source: GTP/trunk/Lib/Vis/Preprocessing/src/RssTree.h @ 1884

// ================================================================
// $Id$
// ****************************************************************
// 
// Initial coding by
/**
   @author Jiri Bittner
*/

#ifndef __RSSTREE_H__
#define __RSSTREE_H__

// Standard headers
#include <iomanip>
#include <vector>
#include <functional>
#include <stack>


// User headers
#include "VssRay.h"
#include "AxisAlignedBox3.h"
#include "Halton.h"
#include "Beam.h"
#include "Statistics.h"
#include "Ray.h"

#include "Containers.h"
#include "SamplingStrategy.h"

namespace GtpVisibilityPreprocessor {

#define USE_KDNODE_VECTORS 1
#define _RSS_STATISTICS
#define _RSS_TRAVERSAL_STATISTICS


// --------------------------------------------------------------
// Static statistics for kd-tree search
// --------------------------------------------------------------
class RssStatistics :
  public StatisticsBase
{
public:  
  // total number of nodes
  int nodes;
  // number of leaves
  int leaves;
  // number of splits along each of the axes
  int splits[7];
  // totals number of rays
  int rays;
  // initial size of the pvs
  int initialPvsSize;
  // total number of query domains
  int queryDomains;
  // total number of ray references
  int rayRefs;

  // max depth nodes
  int maxDepthNodes;
  // max depth nodes
  int minPvsNodes;
  int minRaysNodes;
  // max ray contribution nodes
  int maxRayContribNodes;
  // max depth nodes
  int minSizeNodes;
  int maxCostRatioNodes;

  // max number of rays per node
  int maxRayRefs;
  // number of dynamically added ray refs
  int addedRayRefs;
  // number of dynamically removed ray refs
  int removedRayRefs;



  // dynamically updated values
  float avgPvsSize;
  float avgRays;
  float avgRayContribution;
  float avgPvsEntropy;
  float avgRayLengthEntropy;
  float avgImportance;

  float avgWeightedRayContribution;

  // Constructor
  RssStatistics() {
    Reset();
  }

  int Nodes() const {return nodes;}
  int Interior() const { return nodes/2; }
  int Leaves() const { return Nodes() - Interior(); }

  void Reset() {
    nodes = 0;
    for (int i=0; i<7; i++)
      splits[i] = 0;
    rays = queryDomains = 0;
    rayRefs = 0;
    maxDepthNodes = 0;
    minPvsNodes = 0;
    minRaysNodes = 0;
    maxRayRefs = 0;
    addedRayRefs = removedRayRefs = 0;
        initialPvsSize = 0;
        maxRayContribNodes = 0;
        minSizeNodes = 0;
        maxCostRatioNodes = 0;
  }

  
  void
  Print(ostream &app) const;

  friend ostream &operator<<(ostream &s, const RssStatistics &stat) {
    stat.Print(s);
    return s;
  }
  
};




class RssTreeInterior;


// --------------------------------------------------------------
// KD-tree node - abstract class
// --------------------------------------------------------------
class RssTreeNode
{
public:


  struct RayInfo
  {
        // pointer to the actual ray
        VssRay *mRay;
        
        RayInfo():mRay(NULL) {}
        
        RayInfo(VssRay *r):mRay(r)
        {}
        
        enum {
          SOURCE_RAY = 0,
          TERMINATION_RAY,
          PASSING_RAY,
          CONTAINED_RAY
        };
        
        int GetRayClass() const {
          return SOURCE_RAY;
        }
        
        friend bool operator<(const RayInfo &a, const RayInfo &b) {
          return a.mRay < b.mRay;
        }

        
#define USE_ORIGIN 1
        
        Vector3 GetOrigin() const {
#if USE_ORIGIN
          return mRay->GetOrigin();
#else
          return mRay->GetTermination();
#endif
        }

