source: GTP/trunk/Lib/Vis/Preprocessing/src/HierarchyManager.cpp @ 1643

#include <stack>
#include <time.h>
#include <iomanip>

#include "ViewCell.h"
#include "Plane3.h"
#include "HierarchyManager.h"
#include "Mesh.h"
#include "common.h"
#include "Environment.h"
#include "Polygon3.h"
#include "Ray.h"
#include "AxisAlignedBox3.h"
#include "Exporter.h"
#include "Plane3.h"
#include "ViewCellsManager.h"
#include "Beam.h"
#include "KdTree.h"
#include "IntersectableWrapper.h"
#include "VspTree.h"
#include "OspTree.h"
#include "BvHierarchy.h"


namespace GtpVisibilityPreprocessor {


#define USE_FIXEDPOINT_T 0


/*******************************************************************/
/*              class HierarchyManager implementation              */
/*******************************************************************/


HierarchyManager::HierarchyManager(const int objectSpaceSubdivisionType):
mObjectSpaceSubdivisionType(objectSpaceSubdivisionType),
mOspTree(NULL), 
mBvHierarchy(NULL)
{
        switch(mObjectSpaceSubdivisionType)
        {
        case KD_BASED_OBJ_SUBDIV:
                mOspTree = new OspTree();
                mOspTree->mVspTree = mVspTree;
                mOspTree->mHierarchyManager = this;
                break;
        case BV_BASED_OBJ_SUBDIV:
        mBvHierarchy = new BvHierarchy();
                mBvHierarchy->mHierarchyManager = this;
                break;
        default:
                break;
        }

        // hierarchy manager links view space partition and object space partition
        mVspTree = new VspTree();
        mVspTree->mHierarchyManager = this;
        
        mViewSpaceSubdivisionType = KD_BASED_VIEWSPACE_SUBDIV;
        ParseEnvironment();
}


HierarchyManager::HierarchyManager(KdTree *kdTree): 
mObjectSpaceSubdivisionType(KD_BASED_OBJ_SUBDIV),
mBvHierarchy(NULL)
{
        mOspTree = new OspTree(*kdTree);
        mOspTree->mVspTree = mVspTree;

        mVspTree = new VspTree();
        mVspTree->mHierarchyManager = this;

        mViewSpaceSubdivisionType = KD_BASED_VIEWSPACE_SUBDIV;
        ParseEnvironment();
}


void HierarchyManager::ParseEnvironment()
{
        Environment::GetSingleton()->GetFloatValue(
                "Hierarchy.Termination.minGlobalCostRatio", mTermMinGlobalCostRatio);
        Environment::GetSingleton()->GetIntValue(
                "Hierarchy.Termination.globalCostMissTolerance", mTermGlobalCostMissTolerance);

        Environment::GetSingleton()->GetBoolValue(
                "Hierarchy.Construction.startWithObjectSpace", mStartWithObjectSpace);

        Environment::GetSingleton()->GetIntValue(
                "Hierarchy.Termination.maxLeaves", mTermMaxLeaves);

        Environment::GetSingleton()->GetIntValue(
                "Hierarchy.Construction.type", mConstructionType);

        Environment::GetSingleton()->GetIntValue(
                "Hierarchy.Construction.minDepthForOsp", mMinDepthForObjectSpaceSubdivion);

        Environment::GetSingleton()->GetIntValue(
                "Hierarchy.Construction.minDepthForVsp", mMinDepthForViewSpaceSubdivion);
        
        Environment::GetSingleton()->GetBoolValue(
                "Hierarchy.Construction.repairQueue", mRepairQueue);

        Environment::GetSingleton()->GetBoolValue(
                "Hierarchy.Construction.useMultiLevel", mUseMultiLevelConstruction);

        Environment::GetSingleton()->GetIntValue(
                "Hierarchy.Construction.levels", mNumMultiLevels);

        Environment::GetSingleton()->GetIntValue(
                "Hierarchy.Construction.minStepsOfSameType", mMinStepsOfSameType);
        

        char subdivisionStatsLog[100];
        Environment::GetSingleton()->GetStringValue("Hierarchy.subdivisionStats", subdivisionStatsLog);
        mSubdivisionStats.open(subdivisionStatsLog);

        Environment::GetSingleton()->GetBoolValue(
                "Hierarchy.Construction.recomputeSplitPlaneOnRepair", mRecomputeSplitPlaneOnRepair);

        Debug << "******** Hierachy Manager Options ***********" << endl;
        Debug << "max leaves: " << mTermMaxLeaves << endl;
        Debug << "min global cost ratio: " << mTermMinGlobalCostRatio << endl;
        Debug << "global cost miss tolerance: " << mTermGlobalCostMissTolerance << endl;
        Debug << "min depth for object space subdivision: " << mMinDepthForObjectSpaceSubdivion << endl;
        Debug << "repair queue: " << mRepairQueue << endl;
        Debug << "number of multilevels: " << mNumMultiLevels << endl;
        Debug << "recompute split plane on repair: " << mRecomputeSplitPlaneOnRepair << endl;
        Debug << "minimal number of steps from same type: " << mMinStepsOfSameType << endl;

        switch (mConstructionType)
        {
        case 0:
                Debug << "construction type: sequential" << endl;
                break;
        case 1:
                Debug << "construction type: interleaved" << endl;
                break;
        case 2:
                Debug << "construction type: gradient" << endl;
                break;
        case 3:
                Debug << "construction type: multilevel" << endl;
                break;
        default:
                Debug << "construction type " << mConstructionType << " unknown" << endl;
                break;
        }

        //Debug << "min render cost " << mMinRenderCostDecrease << endl;
        Debug << endl;
}


HierarchyManager::~HierarchyManager()
{
        DEL_PTR(mOspTree);
        DEL_PTR(mVspTree);
        DEL_PTR(mBvHierarchy);
}


int HierarchyManager::GetObjectSpaceSubdivisionType() const
{
        return mObjectSpaceSubdivisionType;
}


int HierarchyManager::GetViewSpaceSubdivisionType() const
{
        return mViewSpaceSubdivisionType;
}


void HierarchyManager::SetViewCellsManager(ViewCellsManager *vcm)
{
        mVspTree->SetViewCellsManager(vcm);

        if (mOspTree)
        {
                mOspTree->SetViewCellsManager(vcm);
        }
        else if (mBvHierarchy)
        {
                mBvHierarchy->SetViewCellsManager(vcm);
        }
}


void HierarchyManager::SetViewCellsTree(ViewCellsTree *vcTree)
{
        mVspTree->SetViewCellsTree(vcTree);
}


