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

#include "ViewCell.h"
#include "Plane3.h"
#include "VspTree.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 "KdIntersectable.h"
#include "HierarchyManager.h"
#include "BvHierarchy.h"
#include "OspTree.h"


namespace GtpVisibilityPreprocessor {


#define USE_FIXEDPOINT_T 0


//-- static members

VspTree *VspTree::VspSubdivisionCandidate::sVspTree = NULL;


// variable for debugging volume contribution for heuristics
static float debugVol;

int VspNode::sMailId = 1;

// pvs penalty can be different from pvs size
inline static float EvalPvsPenalty(const int pvs, 
								   const int lower,
								   const int upper)
{
	// clamp to minmax values
	if (pvs < lower)
	{
		return (float)lower;
	}
	else if (pvs > upper)
	{
		return (float)upper;
	}

	return (float)pvs;
}


static bool ViewCellHasMultipleReferences(Intersectable *obj, 
										  ViewCell *vc, 
										  bool checkOnlyMailed)
{
	MailablePvsData *vdata = obj->mViewCellPvs.Find(vc);
//return false;
	if (vdata)
	{
		// more than one view cell sees this object inside different kd cells
		if (!checkOnlyMailed || !vdata->Mailed())
		{
			if (checkOnlyMailed)
				vdata->Mail();
			//Debug << "sumpdf: " << vdata->mSumPdf << endl;
			if (vdata->mSumPdf > 1.5f) 
				return true;
		}
	}

	return false;
}


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

	app << setprecision(4);

	app << "#N_CTIME  ( Construction time [s] )\n" << Time() << " \n";

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

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

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

	app << "#AXIS_ALIGNED_SPLITS (number of axis aligned splits)\n" << splits[0] + splits[1] + splits[2] << endl;

	app << "#N_SPLITS ( Number of splits in axes x y z)\n";

	for (int i = 0; i < 3; ++ i)
		app << splits[i] << " ";
	app << endl;

	app << "#N_PMAXDEPTHLEAVES ( Percentage of leaves at maximum depth )\n" 
		<<	maxDepthNodes * 100 / (double)Leaves() << endl;

	app << "#N_PMINPVSLEAVES  ( Percentage of leaves with mininimal PVS )\n" 
		<< minPvsNodes * 100 / (double)Leaves() << endl;

	app << "#N_PMINRAYSLEAVES  ( Percentage of leaves with minimal number of rays)\n" 
		<< minRaysNodes * 100 / (double)Leaves() << endl;

	app << "#N_MAXCOSTNODES  ( Percentage of leaves with terminated because of max cost ratio )\n"
		<< maxCostNodes * 100 / (double)Leaves() << endl;

	app << "#N_PMINPROBABILITYLEAVES  ( Percentage of leaves with mininum probability )\n"
		<< minProbabilityNodes * 100 / (double)Leaves() << endl;

	app << "#N_PMAXRAYCONTRIBLEAVES  ( Percentage of leaves with maximal ray contribution )\n" 
		<<	maxRayContribNodes * 100 / (double)Leaves() << endl;

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

	app << "#N_PMINDEPTH ( Minimal reached depth )\n" << minDepth << endl;

	app << "#AVGDEPTH ( average depth )\n" << AvgDepth() << endl;

	app << "#N_INVALIDLEAVES (number of invalid leaves )\n" << invalidLeaves << endl;

	app << "#N_RAYS (number of rays / leaf)\n" << AvgRays() << endl;
	//app << "#N_PVS: " << pvs << endl;

	//app << "#N_MAXOBJECTREFS  ( Max number of object refs / leaf )\n" << maxObjectRefs << "\n";

	app << "========== END OF VspTree statistics ==========\n";
}



/******************************************************************/
/*                  class VspNode implementation                  */
/******************************************************************/


VspNode::VspNode(): 
mParent(NULL), mTreeValid(true), mTimeStamp(0)
{}


VspNode::VspNode(VspInterior *parent): 
mParent(parent), mTreeValid(true)
{}


bool VspNode::IsRoot() const 
{
	return mParent == NULL;
}


VspInterior *VspNode::GetParent() 
{ 
	return mParent; 
}


void VspNode::SetParent(VspInterior *parent)
{
	mParent = parent;
}


bool VspNode::IsSibling(VspNode *n) const
{
	return  ((this != n) && mParent && 
			 (mParent->GetFront() == n) || (mParent->GetBack() == n));
}


int VspNode::GetDepth() const
{
	int depth = 0;
	VspNode *p = mParent;
	
	while (p)
	{
		p = p->mParent;
		++ depth;
	}

	return depth;
}


bool VspNode::TreeValid() const
{
	return mTreeValid;
}


void VspNode::SetTreeValid(const bool v)
{
	mTreeValid = v;
}


/****************************************************************/
/*              class VspInterior implementation                */
/****************************************************************/


VspInterior::VspInterior(const AxisAlignedPlane &plane): 
mPlane(plane), mFront(NULL), mBack(NULL)
{}


VspInterior::~VspInterior() 
{ 
	DEL_PTR(mFront); 
	DEL_PTR(mBack);
}


bool VspInterior::IsLeaf() const
{ 
	return false; 
}


VspNode *VspInterior::GetBack() 
{
	return mBack;
}


VspNode *VspInterior::GetFront() 
{
	return mFront;
}


AxisAlignedPlane VspInterior::GetPlane() const
{
	return mPlane;
}


float VspInterior::GetPosition() const
{
	return mPlane.mPosition;
}


int VspInterior::GetAxis() const
{
	return mPlane.mAxis;
}


void VspInterior::ReplaceChildLink(VspNode *oldChild, VspNode *newChild) 
{
	if (mBack == oldChild)
		mBack = newChild;
	else
		mFront = newChild;
}


void VspInterior::SetupChildLinks(VspNode *front, VspNode *back) 
{
    mBack = back;
    mFront = front;
}


AxisAlignedBox3 VspInterior::GetBoundingBox() const
{
	return mBoundingBox;
}


void VspInterior::SetBoundingBox(const AxisAlignedBox3 &box)
{
	mBoundingBox = box;
}


int VspInterior::Type() const
{
	return Interior;
}



/****************************************************************/
/*                  class VspLeaf implementation                */
/****************************************************************/


VspLeaf::VspLeaf(): mViewCell(NULL), mPvs(NULL)
{
}


VspLeaf::~VspLeaf()
{
	DEL_PTR(mPvs);
	CLEAR_CONTAINER(mVssRays);
}


int VspLeaf::Type() const
{
	return Leaf;
}


VspLeaf::VspLeaf(ViewCellLeaf *viewCell): 
mViewCell(viewCell)
{
}


VspLeaf::VspLeaf(VspInterior *parent): 
VspNode(parent), mViewCell(NULL), mPvs(NULL)
{}



VspLeaf::VspLeaf(VspInterior *parent, ViewCellLeaf *viewCell): 
VspNode(parent), mViewCell(viewCell), mPvs(NULL)
{
}

ViewCellLeaf *VspLeaf::GetViewCell() const
{
	return mViewCell;
}

void VspLeaf::SetViewCell(ViewCellLeaf *viewCell)
{
	mViewCell = viewCell;
}


bool VspLeaf::IsLeaf() const 
{ 
	return true; 
}


/*************************************************************************/
/*                       class VspTree implementation                    */
/*************************************************************************/


VspTree::VspTree():
mRoot(NULL),
mOutOfBoundsCell(NULL),
mStoreRays(false),
mTimeStamp(1),
mHierarchyManager(NULL)
{
	bool randomize = false;
	Environment::GetSingleton()->GetBoolValue("VspTree.Construction.randomize", randomize);
	if (randomize)
		Randomize(); // initialise random generator for heuristics

	//-- termination criteria for autopartition
	Environment::GetSingleton()->GetIntValue("VspTree.Termination.maxDepth", mTermMaxDepth);
	Environment::GetSingleton()->GetIntValue("VspTree.Termination.minPvs", mTermMinPvs);
	Environment::GetSingleton()->GetIntValue("VspTree.Termination.minRays", mTermMinRays);
	Environment::GetSingleton()->GetFloatValue("VspTree.Termination.minProbability", mTermMinProbability);
	Environment::GetSingleton()->GetFloatValue("VspTree.Termination.maxRayContribution", mTermMaxRayContribution);
	
	Environment::GetSingleton()->GetIntValue("VspTree.Termination.missTolerance", mTermMissTolerance);
	Environment::GetSingleton()->GetIntValue("VspTree.Termination.maxViewCells", mMaxViewCells);

	//-- max cost ratio for early tree termination
	Environment::GetSingleton()->GetFloatValue("VspTree.Termination.maxCostRatio", mTermMaxCostRatio);

	Environment::GetSingleton()->GetFloatValue("VspTree.Termination.minGlobalCostRatio", mTermMinGlobalCostRatio);
	Environment::GetSingleton()->GetIntValue("VspTree.Termination.globalCostMissTolerance", mTermGlobalCostMissTolerance);

	//-- factors for bsp tree split plane heuristics
	Environment::GetSingleton()->GetFloatValue("VspTree.Termination.ct_div_ci", mCtDivCi);