        Vector3 GetTermination() const {
#if USE_ORIGIN
          return mRay->GetTermination();
#else
          return mRay->GetOrigin();
#endif
        }

        float GetOrigin(const int axis) const {
#if USE_ORIGIN
          return mRay->GetOrigin(axis);
#else
          return mRay->GetTermination(axis);
#endif
        }

        Vector3 GetDir() const {
#if USE_ORIGIN
          return mRay->GetDir();
#else
          return -mRay->GetDir();
#endif
        }

        float GetDirParametrization(const int axis) const {
#if USE_ORIGIN
          return mRay->GetDirParametrization(axis);
#else
          return mRay->GetOpositeDirParametrization(axis);
#endif
        }

        
//      Vector3 GetTermination() const {
//        return mRay->GetOrigin();
//      }
        
//      float GetTermination(const int axis) const {
//        return mRay->GetTermination(axis);
//      }

        Intersectable *GetObject() const {
#if USE_ORIGIN
          return mRay->mTerminationObject;
#else
          return mRay->mOriginObject;
#endif
        }
        
        Intersectable *GetSourceObject() const {
#if USE_ORIGIN
          return mRay->mOriginObject;
#else
          return mRay->mTerminationObject;
#endif
        }

        //      Vector3 Extrap(const float t) const {
        //        return mRay->Extrap(t);
        //      }
        
        int
        ComputeRaySide(const int axis,
                                   const float position
                                   ) const {
          
          // only compare the side of the origin
          float rpos = (axis < 3) ? GetOrigin(axis) : GetDirParametrization(axis - 3);
          return (rpos <= position) ? -1 : 1;
        }

        static bool GreaterWeightedPvsContribution(const RayInfo &a,
                                                                                           const RayInfo &b) {
          return a.mRay->mWeightedPvsContribution > b.mRay->mWeightedPvsContribution;
        }

        static float Distance(const RayInfo &a,
                                                 const RayInfo &b)
        {
          if (a.mRay->mTerminationObject == b.mRay->mTerminationObject)
                return MAX_FLOAT;
          
          return Min(a.mRay->SqrDistance(b.GetTermination()),
                                 b.mRay->SqrDistance(a.GetTermination()));
        }

        
        static float SqrDistance5D(const RayInfo &a,
                                                           const RayInfo &b,
                                                           const Vector3 &spatialDerivative,
                                                           const Vector3 &directionalDerivative
                                                           )
        {
          Vector3 spatialDiff = b.GetOrigin() - a.GetOrigin();
          Vector3 directionalDiff = b.GetDir() - a.GetDir();
          
          return DotProd(spatialDiff, spatialDerivative) +
                DotProd(directionalDiff, directionalDerivative);
        }

        
  };

  struct SilhouetteRays {
        RayInfo *a;
        RayInfo *b;
        SilhouetteRays() {}
        SilhouetteRays(RayInfo *_a, RayInfo *_b):a(_a), b(_b) {
        }
  };
  
  typedef vector<RayInfo> RayInfoContainer;
        
  enum { EInterior, ELeaf };

  /////////////////////////////////
  // The actual data goes here
  
  // link to the parent
  RssTreeInterior *parent;

  enum {SPLIT_X=0, SPLIT_Y, SPLIT_Z, SPLIT_DIRX, SPLIT_DIRY, SPLIT_DIRZ};
  
  // splitting axis
  char axis;
        
  // depth
  unsigned char depth;
  
  //  short depth;
  //
  /////////////////////////////////


  // the bbox of the node
  AxisAlignedBox3 bbox;
  
  // the bbox of the node
  AxisAlignedBox3 dirBBox;

  // evaluated importance of this node
  float mImportance;

  inline RssTreeNode(RssTreeInterior *p);

  
  virtual ~RssTreeNode() {};
  virtual int Type() const  = 0;
  

  bool IsLeaf() const { return axis == -1; }
  
  virtual void Print(ostream &s) const = 0;

  virtual int GetAccessTime() {
    return 0x7FFFFFF;
  }

  float GetImportance() const;

        
};