VspTree *HierarchyManager::GetVspTree() 
{ 
        return mVspTree; 
}

/*
AxisAlignedBox3 HierarchyManager::GetViewSpaceBox() const
{
        return mVspTree->mBoundingBox;
}*/


AxisAlignedBox3 HierarchyManager::GetObjectSpaceBox() const
{
        switch (mObjectSpaceSubdivisionType)
        {
        case KD_BASED_OBJ_SUBDIV:
                return mOspTree->mBoundingBox;
        case BV_BASED_OBJ_SUBDIV:
                return mBvHierarchy->mBoundingBox;
        default:
                // hack: empty box
                return AxisAlignedBox3();
        }
}


SubdivisionCandidate *HierarchyManager::NextSubdivisionCandidate(SplitQueue &splitQueue)
{
        SubdivisionCandidate *splitCandidate = splitQueue.Top();
        splitQueue.Pop();

        return splitCandidate;
}


void HierarchyManager::EvalSubdivisionStats()
{
        // TODO
        const float objectSpaceMem = GetObjectSpaceMemUsage();
        const float viewSpaceMem = mVspTree->GetMemUsage();
        
        // calculate cost in MB
        const float memoryCost = mHierarchyStats.mMemory  / (1024.0f * 1024.0f)
                                                         + objectSpaceMem + viewSpaceMem;

        //cout << "pvs entries " << mHierarchyStats.pvsEntries << endl;
        AddSubdivisionStats(mHierarchyStats.Leaves(),
                                                mHierarchyStats.mRenderCostDecrease,
                                                mHierarchyStats.mTotalCost,
                                                mHierarchyStats.mPvsEntries,
                                                memoryCost,
                                                1.0f / (mHierarchyStats.mTotalCost * memoryCost)
                                                );
}


void HierarchyManager::AddSubdivisionStats(const int splits,
                                                                                   const float renderCostDecr,
                                                                                   const float totalRenderCost,
                                                                                   const int pvsEntries,
                                                                                   const float memory,
                                                                                   const float renderCostPerStorage)
{
        mSubdivisionStats
                        << "#Splits\n" << splits << endl
                        << "#RenderCostDecrease\n" << renderCostDecr << endl 
                        << "#TotalEntriesInPvs\n" << pvsEntries << endl
                        << "#TotalRenderCost\n" << totalRenderCost << endl
                        << "#Memory\n" << memory << endl
                        << "#RcPerMb\n" << renderCostPerStorage << endl;
}


bool HierarchyManager::GlobalTerminationCriteriaMet(SubdivisionCandidate *candidate) const
{
        const bool terminationCriteriaMet = 
                (0
                || (mHierarchyStats.Leaves() >= mTermMaxLeaves) 
                //|| (mHierarchyStats.mGlobalCostMisses >= mTermGlobalCostMissTolerance)
                || (candidate->GlobalTerminationCriteriaMet())
                //|| (mHierarchyStats.mRenderCostDecrease < mMinRenderCostDecrease)
                );

#if _DEBUG
        if (terminationCriteriaMet)
        {
                Debug << "hierarchy global termination criteria met:" << endl;
                Debug << "leaves: " << mHierarchyStats.Leaves() << " " << mTermMaxLeaves << endl;
                Debug << "cost misses: " << mHierarchyStats.mGlobalCostMisses << " " << mTermGlobalCostMissTolerance << endl;
        }
#endif

        return terminationCriteriaMet;
}


void HierarchyManager::Construct(const VssRayContainer &sampleRays,
                                                                 const ObjectContainer &objects,
                                                                 AxisAlignedBox3 *forcedViewSpace)
{
        switch (mConstructionType)
        {
        case MULTILEVEL:
                ConstructMultiLevel(sampleRays, objects, forcedViewSpace);
                break;
        case INTERLEAVED:
        case SEQUENTIAL:
                ConstructInterleaved(sampleRays, objects, forcedViewSpace);
                break;
        case GRADIENT:
                ConstructInterleavedWithGradient(sampleRays, objects, forcedViewSpace);
                break;
        default:
                break;
        }

        // hack: should be different parameter name
        if (mUseMultiLevelConstruction)
        {
                cout << "starting optimizing multilevel ... " << endl;
                // try to optimize on the above hierarchy
                OptimizeMultiLevel(sampleRays, objects, forcedViewSpace);
                
                cout << "finished" << endl;
        }
}


void HierarchyManager::ConstructInterleavedWithGradient(const VssRayContainer &sampleRays,                                                                                       
                                                                                                                const ObjectContainer &objects,
                                                                                                                AxisAlignedBox3 *forcedViewSpace)
{
        mHierarchyStats.Reset();
        mHierarchyStats.Start();
        
        mHierarchyStats.mNodes = 2;

        // create first nodes
        mVspTree->Initialise(sampleRays, forcedViewSpace);
        InitialiseObjectSpaceSubdivision(objects);

        // hack: assume that object space can be seen from view space
        mHierarchyStats.mTotalCost = (float)objects.size();
        mHierarchyStats.mPvsEntries = 1;
        mHierarchyStats.mMemory = sizeof(PvsData) + sizeof(Intersectable *) / (1024.0f * 1024.0f);

        EvalSubdivisionStats();
        Debug << "setting total cost to " << mHierarchyStats.mTotalCost << endl;

        const long startTime = GetTime();
        cout << "Constructing view space / object space tree ... \n";
        
        SplitQueue objectSpaceQueue;
        SplitQueue viewSpaceQueue;

        // use sah for evaluating osp tree construction 
        // in the first iteration of the subdivision
        mSavedViewSpaceSubdivisionType = mViewSpaceSubdivisionType;
        mViewSpaceSubdivisionType = NO_VIEWSPACE_SUBDIV;
        //mSavedObjectSpaceSubdivisionType = mObjectSpaceSubdivisionType;

        // number of initial splits
        const int minSteps = mMinStepsOfSameType;
        float renderCostDecr = Limits::Infinity;

        SubdivisionCandidate *osc = 
                PrepareObjectSpaceSubdivision(sampleRays, objects);
        
        objectSpaceQueue.Push(osc);


        /////////////////////////
        // calulcate initial object space splits
        
        SubdivisionCandidateContainer dirtyVspList;

