViewCellContainer &GetViewCells();

        /** Helper function used to split ray sets uniformly 
                into one that is currently used and the other that 
                is saved for later processing.
                @param sourceRays the input ray set
                @param maxSize the maximal number of rays that will be used
                @param usedRays returns the used ray set
                @param savedRays if not null, returns the saved ray set
        */
        void GetRaySets(const VssRayContainer &sourceRays,
                                        const int maxSize,
                                        VssRayContainer &usedRays, 
                                        VssRayContainer *savedRays = NULL) const;
        
        /** Returns accumulated area of all view cells.
        */
        float GetAccVcArea();

        /** Returns area of one view cell.
        */
        virtual float GetArea(ViewCell *viewCell) const;

        /** Returns volume of view cell.
        */
        virtual float GetVolume(ViewCell *viewCell) const;

        /** Sets the current renderer mainly for view cells statistics.
        */
        void SetRenderer(Renderer *renderer);

        /** Computes a (random) view point in the valid view space.
                @returns true if valid view point was found
        */
        virtual bool GetViewPoint(Vector3 &viewPoint) const;

        /** Returns true if this view point is in the valid view space.
        */
        virtual bool ViewPointValid(const Vector3 &viewPoint) const;

        /** Sets a view space boundary.
        */
        void SetViewSpaceBox(const AxisAlignedBox3 &box);

        AxisAlignedBox3 GetViewSpaceBox() const;

        /** Creates mesh for this view cell.
        */
        virtual void CreateMesh(ViewCell *vc) = NULL;

        /** Writes view cells to disc.
        */
        virtual bool ExportViewCells(const string filename, 
                                                                 const bool exportPvs, 
                                                                 const ObjectContainer &objects);

        /** Casts beam to collect view cells.
        */
        virtual int CastBeam(Beam &beam);

        /** Checks if view cell is considered as valid.
        */
        virtual bool CheckValidity(ViewCell *vc, 
                                                           int minPvsSize, 
                                                           int maxPvsSize) const;

        
        /** Sets validity of view cell
        */
        virtual void SetValidity(ViewCell *vc, 
                                                         int minPvsSize, 
                                                         int maxPvsSize) const;

        /** sets validy of all viewcells 
        */
        virtual void SetValidity(int minPvsSize, 
                                                         int maxPvsSize) const;


        /** set valid viewcells in the range of pvs. sorts the viewcells
          according to the pvs and then pickups those in the ranges 
          */
        void SetValidityPercentage(const float minValid, const float maxValid);

    int CountValidViewcells() const;

        /** Returns maximal allowed pvs size.
        */
        int GetMaxPvsSize() const;

        /** Returns maximal allowed pvs size.
        */
        int GetMinPvsSize() const;

        /** Returns maximal ratio. i.e., currentPVs / maxPvs,
                where pvs is still considered valid.
        */
        float GetMaxPvsRatio() const;

        /** Exports view cell geometry.
        */
        virtual void ExportViewCellGeometry(Exporter *exporter, 
                                                                                ViewCell *vc,
                                                                                const AxisAlignedPlane *clipPlane = NULL) const = 0;

        /** Brings the view cells into their final state, computes meshes and volume.
        */
        virtual void FinalizeViewCells(const bool createMesh);

        /** Evaluates statistics values on view cells.
        */
        void EvaluateRenderStatistics(float &totalRenderCost,
                                                                  float &expectedRenderCost,
                                                                  float &deviation,
                                                                  float &variance,
                                                                  int &totalPvs,
                                                                  float &avgRenderCost);


        /** Returns hierarchy of the view cells.
        */
        ViewCellsTree *GetViewCellsTree();

        virtual void CollectMergeCandidates(const VssRayContainer &rays, 
                                                                                vector<MergeCandidate> &candidates);

        void CollectViewCells(const int n);

        /** Sets current view cells set to active, i.e., the sampling is done in this view cell set.
        */
        void SetViewCellsActive();

        /** Evaluates worth of current view cell hierarchy.
        */
        void EvalViewCellPartition(Preprocessor *preprocessor);

        /** Sets maximal size of a view cell filter.
        */
        void SetMaxFilterSize(const int size);

        /** Returns maximal filter size.
        */
        int GetMaxFilterSize() const;

        /** Deletes interior nodes from the tree which have negative merge cost set (local merge).
        */  
        void DeleteLocalMergeTree(ViewCell *vc) const;
  
        /** Evaluautes histogram for a given number of view cells.
        */
        void EvalViewCellHistogram(const string filename, const int nViewCells);