// --------------------------------------------------------------
// KD-tree node - interior node
// --------------------------------------------------------------
class RssTreeInterior :
  public RssTreeNode
{
public:
  // plane in world coordinates
  float position;

  // pointers to children
  RssTreeNode *back, *front;


  // data for caching
  long accesses;
  long lastAccessTime;
  
  RssTreeInterior(RssTreeInterior *p):RssTreeNode(p),
                                                                          back(NULL),
                                                                          front(NULL),
                                                                          accesses(0),
                                                                          lastAccessTime(-1)
  { }

  virtual int GetAccessTime() {
    return lastAccessTime;
  }

  float GetRelativePosition() const {
        if (axis < 3)
          return (position - bbox.Min(axis))/bbox.Size(axis);
        else
          return (position - dirBBox.Min(axis-3))/dirBBox.Size(axis-3);
  }

  void SetupChildLinks(RssTreeNode *b, RssTreeNode *f) {
    back = b;
    front = f;
    b->parent = f->parent = this;
  }

  void ReplaceChildLink(RssTreeNode *oldChild, RssTreeNode *newChild) {
    if (back == oldChild)
      back = newChild;
    else
      front = newChild;
  }

  virtual int Type() const  { return EInterior; }
  
  virtual ~RssTreeInterior() {
    if (back)
      delete back;
    if (front)
      delete front;
  }
  
  virtual void Print(ostream &s) const {
    if (axis == 0)
      s<<"x ";
    else
      if (axis == 1)
                s<<"y ";
      else
                s<<"z ";
    s<<position<<" ";
    back->Print(s);
    front->Print(s);
  }

  
        
  int ComputeRaySide(const
                                         RayInfo &rayData
                                         ) {
        return rayData.ComputeRaySide(axis, position);
  }

};


// --------------------------------------------------------------
// KD-tree node - leaf node
// --------------------------------------------------------------
class RssTreeLeaf :
  public RssTreeNode
{
private:
  int mPvsSize;
public:
  static int mailID;
  int mailbox;
  
  RayInfoContainer rays;
  int mTotalRays;
  float mTotalContribution;
  
  bool mValidPvs;
  
  Beam mBeam;
  
  RssTreeLeaf(RssTreeInterior *p,
                          const int nRays
                          ):RssTreeNode(p), rays(), mPvsSize(0), mTotalRays(0),
                                mTotalContribution(0.0f), mValidPvs(false) {
    rays.reserve(nRays);
  }
  
  virtual ~RssTreeLeaf() { }

  virtual int Type() const  { return ELeaf; }

  virtual void Print(ostream &s) const {
    s<<
          "L: rays="<<(int)rays.size()<<
          " pvs="<<mPvsSize<<" importance="<<mImportance<<endl;
  };
  
  void AddRay(const RayInfo &data) {
        mValidPvs = false;
        rays.push_back(data);
        mTotalRays++;
        mTotalContribution +=
          ABS_CONTRIBUTION_WEIGHT*data.mRay->mPvsContribution +
          (1.0f - ABS_CONTRIBUTION_WEIGHT)*data.mRay->mRelativePvsContribution;
        data.mRay->Ref();
  }
        
  int GetPvsSize() const {
        return mPvsSize;
  }

  void SetPvsSize(const int s) {
        mPvsSize = s;
        mValidPvs = true;
  }


  float
  ComputePvsEntropy() const;
  
  float
  ComputeRayLengthEntropy() const;
  
  float
  ComputeRayTerminationEntropy() const;
  

  float
  ComputeEntropyImportance() const;
  
  float
  ComputeRayContributionImportance() const;

  void Mail() { mailbox = mailID; }
  static void NewMail() { mailID++; }
  bool Mailed() const { return mailbox == mailID; }
  
  bool Mailed(const int mail) {
    return mailbox >= mailID + mail;
  }

  float GetAvgRayContribution() const {
        return GetPvsSize()/((float)rays.size() + Limits::Small);
  }

  
  float GetSqrRayContribution() const {
        return sqr(GetPvsSize()/((float)rays.size() + Limits::Small));
  }
  