        // subdivide object space first
        // for first round, use sah splits. Once view space partition
        // has started, use render cost heuristics instead
        const int ospSteps = 
                RunConstruction(objectSpaceQueue, dirtyVspList, renderCostDecr, minSteps);

        cout << "\n" << ospSteps << " object space partition steps taken" << endl;

        // create view space
        SubdivisionCandidate *vsc = 
                        PrepareViewSpaceSubdivision(sampleRays, objects);

        viewSpaceQueue.Push(vsc);
        
        // view space subdivision started
        mViewSpaceSubdivisionType = mSavedViewSpaceSubdivisionType;

        // the priorities were calculated for driving sha.
        // => recalculate "real" priorities taking visibility into
        // account so we can compare to view space splits
        ResetQueue(objectSpaceQueue, false);

        
        // lower number of minsteps: the decicion of which domain to subdivide
        // should be decided using the render cost decrease from now
        //minSteps = 1;

        // This method subdivides view space / object space 
        // in order to converge to some optimal cost for this partition
        // start with object space partiton
        // then optimizate view space partition for the current osp
        // and vice versa until iteration depth is reached.

        while (!(viewSpaceQueue.Empty() && objectSpaceQueue.Empty()))
        {
                const float vspPriority = viewSpaceQueue.Empty() ? 0 : viewSpaceQueue.Top()->GetPriority();
                const float ospPriority = objectSpaceQueue.Empty() ? 0 : objectSpaceQueue.Top()->GetPriority();

                cout << "new decicion, vsp: " << vspPriority << ", osp: " << ospPriority << endl;

                // should view or object space be subdivided further?
                if (ospPriority >= vspPriority)
                {
                        // use splits of one kind until rendercost decrease of other domain is reached
                        renderCostDecr = vspPriority;
                        cout << "comparing with this render cost: " << renderCostDecr << endl;
                        // dirtied view space candidates
                        SubdivisionCandidateContainer dirtyVspList;

                        // subdivide object space first
                        // for first round, use sah splits. Once view space partition
                        // has started, use render cost heuristics instead
                        const int ospSteps = 
                                RunConstruction(objectSpaceQueue, dirtyVspList, renderCostDecr, minSteps);

                        cout << "\n" << ospSteps << " object space partition steps taken" << endl;
                
                        /// Repair split queue, i.e., affected view space candidates
                        cout << "repairing queue ... " << endl;
                        RepairQueue(dirtyVspList, viewSpaceQueue, true);
                        cout << "\nrepaired " << (int)dirtyVspList.size() << " candidates" << endl;
                }
                else
                {
                        // use splits of one kind until rendercost slope is reached
                        renderCostDecr = ospPriority;
                        cout << "comparing with this render cost: " << renderCostDecr << endl;

                        /////////////////
                        // subdivide view space with respect to the objects

                        SubdivisionCandidateContainer dirtyOspList;

                        // process view space candidates
                        const int vspSteps = 
                                RunConstruction(viewSpaceQueue, dirtyOspList, renderCostDecr, minSteps);

                        cout << "\n" << vspSteps << " view space partition steps taken" << endl;

                        // view space subdivision constructed
                        mViewSpaceSubdivisionType = mSavedViewSpaceSubdivisionType;

                        /// Repair split queue
                        cout << "repairing queue ... " << endl;
                        RepairQueue(dirtyOspList, objectSpaceQueue, true);
                        cout << "repaired " << (int)dirtyOspList.size() << " candidates" << endl;
                }
        }

        cout << "\nfinished in " << TimeDiff(startTime, GetTime()) * 1e-3 << " secs" << endl;

        mHierarchyStats.Stop();
        mVspTree->mVspStats.Stop();

        FinishObjectSpaceSubdivision(objects);
}


void HierarchyManager::ConstructInterleaved(const VssRayContainer &sampleRays,
                                                                                        const ObjectContainer &objects,
                                                                                        AxisAlignedBox3 *forcedViewSpace)
{
        mHierarchyStats.Reset();
        mHierarchyStats.Start();
        mHierarchyStats.mNodes = 2; // two nodes for view space and object space
        mHierarchyStats.mPvsEntries = 1;
        mHierarchyStats.mMemory = sizeof(PvsData) + sizeof(Intersectable *) / (1024.0f * 1024.0f);
        mHierarchyStats.mTotalCost = (float)objects.size();

        mHierarchyStats.mRenderCostDecrease = 0;

        EvalSubdivisionStats();
        Debug << "setting total cost to " << mHierarchyStats.mTotalCost << endl;

        const long startTime = GetTime();
        cout << "Constructing view space / object space tree ... \n";
        
        // create only roots
        mVspTree->Initialise(sampleRays, forcedViewSpace);
        InitialiseObjectSpaceSubdivision(objects);

        // use objects for evaluating vsp tree construction in the 
        // first levels of the subdivision
        mSavedObjectSpaceSubdivisionType = mObjectSpaceSubdivisionType;
        mObjectSpaceSubdivisionType = NO_OBJ_SUBDIV;

        mSavedViewSpaceSubdivisionType = mViewSpaceSubdivisionType;
        mViewSpaceSubdivisionType = NO_VIEWSPACE_SUBDIV;

        // start view space subdivison immediately?
        if (StartViewSpaceSubdivision())
        {
                // prepare vsp tree for traversal
        mViewSpaceSubdivisionType = mSavedViewSpaceSubdivisionType;
                SubdivisionCandidate *vspSc = 
                        PrepareViewSpaceSubdivision(sampleRays, objects);

                mTQueue.Push(vspSc);
        }
        
        // start object space subdivision immediately?
        if (StartObjectSpaceSubdivision())
        {
                mObjectSpaceSubdivisionType = mSavedObjectSpaceSubdivisionType;
                SubdivisionCandidate *ospSc =
                        PrepareObjectSpaceSubdivision(sampleRays, objects);
                mTQueue.Push(ospSc);
        }

        // begin subdivision
        RunConstruction(mRepairQueue, 
                                        sampleRays, 
                                        objects, 
                                        forcedViewSpace);
        
        cout << "\nfinished in " << TimeDiff(startTime, GetTime()) * 1e-3 << " secs" << endl;

        mObjectSpaceSubdivisionType = mSavedObjectSpaceSubdivisionType;
        mViewSpaceSubdivisionType = mSavedViewSpaceSubdivisionType;

        mHierarchyStats.Stop();
        mVspTree->mVspStats.Stop();
        FinishObjectSpaceSubdivision(objects);
}


