source: GTP/trunk/Lib/Vis/Preprocessing/src/BvHierarchy.h @ 1315

#ifndef _BvHierarchy_H__
#define _BvHierarchy_H__

#include <stack>

#include "Mesh.h"
#include "Containers.h"
#include "Statistics.h"
#include "VssRay.h"
#include "RayInfo.h"
#include "gzstream.h"
#include "SubdivisionCandidate.h"
#include "AxisAlignedBox3.h"
#include "IntersectableWrapper.h"


namespace GtpVisibilityPreprocessor {


class ViewCellLeaf;
class Plane3;
class AxisAlignedBox3;
class Ray;
class ViewCellsStatistics;
class ViewCellsManager;
class MergeCandidate;
class Beam;
class ViewCellsTree;
class Environment;
class BvhInterior;
class BvhLeaf;
class BvhNode;
class BvhIntersectable;
class BvhTree;
class VspTree;
class ViewCellsContainer;
//class BvhSubdivisionCandidate;


/** View space partition statistics.
*/
class BvhStatistics: public StatisticsBase
{
public:
        // total number of nodes
        int nodes;
        // number of splits
        int splits;
        // maximal reached depth
        int maxDepth;
        // minimal depth
        int minDepth;
        // max depth nodes
        int maxDepthNodes;
        // minimum depth nodes
        int minDepthNodes;
        // nodes with minimum objects
        int minObjectsNodes;
        // minimum area nodes
        int minProbabilityNodes;
        /// nodes termination because of max cost ratio;
        int maxCostNodes;
        // max number of rays per node
        int maxObjectRefs;
        /// number of invalid leaves
        int invalidLeaves;
        /// accumulated number of rays refs
        //int accumRays;
        // accumulated depth (used to compute average)
        int accumDepth;
        /// object references
        int objectRefs;

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

        int Nodes() const {return nodes;}
        int Interior() const { return nodes / 2; }
        int Leaves() const { return (nodes / 2) + 1; }
        
        // TODO: computation wrong
        double AvgDepth() const 
        { return accumDepth / (double)Leaves(); } 

        void Reset() 
        {
                nodes = 0;
                splits = 0;
                
                maxDepth = 0;
                minDepth = 99999;
                accumDepth = 0;
        maxDepthNodes = 0;
                minObjectsNodes = 0;
                minProbabilityNodes = 0;
                maxCostNodes = 0;
                invalidLeaves = 0;
                maxObjectRefs = 0;
                objectRefs = 0;
        }

        void Print(ostream &app) const;

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


/**
    VspNode abstract class serving for interior and leaf node implementation
*/
class BvhNode
{
public:
        
        // types of vsp nodes
        enum {Interior, Leaf};

        BvhNode();
        BvhNode(const AxisAlignedBox3 &bbox);
        BvhNode(const AxisAlignedBox3 &bbox, BvhInterior *parent);

        virtual ~BvhNode(){};

        /** Determines whether this node is a leaf or not
                @return true if leaf
        */
        virtual bool IsLeaf() const = 0;

        /** Determines whether this node is a root
                @return true if root
        */
        virtual bool IsRoot() const;

        /** Returns parent node.
        */
        BvhInterior *GetParent();

        /** Sets parent node.
        */
        void SetParent(BvhInterior *parent);

        /** The bounding box specifies the node extent.
        */
        AxisAlignedBox3 GetBoundingBox() const
        { return mBoundingBox; }


        void SetBoundingBox(const AxisAlignedBox3 &boundingBox) 
        { mBoundingBox = boundingBox; }


        /////////////////////////////////////
        //-- mailing options
        
        static void NewMail(const int reserve = 1) {
                sMailId += sReservedMailboxes;
                sReservedMailboxes = reserve;
        }
        
        void Mail() { mMailbox = sMailId; }
        bool Mailed() const { return mMailbox == sMailId; }

        void Mail(const int mailbox) { mMailbox = sMailId + mailbox; }
        bool Mailed(const int mailbox) const { return mMailbox == sMailId + mailbox; }

        int IncMail() { return ++ mMailbox - sMailId; }

        static int sMailId;
        int mMailbox;
        static int sReservedMailboxes;

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

protected:
        