  // comparator for the 
  struct less_contribution : public
  binary_function<const RssTreeLeaf *, const RssTreeLeaf *, bool> {
        
        bool operator()(const RssTreeLeaf * a, const RssTreeLeaf *b) {
          return a->GetAvgRayContribution() < b->GetAvgRayContribution();
        }
  };
  
  struct greater_contribution : public
  binary_function<const RssTreeLeaf *, const RssTreeLeaf *, bool> {
        
        bool operator()(const RssTreeLeaf * a, const RssTreeLeaf *b) {
          return a->GetAvgRayContribution() > b->GetAvgRayContribution();
        }
  };
  
  friend bool GreaterContribution(const RssTreeLeaf * a, const RssTreeLeaf *b) {
        return a->GetAvgRayContribution() > b->GetAvgRayContribution();
  }

  
};

// Inline functions
inline
RssTreeNode::RssTreeNode(RssTreeInterior *p):
  parent(p), axis(-1), depth(p ? p->depth + 1 : 0) {}



// ---------------------------------------------------------------
// Main LSDS search class
// ---------------------------------------------------------------
class RssTree
{
  struct TraversalData
  {  
    RssTreeNode *node;
    AxisAlignedBox3 bbox;
    int depth;
    float priority;
    
    TraversalData() {}

    TraversalData(RssTreeNode *n, const float p):
      node(n), priority(p)
    {}

    TraversalData(RssTreeNode *n,
                                  const AxisAlignedBox3 &b,
                                  const int d):
      node(n), bbox(b), depth(d) {}
    
                
    // comparator for the 
    struct less_priority : public
    binary_function<const TraversalData, const TraversalData, bool> {
                        
      bool operator()(const TraversalData a, const TraversalData b) {
                return a.priority < b.priority;
      }
      
    };

    //    ~TraversalData() {}
    //    TraversalData(const TraversalData &s):node(s.node), bbox(s.bbox), depth(s.depth) {}
    
    friend bool operator<(const TraversalData &a,
                                                  const TraversalData &b) {
      //      return a.node->queries.size() < b.node->queries.size();
      RssTreeLeaf *leafa = (RssTreeLeaf *) a.node;
      RssTreeLeaf *leafb = (RssTreeLeaf *) b.node;
#if 0
          return
                leafa->rays.size()*a.bbox.GetVolume()
                <
                leafb->rays.size()*b.bbox.GetVolume();
#endif
#if 0
          return
                leafa->GetPvsSize()*a.bbox.GetVolume()
                <
                leafb->GetPvsSize()*b.bbox.GetVolume();
#endif
#if 0
          return
                leafa->GetPvsSize()
                <
                leafb->GetPvsSize();
#endif
#if 0
          return
                leafa->GetPvsSize()/(leafa->rays.size()+1)
                >
                leafb->GetPvsSize()/(leafb->rays.size()+1);
#endif
#if 1
          return
                leafa->GetPvsSize()*leafa->rays.size()
                <
                leafb->GetPvsSize()*leafb->rays.size();
#endif
    }
  };
  
  // simplified data for ray traversal only...

  struct RayTraversalData {
    
    RssTreeNode::RayInfo rayData;
    RssTreeNode *node;
    
    RayTraversalData() {}
    RayTraversalData(RssTreeNode *n,
                                         const RssTreeNode::RayInfo &data):
      rayData(data), node(n) {}
  };
        
public:
  /////////////////////////////
  // The core pointer
  vector<RssTreeNode *> mRoots;
  
  
  HaltonSequence mHalton;
  

  /////////////////////////////
  // Basic properties

  // total number of nodes of the tree
  int nodes;

  // axis aligned bounding box of the scene
  AxisAlignedBox3 bbox;

  // axis aligned bounding box of directions
  AxisAlignedBox3 dirBBox;