SubdivisionCandidate *HierarchyManager::PrepareViewSpaceSubdivision(const VssRayContainer &sampleRays,
                                                                                                                                        const ObjectContainer &objects)
{
        cout << "\npreparing view space hierarchy construction ... " << endl;

        // hack: reset global cost misses
        mHierarchyStats.mGlobalCostMisses = 0;

        RayInfoContainer *viewSpaceRays = new RayInfoContainer();
        SubdivisionCandidate *vsc = 
                mVspTree->PrepareConstruction(sampleRays, *viewSpaceRays);

        mHierarchyStats.mTotalCost = mVspTree->mTotalCost;
        cout << "\nreseting cost for vsp, new total cost: " << mHierarchyStats.mTotalCost << endl;

        return vsc;
}


float HierarchyManager::GetObjectSpaceMemUsage() const
{
        if (mObjectSpaceSubdivisionType == KD_BASED_OBJ_SUBDIV)
        {
                // TODO;
        }
        else if (mObjectSpaceSubdivisionType == BV_BASED_OBJ_SUBDIV)
        {
                return mBvHierarchy->GetMemUsage();
        }

        return -1;
}

void HierarchyManager::InitialiseObjectSpaceSubdivision(const ObjectContainer &objects)
{
        if (mObjectSpaceSubdivisionType == KD_BASED_OBJ_SUBDIV)
        {
                // TODO;
        }
        else if (mObjectSpaceSubdivisionType == BV_BASED_OBJ_SUBDIV)
        {
                mBvHierarchy->Initialise(objects);
        }
}


SubdivisionCandidate *HierarchyManager::PrepareObjectSpaceSubdivision(const VssRayContainer &sampleRays,
                                                                                                                                          const ObjectContainer &objects)
{
        // hack: reset global cost misses
        mHierarchyStats.mGlobalCostMisses = 0;

        if (mObjectSpaceSubdivisionType == KD_BASED_OBJ_SUBDIV)
        {
                return PrepareOspTree(sampleRays, objects);
        }
        else if (mObjectSpaceSubdivisionType == BV_BASED_OBJ_SUBDIV)
        {
                return PrepareBvHierarchy(sampleRays, objects);
        }
        
        return NULL;
}


SubdivisionCandidate *HierarchyManager::PrepareBvHierarchy(const VssRayContainer &sampleRays,
                                                                                                                   const ObjectContainer &objects)
{
        const long startTime = GetTime();

        cout << "preparing bv hierarchy construction ... " << endl;
        
        // compute first candidate
        SubdivisionCandidate *sc =
                mBvHierarchy->PrepareConstruction(sampleRays, objects);

        mHierarchyStats.mTotalCost = mBvHierarchy->mTotalCost;
        Debug << "\nreseting cost, new total cost: " << mHierarchyStats.mTotalCost << endl;

        cout << "finished bv hierarchy preparation in " 
                 << TimeDiff(startTime, GetTime()) * 1e-3 << " secs" << endl;
         
        return sc;
}


SubdivisionCandidate *HierarchyManager::PrepareOspTree(const VssRayContainer &sampleRays,
                                                                                                           const ObjectContainer &objects)
{
        cout << "starting osp tree construction ... " << endl;

        RayInfoContainer *objectSpaceRays = new RayInfoContainer();

        // start with one big kd cell - all objects can be seen from everywhere
        // note: only true for view space = object space

        // compute first candidate
        SubdivisionCandidate *osc =
                mOspTree->PrepareConstruction(sampleRays, objects, *objectSpaceRays);

        mHierarchyStats.mTotalCost = mOspTree->mTotalCost;
        Debug << "\nreseting cost for osp, new total cost: " << mHierarchyStats.mTotalCost << endl;
        
    return osc;
}


bool HierarchyManager::ApplySubdivisionCandidate(SubdivisionCandidate *sc, 
                                                                                                 SplitQueue &splitQueue,
                                                                                                 const bool repairQueue)
{
        const bool terminationCriteriaMet = GlobalTerminationCriteriaMet(sc);

        const bool success = sc->Apply(splitQueue, terminationCriteriaMet);

        if (!success) // split was not taken
        {
                return false;
        }

        ///////////////
        //-- split was successful => update stats and queue

    // cost ratio of cost decrease / totalCost
        const float costRatio = sc->GetRenderCostDecrease() / mHierarchyStats.mTotalCost;
        //Debug << "ratio: " << costRatio << " min ratio: " << mTermMinGlobalCostRatio << endl;
        
        if (costRatio < mTermMinGlobalCostRatio)
        {
                ++ mHierarchyStats.mGlobalCostMisses;
        }
        
        cout << sc->Type() << " ";
                
        /////////////
        // update stats

        mHierarchyStats.mNodes += 2;
        mHierarchyStats.mTotalCost -= sc->GetRenderCostDecrease();

        const int pvsEntriesIncr = sc->GetPvsEntriesIncr();
        mHierarchyStats.mPvsEntries += pvsEntriesIncr;
        //cout << "pvs entries: " << pvsEntriesIncr << " " << mHierarchyStats.pvsEntries << endl;

        const int sizeOfEntry = sizeof(PvsData) + sizeof(Intersectable *);
        // memory size in byte
        mHierarchyStats.mMemory += float(pvsEntriesIncr * sizeOfEntry);
        mHierarchyStats.mRenderCostDecrease = sc->GetRenderCostDecrease();

        // output stats
        EvalSubdivisionStats();
                
        if (repairQueue) 
        {
                // reevaluate candidates affected by the split for view space splits, 
                // this would be object space splits and other way round
                vector<SubdivisionCandidate *> dirtyList;
                sc->CollectDirtyCandidates(dirtyList, false);

                RepairQueue(dirtyList, splitQueue, mRecomputeSplitPlaneOnRepair);
        }

        return true;
}


int HierarchyManager::GetObjectSpaceSubdivisionDepth() const
{
        int maxDepth = 0;

        if (mObjectSpaceSubdivisionType == KD_BASED_OBJ_SUBDIV)
        {
                maxDepth = mOspTree->mOspStats.maxDepth;
        }
        else if (mObjectSpaceSubdivisionType == BV_BASED_OBJ_SUBDIV)
        {
                maxDepth = mBvHierarchy->mBvhStats.maxDepth;
        }

        return maxDepth;
}


int HierarchyManager::GetObjectSpaceSubdivisionLeaves() const
{
        int maxLeaves= 0;

        if (mObjectSpaceSubdivisionType == KD_BASED_OBJ_SUBDIV)
        {
                maxLeaves = mOspTree->mOspStats.Leaves();
        }
        else if (mObjectSpaceSubdivisionType == BV_BASED_OBJ_SUBDIV)
        {
                maxLeaves = mBvHierarchy->mBvhStats.Leaves();
        }

        return maxLeaves;
}


bool HierarchyManager::StartObjectSpaceSubdivision() const
{
        // view space construction already started
        if (ObjectSpaceSubdivisionConstructed())
                return false;