        /** Evaluautes histogram for a given number of view cells.
        */
        void EvalViewCellHistogramForPvsSize(const string filename, const int nViewCells);

        /** Evaluates the render cost of a view cell.
        */
        float EvalRenderCost(Intersectable *obj) const;
   
        /** Sets pvs size of view cell as a scalar. Used when storing pvs only in the leaves
                of the hierarchy.
        */
        void SetScalarPvsSize(ViewCell *vc, const int pvsSize) const;


        /** Returns bounding box of a view cell.
        */
        AxisAlignedBox3 GetViewCellBox(ViewCell *vc);

        /** Exports bounding boxes of objects to file.
        */
        bool ExportBoundingBoxes(const string filename, const ObjectContainer &objects) const;
    
        /** Load the bounding boxes into the container.
        */
        bool LoadBoundingBoxes(const string filename, IndexedBoundingBoxContainer &boxes) const;

        /** Returns true if pvs should be exported together with the view cells.
        */
        bool GetExportPvs() const;

        /** Loads view cells from file. The view cells manager is created with 
                respect to the loaded view cells.

                @param filename the filename of the view cells
                @param objects the scene objects
                @param finalizeViewCells if the view cells should be post processed, i.e.
                        a mesh is created representing the geometry
                @param bconverter a conversion routine working with the similarities of bounding
                boxes: if there is a certain similarity of overlap between bounding boxes, two tested
                candidate objects are considered to be the same objects
                @returns the view cells manager if loading was successful, false otherwise
        */
        static ViewCellsManager *LoadViewCells(const string &filename, 
                                                                                   ObjectContainer *objects, 
                                                                                   const bool finalizeViewCells,
                                                                                   BoundingBoxConverter *bconverter = NULL);


        ////////////////////////////////////////////////////////7
        // visiblity filter options
        // TODO: write own visibiltiy filter class
        void ApplyFilter(KdTree *kdTree,
                                         const float viewSpaceFilterSize,
                                         const float spatialFilterSize);

        void ApplySpatialFilter(KdTree *kdTree,
                                                        const float spatialFilterSize,
                                                        ObjectPvs &pvs);

         void ApplyFilter(ViewCell *viewCell,
                                          KdTree *kdTree,
                                          const float viewSpaceFilterSize,
                                          const float spatialFilterSize,
                                          ObjectPvs &pvs);

        float GetFilterWidth();

        float GetAbsFilterWidth();

        
        /** Returns the bounding box of filter width.
        */
        AxisAlignedBox3 GetFilterBBox(const Vector3 &viewPoint, const float width) const;


        /** Returns true if this view cell is equivalent to a node of the spatial hierarchy.
        */
        virtual bool EqualToSpatialNode(ViewCell *viewCell) const;

protected:
        /** Exports bounding boxes as xml stream
        */
        //bool ExportBoundingBoxes(ofstream &xmlstream, const ObjectContainer &objects) const;

        /** Intersects box with the tree and returns the number of intersected boxes.
                @returns number of view cells found
        */
        virtual int ComputeBoxIntersections(const AxisAlignedBox3 &box, 
                                                                                ViewCellContainer &viewCells) const;

        /** Tests the visibility filter functionality.
        */
        virtual void TestFilter(const ObjectContainer &objects) {};

        /** If the view cells tree was already constructed or not.
        */
        bool ViewCellsTreeConstructed() const;

        int CastPassSamples(const int samplesPerPass, 
                                                const int sampleType, 
                                                VssRayContainer &vssRays) const;

        /** Parse the options from the environment file.
        */
        void ParseEnvironment();

        /** Creates unique view cell ids.
        */
        void CreateUniqueViewCellIds();

        /** Finalizes, i.e., creates mesh, volume, area etc. for the view cell.
        */
        virtual void Finalize(ViewCell *viewCell, const bool createMesh);

        /** Recollects view cells and resets statistics.
        */
        void ResetViewCells();
        
        /** Collects the view cells in the view cell container.
        */
        virtual void CollectViewCells() = 0;
        
        /** Evaluates view cells statistics and stores it in
                mViewCellsStatistics.
        */
        void EvaluateViewCellsStats();

        //-- helper functions for view cell visualization

        /** Exports the view cell partition.
        */
        void ExportViewCellsForViz(Exporter *exporter) const;

        /** Sets exporter color.
        */
        virtual void ExportColor(Exporter *exporter, ViewCell *vc) const;

        /** Returns volume of the view space.
        */
        virtual float GetViewSpaceVolume();
        