	//-- partition criteria
	Environment::GetSingleton()->GetFloatValue("VspTree.Construction.epsilon", mEpsilon);
	Environment::GetSingleton()->GetFloatValue("VspTree.Construction.renderCostDecreaseWeight", mRenderCostDecreaseWeight);

	// if only the driving axis is used for axis aligned split
	Environment::GetSingleton()->GetBoolValue("VspTree.splitUseOnlyDrivingAxis", mOnlyDrivingAxis);
	
	Environment::GetSingleton()->GetIntValue("VspTree.maxTests", mMaxTests);
	Environment::GetSingleton()->GetFloatValue("VspTree.maxStaticMemory", mMaxMemory);

	Environment::GetSingleton()->GetBoolValue("VspTree.useCostHeuristics", mUseCostHeuristics);
	Environment::GetSingleton()->GetBoolValue("VspTree.simulateOctree", mCirculatingAxis);
	
	//Environment::GetSingleton()->GetBoolValue("VspTree.useKdPvsForHeuristics", mUseKdPvsForHeuristics);

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

	Environment::GetSingleton()->GetFloatValue("VspTree.Construction.minBand", mMinBand);
	Environment::GetSingleton()->GetFloatValue("VspTree.Construction.maxBand", mMaxBand);
	

	//-- debug output

	Debug << "******* VSP options ******** " << endl;

    Debug << "max depth: " << mTermMaxDepth << endl;
	Debug << "min PVS: " << mTermMinPvs << endl;
	Debug << "min probabiliy: " << mTermMinProbability << endl;
	Debug << "min rays: " << mTermMinRays << endl;
	Debug << "max ray contri: " << mTermMaxRayContribution << endl;
	Debug << "max cost ratio: " << mTermMaxCostRatio << endl;
	Debug << "miss tolerance: " << mTermMissTolerance << endl;
	Debug << "max view cells: " << mMaxViewCells << endl;
	Debug << "randomize: " << randomize << endl;

	Debug << "min global cost ratio: " << mTermMinGlobalCostRatio << endl;
	Debug << "global cost miss tolerance: " << mTermGlobalCostMissTolerance << endl;
	Debug << "only driving axis: " << mOnlyDrivingAxis << endl;
	Debug << "max memory: " << mMaxMemory << endl;
	Debug << "use cost heuristics: " << mUseCostHeuristics << endl;
	Debug << "subdivision stats log: " << subdivisionStatsLog << endl;
	Debug << "render cost decrease weight: " << mRenderCostDecreaseWeight << endl;

	Debug << "circulating axis: " << mCirculatingAxis << endl;
	Debug << "minband: " << mMinBand << endl;
	Debug << "maxband: " << mMaxBand << endl;

	mLocalSubdivisionCandidates = new vector<SortableEntry>;

	Debug << endl;
}


VspViewCell *VspTree::GetOutOfBoundsCell()
{
	return mOutOfBoundsCell;
}


VspViewCell *VspTree::GetOrCreateOutOfBoundsCell()
{
	if (!mOutOfBoundsCell)
	{
		mOutOfBoundsCell = new VspViewCell();
		mOutOfBoundsCell->SetId(-1);
		mOutOfBoundsCell->SetValid(false);
	}

	return mOutOfBoundsCell;
}


const VspTreeStatistics &VspTree::GetStatistics() const
{
	return mVspStats;
}


VspTree::~VspTree()
{
	DEL_PTR(mRoot);
	DEL_PTR(mLocalSubdivisionCandidates);
}


void VspTree::ComputeBoundingBox(const VssRayContainer &rays,
								 AxisAlignedBox3 *forcedBoundingBox) 
{	
	if (forcedBoundingBox)
	{
		mBoundingBox = *forcedBoundingBox;
	}
	else // compute vsp tree bounding box
	{
		mBoundingBox.Initialize();
		VssRayContainer::const_iterator rit, rit_end = rays.end();

		//-- compute bounding box
        for (rit = rays.begin(); rit != rit_end; ++ rit)
		{
			VssRay *ray = *rit;

			// compute bounding box of view space
			mBoundingBox.Include(ray->GetTermination());
			mBoundingBox.Include(ray->GetOrigin());
		}
	}
}


void VspTree::AddSubdivisionStats(const int viewCells,
								  const float renderCostDecr,
								  const float totalRenderCost,
								  const float avgRenderCost)
{
	mSubdivisionStats 
			<< "#ViewCells\n" << viewCells << endl
			<< "#RenderCostDecrease\n" << renderCostDecr << endl 
			<< "#TotalRenderCost\n" << totalRenderCost << endl
			<< "#AvgRenderCost\n" << avgRenderCost << endl;
}


// TODO: return memory usage in MB
float VspTree::GetMemUsage() const
{
	return (float)
		 (sizeof(VspTree) + 
		  mVspStats.Leaves() * sizeof(VspLeaf) + 
		  mCreatedViewCells * sizeof(VspViewCell) +
		  mVspStats.pvs * sizeof(PvsData) +
		  mVspStats.Interior() * sizeof(VspInterior) +
		  mVspStats.accumRays * sizeof(RayInfo)) / (1024.0f * 1024.0f);
}


inline bool VspTree::LocalTerminationCriteriaMet(const VspTraversalData &data) const
{
	const bool localTerminationCriteriaMet = (
		((int)data.mRays->size() <= mTermMinRays) ||
		(data.mPvs <= mTermMinPvs)   ||
		(data.mProbability <= mTermMinProbability) ||
		(data.GetAvgRayContribution() > mTermMaxRayContribution) ||
		(data.mDepth >= mTermMaxDepth)
		);

	if (0 && localTerminationCriteriaMet)
	{
		Debug << "********local termination *********" << endl;
		Debug << "rays: " << (int)data.mRays->size() << "  " << mTermMinRays << endl;
		Debug << "pvs: " << data.mPvs << " " << mTermMinPvs << endl;
		Debug << "p: " <<  data.mProbability << " " << mTermMinProbability << endl;
		Debug << "avg contri: " << data.GetAvgRayContribution() << " " << mTermMaxRayContribution << endl;
		Debug << "depth " << data.mDepth << " " << mTermMaxDepth << endl;
	}

	return localTerminationCriteriaMet;
		
}


inline bool VspTree::GlobalTerminationCriteriaMet(const VspTraversalData &data) const
{
	const bool terminationCriteriaMet = (
		// mOutOfMemory || 
		(mVspStats.Leaves() >= mMaxViewCells) || 
        (mGlobalCostMisses >= mTermGlobalCostMissTolerance) 
		);

	if (0 && terminationCriteriaMet)
	{
		Debug << "********* terminationCriteriaMet *********" << endl;
		Debug << "cost misses: " << mGlobalCostMisses << " " << mTermGlobalCostMissTolerance << endl;
		Debug << "leaves: " << mVspStats.Leaves() << " " <<  mMaxViewCells << endl;
	}
	return terminationCriteriaMet;
}


void VspTree::CreateViewCell(VspTraversalData &tData, const bool updatePvs)
{
	//-- create new view cell
	VspLeaf *leaf = dynamic_cast<VspLeaf *>(tData.mNode);
	
	VspViewCell *viewCell = new VspViewCell();
    leaf->SetViewCell(viewCell);
	
	int conSamp = 0;
	float sampCon = 0.0f;

	if (updatePvs)
	{
		//-- update pvs of view cell
		AddSamplesToPvs(leaf, *tData.mRays, sampCon, conSamp);

		// update scalar pvs size value
		ObjectPvs &pvs = viewCell->GetPvs();
		mViewCellsManager->UpdateScalarPvsSize(viewCell, pvs.CountObjectsInPvs(), pvs.GetSize());

		mVspStats.contributingSamples += conSamp;
		mVspStats.sampleContributions += (int)sampCon;
	}


	//-- store additional info
	if (mStoreRays)
	{
		RayInfoContainer::const_iterator it, it_end = tData.mRays->end();

		for (it = tData.mRays->begin(); it != it_end; ++ it)
		{
			(*it).mRay->Ref();			
			leaf->mVssRays.push_back((*it).mRay);
		}
	}
		
	// set view cell values
	viewCell->mLeaf = leaf;

	viewCell->SetVolume(tData.mProbability);
    leaf->mProbability = tData.mProbability;
}


void VspTree::EvalSubdivisionStats(const SubdivisionCandidate &sc)
{
	const float costDecr = sc.GetRenderCostDecrease();
	
	AddSubdivisionStats(mVspStats.Leaves(),
						costDecr,
						mTotalCost,
						(float)mTotalPvsSize / (float)mVspStats.Leaves());
}


VspNode *VspTree::Subdivide(SplitQueue &tQueue,
							SubdivisionCandidate *splitCandidate,
							const bool globalCriteriaMet)
{
	// todo remove dynamic cast
	VspSubdivisionCandidate *sc = dynamic_cast<VspSubdivisionCandidate *>(splitCandidate);
	VspTraversalData &tData = sc->mParentData;