        /// the bounding box of the node
        AxisAlignedBox3 mBoundingBox;
        /// parent of this node
        BvhInterior *mParent;
};


/** BSP interior node implementation 
*/
class BvhInterior: public BvhNode 
{
public:
        /** Standard contructor taking a bounding box as argument.
        */
        BvhInterior(const AxisAlignedBox3 &bbox);
        BvhInterior(const AxisAlignedBox3 &bbox, BvhInterior *parent);

        ~BvhInterior();
        /** @return false since it is an interior node 
        */
        bool IsLeaf() const;
        
        BvhNode *GetBack() { return mBack; }
        BvhNode *GetFront() { return mFront; }

        /** Replace front or back child with new child.
        */
        void ReplaceChildLink(BvhNode *oldChild, BvhNode *newChild);

        /** Replace front and back child.
        */
        void SetupChildLinks(BvhNode *front, BvhNode *back);

        friend ostream &operator<<(ostream &s, const BvhInterior &A)
        {
                return s << A.mBoundingBox;
        }

protected:

        /// back node
        BvhNode *mBack;
        /// front node
        BvhNode *mFront;
};


/** BSP leaf node implementation.
*/
class BvhLeaf: public BvhNode 
{
public:
        /** Standard contructor taking a bounding box as argument.
        */
        BvhLeaf(const AxisAlignedBox3 &bbox);
        BvhLeaf(const AxisAlignedBox3 &bbox, BvhInterior *parent);
        BvhLeaf(const AxisAlignedBox3 &bbox, BvhInterior *parent, const int numObjects);

        ~BvhLeaf();

        /** @return true since it is an interior node 
        */
        bool IsLeaf() const;
        
        SubdivisionCandidate *GetSubdivisionCandidate()// const
        { 
                return mSubdivisionCandidate; 
        }

        void SetSubdivisionCandidate(SubdivisionCandidate *candidate)
        { 
                mSubdivisionCandidate = candidate; 
        }

public:

        /// Rays piercing this leaf.
        VssRayContainer mVssRays;
        /// objects
        ObjectContainer mObjects;
        /// universal counter
        int mCounter;

protected:

        /// pointer to a split plane candidate splitting this leaf
        SubdivisionCandidate *mSubdivisionCandidate;
};


typedef map<BvhNode *, BvhIntersectable *> BvhIntersectableMap;


/** View Space Partitioning tree.
*/
class BvHierarchy 
{
        friend class ViewCellsParseHandlers;
        friend class HierarchyManager;

public:
        
        /** Additional data which is passed down the BSP tree during traversal.
        */
        class BvhTraversalData
        {  
        public:
                
                BvhTraversalData():
                mNode(NULL),
                mDepth(0),
                mProbability(0.0),
                mMaxCostMisses(0), 
                mPriority(0),
                mAxis(0)
                {}
                
                BvhTraversalData(BvhLeaf *node, 
                                                 const int depth,
                                                 const AxisAlignedBox3 &box,
                                                 const float v):
                mNode(node), 
                mDepth(depth),
                mBoundingBox(box),
                mProbability(v),
                mMaxCostMisses(0),
                mPriority(0),
                mAxis(0)
                {}


                /** Returns cost of the traversal data.
                */
                float GetCost() const
                {
                        return mPriority;
                }

                /// deletes contents and sets them to NULL
                void Clear()
                {
                        DEL_PTR(mNode);
                }

                /// the current node
                BvhLeaf *mNode;
                /// current depth
                int mDepth;
                /// the probability that this node is seen
                float mProbability;
                /// the bounding box of the node
                AxisAlignedBox3 mBoundingBox;
                /// how often this branch has missed the max-cost ratio
                int mMaxCostMisses;
                /// current axis
                int mAxis;
                /// current priority
                float mPriority;


                friend bool operator<(const BvhTraversalData &a, const BvhTraversalData &b)
                {
                        return a.GetCost() < b.GetCost();
                }
    };

        /** Candidate for a view space split.
        */
        class BvhSubdivisionCandidate: public SubdivisionCandidate
        {  
        public:

        BvhSubdivisionCandidate(const BvhTraversalData &tData): mParentData(tData)
                {};