        /** Creates meshes from the view cells.
        */
        void CreateViewCellMeshes();

        /** Takes different measures to prepares the view cells after loading them from disc.
        */
        virtual void PrepareLoadedViewCells() {};

        /** Constructs local view cell merge hierarchy.
        */
        ViewCell *ConstructLocalMergeTree(ViewCell *currentViewCell, 
                                                                          const ViewCellContainer &viewCells);

        /** Constructs local view cell merge hierarchy based solely on similarity with the
                current viewcell
        */
        ViewCell *ConstructLocalMergeTree2(ViewCell *currentViewCell, 
                                                                           const ViewCellContainer &viewCells);
  
        /** Creates clip plane for visualization.
        */
        void CreateClipPlane();

        /** Updates pvs of all view cells for statistical evaluation after some more sampling
        */
        virtual void UpdatePvsForEvaluation(ViewCell *root, ObjectPvs &pvs) = 0;

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

        /// if bounding boxes should also be exported
        bool mExportBboxesForPvs;
                
        //Environment *environment;
        AxisAlignedPlane mClipPlane;

        bool mUseClipPlaneForViz;


        /// Renders the view cells.
        Renderer *mRenderer;

        /// Loaded view cells
        ViewCellContainer mViewCells;
        /// the corresponding view cell tree holding the logical description of view cells
        ViewCellsTree *mViewCellsTree;
        /// if empty view cells should be pruned (i.e., invalidated) from this point on
        bool mPruneEmptyViewCells;

        /// if the pvss in the view cell leaves and the interiors are up to date
        bool mViewCellPvsIsUpdated;

        /// maximum number of samples taken for construction of the view cells
        int mConstructionSamples;
        int mSamplesPerPass;
        int mInitialSamples;
        int mPostProcessSamples;
        int mVisualizationSamples;

        float mTotalAreaValid;
        float mTotalArea;

        int mMaxPvsSize;
        int mMinPvsSize;
        float mMaxPvsRatio;

        int mSamplingType;
        int mEvaluationSamplingType;
        int mNumActiveViewCells;
        bool mCompressViewCells;

        /// holds the current view cell statistics
        ViewCellsStatistics mCurrentViewCellsStats;
        /// the scene bounding box
        AxisAlignedBox3 mViewSpaceBox;
        
        /// if view cells should be exported
        bool mExportViewCells;

        // if only valid view cells should be considered for processing
        bool mOnlyValidViewCells;

        /// if rays should be used to collect merge candidates
        bool mUseRaysForMerge;

        /// if there should be an additional merge step after the subdivision
        bool mMergeViewCells;

        /// the width of the box filter
        float mFilterWidth;
        int mMaxFilterSize;

        //-- visualization options
        
        /// color code for view cells visualization
        int mColorCode;
        bool mExportGeometry;
        bool mExportRays;

        bool mViewCellsFinished;

        bool mEvaluateViewCells;

        bool mShowVisualization;

        // HACK in order to detect empty view cells
        void CollectEmptyViewCells();
        void TestEmptyViewCells(const ObjectContainer &obj);

        ViewCellContainer mEmptyViewCells;

        int mRenderCostEvaluationType;

        /// if pvs should be exported with view cells
        bool mExportPvs;

        bool mCountKdPvs;
};


/**
        Manages different higher order operations on the view cells.
*/
class BspViewCellsManager: public ViewCellsManager
{

public:
        /** Constructor taking the bsp tree and the number of samples
                used to construct the bsp tree.
        */
        BspViewCellsManager(BspTree *tree);

        ~BspViewCellsManager();

        int ConstructSubdivision(const ObjectContainer &objects, 
                                  const VssRayContainer &rays);

        int PostProcess(const ObjectContainer &objects, 
                                        const VssRayContainer &rays);

        void Visualize(const ObjectContainer &objects,
                                   const VssRayContainer &sampleRays);

        int GetType() const;
        
        ViewCell *GenerateViewCell(Mesh *mesh = NULL) const;

        bool ViewCellsConstructed() const;

        //void PrintStatistics(ostream &s) const;

        int CastLineSegment(const Vector3 &origin,
                                                const Vector3 &termination,
                                                ViewCellContainer &viewcells);
        
        float GetProbability(ViewCell *viewCell);
        

        /** Get a viewcell containing the specified point 
        */
        ViewCell *GetViewCell(const Vector3 &point, const bool active = false) const;

        void CreateMesh(ViewCell *vc);

        void ExportViewCellGeometry(Exporter *exporter, 
                                                                ViewCell *vc, 
                                                                const AxisAlignedPlane *clipPlane = NULL) const;
        
        void CollectMergeCandidates(const VssRayContainer &rays, 
                                                                vector<MergeCandidate> &candidates);

        void Finalize(ViewCell *viewCell, const bool createMesh);

        bool ExportViewCells(const string filename, const bool exportPvs, const ObjectContainer &objects);