	VspNode *newNode = tData.mNode;


	if (!LocalTerminationCriteriaMet(tData) && !globalCriteriaMet)
	{	
		VspTraversalData tFrontData;
		VspTraversalData tBackData;

		//-- continue subdivision
		
		// create new interior node and two leaf node
		const AxisAlignedPlane splitPlane = sc->mSplitPlane;
		newNode = SubdivideNode(splitPlane, tData, tFrontData, tBackData);
	
		const int maxCostMisses = sc->mMaxCostMisses;


		// how often was max cost ratio missed in this branch?
		tFrontData.mMaxCostMisses = maxCostMisses;
		tBackData.mMaxCostMisses = maxCostMisses;
			
		mTotalCost -= sc->GetRenderCostDecrease();
		mTotalPvsSize += tFrontData.mPvs + tBackData.mPvs - tData.mPvs;

		// subdivision statistics
		if (1) EvalSubdivisionStats(*sc);
		
		//-- evaluate new split candidates for global greedy cost heuristics

		VspSubdivisionCandidate *frontCandidate = new VspSubdivisionCandidate(tFrontData);
		VspSubdivisionCandidate *backCandidate = new VspSubdivisionCandidate(tBackData);

		EvalSubdivisionCandidate(*frontCandidate);
		EvalSubdivisionCandidate(*backCandidate);

		tQueue.Push(frontCandidate);
		tQueue.Push(backCandidate);
		
		// delete old view cell
		delete tData.mNode->mViewCell;

		// delete old leaf node
		DEL_PTR(tData.mNode);
	}

	if (newNode->IsLeaf()) // subdivision terminated
	{
		// view cell is created during subdivision
		//CreateViewCell(tData); 

		VspLeaf *leaf = dynamic_cast<VspLeaf *>(newNode);
		ViewCell *viewCell = leaf->GetViewCell();

		int conSamp = 0;
		float sampCon = 0.0f;

#if 0
		//-- store pvs optained from rays

		AddSamplesToPvs(leaf, *tData.mRays, sampCon, conSamp);

		// update scalar pvs size value
		ObjectPvs &pvs = viewCell->GetPvs();
		mViewCellsManager->UpdateScalarPvsSize(viewCell, pvs.CountObjectsInPvs(), pvs.GetSize());

		mVspStats.contributingSamples += conSamp;
		mVspStats.sampleContributions += (int)sampCon;
#endif
		//-- store additional info
		if (mStoreRays)
		{
			RayInfoContainer::const_iterator it, it_end = tData.mRays->end();
			for (it = tData.mRays->begin(); it != it_end; ++ it)
			{
				(*it).mRay->Ref();			
				leaf->mVssRays.push_back((*it).mRay);
			}
		}

		// finally evaluate statistics for this leaf
		EvaluateLeafStats(tData);
	}

	//-- cleanup
	tData.Clear();
	
	return newNode;
}


void VspTree::EvalSubdivisionCandidate(VspSubdivisionCandidate &splitCandidate)
{
	float frontProb;
	float backProb;
	
	VspLeaf *leaf = dynamic_cast<VspLeaf *>(splitCandidate.mParentData.mNode);
	
	// compute locally best split plane
	const float ratio = SelectSplitPlane(
		splitCandidate.mParentData, 
		splitCandidate.mSplitPlane, 
		frontProb, 
		backProb);

	const bool success = ratio < mTermMaxCostRatio;

	float oldRenderCost;

	// compute global decrease in render cost
	const float renderCostDecr = EvalRenderCostDecrease(splitCandidate.mSplitPlane, 
														splitCandidate.mParentData,
														oldRenderCost);

	splitCandidate.SetRenderCostDecrease(renderCostDecr);

#if 0
	const float priority = (float)-data.mDepth;
#else	

	// take render cost of node into account 
	// otherwise danger of being stuck in a local minimum!!
	const float factor = mRenderCostDecreaseWeight;
	const float priority = factor * renderCostDecr + (1.0f - factor) * oldRenderCost;
#endif
	
	splitCandidate.SetPriority(priority);

	// max cost threshold violated?
	splitCandidate.mMaxCostMisses = 
		success ? splitCandidate.mParentData.mMaxCostMisses : splitCandidate.mParentData.mMaxCostMisses + 1;
	//Debug << "p: " << tData.mNode << " depth: " << tData.mDepth << endl;
}


VspInterior *VspTree::SubdivideNode(const AxisAlignedPlane &splitPlane,
									VspTraversalData &tData,
									VspTraversalData &frontData,
									VspTraversalData &backData)
{
	VspLeaf *leaf = dynamic_cast<VspLeaf *>(tData.mNode);
	
	//-- the front and back traversal data is filled with the new values

	frontData.mDepth = tData.mDepth + 1;
	backData.mDepth = tData.mDepth + 1;

	frontData.mRays = new RayInfoContainer();
	backData.mRays = new RayInfoContainer();

	//-- subdivide rays
	SplitRays(splitPlane,
			  *tData.mRays,
			  *frontData.mRays,
			  *backData.mRays);
	
	//Debug << "f: " << frontData.mRays->size() << " b: " << backData.mRays->size() << "d: " << tData.mRays->size() << endl;

	//-- compute pvs
	frontData.mPvs = EvalPvsSize(*frontData.mRays);
	backData.mPvs = EvalPvsSize(*backData.mRays);

	// split front and back node geometry and compute area
	tData.mBoundingBox.Split(splitPlane.mAxis, splitPlane.mPosition, 
							 frontData.mBoundingBox, backData.mBoundingBox);


	frontData.mProbability = frontData.mBoundingBox.GetVolume();
	backData.mProbability = tData.mProbability - frontData.mProbability;

	
    ///////////////////////////////////////////
	// subdivide further

	// store maximal and minimal depth
	if (tData.mDepth > mVspStats.maxDepth)
	{
		Debug << "max depth increases to " << tData.mDepth << " at " << mVspStats.Leaves() << " leaves" << endl;
		mVspStats.maxDepth = tData.mDepth;
	}

	// two more leaves
	mVspStats.nodes += 2;
    
	VspInterior *interior = new VspInterior(splitPlane);

#ifdef _DEBUG
	Debug << interior << endl;
#endif+


	//-- create front and back leaf

	VspInterior *parent = leaf->GetParent();

	// replace a link from node's parent
	if (parent)
	{
		parent->ReplaceChildLink(leaf, interior);
		interior->SetParent(parent);

		// remove "parent" view cell from pvs of all objects (traverse trough rays)
		RemoveParentViewCellReferences(tData.mNode->GetViewCell());
	}
	else // new root
	{
		mRoot = interior;
	}

	VspLeaf *frontLeaf = new VspLeaf(interior);
	VspLeaf *backLeaf = new VspLeaf(interior);

	// and setup child links
	interior->SetupChildLinks(frontLeaf, backLeaf);
	
	// add bounding box
	interior->SetBoundingBox(tData.mBoundingBox);

	// set front and back leaf
	frontData.mNode = frontLeaf;
	backData.mNode = backLeaf;

	// explicitely create front and back view cell
	CreateViewCell(frontData, false);
	CreateViewCell(backData, false);


#if WORK_WITH_VIEWCELL_PVS
	// create front and back view cell
	// add front and back view cell to "Potentially Visbilie View Cells" 
	// of the objects in front and back pvs

	AddViewCellReferences(frontLeaf->GetViewCell());
	AddViewCellReferences(backLeaf->GetViewCell());
#endif

	interior->mTimeStamp = mTimeStamp ++;
	
	return interior;
}


void VspTree::RemoveParentViewCellReferences(ViewCell *parent) const
{
	KdLeaf::NewMail();

	// remove the parents from the object pvss
	ObjectPvsMap::const_iterator oit, oit_end = parent->GetPvs().mEntries.end();

	for (oit = parent->GetPvs().mEntries.begin(); oit != oit_end; ++ oit)
	{
		Intersectable *object = (*oit).first;
		// HACK: make sure that the view cell is removed from the pvs
		const float high_contri = 9999999;

		// remove reference count of view cells
		object->mViewCellPvs.RemoveSample(parent, high_contri);
	}
}


void VspTree::AddViewCellReferences(ViewCell *vc) const
{
	KdLeaf::NewMail();

	// Add front view cell to the object pvsss
	ObjectPvsMap::const_iterator oit, oit_end = vc->GetPvs().mEntries.end();

	for (oit = vc->GetPvs().mEntries.begin(); oit != oit_end; ++ oit)
	{
		Intersectable *object = (*oit).first;

		// increase reference count of view cells
		object->mViewCellPvs.AddSample(vc, 1);
	}
}




void VspTree::AddSamplesToPvs(VspLeaf *leaf,
							  const RayInfoContainer &rays,
							  float &sampleContributions,
							  int &contributingSamples)
{
	sampleContributions = 0;
	contributingSamples = 0;
  
	RayInfoContainer::const_iterator it, it_end = rays.end();
  
	ViewCellLeaf *vc = leaf->GetViewCell();

	// add contributions from samples to the PVS
	for (it = rays.begin(); it != it_end; ++ it)
	{
		float sc = 0.0f;
		VssRay *ray = (*it).mRay;

		bool madeContrib = false;
		float contribution;