        // start immediately with object space subdivision?
        if (mStartWithObjectSpace)
                return true;

        // is the queue empty again?
        if (ViewSpaceSubdivisionConstructed() && mTQueue.Empty())
                return true;

        // has the depth for subdivision been reached?
        return 
                ((mConstructionType == INTERLEAVED) && 
                 (mMinStepsOfSameType <= mVspTree->mVspStats.nodes));
}


bool HierarchyManager::StartViewSpaceSubdivision() const
{
        // view space construction already started
        if (ViewSpaceSubdivisionConstructed())
                return false;

        // start immediately with view space subdivision?
        if (!mStartWithObjectSpace)
                return true;

        // is the queue empty again?
        if (ObjectSpaceSubdivisionConstructed() && mTQueue.Empty())
                return true;

        // has the depth for subdivision been reached?
        return 
                ((mConstructionType == INTERLEAVED) && 
                 (mMinStepsOfSameType <= GetObjectSpaceSubdivisionLeaves()));
}


void HierarchyManager::RunConstruction(const bool repairQueue,
                                                                           const VssRayContainer &sampleRays,
                                                                           const ObjectContainer &objects,
                                                                           AxisAlignedBox3 *forcedViewSpace)
{
        while (!FinishedConstruction())
        {
                SubdivisionCandidate *sc = NextSubdivisionCandidate(mTQueue);    
        
                ///////////////////
                //-- subdivide leaf node

                ApplySubdivisionCandidate(sc, mTQueue, repairQueue);
                                
                // we use objects for evaluating vsp tree construction until 
                // a certain depth once a certain depth existiert ...
                if (StartObjectSpaceSubdivision())
                {
                        mObjectSpaceSubdivisionType = mSavedObjectSpaceSubdivisionType;

                        cout << "\nstarting object space subdivision after " 
                                 << mVspTree->mVspStats.nodes << " (" 
                                 << mMinStepsOfSameType << ") " << endl;

                        SubdivisionCandidate *ospSc = PrepareObjectSpaceSubdivision(sampleRays, objects);
                        
                        cout << "reseting queue ... ";
                        ResetQueue(mTQueue, mRecomputeSplitPlaneOnRepair);
                        cout << "finished" << endl;

                        mTQueue.Push(ospSc);
                }

                if (StartViewSpaceSubdivision())
                {
                        mViewSpaceSubdivisionType = mSavedViewSpaceSubdivisionType;

                        cout << "\nstarting view space subdivision at depth " 
                                 << GetObjectSpaceSubdivisionLeaves() << " (" 
                                 << mMinStepsOfSameType << ") " << endl;

                        SubdivisionCandidate *vspSc = PrepareViewSpaceSubdivision(sampleRays, objects);

                        cout << "reseting queue ... ";
                        ResetQueue(mTQueue, mRecomputeSplitPlaneOnRepair);
                        cout << "finished" << endl;

                        // push view space candidate                    
                        mTQueue.Push(vspSc);
                }

                DEL_PTR(sc);
        }
}


void HierarchyManager::RunConstruction(const bool repairQueue)
{
        // main loop
        while (!FinishedConstruction())
        {
                SubdivisionCandidate *sc = NextSubdivisionCandidate(mTQueue);    
                cout << "p=" << sc->GetPriority() << " ";

                ////////
                //-- subdivide leaf node of either type
        ApplySubdivisionCandidate(sc, mTQueue, repairQueue);
        //cout << "\nhere45 " << sc->GetPriority() << " " << sc->GetRenderCostDecrease() << " " << mObjectSpaceSubdivisionType << " " << mViewSpaceSubdivisionType << endl;
                
                DEL_PTR(sc);
        }
}


int HierarchyManager::RunConstruction(SplitQueue &splitQueue,
                                                                          SubdivisionCandidateContainer &dirtyCandidates,
                                                                          const float minRenderCostDecr,
                                                                          const int minSteps)
{
        int steps = 0;
        SubdivisionCandidate::NewMail();

        // main loop
        while (!splitQueue.Empty())
        {
                SubdivisionCandidate *sc = NextSubdivisionCandidate(splitQueue); 
                
                // minimum slope reached
                if ((sc->GetRenderCostDecrease() < minRenderCostDecr) &&
                        !(steps < minSteps))
                {
                        cout << "breaking on " << sc->GetRenderCostDecrease() << " smaller than " << minRenderCostDecr << endl;
                        break;
                }
                ////////
                //-- subdivide leaf node of either type

                const bool repairQueue = false;
                const bool success = ApplySubdivisionCandidate(sc, splitQueue, repairQueue);

                if (success)
                {
                        sc->CollectDirtyCandidates(dirtyCandidates, true);
                        //cout << "collected " << dirtyCandidates.size() << "dirty candidates" << endl;
                        ++ steps;
                }
        }

        return steps;
}


SubdivisionCandidate *HierarchyManager::ResetObjectSpaceSubdivision(const VssRayContainer &sampleRays, 
                                                                                                                                        const ObjectContainer &objects)
{       
        SubdivisionCandidate *firstCandidate;

        // object space partition constructed => reconstruct
        switch (mObjectSpaceSubdivisionType)
        {
        case BV_BASED_OBJ_SUBDIV:
                {
                        cout << "\nreseting bv hierarchy" << endl;
                        Debug << "old bv hierarchy:\n " << mBvHierarchy->mBvhStats << endl;

                        mBvHierarchy->Initialise(objects);

                        // rather use this: remove previous nodes and add the two new ones
                        //mHierarchyStats.mNodes -= mBvHierarchy->mBvhStats.nodes + 2;
                        mHierarchyStats.mNodes = 2;

                        firstCandidate = mBvHierarchy->Reset(sampleRays, objects);
                
                        mHierarchyStats.mTotalCost = mBvHierarchy->mTotalCost;
                        mHierarchyStats.mRenderCostDecrease = 0;