                ~BvhSubdivisionCandidate() 
                { 
                        mParentData.Clear(); 
                }

                int Type() const { return OBJECT_SPACE; }
        
                void EvalPriority()
                {
                        sBvHierarchy->EvalSubdivisionCandidate(*this);  
                }

                bool GlobalTerminationCriteriaMet() const
                {
                        return sBvHierarchy->GlobalTerminationCriteriaMet(mParentData);
                }

                BvhSubdivisionCandidate(
                        const ObjectContainer &frontObjects, 
                        const ObjectContainer &backObjects, 
                        const BvhTraversalData &tData): 
                mFrontObjects(frontObjects), mBackObjects(backObjects), mParentData(tData)
                {}

                /// pointer to parent tree.
                static BvHierarchy *sBvHierarchy;
                /// parent data
                BvhTraversalData mParentData;
                /// the objects on the front of the potential split
                ObjectContainer mFrontObjects;
                /// the objects on the back of the potential split
                ObjectContainer mBackObjects;
        };

        /** Struct for traversing line segment.
        */
        struct LineTraversalData 
        {
                BvhNode *mNode;
                Vector3 mExitPoint;
                
                float mMaxT;
    
                LineTraversalData () {}
                LineTraversalData (BvhNode *n, const Vector3 &p, const float maxt):
                mNode(n), mExitPoint(p), mMaxT(maxt) {}
        };


        /** Default constructor creating an empty tree.
        */ 
        BvHierarchy();

        /** Default destructor.
        */
        ~BvHierarchy();

        /** Returns tree statistics.
        */
        const BvhStatistics &GetStatistics() const; 
  
        /** Returns bounding box of the specified node.
        */
        AxisAlignedBox3 GetBoundingBox(BvhNode *node) const;

        /** Reads parameters from environment singleton.
        */
        void ReadEnvironment();

        /** Evaluates candidate for splitting.
        */
        void EvalSubdivisionCandidate(BvhSubdivisionCandidate &splitData);

        /** Returns list of leaves with pvs smaller than
                a certain threshold.
                @param onlyUnmailed if only the unmailed leaves should be considered
                @param maxPvs the maximal pvs of a leaf to be added (-1 means unlimited)
        */
        void CollectLeaves(vector<BvhLeaf *> &leaves) const;

        /** Returns bounding box of the whole tree (= bbox of root node)
        */
        AxisAlignedBox3 GetBoundingBox()const;

        /** Returns root of the view space partitioning tree.
        */
        BvhNode *GetRoot() const;

        /** A ray is cast possible intersecting the tree.
                @param the ray that is cast.
                @returns the number of intersections with objects stored in the tree.
        */
        //int CastRay(Ray &ray);

        /** finds neighbouring leaves of this tree node.
        */
        int FindNeighbors(BvhLeaf *n, 
                                          vector<BvhLeaf *> &neighbors, 
                                          const bool onlyUnmailed) const;

        /** Returns random leaf of BSP tree.
                @param halfspace defines the halfspace from which the leaf is taken.
        */
        BvhLeaf *GetRandomLeaf(const Plane3 &halfspace);

        /** Returns random leaf of BSP tree.
                @param onlyUnmailed if only unmailed leaves should be returned.
        */
        BvhLeaf *GetRandomLeaf(const bool onlyUnmailed = false);

        /** Casts line segment into the tree.
                @param origin the origin of the line segment
                @param termination the end point of the line segment
                @returns view cells intersecting the line segment.
        */
    int CastLineSegment(const Vector3 &origin,
                                                const Vector3 &termination,
                                                ViewCellContainer &viewcells);
                
        /** Sets pointer to view cells manager.
        */
        void SetViewCellsManager(ViewCellsManager *vcm);

        /** Writes tree to output stream
        */
        bool Export(OUT_STREAM &stream);

        /** Returns or creates a new intersectable for use in a kd based pvs.
                The OspTree is responsible for destruction of the intersectable.
        */
        BvhIntersectable *GetOrCreateBvhIntersectable(BvhNode *node);

        /** Collects rays.
        */
        void CollectRays(const ObjectContainer &objects, VssRayContainer &rays) const;

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


        /** Returns leaf the point pt lies in, starting from root.
        */
        BvhLeaf *GetLeaf(Intersectable *obj, BvhNode *root = NULL) const;