		Intersectable *obj = ray->mTerminationObject;

		if (obj) 
		{
			madeContrib = 
				mViewCellsManager->AddSampleToPvs(
					obj, 
					ray->mTermination, 
					vc, 
					ray->mPdf, 
					contribution);

			sc += contribution;
		}

		obj = ray->mOriginObject;

		if (obj) 
		{
			madeContrib = 
				mViewCellsManager->AddSampleToPvs(
					obj,
					ray->mOrigin, 
					vc, 
					ray->mPdf, 
					contribution);

			sc += contribution;
		}

		if (madeContrib)
		{
			++ contributingSamples;
		}

		// store rays for visualization
		if (0) leaf->mVssRays.push_back(new VssRay(*ray));
	}
}


void VspTree::SortSubdivisionCandidates(const RayInfoContainer &rays,
								  const int axis, 
								  float minBand, 
								  float maxBand)
{
	mLocalSubdivisionCandidates->clear();

	int requestedSize = 2 * (int)(rays.size());

	// creates a sorted split candidates array
	if (mLocalSubdivisionCandidates->capacity() > 500000 &&
		requestedSize < (int)(mLocalSubdivisionCandidates->capacity() / 10) )
	{
    	delete mLocalSubdivisionCandidates;
   		mLocalSubdivisionCandidates = new vector<SortableEntry>;
	}

	mLocalSubdivisionCandidates->reserve(requestedSize);


	float pos;

	RayInfoContainer::const_iterator rit, rit_end = rays.end();

	//-- insert all queries
	for (rit = rays.begin(); rit != rit_end; ++ rit)
	{
		const bool positive = (*rit).mRay->HasPosDir(axis);
				
		pos = (*rit).ExtrapOrigin(axis);
		
		mLocalSubdivisionCandidates->push_back(SortableEntry(positive ? SortableEntry::ERayMin : SortableEntry::ERayMax, 
									pos, (*rit).mRay));

		pos = (*rit).ExtrapTermination(axis);

		mLocalSubdivisionCandidates->push_back(SortableEntry(positive ? SortableEntry::ERayMax : SortableEntry::ERayMin, 
									pos, (*rit).mRay));
	}

	stable_sort(mLocalSubdivisionCandidates->begin(), mLocalSubdivisionCandidates->end());
}


int VspTree::GetPvsContribution(Intersectable *object) const
{
    int pvsContri = 0;

	KdPvsMap::const_iterator kit, kit_end = object->mKdPvs.mEntries.end();

	Intersectable::NewMail();

	// Search kd leaves this object is attached to
	for (kit = object->mKdPvs.mEntries.begin(); kit != kit_end; ++ kit)
	{
		KdNode *l = (*kit).first;

		// new object found during sweep 
		// => increase pvs contribution of this kd node
		if (!l->Mailed())
		{
			l->Mail();
			++ pvsContri;
		}
	}

	return pvsContri;
}


int VspTree::PrepareHeuristics(const VssRay &ray, const bool isTermination)
{
	int pvsSize = 0;
	
	Intersectable *obj;
	Vector3 pt;
	KdNode *node;

	ray.GetSampleData(isTermination, pt, &obj, &node);

	if (!obj)
		return 0;

	switch (mHierarchyManager->GetObjectSpaceSubdivisonType())
	{
	case HierarchyManager::NO_OBJ_SUBDIV:
		{
			if (!obj->Mailed())
			{
				obj->Mail();
				obj->mCounter = 1;

				++ pvsSize;
			}
			else
			{
				++ obj->mCounter;
			}
			break;
		}
	case HierarchyManager::KD_BASED_OBJ_SUBDIV:
		{
			KdLeaf *leaf = mHierarchyManager->mOspTree->GetLeaf(pt, node);
			pvsSize += PrepareHeuristics(leaf);	
			break;
		}
	case HierarchyManager::BV_BASED_OBJ_SUBDIV:
		{
			BvhLeaf *leaf = mHierarchyManager->mBvHierarchy->GetLeaf(obj);

			if (!leaf->Mailed())
			{
				leaf->Mail();
				leaf->mCounter = 1;

				pvsSize += (int)leaf->mObjects.size();
			}
			else
			{
				++ leaf->mCounter;
			}
			break;
		}
	default:
		break;
	}

	return pvsSize;
}


int VspTree::PrepareHeuristics(KdLeaf *leaf)
{	
	int pvsSize = 0;
	
	if (!leaf->Mailed())
	{
		leaf->Mail();
		leaf->mCounter = 1;

		// add objects without the objects which are in several kd leaves
		pvsSize += (int)(leaf->mObjects.size() - leaf->mMultipleObjects.size());
		//Debug << "adding " << (int)leaf->mObjects.size() << " " << leaf->mMultipleObjects.size() << endl;
	}
	else
	{
		++ leaf->mCounter;
	}

	//-- the objects belonging to several leaves must be handled seperately

	ObjectContainer::const_iterator oit, oit_end = leaf->mMultipleObjects.end();

	for (oit = leaf->mMultipleObjects.begin(); oit != oit_end; ++ oit)
	{
		Intersectable *object = *oit;
						
		if (!object->Mailed())
		{
			object->Mail();
			object->mCounter = 1;

			++ pvsSize;
		}
		else
		{
			++ object->mCounter;
		}
	}
	
	return pvsSize;
}


int VspTree::PrepareHeuristics(const RayInfoContainer &rays)
{	
	Intersectable::NewMail();
	KdNode::NewMail();

	int pvsSize = 0;

	RayInfoContainer::const_iterator ri, ri_end = rays.end();

    // set all kd nodes / objects as belonging to the front pvs
	for (ri = rays.begin(); ri != ri_end; ++ ri)
	{
		VssRay *ray = (*ri).mRay;
		
		pvsSize += PrepareHeuristics(*ray, true);
		pvsSize += PrepareHeuristics(*ray, false);
	}

	return pvsSize;
}


int VspTree::EvalMaxEventContribution(KdLeaf *leaf) const
{
	int pvs = 0;

	// leaf falls out of right pvs
	if (-- leaf->mCounter == 0)
	{
		pvs -= ((int)leaf->mObjects.size() - (int)leaf->mMultipleObjects.size());
	}

	//-- separately handle objects which are in several kd leaves

	ObjectContainer::const_iterator oit, oit_end = leaf->mMultipleObjects.end();

	for (oit = leaf->mMultipleObjects.begin(); oit != oit_end; ++ oit)
	{
		Intersectable *object = *oit;

		if (-- object->mCounter == 0)
		{
			++ pvs;
		}
	}

	return pvs;
}


int VspTree::EvalMinEventContribution(KdLeaf *leaf) const
{
	if (leaf->Mailed())
		return 0;
	
	leaf->Mail();

	// add objects without those which are part of several kd leaves
	int pvs = ((int)leaf->mObjects.size() - (int)leaf->mMultipleObjects.size());

	// separately handle objects which are part of several kd leaves 
	ObjectContainer::const_iterator oit, oit_end = leaf->mMultipleObjects.end();

	for (oit = leaf->mMultipleObjects.begin(); oit != oit_end; ++ oit)
	{
		Intersectable *object = *oit;

		// object not previously in pvs
		if (!object->Mailed())
		{
			object->Mail();
			++ pvs;
		}
	}	

	return pvs;
}


int VspTree::EvalMinEventContribution(const VssRay &ray, 
									  const bool isTermination) const
{
	Intersectable *obj;
	Vector3 pt;
	KdNode *node;

	ray.GetSampleData(isTermination, pt, &obj, &node);

	if (!obj) return 0;

	int pvs = 0;

	switch (mHierarchyManager->GetObjectSpaceSubdivisonType())
	{
	case HierarchyManager::NO_OBJ_SUBDIV:
		{
			if (!obj->Mailed())
			{
				obj->Mail();
				++ pvs;
			}

			break;
		}
	case HierarchyManager::KD_BASED_OBJ_SUBDIV:
		{
			KdLeaf *leaf = mHierarchyManager->mOspTree->GetLeaf(pt, node);
			// add contributions of the kd nodes
			pvs += EvalMinEventContribution(leaf);
					
			break;
		}
	case HierarchyManager::BV_BASED_OBJ_SUBDIV:
		{
			BvhLeaf *leaf = mHierarchyManager->mBvHierarchy->GetLeaf(obj);

			if (!leaf->Mailed())
			{
				leaf->Mail();
				pvs += (int)leaf->mObjects.size();
			}
			break;
		}
	default:
		break;
	}
	return pvs;
}


int VspTree::EvalMaxEventContribution(const VssRay &ray, 
									  const bool isTermination) const
{
	Intersectable *obj;
	Vector3 pt;
	KdNode *node;

	ray.GetSampleData(isTermination, pt, &obj, &node);

	if (!obj) return 0;

	int pvs = 0;

	switch (mHierarchyManager->GetObjectSpaceSubdivisonType())
	{
	case HierarchyManager::NO_OBJ_SUBDIV:
		{
			if (-- obj->mCounter == 0)
				++ pvs;
			break;
		}
	case HierarchyManager::KD_BASED_OBJ_SUBDIV:
		{
			KdLeaf *leaf = mHierarchyManager->mOspTree->GetLeaf(pt, node);