                        // bug!! pvs entries cab be much higher at this stage
                        // (if view space was already subdivided)
                        mHierarchyStats.mPvsEntries = 1;
                        mHierarchyStats.mMemory = sizeof(PvsData) + sizeof(Intersectable *) / (1024.0f * 1024.0f);

                        // evaluate stats before first subdivision
                        EvalSubdivisionStats();
                }
                break;

        case KD_BASED_OBJ_SUBDIV:
                // TODO
        default:
                firstCandidate = NULL;
                break;
        }

        return firstCandidate;
}


SubdivisionCandidate *HierarchyManager::ResetViewSpaceSubdivision(const VssRayContainer &sampleRays, 
                                                                                                                                  const ObjectContainer &objects,
                                                                                                                                  AxisAlignedBox3 *forcedViewSpace)
{
        ViewCellsManager *vc = mVspTree->mViewCellsManager;

        // HACK: rather not destroy vsp tree
        DEL_PTR(mVspTree);
        mVspTree = new VspTree();
        mVspTree->mHierarchyManager = this;

        mVspTree->Initialise(sampleRays, forcedViewSpace);
        
        SubdivisionCandidate *vsc = 
                PrepareViewSpaceSubdivision(sampleRays, objects);
        
        mHierarchyStats.mNodes = 2;
        // bug!! pvs entries could be much higher at this stage
        mHierarchyStats.mPvsEntries = 1;
        mHierarchyStats.mRenderCostDecrease = 0;

        // evaluate new stats before first subdivsiion
        EvalSubdivisionStats();

        return vsc;
}


void HierarchyManager::ConstructMultiLevel(const VssRayContainer &sampleRays,                                                                                    
                                                                                   const ObjectContainer &objects,
                                                                                   AxisAlignedBox3 *forcedViewSpace)
{
        mHierarchyStats.Reset();
        mHierarchyStats.Start();
        mHierarchyStats.mNodes = 2;
        
        mHierarchyStats.mTotalCost = (float)objects.size();
        Debug << "setting total cost to " << mHierarchyStats.mTotalCost << endl;

        const long startTime = GetTime();
        cout << "Constructing view space / object space tree ... \n";
        
        // initialise view / object space
        mVspTree->Initialise(sampleRays, forcedViewSpace);
        InitialiseObjectSpaceSubdivision(objects);

        // use sah for evaluating osp tree construction 
        // in the first iteration of the subdivision

        mSavedViewSpaceSubdivisionType = mViewSpaceSubdivisionType;
        mViewSpaceSubdivisionType = NO_VIEWSPACE_SUBDIV;

        SubdivisionCandidate *osc = 
                PrepareObjectSpaceSubdivision(sampleRays, objects);
        mTQueue.Push(osc);

        //////////////////////////7


        const int limit = mNumMultiLevels;
        int i = 0;

        // This method subdivides view space / object space 
        // in order to converge to some optimal cost for this partition
        // start with object space partiton
        // then optimizate view space partition for the current osp
        // and vice versa until iteration depth is reached.
        while (1)
        {
                char subdivisionStatsLog[100];
                sprintf(subdivisionStatsLog, "tests/i3d/subdivision-%04d.log", i);
                mSubdivisionStats.open(subdivisionStatsLog);

                // subdivide object space first
                osc = ResetObjectSpaceSubdivision(sampleRays, objects);
                mTQueue.Push(osc);

                // process object space candidates
                RunConstruction(false);

                // object space subdivision constructed
                mObjectSpaceSubdivisionType = mSavedObjectSpaceSubdivisionType;

                cout << "iteration " << i << " of " << limit << " finished" << endl;

                mSubdivisionStats.close();

                if ((i ++) >= limit)
                        break;

                sprintf(subdivisionStatsLog, "tests/i3d/subdivision-%04d.log", i);
                mSubdivisionStats.open(subdivisionStatsLog);

                /////////////////
                // subdivide view space with respect to the objects

                SubdivisionCandidate *vspVc = ResetViewSpaceSubdivision(sampleRays, objects, forcedViewSpace);
                mTQueue.Push(vspVc);

                // view space subdivision constructed
                mViewSpaceSubdivisionType = mSavedViewSpaceSubdivisionType;
                
                // process view space candidates
                RunConstruction(false);

                cout << "iteration " << i << " of " << limit << " finished" << endl;

                mSubdivisionStats.close();

                if ((i ++) >= limit)
                        break;
        }
        
        cout << "\nfinished in " << TimeDiff(startTime, GetTime()) * 1e-3 << " secs" << endl;

        mHierarchyStats.Stop();
        mVspTree->mVspStats.Stop();
        FinishObjectSpaceSubdivision(objects);
}


void HierarchyManager::OptimizeMultiLevel(const VssRayContainer &sampleRays,                                                                                     
                                                                                  const ObjectContainer &objects,
                                                                                  AxisAlignedBox3 *forcedViewSpace)
{
        // assume object space subdivision constructed
        //mObjectSpaceSubdivisionType = mSavedObjectSpaceSubdivisionType;

        // set the number of leaves 'evaluated' from the previous methods
        // we go for the same numbers, but we try to optimize both
        // subdivisions
        switch (mObjectSpaceSubdivisionType)
        {
        case BV_BASED_OBJ_SUBDIV:
                mBvHierarchy->mTermMaxLeaves = mBvHierarchy->mBvhStats.Leaves();
                break;
        case KD_BASED_OBJ_SUBDIV:
                mOspTree->mTermMaxLeaves = mOspTree->mOspStats.Leaves();
        default:
                break;
        }
        
        mVspTree->mMaxViewCells = mVspTree->mVspStats.Leaves();

        const long startTime = GetTime();
        const int limit = mNumMultiLevels;

        // open up new subdivision
        mSubdivisionStats.close();

        int steps = 0;

        // This method subdivides view space / object space 
        // in order to converge to some optimal cost for this partition
        // start with object space partiton
        // then optimizate view space partition for the current osp
        // and vice versa until iteration depth is reached.
        while (1)
        {
                char subdivisionStatsLog[100];
                sprintf(subdivisionStatsLog, "tests/i3d/subdivision-%04d.log", steps);
                mSubdivisionStats.open(subdivisionStatsLog);

                // subdivide object space first
                SubdivisionCandidate *ospVc = 
                        ResetObjectSpaceSubdivision(sampleRays, objects);
                mTQueue.Push(ospVc);