        /** Constructs merge hierarchy which corresponds to the spatial hierarchy.
        */
        ViewCell *ConstructSpatialMergeTree(BspNode *root);

        /** Updates the pvs in the view cells tree.
        */
        void UpdatePvsForEvaluation(ViewCell *root, ObjectPvs &pvs);


protected:

        void CollectViewCells();

        
        /// the BSP tree.
        BspTree *mBspTree;
        
        vector<BspRay *> mBspRays;

private:

        /** Exports visualization of the BSP splits.
        */
        void ExportSplits(const ObjectContainer &objects);

        /** Exports visualization of the BSP PVS.
        */
        void ExportBspPvs(const ObjectContainer &objects);

        /** test if subdivision is valid in terms of volume / area.
        */
        void TestSubdivision();
};

/**
        Manages different higher order operations on the KD type view cells.
*/
class KdViewCellsManager: public ViewCellsManager
{

public:

        KdViewCellsManager(KdTree *tree);

        int ConstructSubdivision(const ObjectContainer &objects, 
                                  const VssRayContainer &rays);

        int CastLineSegment(const Vector3 &origin,
                                                const Vector3 &termination,
                                                ViewCellContainer &viewcells);

        int PostProcess(const ObjectContainer &objects, 
                                        const VssRayContainer &rays);

        void Visualize(const ObjectContainer &objects,
                                   const VssRayContainer &sampleRays);

        int GetType() const;

        bool ViewCellsConstructed() const;

        ViewCell *GenerateViewCell(Mesh *mesh) const;

        /** Prints out statistics of this approach.
        */
        //  virtual void PrintStatistics(ostream &s) const;
        ViewCell *GetViewCell(const Vector3 &point, const bool active = false) const { return NULL; }

        float GetProbability(ViewCell *viewCell);
        

        void CreateMesh(ViewCell *vc);

        void ExportViewCellGeometry(Exporter *exporter, 
                                                                ViewCell *vc,
                                                                const AxisAlignedPlane *clipPlane = NULL) const;

        void CollectMergeCandidates(const VssRayContainer &rays, 
                                                                vector<MergeCandidate> &candidates);


protected:

        virtual void UpdatePvsForEvaluation(ViewCell *root, ObjectPvs &pvs) {};
        /** Collects view cells from a hierarchy.
        */
        void CollectViewCells();

        KdNode *GetNodeForPvs(KdLeaf *leaf);


        /// the BSP tree.
        KdTree *mKdTree;

        /// depth of the KD tree nodes with represent the view cells
        int mKdPvsDepth;


};

/**
        Manages different higher order operations on the view cells.
*/
class VspBspViewCellsManager: public ViewCellsManager
{

public:

        VspBspViewCellsManager(VspBspTree *tree);
        ~VspBspViewCellsManager();

        int ConstructSubdivision(const ObjectContainer &objects, 
                                  const VssRayContainer &rays);

        int PostProcess(const ObjectContainer &objects, 
                                        const VssRayContainer &rays);

        void Visualize(const ObjectContainer &objects,
                                   const VssRayContainer &sampleRays);

        int GetType() const;
        
        ViewCell *GenerateViewCell(Mesh *mesh = NULL) const;

        bool ViewCellsConstructed() const;

        
        int CastLineSegment(const Vector3 &origin,
                                                const Vector3 &termination,
                                                ViewCellContainer &viewcells);

        float GetProbability(ViewCell *viewCell);
        
        ViewCell *GetViewCell(const Vector3 &point, const bool active = false) const;

        bool GetViewPoint(Vector3 &viewPoint) const;

        bool ViewPointValid(const Vector3 &viewPoint) const;

        void CreateMesh(ViewCell *vc);

        bool ExportViewCells(const string filename, const bool exportPvs, const ObjectContainer &objects);

        int CastBeam(Beam &beam);

        void ExportViewCellGeometry(Exporter *exporter, 
                                                                ViewCell *vc,
                                                                const AxisAlignedPlane *clipPlane = NULL) const;

        //float GetVolume(ViewCell *viewCell) const;

        void Finalize(ViewCell *viewCell, const bool createMesh);

        void CollectMergeCandidates(const VssRayContainer &rays, vector<MergeCandidate> &candidates);