			// add contributions of the kd nodes
			pvs += EvalMaxEventContribution(leaf);
			break;
		}
	case HierarchyManager::BV_BASED_OBJ_SUBDIV:
		{
			BvhLeaf *leaf = mHierarchyManager->mBvHierarchy->GetLeaf(obj);

			if (-- leaf->mCounter == 0)
				pvs += (int)leaf->mObjects.size();
			break;
		}
	default:
		break;
	}

	return pvs;
}


void VspTree::EvalHeuristicsContribution(const SortableEntry &ci,
										 int &pvsLeft,
										 int &pvsRight) const
{
	VssRay *ray = ci.ray;

	if (ci.type == SortableEntry::ERayMin)
	{
		pvsLeft += EvalMinEventContribution(*ray, true);
		pvsLeft += EvalMinEventContribution(*ray, false);
	}
	else
	{
		pvsRight -= EvalMaxEventContribution(*ray, true);
		pvsRight -= EvalMaxEventContribution(*ray, false);
	}
}


float VspTree::EvalLocalCostHeuristics(const VspTraversalData &tData,
									   const AxisAlignedBox3 &box,
									   const int axis,
									   float &position)
{
	// get subset of rays
	RayInfoContainer usedRays;

	if (mMaxTests < (int)tData.mRays->size())
	{
		GetRayInfoSets(*tData.mRays, mMaxTests, usedRays);
	}
	else
	{
		usedRays = *tData.mRays;
	}

	int pvsSize = tData.mPvs;

	const float minBox = box.Min(axis);
	const float maxBox = box.Max(axis);

	const float sizeBox = maxBox - minBox;

	const float minBand = minBox + mMinBand * sizeBox;
	const float maxBand = minBox + mMaxBand * sizeBox;

	SortSubdivisionCandidates(usedRays, axis, minBand, maxBand);

	// prepare the sweep
	// (note: returns pvs size, so there would be no need 
	// to give pvs size as argument)
	pvsSize = PrepareHeuristics(usedRays);

	// go through the lists, count the number of objects left and right
	// and evaluate the following cost funcion:
	// C = ct_div_ci  + (ql*rl + qr*rr)/queries

	int pvsl = 0;
	int pvsr = pvsSize;

	int pvsBack = pvsl;
	int pvsFront = pvsr;

	float sum = (float)pvsSize * sizeBox;
	float minSum = 1e20f;

	
	// if no good split can be found, take mid split
	position = minBox + 0.5f * sizeBox;
	
	// the relative cost ratio
	float ratio = 99999999.0f;
	bool splitPlaneFound = false;

	Intersectable::NewMail();
	KdLeaf::NewMail();


	//-- traverse through visibility events

	vector<SortableEntry>::const_iterator ci, ci_end = mLocalSubdivisionCandidates->end();

	for (ci = mLocalSubdivisionCandidates->begin(); ci != ci_end; ++ ci)
	{
		EvalHeuristicsContribution(*ci, pvsl, pvsr);

		// Note: sufficient to compare size of bounding boxes of front and back side?
		if (((*ci).value >= minBand) && ((*ci).value <= maxBand))
		{

			float currentPos;
			
			// HACK: current positition is BETWEEN visibility events
			if (0 && ((ci + 1) != ci_end))
				currentPos = ((*ci).value + (*(ci + 1)).value) * 0.5f;
			else
				currentPos = (*ci).value;			

			sum = pvsl * ((*ci).value - minBox) + pvsr * (maxBox - (*ci).value);
			//Debug  << "pos=" << (*ci).value << "\t newpos=" << currentPos << "\t pvs=(" <<  pvsl << "," << pvsr << ")" << "\t cost= " << sum << endl;

			if (sum < minSum)
			{
				splitPlaneFound = true;

				minSum = sum;
				position = currentPos;
				
				pvsBack = pvsl;
				pvsFront = pvsr;
			}
		}
	}
	
	
	//-- compute cost

	const int lowerPvsLimit = mViewCellsManager->GetMinPvsSize();
	const int upperPvsLimit = mViewCellsManager->GetMaxPvsSize();

	const float pOverall = sizeBox;
	const float pBack = position - minBox;
	const float pFront = maxBox - position;

	const float penaltyOld = EvalPvsPenalty(pvsSize, lowerPvsLimit, upperPvsLimit);
    const float penaltyFront = EvalPvsPenalty(pvsFront, lowerPvsLimit, upperPvsLimit);
	const float penaltyBack = EvalPvsPenalty(pvsBack, lowerPvsLimit, upperPvsLimit);
	
	const float oldRenderCost = penaltyOld * pOverall + Limits::Small;
	const float newRenderCost = penaltyFront * pFront + penaltyBack * pBack;

	if (splitPlaneFound)
	{
		ratio = newRenderCost / oldRenderCost;
	}
	
	const float volRatio = tData.mBoundingBox.GetVolume() / (sizeBox * mBoundingBox.GetVolume());

/*	
//if (axis != 1)
	//Debug << "axis=" << axis << " costRatio=" << ratio << " pos=" << position << " t=" << (position - minBox) / (maxBox - minBox)
	//      <<"\t pb=(" << pvsBack << ")\t pf=(" << pvsFront << ")" << endl;

Debug << "\n§§§§ eval local cost §§§§" << endl
		  << "back pvs: " << penaltyBack << " front pvs: " << penaltyFront << " total pvs: " << penaltyOld << endl 
		  << "back p: " << pBack * volRatio << " front p " << pFront * volRatio << " p: " << pOverall * volRatio << endl
		  << "old rc: " << oldRenderCost * volRatio << " new rc: " << newRenderCost * volRatio << endl
		  << "render cost decrease: " << oldRenderCost * volRatio - newRenderCost * volRatio << endl;
*/
	return ratio;
}


float VspTree::SelectSplitPlane(const VspTraversalData &tData,
								AxisAlignedPlane &plane,
								float &pFront,
								float &pBack)
{
	float nPosition[3];
	float nCostRatio[3];
	float nProbFront[3];
	float nProbBack[3];

	// create bounding box of node geometry
	AxisAlignedBox3 box = tData.mBoundingBox;
		
	int sAxis = 0;
	int bestAxis = -1;

	// if we use some kind of specialised fixed axis
    const bool useSpecialAxis = 
		mOnlyDrivingAxis || mCirculatingAxis;
	//Debug << "data: " << tData.mBoundingBox << " pvs " << tData.mPvs << endl;
	if (mCirculatingAxis)
	{
		int parentAxis = 0;
		VspNode *parent = tData.mNode->GetParent();

		if (parent)
			parentAxis = dynamic_cast<VspInterior *>(parent)->GetAxis();

		sAxis = (parentAxis + 1) % 3;
	}
	else if (mOnlyDrivingAxis)
	{
		sAxis = box.Size().DrivingAxis();
	}
	
	for (int axis = 0; axis < 3; ++ axis)
	{
		if (!useSpecialAxis || (axis == sAxis))
		{
			if (mUseCostHeuristics)
			{
				//-- place split plane using heuristics
				nCostRatio[axis] =
					EvalLocalCostHeuristics(tData,
											box,
											axis,
											nPosition[axis]);			
			}
			else
			{
				//-- split plane position is spatial median
				nPosition[axis] = (box.Min()[axis] + box.Max()[axis]) * 0.5f;
				nCostRatio[axis] = EvalLocalSplitCost(tData,
													  box,
													  axis,
													  nPosition[axis],
													  nProbFront[axis], 
													  nProbBack[axis]);
			}
						
			if (bestAxis == -1)
			{
				bestAxis = axis;
			}
			else if (nCostRatio[axis] < nCostRatio[bestAxis])
			{
				bestAxis = axis;
			} 
		}
	}


	//-- assign values of best split
	
	plane.mAxis = bestAxis;
	plane.mPosition = nPosition[bestAxis]; // split plane position

	pFront = nProbFront[bestAxis];
	pBack = nProbBack[bestAxis];

	//Debug << "val: " << nCostRatio[bestAxis] << " axis: " << bestAxis << endl;
	return nCostRatio[bestAxis];
}


float VspTree::EvalRenderCostDecrease(const AxisAlignedPlane &candidatePlane,
									  const VspTraversalData &data,
									  float &normalizedOldRenderCost) const
{
	float pvsFront = 0;
	float pvsBack = 0;
	float totalPvs = 0;

	// probability that view point lies in back / front node
	float pOverall = data.mProbability;
	float pFront = 0;
	float pBack = 0;

	const float viewSpaceVol = mBoundingBox.GetVolume();

	// create unique ids for pvs heuristics
	Intersectable::NewMail(3);
	KdLeaf::NewMail(3);