  // forced bounding box for from viewcell visibility
  //  AxisAlignedBox3 *mForcedBoundingBox;

  /////////////////////////////
  // Construction parameters

  // epsilon used for the construction
  float epsilon;

  // ratio between traversal and intersection costs
  float ct_div_ci;
  // max depth of the tree
  int termMaxDepth;
  // minimal ratio of the volume of the cell and the query volume
  float termMinSize;

  // minimal pvs per node to still get subdivided
  int termMinPvs;

  // minimal ray number per node to still get subdivided
  int termMinRays;
        
  // maximal cost ration to subdivide a node
  float termMaxCostRatio;
        
  // maximal contribution per ray to subdivide the node
  float termMaxRayContribution;

  // randomized construction
  bool randomize;

  // use a root per object in the tree
  bool mPerObjectTree;
  
  // type of the splitting to use fo rthe tree construction
  enum {ESplitRegular, ESplitHeuristic, ESplitHybrid };
  int splitType;

  bool mSplitUseOnlyDrivingAxis;
  

  // interleave directional and spatial splits based on their costs
  // if false directional splits are only performed after spatial splits
  bool mInterleaveDirSplits;

  // depth at which directional splits are performed if mInterleaveDirSplits is false
  int mDirSplitDepth;

  // depth till which the regular splits are applied for hybrid split type
  int mHybridDepth;
  
  // maximal number of rays maintained in the rss tree
  int mMaxRays;
  
  // maximal size of the box on which the refdir splitting can be performed
  // (relative to the scene bbox
  float refDirBoxMaxSize;
  
  // maximum alovable memory in MB
  float maxTotalMemory;

  // maximum alovable memory for static kd tree in MB
  float maxStaticMemory;

  // this is used during the construction depending
  // on the type of the tree and queries...
  float maxMemory;


  // minimal acess time for collapse
  int accessTimeThreshold;

  // minimal depth at which to perform collapse
  int minCollapseDepth;

  bool mImportanceBasedCost;

  // sampling pass
  int mCurrentPass;
  
  // reusable array of split candidates
  vector<SortableEntry> *splitCandidates;
  /////////////////////////////

  RssStatistics stat;
        
  
  RssTree();
  virtual ~RssTree();

  virtual void
  Construct(
                        ObjectContainer &objects,
                        VssRayContainer &rays
                        //                      AxisAlignedBox3 *forcedBoundingBox = NULL
                        );
        
  // incemental construction
  virtual void UpdateRays(VssRayContainer &remove,
                                                  VssRayContainer &add
                                                  );

  virtual void AddRays(
                                           VssRayContainer &add
                                           )
  {
        VssRayContainer remove;
        UpdateRays(remove, add);
  }

  
        
  RssTreeNode *
  Locate(const Vector3 &v);
        
  RssTreeNode *
  SubdivideNode(RssTreeLeaf *leaf,
                                const AxisAlignedBox3 &box,
                                AxisAlignedBox3 &backBox,
                                AxisAlignedBox3 &frontBox
                                );
        
  RssTreeNode *
  Subdivide(const TraversalData &tdata);
        

  void
  SortSubdivisionCandidates(
                                          RssTreeLeaf *node,
                                          const int axis
                                          );
        
  
  // return memory usage in MB
  float GetMemUsage() const {
    return 
      (sizeof(RssTree) +
       stat.Leaves()*sizeof(RssTreeLeaf) +
       stat.Interior()*sizeof(RssTreeInterior) +
       stat.rayRefs*sizeof(RssTreeNode::RayInfo))/(1024.0f*1024.0f);
  }
        
  float GetRayMemUsage() const {
    return 
      stat.rays*(sizeof(VssRay))/(1024.0f*1024.0f);
  }
  
  struct SplitInfo {
        
        int axis;
        float position;
        float costRatio;
        
        int rays;
        int raysBack;
        int raysFront;

        int pvs;
        int pvsBack;
        int pvsFront;

        float contribution;
        float contributionBack;
        float contributionFront;

        int viewCells;
        int viewCellsBack;
        int viewCellsFront;

        float volume;
        float volumeBack;
        float volumeFront;
        