        ViewCellsTree *GetViewCellsTree() const { return mViewCellsTree; }
        
        void SetViewCellsTree(ViewCellsTree *vt) { mViewCellsTree = vt; }

        /** Add the bvh leaf to the pvs of the view cell.
        */
        bool AddLeafToPvs(
                BvhLeaf *leaf, 
                ViewCell *vc, 
                const float pdf, 
                float &contribution);

protected:

        /** Returns true if tree can be terminated.
        */
        bool LocalTerminationCriteriaMet(const BvhTraversalData &data) const;

        /** Returns true if global tree can be terminated.
        */
        bool GlobalTerminationCriteriaMet(const BvhTraversalData &data) const;

        /** For sorting the objects during the heuristics
        */
        struct SortableEntry
        {
                Intersectable *mObject;
                float mPos;

                SortableEntry() {}

                SortableEntry(Intersectable *obj, const float pos): 
                mObject(obj), mPos(pos)
                {}

                bool operator<(const SortableEntry &b) const 
                {
                        return mPos < b.mPos;
                }
        };
 
        /** Evaluate balanced object partition.
        */
        float EvalLocalObjectPartition(
                const BvhTraversalData &tData,
                const int axis,
                ObjectContainer &objectsFront,
                ObjectContainer &objectsBack);

        /** Computes priority of the traversal data and stores it in tData.
        */
        void EvalPriority(BvhTraversalData &tData) const;

        /** Evaluates render cost of next split.
        */
        float EvalRenderCost(
                const BvhTraversalData &tData,
                const ObjectContainer &objectsLeft,
                const ObjectContainer &objectsRight) const;

        /** Evaluates tree stats in the BSP tree leafs.
        */
        void EvaluateLeafStats(const BvhTraversalData &data);

        /** Subdivides node using a best split priority queue.
            @param tQueue the best split priority queue
                @param splitCandidate the candidate for the next split
                @param globalCriteriaMet if the global termination criteria were already met
                @returns new root of the subtree
        */
        BvhNode *Subdivide(
                SplitQueue &tQueue, 
                SubdivisionCandidate *splitCandidate,
                const bool globalCriteriaMet);
        
        /** Subdivides leaf.
                @param leaf the leaf to be subdivided
                
                @param polys the polygons to be split
                @param frontPolys returns the polygons in front of the split plane
                @param backPolys returns the polygons in the back of the split plane
                
                @param rays the polygons to be filtered
                @param frontRays returns the polygons in front of the split plane
                @param backRays returns the polygons in the back of the split plane

                @returns the root of the subdivision
        */
        BvhInterior *SubdivideNode(
                const ObjectContainer &frontObjects,
                const ObjectContainer &backObjects,
                const BvhTraversalData &tData,
                BvhTraversalData &frontData,
                BvhTraversalData &backData);

        /** Splits the objects for the next subdivision.
                @returns cost for this split
        */
        float SelectObjectPartition(
                const BvhTraversalData &tData,
                ObjectContainer &frontObjects,
                ObjectContainer &backObjects);
        
        /** Writes the node to disk
                @note: should be implemented as visitor.
        */
        void ExportNode(BvhNode *node, OUT_STREAM &stream);

        void ExportObjects(BvhLeaf *leaf, OUT_STREAM &stream);

        /** Returns estimated memory usage of tree.
        */
        float GetMemUsage() const;

        /** Creates new root of hierarchy.
        */
        void CreateRoot(const ObjectContainer &objects);

        /////////////////////////////
        // Helper functions for local cost heuristics

        
        /** Sorts split candidates for cost heuristics using axis aligned splits.
                @param node the current node
                @param axis the current split axis
        */
        void SortSubdivisionCandidates(
                const BvhTraversalData &data,
                const int axis);

        /** Computes best cost for axis aligned planes.
        */
        float EvalLocalCostHeuristics(
                const BvhTraversalData &tData,
                const int axis,
                ObjectContainer &objectsFront,
                ObjectContainer &objectsFBack);

        /** Evaluates the contribution to the front and back volume
                when this object is changing sides in the bvs.