	RayInfoContainer::const_iterator rit, rit_end = data.mRays->end();

	for (rit = data.mRays->begin(); rit != rit_end; ++ rit)
	{
		RayInfo rayInf = *rit;

		float t;
		VssRay *ray = rayInf.mRay;

		const int cf = 
			rayInf.ComputeRayIntersection(candidatePlane.mAxis, 
										  candidatePlane.mPosition, t);
/*
		if (!mUseKdPvsForHeuristics)
		{
			// find front and back pvs for origing and termination object
			UpdateObjPvsContri(ray->mTerminationObject, cf, pvsFront, pvsBack, totalPvs);
			UpdateObjPvsContri(ray->mOriginObject, cf, pvsFront, pvsBack, totalPvs);
		}
		else
		{
			if (ray->mTerminationObject)
			{
				KdLeaf *leaf = mHierarchyManager->mOspTree->GetLeaf(ray->mTermination, ray->mTerminationNode);
				UpdateKdLeafPvsContri(leaf, cf, pvsFront, pvsBack, totalPvs);
			}

			if (ray->mOriginObject)
			{
				KdLeaf *leaf = mHierarchyManager->mOspTree->GetLeaf(ray->mOrigin, ray->mOriginNode);
				UpdateKdLeafPvsContri(leaf, cf, pvsFront, pvsBack, totalPvs);
			}
		}
*/
	}


	AxisAlignedBox3 frontBox;
	AxisAlignedBox3 backBox;

	data.mBoundingBox.Split(candidatePlane.mAxis, candidatePlane.mPosition, frontBox, backBox);

	pFront = frontBox.GetVolume();
	pBack = pOverall - pFront;
		

	//-- pvs rendering heuristics
	const int lowerPvsLimit = mViewCellsManager->GetMinPvsSize();
	const int upperPvsLimit = mViewCellsManager->GetMaxPvsSize();

	//-- only render cost heuristics or combined with standard deviation
	const float penaltyOld = EvalPvsPenalty((int)totalPvs, lowerPvsLimit, upperPvsLimit);
    const float penaltyFront = EvalPvsPenalty((int)pvsFront, lowerPvsLimit, upperPvsLimit);
	const float penaltyBack = EvalPvsPenalty((int)pvsBack, lowerPvsLimit, upperPvsLimit);
			
	const float oldRenderCost = pOverall * penaltyOld;
	const float newRenderCost = penaltyFront * pFront + penaltyBack * pBack;

	normalizedOldRenderCost = oldRenderCost / viewSpaceVol;

	const float renderCostDecrease = (oldRenderCost - newRenderCost) / viewSpaceVol;
	/*
	Debug << "\n==== eval render cost decrease ===" << endl
		  << "back pvs: " << pvsBack << " front pvs " << pvsFront << " total pvs: " << totalPvs << endl 
		  << "back p: " << pBack / viewSpaceVol << " front p " << pFront / viewSpaceVol << " p: " << pOverall / viewSpaceVol << endl
		  << "old rc: " << normalizedOldRenderCost << " new rc: " << newRenderCost / viewSpaceVol << endl
		  << "render cost decrease: " << renderCostDecrease << endl;
*/
	return renderCostDecrease;
}


float VspTree::EvalLocalSplitCost(const VspTraversalData &data,
								  const AxisAlignedBox3 &box,
								  const int axis,
								  const float &position,
								  float &pFront,
								  float &pBack) const
{
	float pvsTotal = 0;
	float pvsFront = 0;
	float pvsBack = 0;
	
	// create unique ids for pvs heuristics
	Intersectable::NewMail(3);

	const int pvsSize = data.mPvs;

	RayInfoContainer::const_iterator rit, rit_end = data.mRays->end();

	// this is the main ray classification loop!
	for(rit = data.mRays->begin(); rit != rit_end; ++ rit)
	{
		// determine the side of this ray with respect to the plane
		float t;
		const int side = (*rit).ComputeRayIntersection(axis, position, t);
	
		UpdateObjPvsContri((*rit).mRay->mTerminationObject, side, pvsFront, pvsBack, pvsTotal);
		UpdateObjPvsContri((*rit).mRay->mOriginObject, side, pvsFront, pvsBack, pvsTotal);
	}

	//-- evaluate cost heuristics

	float pOverall;
	
	pOverall = data.mProbability;

	// we use spatial mid split => simplified computation
	pBack = pFront = pOverall * 0.5f;
	
	const float newCost = pvsBack * pBack + pvsFront * pFront;
	const float oldCost = (float)pvsSize * pOverall + Limits::Small;
	
#ifdef _DEBUG
	Debug << axis << " " << pvsSize << " " << pvsBack << " " << pvsFront << endl;
	Debug << pFront << " " << pBack << " " << pOverall << endl;
#endif

	return  (mCtDivCi + newCost) / oldCost;
}


void VspTree::UpdateObjPvsContri(Intersectable *obj,
						  const int cf,
						  float &frontPvs,
						  float &backPvs,
						  float &totalPvs) const
{
	if (!obj) return;

	//const float renderCost = mViewCellsManager->SimpleRay &raynderCost(obj);
	const int renderCost = 1;

	// object in no pvs => new
	if (!obj->Mailed() && !obj->Mailed(1) && !obj->Mailed(2))
	{
		totalPvs += renderCost;
	}

	// QUESTION matt: is it safe to assume that 
	// the object belongs to no pvs in this case?
	//if (cf == Ray::COINCIDENT) return;

	if (cf >= 0) // front pvs
	{
		if (!obj->Mailed() && !obj->Mailed(2))
		{
			frontPvs += renderCost;
		
			// already in back pvs => in both pvss
			if (obj->Mailed(1))
				obj->Mail(2);
			else
				obj->Mail();
		}
	}

	if (cf <= 0) // back pvs
	{
		if (!obj->Mailed(1) && !obj->Mailed(2))
		{
			backPvs += renderCost;
		
			// already in front pvs => in both pvss
			if (obj->Mailed())
				obj->Mail(2);
			else
				obj->Mail(1);
		}
	}
}


void VspTree::UpdateKdLeafPvsContri(KdLeaf *leaf,
									const int cf,
									float &frontPvs,
									float &backPvs,
									float &totalPvs) const
{
	if (!leaf) return;

	// the objects which are referenced in this and only this leaf
	const int contri = (int)(leaf->mObjects.size() - leaf->mMultipleObjects.size());
	
	// newly found leaf
	if (!leaf->Mailed() && !leaf->Mailed(1) && !leaf->Mailed(2))
	{
		totalPvs += contri;
	}

	// compute contribution of yet unclassified objects
	ObjectContainer::const_iterator oit, oit_end = leaf->mMultipleObjects.end();

	for (oit = leaf->mMultipleObjects.begin(); oit != oit_end; ++ oit)
	{	
		UpdateObjPvsContri(*oit, cf, frontPvs, backPvs, totalPvs);
    }	
	
	// QUESTION matt: is it safe to assume that 
	// the object belongs to no pvs in this case?
	//if (cf == Ray::COINCIDENT) return;

	if (cf >= 0) // front pvs
	{
		if (!leaf->Mailed() && !leaf->Mailed(2))
		{
			frontPvs += contri;
		
			// already in back pvs => in both pvss
			if (leaf->Mailed(1))
				leaf->Mail(2);
			else
				leaf->Mail();
		}
	}

	if (cf <= 0) // back pvs
	{
		if (!leaf->Mailed(1) && !leaf->Mailed(2))
		{
			backPvs += contri;
		
			// already in front pvs => in both pvss
			if (leaf->Mailed())
				leaf->Mail(2);
			else
				leaf->Mail(1);
		}
	}
}


void VspTree::CollectLeaves(vector<VspLeaf *> &leaves, 
							const bool onlyUnmailed,
							const int maxPvsSize) const
{
	stack<VspNode *> nodeStack;
	nodeStack.push(mRoot);

	while (!nodeStack.empty())
	{
		VspNode *node = nodeStack.top();
		nodeStack.pop();
		
		if (node->IsLeaf())
		{
			// test if this leaf is in valid view space
			VspLeaf *leaf = dynamic_cast<VspLeaf *>(node);
			if (leaf->TreeValid() && 
				(!onlyUnmailed || !leaf->Mailed()) &&
				((maxPvsSize < 0) || (leaf->GetViewCell()->GetPvs().CountObjectsInPvs() <= maxPvsSize)))
			{
				leaves.push_back(leaf);
			}
		}
		else
		{
			VspInterior *interior = dynamic_cast<VspInterior *>(node);

			nodeStack.push(interior->GetBack());
			nodeStack.push(interior->GetFront());
		}
	}
}


AxisAlignedBox3 VspTree::GetBoundingBox() const
{
	return mBoundingBox;
}


VspNode *VspTree::GetRoot() const
{
	return mRoot;
}


void VspTree::EvaluateLeafStats(const VspTraversalData &data)
{
	// the node became a leaf -> evaluate stats for leafs
	VspLeaf *leaf = dynamic_cast<VspLeaf *>(data.mNode);


	if (data.mPvs > mVspStats.maxPvs)
	{
		mVspStats.maxPvs = data.mPvs;
	}

	mVspStats.pvs += data.mPvs;

	if (data.mDepth < mVspStats.minDepth)
	{
		mVspStats.minDepth = data.mDepth;
	}
	
	if (data.mDepth >= mTermMaxDepth)
	{
        ++ mVspStats.maxDepthNodes;
		//Debug << "new max depth: " << mVspStats.maxDepthNodes << endl;
	}