  };
  
  void
  BestCostRatio(
                                RssTreeLeaf *node,
                                SplitInfo &info
//                              int &axis,
//                              float &position,
//                              int &raysBack,
//                              int &raysFront,
//                              int &pvsBack,
//                              int &pvsFront
                                );
        
  
  void
  EvalCostRatio(
                                RssTreeLeaf *node,
                                SplitInfo &info
//                              const int axis,
//                              const float position,
//                              int &raysBack,
//                              int &raysFront,
//                              int &pvsBack,
//                              int &pvsFront
                                );

  void
  EvalCostRatioHeuristic(
                                                 RssTreeLeaf *node,
                                                 SplitInfo &info
//                                               const int axis,
//                                               float &position,
//                                               int &raysBack,
//                                               int &raysFront,
//                                               int &pvsBack,
//                                               int &pvsFront
                                                 );

  int
  SelectPlane(RssTreeLeaf *leaf,
                          const AxisAlignedBox3 &box,
                          SplitInfo &info
                          );
  
  void
  GetCostRatio(
                           RssTreeLeaf *leaf,
                           SplitInfo &info
                           //                      const int axis,
                           //                      const float position,
                           //                      const int raysBack,
                           //                      const int raysFront,
                           //                      const int pvsBack,
                           //                      const int pvsFront
                           );
  
  AxisAlignedBox3 GetBBox(const RssTreeNode *node) const {
        return node->bbox;

//     if (node->parent == NULL)
//       return bbox;

//     if (!node->IsLeaf())
//       return ((RssTreeInterior *)node)->bbox;

//     if (node->parent->axis >= 3)
//       return node->parent->bbox;
      
//     AxisAlignedBox3 box(node->parent->bbox);
//     if (node->parent->front == node)
//       box.SetMin(node->parent->axis, node->parent->position);
//     else
//       box.SetMax(node->parent->axis, node->parent->position);
//     return box;
  }

  AxisAlignedBox3 GetShrankedBBox(const RssTreeNode *node) const;

  AxisAlignedBox3 GetDirBBox(const RssTreeNode *node) const {
        return node->dirBBox;
//     if (node->parent == NULL)
//       return dirBBox;
    
//     if (!node->IsLeaf() )
//       return ((RssTreeInterior *)node)->dirBBox;

//     if (node->parent->axis < 3)
//       return node->parent->dirBBox;
    
//     AxisAlignedBox3 dBBox(node->parent->dirBBox);

//     if (node->parent->front == node)
//       dBBox.SetMin(node->parent->axis - 3, node->parent->position);
//     else
//       dBBox.SetMax(node->parent->axis - 3, node->parent->position);
//     return dBBox;
  }
  
  int
  ReleaseMemory(const int time);

  int
  CollapseSubtree(RssTreeNode *node, const int time);

  void
  CountAccess(RssTreeInterior *node, const long time) {
    node->accesses++;
    node->lastAccessTime = time;
  }

  RssTreeNode *
  SubdivideLeaf(
                                RssTreeLeaf *leaf
                                );

  void
  RemoveRay(VssRay *ray,
                        vector<RssTreeLeaf *> *affectedLeaves,
                        const bool removeAllScheduledRays
                        );

  //  void
  //  AddRay(VssRay *ray);
  void
  AddRay(RssTreeNode::RayInfo &info);
  
  void
  TraverseInternalNode(
                                           RayTraversalData &data,
                                           stack<RayTraversalData> &tstack);

  void
  EvaluateLeafStats(const TraversalData &data);


  int
  GetRootPvsSize() const {
        return GetPvsSize(bbox);
  }
  
  int
  GetPvsSize(const AxisAlignedBox3 &box) const;

  int
  CollectPvs(const AxisAlignedBox3 &box,
                         ObjectContainer &pvs
                         ) const;