                // process object space candidates
                RunConstruction(false);

                cout << "iteration " << steps << " of " << limit << " finished" << endl;

                mSubdivisionStats.close();

                if ((++ steps) >= limit)
                        break;

                sprintf(subdivisionStatsLog, "tests/i3d/subdivision-%04d.log", steps);
                mSubdivisionStats.open(subdivisionStatsLog);

                /////////////////
                // subdivide view space with respect to the objects

                SubdivisionCandidate *vspVc = 
                        ResetViewSpaceSubdivision(sampleRays, objects, forcedViewSpace);
                mTQueue.Push(vspVc);

                // process view space candidates
                RunConstruction(false);

                cout << "iteration " << steps << " of " << limit << " finished" << endl;

                mSubdivisionStats.close();

                if ((++ steps) >= limit)
                        break;
        }
        
        cout << "\nfinished in " << TimeDiff(startTime, GetTime()) * 1e-3 << " secs" << endl;

        mHierarchyStats.Stop();
        mVspTree->mVspStats.Stop();
        FinishObjectSpaceSubdivision(objects);
}



bool HierarchyManager::FinishedConstruction() const
{
        return mTQueue.Empty();
}


bool HierarchyManager::ObjectSpaceSubdivisionConstructed() const
{
        /*switch (mObjectSpaceSubdivisionType)
        {
        case KD_BASED_OBJ_SUBDIV:
                return mOspTree && mOspTree->GetRoot();
        case BV_BASED_OBJ_SUBDIV:
                return mBvHierarchy && mBvHierarchy->GetRoot();
        default:
                return false;
        }*/
        return mObjectSpaceSubdivisionType != NO_OBJ_SUBDIV;
}


bool HierarchyManager::ViewSpaceSubdivisionConstructed() const
{
        return mViewSpaceSubdivisionType != NO_VIEWSPACE_SUBDIV;
        //return mVspTree && mVspTree->GetRoot();
}


void HierarchyManager::CollectDirtyCandidates(const SubdivisionCandidateContainer &chosenCandidates, 
                                                                                          SubdivisionCandidateContainer &dirtyList)
{
        SubdivisionCandidateContainer::const_iterator sit, sit_end = chosenCandidates.end();
        SubdivisionCandidate::NewMail();

        for (sit = chosenCandidates.begin(); sit != sit_end; ++ sit)
        {
                (*sit)->CollectDirtyCandidates(dirtyList, true);
        }
}


void HierarchyManager::RepairQueue(const SubdivisionCandidateContainer &dirtyList, 
                                                                   SplitQueue &splitQueue,
                                                                   const bool recomputeSplitPlaneOnRepair)
{
        // for each update of the view space partition:
        // the candidates from object space partition which
        // have been afected by the view space split (the kd split candidates
        // which saw the view cell which was split) must be reevaluated 
        // (maybe not locally, just reinsert them into the queue)
        //
        // vice versa for the view cells
        // for each update of the object space partition
        // reevaluate split candidate for view cells which saw the split kd cell
        // 
        // the priority queue update can be solved by implementing a binary heap
        // (explicit data structure, binary tree)
        // *) inserting and removal is efficient
        // *) search is not efficient => store queue position with each
        // split candidate

        // collect list of "dirty" candidates
        const long startTime = GetTime();
        if (0) cout << "repairing " << (int)dirtyList.size() << " candidates ... ";
        

        /////////////////////////////////
        //-- reevaluate the dirty list

        SubdivisionCandidateContainer::const_iterator sit, sit_end = dirtyList.end();
        
        for (sit = dirtyList.begin(); sit != sit_end; ++ sit)
        {
                SubdivisionCandidate* sc = *sit;
                const float rcd = sc->GetRenderCostDecrease();
                
                splitQueue.Erase(sc); // erase from queue
                sc->EvalPriority(recomputeSplitPlaneOnRepair); // reevaluate
                
#ifdef _DEBUG
                Debug << "candidate " << sc << " reevaluated\n" 
                          << "render cost decrease diff " <<  rcd - sc->GetRenderCostDecrease()
                          << " old: " << rcd << " new " << sc->GetRenderCostDecrease() << endl;
#endif  
                splitQueue.Push(sc); // reinsert
                cout << ".";
        }

        const long endTime = GetTime();
        const Real timeDiff = TimeDiff(startTime, endTime);

        mHierarchyStats.mRepairTime += timeDiff;

        if (0) cout << "repaired in " << timeDiff * 1e-3f << " secs" << endl;
}


void HierarchyManager::ResetQueue(SplitQueue &splitQueue, const bool recomputeSplitPlane)
{
        SubdivisionCandidateContainer mCandidateBuffer;

        // remove from queue
        while (!splitQueue.Empty())
        {
                SubdivisionCandidate *candidate = NextSubdivisionCandidate(splitQueue);
                 // reevaluate local split plane and priority
                candidate->EvalPriority(recomputeSplitPlane);
                cout << ".";
                mCandidateBuffer.push_back(candidate);
        }

        // put back into queue
        SubdivisionCandidateContainer::const_iterator sit, sit_end = mCandidateBuffer.end();
    for (sit = mCandidateBuffer.begin(); sit != sit_end; ++ sit)
        {
                splitQueue.Push(*sit);
        }
}


void HierarchyManager::ExportObjectSpaceHierarchy(OUT_STREAM &stream)
{
        // the type of the view cells hierarchy
        switch (mObjectSpaceSubdivisionType)
        {
        case KD_BASED_OBJ_SUBDIV:
                stream << "<ObjectSpaceHierarchy type=\"osp\">" << endl;
                mOspTree->Export(stream);
                stream << endl << "</ObjectSpaceHierarchy>" << endl;
                break;          
        case BV_BASED_OBJ_SUBDIV:
                stream << "<ObjectSpaceHierarchy type=\"bvh\">" << endl;
                mBvHierarchy->Export(stream);
                stream << endl << "</ObjectSpaceHierarchy>" << endl;
                break;
        }
}


bool HierarchyManager::AddSampleToPvs(Intersectable *obj, 
                                                                          const Vector3 &hitPoint,
                                                                          ViewCell *vc,
                                                                          const float pdf, 
                                                                          float &contribution) const
{
        if (!obj) return false;

        switch (mObjectSpaceSubdivisionType)
        {
        case NO_OBJ_SUBDIV:
                {
                        // potentially visible objects
                        return vc->AddPvsSample(obj, pdf, contribution);
                }
        case KD_BASED_OBJ_SUBDIV:
                {
                        // potentially visible kd cells
                        KdLeaf *leaf = mOspTree->GetLeaf(hitPoint/*ray->mOriginNode*/);
                        return mOspTree->AddLeafToPvs(leaf, vc, pdf, contribution);
                }
        case BV_BASED_OBJ_SUBDIV:
                {
                        BvhLeaf *leaf = mBvHierarchy->GetLeaf(obj);
                        BvhIntersectable *bvhObj = mBvHierarchy->GetOrCreateBvhIntersectable(leaf);
                        