	// accumulate rays to compute rays /  leaf
	mVspStats.accumRays += (int)data.mRays->size();

	if (data.mPvs < mTermMinPvs)
		++ mVspStats.minPvsNodes;

	if ((int)data.mRays->size() < mTermMinRays)
		++ mVspStats.minRaysNodes;

	if (data.GetAvgRayContribution() > mTermMaxRayContribution)
		++ mVspStats.maxRayContribNodes;

	if (data.mProbability <= mTermMinProbability)
		++ mVspStats.minProbabilityNodes;
	
	// accumulate depth to compute average depth
	mVspStats.accumDepth += data.mDepth;

	++ mCreatedViewCells;

#ifdef _DEBUG
	Debug << "BSP stats: "
		  << "Depth: " << data.mDepth << " (max: " << mTermMaxDepth << "), "
		  << "PVS: " << data.mPvs << " (min: " << mTermMinPvs << "), "
		  << "#rays: " << (int)data.mRays->size() << " (max: " << mTermMinRays << "), "
		  << "#pvs: " << leaf->GetViewCell()->GetPvs().CountObjectsInPvs() << "), "
		  << "#avg ray contrib (pvs): " << (float)data.mPvs / (float)data.mRays->size() << endl;
#endif
}


void VspTree::CollectViewCells(ViewCellContainer &viewCells, bool onlyValid) const
{
	ViewCell::NewMail();
	CollectViewCells(mRoot, onlyValid, viewCells, true);
}


void VspTree::CollapseViewCells()
{
// TODO matt
#if HAS_TO_BE_REDONE
	stack<VspNode *> nodeStack;

	if (!mRoot)
		return;

	nodeStack.push(mRoot);
	
	while (!nodeStack.empty()) 
	{
		VspNode *node = nodeStack.top();
		nodeStack.pop();
		
		if (node->IsLeaf())
        {
			BspViewCell *viewCell = dynamic_cast<VspLeaf *>(node)->GetViewCell();

			if (!viewCell->GetValid())
			{
				BspViewCell *viewCell = dynamic_cast<VspLeaf *>(node)->GetViewCell();
	
				ViewCellContainer leaves;
				mViewCellsTree->CollectLeaves(viewCell, leaves);

				ViewCellContainer::const_iterator it, it_end = leaves.end();

				for (it = leaves.begin(); it != it_end; ++ it)
				{
					VspLeaf *l = dynamic_cast<BspViewCell *>(*it)->mLeaf;
					l->SetViewCell(GetOrCreateOutOfBoundsCell());
					++ mVspStats.invalidLeaves;
				}

				// add to unbounded view cell
				GetOrCreateOutOfBoundsCell()->GetPvs().AddPvs(viewCell->GetPvs());
				DEL_PTR(viewCell);
			}
		}
		else
		{
			VspInterior *interior = dynamic_cast<VspInterior *>(node);
		
			nodeStack.push(interior->GetFront());
			nodeStack.push(interior->GetBack());
		}
	}

	Debug << "invalid leaves: " << mVspStats.invalidLeaves << endl;
#endif
}


void VspTree::CollectRays(VssRayContainer &rays)
{
	vector<VspLeaf *> leaves;
	CollectLeaves(leaves);

	vector<VspLeaf *>::const_iterator lit, lit_end = leaves.end();

	for (lit = leaves.begin(); lit != lit_end; ++ lit)
	{
		VspLeaf *leaf = *lit;
		VssRayContainer::const_iterator rit, rit_end = leaf->mVssRays.end();

		for (rit = leaf->mVssRays.begin(); rit != rit_end; ++ rit)
			rays.push_back(*rit);
	}
}


void VspTree::SetViewCellsManager(ViewCellsManager *vcm)
{
	mViewCellsManager = vcm;
}


void VspTree::ValidateTree()
{
	mVspStats.invalidLeaves = 0;

	stack<VspNode *> nodeStack;

	if (!mRoot)
		return;

	nodeStack.push(mRoot);

	while (!nodeStack.empty()) 
	{
		VspNode *node = nodeStack.top();
		nodeStack.pop();
		
		if (node->IsLeaf())
		{
			VspLeaf *leaf = dynamic_cast<VspLeaf *>(node);

			if (!leaf->GetViewCell()->GetValid())
				++ mVspStats.invalidLeaves;

			// validity flags don't match => repair
			if (leaf->GetViewCell()->GetValid() != leaf->TreeValid())
			{
				leaf->SetTreeValid(leaf->GetViewCell()->GetValid());
				PropagateUpValidity(leaf);
			}
		}
		else
		{
			VspInterior *interior = dynamic_cast<VspInterior *>(node);
		
			nodeStack.push(interior->GetFront());
			nodeStack.push(interior->GetBack());
		}
	}

	Debug << "invalid leaves: " << mVspStats.invalidLeaves << endl;
}



void VspTree::CollectViewCells(VspNode *root,
								  bool onlyValid,
								  ViewCellContainer &viewCells,
								  bool onlyUnmailed) const
{
	stack<VspNode *> nodeStack;

	if (!root)
		return;

	nodeStack.push(root);
	
	while (!nodeStack.empty()) 
	{
		VspNode *node = nodeStack.top();
		nodeStack.pop();
		
		if (node->IsLeaf())
		{
			if (!onlyValid || node->TreeValid())
			{
				ViewCellLeaf *leafVc = dynamic_cast<VspLeaf *>(node)->GetViewCell();

				ViewCell *viewCell = mViewCellsTree->GetActiveViewCell(leafVc);
						
				if (!onlyUnmailed || !viewCell->Mailed()) 
				{
					viewCell->Mail();
					viewCells.push_back(viewCell);
				}
			}
		}
		else
		{
			VspInterior *interior = dynamic_cast<VspInterior *>(node);
		
			nodeStack.push(interior->GetFront());
			nodeStack.push(interior->GetBack());
		}
	}
}


int VspTree::FindNeighbors(VspLeaf *n,
						   vector<VspLeaf *> &neighbors,
						   const bool onlyUnmailed) const
{
	stack<VspNode *> nodeStack;
	nodeStack.push(mRoot);

	const AxisAlignedBox3 box = GetBoundingBox(n);

	while (!nodeStack.empty())
	{
		VspNode *node = nodeStack.top();
		nodeStack.pop();

		if (node->IsLeaf())
		{
			VspLeaf *leaf = dynamic_cast<VspLeaf *>(node);

			if (leaf != n && (!onlyUnmailed || !leaf->Mailed()))
				neighbors.push_back(leaf);
		}
		else
		{
			VspInterior *interior = dynamic_cast<VspInterior *>(node);
			
			if (interior->GetPosition() > box.Max(interior->GetAxis()))
				nodeStack.push(interior->GetBack());
			else
			{
				if (interior->GetPosition() < box.Min(interior->GetAxis()))
					nodeStack.push(interior->GetFront());
				else
				{
					// random decision
					nodeStack.push(interior->GetBack());
					nodeStack.push(interior->GetFront());
				}
			}
		}
	}

	return (int)neighbors.size();
}


// Find random neighbor which was not mailed
VspLeaf *VspTree::GetRandomLeaf(const Plane3 &plane)
{
	stack<VspNode *> nodeStack;
	nodeStack.push(mRoot);
  
	int mask = rand();
  
	while (!nodeStack.empty()) 
	{
		VspNode *node = nodeStack.top();
		
		nodeStack.pop();
		
		if (node->IsLeaf()) 
		{
			return dynamic_cast<VspLeaf *>(node);
		} 
		else 
		{
			VspInterior *interior = dynamic_cast<VspInterior *>(node);
			VspNode *next;
			
			if (GetBoundingBox(interior->GetBack()).Side(plane) < 0)
			{
				next = interior->GetFront();
			}
            else
			{
				if (GetBoundingBox(interior->GetFront()).Side(plane) < 0)
				{
					next = interior->GetBack();
				}
				else 
				{
					// random decision
					if (mask & 1)
						next = interior->GetBack();
					else
						next = interior->GetFront();
					mask = mask >> 1;
				}
			}
			
			nodeStack.push(next);
		}
	}
  
	return NULL;
}


VspLeaf *VspTree::GetRandomLeaf(const bool onlyUnmailed)
{
	stack<VspNode *> nodeStack;

	nodeStack.push(mRoot);

	int mask = rand();

	while (!nodeStack.empty())
	{
		VspNode *node = nodeStack.top();
		nodeStack.pop();

		if (node->IsLeaf())
		{
			if ( (!onlyUnmailed || !node->Mailed()) )
				return dynamic_cast<VspLeaf *>(node);
		}
		else
		{
			VspInterior *interior = dynamic_cast<VspInterior *>(node);

			// random decision
			if (mask & 1)
				nodeStack.push(interior->GetBack());
			else
				nodeStack.push(interior->GetFront());

			mask = mask >> 1;
		}
	}

	return NULL;
}


void VspTree::CollectPvs(const RayInfoContainer &rays, 
						 ObjectContainer &objects) const
{
	RayInfoContainer::const_iterator rit, rit_end = rays.end();