        /** Returns true if this view cell is equivavalent to a spatial node.
        */
        bool EqualToSpatialNode(ViewCell *viewCell) const;


protected:

        int ComputeBoxIntersections(const AxisAlignedBox3 &box, ViewCellContainer &viewCells) const;
        
        /** Returns node of the spatial hierarchy corresponding to the view cell
                if such a node exists.
        */
        BspNode *GetSpatialNode(ViewCell *viewCell) const;

        /** Merges view cells according to some criteria
        */
        void MergeViewCells(const VssRayContainer &rays, 
                                                const ObjectContainer &objects);
        
        void RefineViewCells(const VssRayContainer &rays, const ObjectContainer &objects);

        void CollectViewCells();

        /** Returns maximal depth difference of view cell 
                leaves in tree.
        */
        int GetMaxTreeDiff(ViewCell *vc) const;
        

        /** Prepare view cells for use after loading them from disc.
        */
        void PrepareLoadedViewCells();

        /** Constructs merge hierarchy which corresponds to the spatial hierarchy.
        */
        ViewCell *ConstructSpatialMergeTree(BspNode *root);

        void UpdatePvsForEvaluation(ViewCell *root, ObjectPvs &pvs);


        /// HACK for testing visibility filter functionality
        void TestFilter(const ObjectContainer &objects);


        /** Visualization of the pvs difference to exact visubility using 
                from point queries.
        */
        void VisualizeWithFromPointQueries();

        /** Evaluate from point queries for the current scene.
        */
        void EvalFromPointQueries();

        /** Exports visualization of the BSP splits.
        */
        void ExportSplits(const ObjectContainer &objects, 
                                          const VssRayContainer &rays);

        /** Exports visualization of the BSP PVS.
        */
        void ExportBspPvs(const ObjectContainer &objects,
                                          const VssRayContainer &rays);


        /// the view space partition BSP tree.
        VspBspTree *mVspBspTree;


private:

        /** test if subdivision is valid in terms of volume / area.
        */
        void TestSubdivision();
};


/**
        Manages different higher order operations on the view cells.
*/
class VspOspViewCellsManager: public ViewCellsManager
{

public:

        VspOspViewCellsManager(VspTree *tree, OspTree *ospTree);
        ~VspOspViewCellsManager();

        int ConstructSubdivision(const ObjectContainer &objects,
                                                         const VssRayContainer &rays);

        int PostProcess(const ObjectContainer &objects, 
                                        const VssRayContainer &rays);

        void Visualize(const ObjectContainer &objects,
                                   const VssRayContainer &sampleRays);

        int GetType() const;
        
        ViewCell *GenerateViewCell(Mesh *mesh = NULL) const;

        bool ViewCellsConstructed() const;

        
        int CastLineSegment(const Vector3 &origin,
                                                const Vector3 &termination,
                                                ViewCellContainer &viewcells);

        float GetProbability(ViewCell *viewCell);
        
        ViewCell *GetViewCell(const Vector3 &point, const bool active = false) const;

        bool GetViewPoint(Vector3 &viewPoint) const;

        bool ViewPointValid(const Vector3 &viewPoint) const;

        void CreateMesh(ViewCell *vc);

        bool ExportViewCells(const string filename, 
                                                 const bool exportPvs, 
                                                 const ObjectContainer &objects);

        int CastBeam(Beam &beam);

        void Finalize(ViewCell *viewCell, const bool createMesh);


protected:

        
        /** Exports view cell geometry.
        */
        void ExportViewCellGeometry(Exporter *exporter, 
                ViewCell *vc,
                const AxisAlignedPlane *clipPlane = NULL) const;

        int ComputeBoxIntersections(const AxisAlignedBox3 &box, 
                ViewCellContainer &viewCells) const;
        
        void CollectViewCells();


        /** Prepare view cells for use after loading them from disc.
        */
        void PrepareLoadedViewCells();

        /** Constructs merge hierarchy which corresponds to the spatial hierarchy.
        */
        ViewCell *ConstructSpatialMergeTree(VspNode *root);

        void UpdatePvsForEvaluation(ViewCell *root, ObjectPvs &pvs);

        /** Exports visualization of the PVS.
        */
        void ExportPvs(const ObjectContainer &objects,
                const VssRayContainer &rays);


        /// the view space partition tree.
        VspTree *mVspTree;
        OspTree *mOspTree;

        HierarchyManager *mHierarchyManager;
};


/*class ViewCellsManagerFactory
{
public:
        ViewCellsManager *Create(const string mName);
};*/

}

#endif