  int
  CollectRootPvs(
                                 ObjectContainer &pvs
                                 ) const
  {
        return CollectPvs(bbox, pvs);
  }
  
        
  void
  UpdateTreeStatistics();


  int
  GenerateRays(const float ratioPerLeaf,
                           SimpleRayContainer &rays);

  int
  GenerateRays(const int numberOfRays,
                           const int numberOfLeaves,
                           SimpleRayContainer &rays);
                
  float
  GetAvgPvsSize();

  int
  UpdateSubdivision();

  bool
  TerminationCriteriaSatisfied(RssTreeLeaf *leaf);

  void
  CollectLeaves(vector<RssTreeLeaf *> &leaves);

  bool
  ClipRay(
                  RssTreeNode::RayInfo &rayInfo,
                  const AxisAlignedBox3 &box
                  );

  RssTreeNode *GetRoot(Intersectable *object = NULL) const;

  bool
  ValidLeaf(RssTreeLeaf *leaf) const;

  void
  GenerateLeafRays(RssTreeLeaf *leaf,
                                   const int numberOfRays,
                                   SimpleRayContainer &rays);

  void
  GenerateLeafRaysSimple(RssTreeLeaf *leaf,
                                                 const int numberOfRays,
                                                 SimpleRayContainer &rays);
        

  void
  PickEdgeRays(RssTreeLeaf *leaf,
                           int &r1,
                           int &r2
                           );

  int
  CollectRays(VssRayContainer &rays,
                          const int number);

  int
  CollectRays(VssRayContainer &rays
                          );

  void
  UpdatePvsSize(RssTreeLeaf *leaf);

  void
  ComputeImportance(RssTreeLeaf *leaf);
  
  void
  SetPass(const int p) {
        mCurrentPass = p;
  }
  
  void GetRayContribution(const RssTreeNode::RayInfo &info,
                                                  float &weight,
                                                  float &contribution);

  float
  GetSampleWeight(const int pass);

  int
  RemoveInteriorRays(
                                         RssTreeLeaf *leaf
                                         );

  bool
  IsRayConvexCombination(const RssTreeNode::RayInfo &ray,
                                                 const RssTreeNode::RayInfo &r1,
                                                 const RssTreeNode::RayInfo &r2,
                                                 const RssTreeNode::RayInfo &r3);

  int
  PruneRaysRandom(RssTreeLeaf *leaf,
                                  const float ratio);

  int
  PruneRaysContribution(RssTreeLeaf *leaf,
                                                const float ratio);

  int
  PruneRays(
                        const int desired
                        );
  

  void
  FindSilhouetteRays(RssTreeLeaf *leaf,
                                         vector<RssTreeLeaf::SilhouetteRays> &rays
                                         );

  void
  PushRoots(priority_queue<TraversalData> &stack) const;

  void
  PushRoots(stack<RssTreeNode *> &st) const;

  void
  PushRoots(stack<RayTraversalData> &st, RssTreeNode::RayInfo &info) const;

  void
  UpdateImportance(
                                   RssTreeNode *node);

  void
  GenerateRay(float *params, SimpleRayContainer &rays);

  void
  GenerateLeafRay(
                                  float *params,
                                  SimpleRayContainer &rays,
                                  const AxisAlignedBox3 &box,
                                  const AxisAlignedBox3 &dirBBox
                                  );
        
};


class RssBasedDistribution: public SamplingStrategy
{
 public:
  HaltonSequence mHalton;
  RssTree *mRssTree;
  // id of sampling pass (a pass is defined by two consecutive updates)
  int mPass;

  RssBasedDistribution(Preprocessor &preprocessor):
        SamplingStrategy(preprocessor){
        mType = RSS_BASED_DISTRIBUTION;
        mRssTree = NULL;
        mPass = 0;
  }
  
  virtual void Update(VssRayContainer &vssRays);
  
private:

  virtual bool GenerateSample(SimpleRay &ray);
  
};


};

#endif // __RSSTREE_H__