                        return vc->AddPvsSample(bvhObj, pdf, contribution);
                }
        default:
                return false;
        }
}


void HierarchyManager::PrintHierarchyStatistics(ostream &stream) const
{
        stream << mHierarchyStats << endl;
        stream << "\nview space:" << endl << endl;
        stream << mVspTree->GetStatistics() << endl;
        stream << "\nobject space:" << endl << endl;

        switch (mObjectSpaceSubdivisionType)
        {
        case KD_BASED_OBJ_SUBDIV:
                {
                        stream << mOspTree->GetStatistics() << endl;
                        break;
                }
        case BV_BASED_OBJ_SUBDIV:
                {
                        stream << mBvHierarchy->GetStatistics() << endl;
                        break;
                }
        default:
                break;
        }
}


void HierarchyManager::ExportObjectSpaceHierarchy(Exporter *exporter,
                                                                                                  const ObjectContainer &objects,
                                                                                                  const AxisAlignedBox3 *bbox,
                                                                                                  const bool exportBounds) const
{
        switch (mObjectSpaceSubdivisionType)
        {
        case KD_BASED_OBJ_SUBDIV:
                {
                        ExportOspTree(exporter, objects);
                        break;
                }
        case BV_BASED_OBJ_SUBDIV:
                {
                        exporter->ExportBvHierarchy(*mBvHierarchy, 0, bbox, exportBounds);
                        break;
                }
        default:
                break;
        }
}


void HierarchyManager::ExportOspTree(Exporter *exporter, 
                                                                         const ObjectContainer &objects) const
{
        if (0) exporter->ExportGeometry(objects);
                        
        exporter->SetWireframe();
        exporter->ExportOspTree(*mOspTree, 0);
}


Intersectable *HierarchyManager::GetIntersectable(const VssRay &ray, 
                                                                                                  const bool isTermination) const
{

        Intersectable *obj;
        Vector3 pt;
        KdNode *node;

        ray.GetSampleData(isTermination, pt, &obj, &node);
        
        if (!obj) return NULL;

        switch (mObjectSpaceSubdivisionType)
        {
        case HierarchyManager::KD_BASED_OBJ_SUBDIV:
                {
                        KdLeaf *leaf = mOspTree->GetLeaf(pt, node);
                        return mOspTree->GetOrCreateKdIntersectable(leaf);
                }
        case HierarchyManager::BV_BASED_OBJ_SUBDIV:
                {
                        BvhLeaf *leaf = mBvHierarchy->GetLeaf(obj);
                        return mBvHierarchy->GetOrCreateBvhIntersectable(leaf);
                }
        default:
                return obj;
        }
}


void HierarchyStatistics::Print(ostream &app) const
{
        app << "=========== Hierarchy statistics ===============\n";

        app << setprecision(4);

        app << "#N_CTIME  ( Construction time [s] )\n" << Time() << " \n";
        
        app << "#N_RTIME  ( Repair time [s] )\n" << mRepairTime * 1e-3f << " \n";

        app << "#N_NODES ( Number of nodes )\n" << mNodes << "\n";

        app << "#N_INTERIORS ( Number of interior nodes )\n" << Interior() << "\n";

        app << "#N_LEAVES ( Number of leaves )\n" << Leaves() << "\n";

        app << "#N_PMAXDEPTH ( Maximal reached depth )\n" << mMaxDepth << endl;

        app << "#N_GLOBALCOSTMISSES ( Global cost misses )\n" << mGlobalCostMisses << endl;
        
        app << "========== END OF Hierarchy statistics ==========\n";
}


static void RemoveRayRefs(const ObjectContainer &objects)
{
        ObjectContainer::const_iterator oit, oit_end = objects.end();
        for (oit = objects.begin(); oit != oit_end; ++ oit)
        {
                (*oit)->mVssRays.clear();
        }
}


void HierarchyManager::FinishObjectSpaceSubdivision(const ObjectContainer &objects) const
{
        switch (mObjectSpaceSubdivisionType)
        {
        case KD_BASED_OBJ_SUBDIV:
                {
                        mOspTree->mOspStats.Stop();
                        break;
                }
        case BV_BASED_OBJ_SUBDIV:
                {
                        mBvHierarchy->mBvhStats.Stop();
                        RemoveRayRefs(objects);
                        break;
                }
        default:
                break;
        }
}


void HierarchyManager::ExportBoundingBoxes(OUT_STREAM &stream, const ObjectContainer &objects)
{
        stream << "<BoundingBoxes>" << endl;
            
        if (mObjectSpaceSubdivisionType == KD_BASED_OBJ_SUBDIV)
        {
                KdIntersectableMap::const_iterator kit, kit_end = mOspTree->mKdIntersectables.end();

                int id = 0;
                for (kit = mOspTree->mKdIntersectables.begin(); kit != kit_end; ++ kit, ++ id)
                {
                        Intersectable *obj = (*kit).second;
                        const AxisAlignedBox3 box = obj->GetBox();
                
                        obj->SetId(id);

                        stream << "<BoundingBox" << " id=\"" << id << "\""
                                   << " min=\"" << box.Min().x << " " << box.Min().y << " " << box.Min().z << "\""
                                   << " max=\"" << box.Max().x << " " << box.Max().y << " " << box.Max().z << "\" />" << endl;
                }
        }
        else
        {
                ObjectContainer::const_iterator oit, oit_end = objects.end();

                for (oit = objects.begin(); oit != oit_end; ++ oit)
                {
                        const AxisAlignedBox3 box = (*oit)->GetBox();
                
                        stream << "<BoundingBox" << " id=\"" << (*oit)->GetId() << "\""
                                   << " min=\"" << box.Min().x << " " << box.Min().y << " " << box.Min().z << "\""
                                   << " max=\"" << box.Max().x << " " << box.Max().y << " " << box.Max().z << "\" />" << endl;
                }
        }
                
        stream << "</BoundingBoxes>" << endl;
}

}