                @param object the object
                @param volLeft updates the left pvs
                @param volPvs updates the right pvs
        */
        void EvalHeuristicsContribution(
                Intersectable *obj,
                float &volLeft, 
                float &volRight);

        /** Prepares objects for the cost heuristics.
                @returns sum of volume of associated view cells
        */
        float PrepareHeuristics(const BvhTraversalData &tData, const int axis);
        

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


        /** Prepares construction for vsp and osp trees.
        */
        AxisAlignedBox3 ComputeBoundingBox(
                const ObjectContainer &objects, 
                const AxisAlignedBox3 *parentBox = NULL);

        void CollectDirtyCandidates(
                BvhSubdivisionCandidate *sc,
                vector<SubdivisionCandidate *> &dirtyList);

        /** Collect view cells which see this bvh leaf.
        */
        void CollectViewCells(
                const ObjectContainer &objects, 
                ViewCellContainer &viewCells,
                const bool setCounter = false) const;

        /** Collects view cells which see an object.
        */
        void CollectViewCells(
                Intersectable *object, 
                ViewCellContainer &viewCells, 
                const bool useMailBoxing,
                const bool setCounter = false) const;

        /** Rays will be clipped to the bounding box.
        */
        void PreprocessRays(
                BvhLeaf *root, 
                const VssRayContainer &sampleRays,
                RayInfoContainer &rays);

        /** Print the subdivision stats in the subdivison log.
        */
        void PrintSubdivisionStats(const SubdivisionCandidate &tData);

        void AddSubdivisionStats(
                const int viewCells,
                const float renderCostDecr,
                const float totalRenderCost);

        void AssociateObjectsWithRays(const VssRayContainer &rays);

        bool IsObjectInLeaf(BvhLeaf *, Intersectable *object) const;

        SubdivisionCandidate *PrepareConstruction(
                const VssRayContainer &sampleRays,
                const ObjectContainer &objects
                );

        float EvalViewCellsVolume(const ObjectContainer &objects) const;


protected:
        
        /// pointer to the hierarchy of view cells
        ViewCellsTree *mViewCellsTree;

        VspTree *mVspTree;

        /// The view cells manager
        ViewCellsManager *mViewCellsManager;

        /// candidates for placing split planes during cost heuristics
        vector<SortableEntry> *mSubdivisionCandidates;

        /// Pointer to the root of the tree
        BvhNode *mRoot;
                
        /// Statistics for the object space partition
        BvhStatistics mBvhStats;
        
        /// box around the whole view domain
        AxisAlignedBox3 mBoundingBox;


        //-- local termination

        /// maximal possible depth
        int mTermMaxDepth;
        /// mininum probability
        float mTermMinProbability;
        /// minimal number of objects
        int mTermMinObjects;
        /// maximal contribution per ray
        float mTermMaxRayContribution;
        /// maximal acceptable cost ratio
        float mTermMaxCostRatio;
        /// tolerance value indicating how often the max cost ratio can be failed
        int mTermMissTolerance;


        //-- global criteria

        float mTermMinGlobalCostRatio;
        int mTermGlobalCostMissTolerance;
        int mGlobalCostMisses;

        /// maximal number of view cells
        int mTermMaxLeaves;
        /// maximal tree memory
        float mMaxMemory;
        /// the tree is out of memory
        bool mOutOfMemory;


        //-- split heuristics based parameters
        
        bool mUseCostHeuristics;
        /// balancing factor for PVS criterium
        float mCtDivCi; 
        /// if only driving axis should be used for split
        bool mOnlyDrivingAxis;
        
        /// current time stamp (used for keeping split history)
        int mTimeStamp;
        // if rays should be stored in leaves
        bool mStoreRays;

        /// epsilon for geometric comparisons
        float mEpsilon;

        /// subdivision stats output file
        ofstream  mSubdivisionStats;
        /// keeps track of cost during subdivision
        float mTotalCost;
        /// keeps track of overall pvs size during subdivision
        int mTotalPvsSize;
        /// number of currenly generated view cells
        int mCreatedLeaves;

        /// represents min and max band for sweep
        float mSplitBorder;

        /// weight between render cost decrease and node render cost
        float mRenderCostDecreaseWeight;

        /// stores the kd node intersectables used for pvs
        BvhIntersectableMap mBvhIntersectables;

};

}

#endif