	Intersectable::NewMail();

	for (rit = rays.begin(); rit != rays.end(); ++ rit)
	{
		VssRay *ray = (*rit).mRay;

		Intersectable *object;
		object = ray->mOriginObject;

        if (object)
		{
			if (!object->Mailed())
			{
				object->Mail();
				objects.push_back(object);
			}
		}

		object = ray->mTerminationObject;

		if (object)
		{
			if (!object->Mailed())
			{
				object->Mail();
				objects.push_back(object);
			}
		}
	}
}


int VspTree::EvalPvsContribution(const VssRay &ray, const bool isTermination) const
{	
	Intersectable *obj; 
	Vector3 pt;
	KdNode *node;

	ray.GetSampleData(isTermination, pt, &obj, &node);

	if (!obj) return 0;

	int pvs = 0;

	switch(mHierarchyManager->GetObjectSpaceSubdivisonType())
	{
	case HierarchyManager::NO_OBJ_SUBDIV:
		{
			if (!obj->Mailed())
			{
				obj->Mail();
				++ pvs;
			}

			break;
		}
	case HierarchyManager::KD_BASED_OBJ_SUBDIV:
		{
			KdLeaf *leaf = mHierarchyManager->mOspTree->GetLeaf(pt, node);

			if (!leaf->Mailed())
			{
				leaf->Mail();
				pvs += (int)(leaf->mObjects.size() - leaf->mMultipleObjects.size());
				
				ObjectContainer::const_iterator oit, oit_end = leaf->mMultipleObjects.end();
				for (oit = leaf->mMultipleObjects.begin(); oit != oit_end; ++ oit)
				{
					Intersectable *obj = *oit;

					if (!obj->Mailed())
					{
						obj->Mail();
						++ pvs;
					}
				}
			}

			break;
		}
	case HierarchyManager::BV_BASED_OBJ_SUBDIV:
		{
			BvhLeaf *bvhleaf = mHierarchyManager->mBvHierarchy->GetLeaf(obj);

			if (!bvhleaf->Mailed())
			{
				bvhleaf->Mail();
				pvs += (int)bvhleaf->mObjects.size();
			}

			break;
		}
	default:
		break;
	}

	return pvs;
}


int VspTree::EvalPvsSize(const RayInfoContainer &rays) const
{
	int pvsSize = 0;
	
	Intersectable::NewMail();
	KdNode::NewMail();
	BvhNode::NewMail();

	RayInfoContainer::const_iterator rit, rit_end = rays.end();

	for (rit = rays.begin(); rit != rays.end(); ++ rit)
	{
		VssRay *ray = (*rit).mRay;
		pvsSize += EvalPvsContribution(*ray, true);
		pvsSize += EvalPvsContribution(*ray, false);
	}
	
	return pvsSize;
}


float VspTree::GetEpsilon() const
{
	return mEpsilon;
}


int VspTree::CastLineSegment(const Vector3 &origin,
							 const Vector3 &termination,
                             ViewCellContainer &viewcells)
{
	int hits = 0;

	float mint = 0.0f, maxt = 1.0f;
	const Vector3 dir = termination - origin;

	stack<LineTraversalData> tStack;

	//Intersectable::NewMail();
	//ViewCell::NewMail();

	Vector3 entp = origin;
	Vector3 extp = termination;

	VspNode *node = mRoot;
	VspNode *farChild;

	float position;
	int axis;

	while (1)
	{
		if (!node->IsLeaf())
		{
			VspInterior *in = dynamic_cast<VspInterior *>(node);
			position = in->GetPosition();
			axis = in->GetAxis();

			if (entp[axis] <= position)
			{
				if (extp[axis] <= position)
				{
					node = in->GetBack();
					// cases N1,N2,N3,P5,Z2,Z3
					continue;
				} else
				{
					// case N4
					node = in->GetBack();
					farChild = in->GetFront();
				}
			}
			else
			{
				if (position <= extp[axis])
				{
					node = in->GetFront();
					// cases P1,P2,P3,N5,Z1
					continue;
				}
				else
				{
					node = in->GetFront();
					farChild = in->GetBack();
					// case P4
				}
			}

 			// $$ modification 3.5.2004 - hints from Kamil Ghais
			// case N4 or P4
			const float tdist = (position - origin[axis]) / dir[axis];
			tStack.push(LineTraversalData(farChild, extp, maxt)); //TODO

			extp = origin + dir * tdist;
			maxt = tdist;
		}
		else
		{
			// compute intersection with all objects in this leaf
			VspLeaf *leaf = dynamic_cast<VspLeaf *>(node);
			ViewCell *vc = leaf->GetViewCell();

			// don't have to mail because each view cell belongs to exactly one leaf
			//if (!vc->Mailed())
			//{
			//	vc->Mail();
				viewcells.push_back(vc);
				++ hits;
			//}
#if 0
			leaf->mRays.push_back(RayInfo(new VssRay(origin, termination, NULL, NULL, 0)));
#endif
			// get the next node from the stack
			if (tStack.empty())
				break;

			entp = extp;
			mint = maxt;
			
			LineTraversalData &s  = tStack.top();
			node = s.mNode;
			extp = s.mExitPoint;
			maxt = s.mMaxT;
			tStack.pop();
		}
	}

	return hits;
}


int VspTree::CastRay(Ray &ray)
{
	int hits = 0;

	stack<LineTraversalData> tStack;
	const Vector3 dir = ray.GetDir();

	float maxt, mint;

	if (!mBoundingBox.GetRaySegment(ray, mint, maxt))
		return 0;

	Intersectable::NewMail();
	ViewCell::NewMail();

	Vector3 entp = ray.Extrap(mint);
	Vector3 extp = ray.Extrap(maxt);

	const Vector3 origin = entp;

	VspNode *node = mRoot;
	VspNode *farChild = NULL;

	float position;
	int axis;

	while (1)
	{
		if (!node->IsLeaf())
		{
			VspInterior *in = dynamic_cast<VspInterior *>(node);
			position = in->GetPosition();
			axis = in->GetAxis();

			if (entp[axis] <= position)
			{
				if (extp[axis] <= position)
				{
					node = in->GetBack();
					// cases N1,N2,N3,P5,Z2,Z3
					continue;
				} 
				else
				{
					// case N4
					node = in->GetBack();
					farChild = in->GetFront();
				}
			}
			else
			{
				if (position <= extp[axis])
				{
					node = in->GetFront();
					// cases P1,P2,P3,N5,Z1
					continue;
				}
				else
				{
					node = in->GetFront();
					farChild = in->GetBack();
					// case P4
				}
			}

 			// $$ modification 3.5.2004 - hints from Kamil Ghais
			// case N4 or P4
			const float tdist = (position - origin[axis]) / dir[axis];
			tStack.push(LineTraversalData(farChild, extp, maxt)); //TODO
			extp = origin + dir * tdist;
			maxt = tdist;
		}
		else
		{
			// compute intersection with all objects in this leaf
			VspLeaf *leaf = dynamic_cast<VspLeaf *>(node);
			ViewCell *vc = leaf->GetViewCell();

			if (!vc->Mailed())
			{
				vc->Mail();
				// todo: add view cells to ray
				++ hits;
			}
#if 0
			leaf->mRays.push_back(RayInfo(new VssRay(origin, termination, NULL, NULL, 0)));
#endif
			// get the next node from the stack
			if (tStack.empty())
				break;

			entp = extp;
			mint = maxt;
			
			LineTraversalData &s  = tStack.top();
			node = s.mNode;
			extp = s.mExitPoint;
			maxt = s.mMaxT;
			tStack.pop();
		}
	}

	return hits;
}


ViewCell *VspTree::GetViewCell(const Vector3 &point, const bool active)
{
	if (mRoot == NULL)
		return NULL;

	stack<VspNode *> nodeStack;
	nodeStack.push(mRoot);
  
	ViewCellLeaf *viewcell = NULL;
  
	while (!nodeStack.empty())  
	{
		VspNode *node = nodeStack.top();
		nodeStack.pop();
	
		if (node->IsLeaf()) 
		{
			viewcell = dynamic_cast<VspLeaf *>(node)->GetViewCell();
			break;
		} 
		else 	
		{	
			VspInterior *interior = dynamic_cast<VspInterior *>(node);
     
			// random decision
			if (interior->GetPosition() - point[interior->GetAxis()] < 0)
				nodeStack.push(interior->GetBack());
			else
				nodeStack.push(interior->GetFront());
		}
	}
  
	if (active)
		return mViewCellsTree->GetActiveViewCell(viewcell);
	else
		return viewcell;
}


bool VspTree::ViewPointValid(const Vector3 &viewPoint) const
{
	VspNode *node = mRoot;

	while (1)
	{
		// early exit
		if (node->TreeValid())
			return true;

		if (node->IsLeaf())
			return false;
			
		VspInterior *in = dynamic_cast<VspInterior *>(node);
					
		if (in->GetPosition() - viewPoint[in->GetAxis()] <= 0) 
		{
			node = in->GetBack();
		} 
		else
		{
			node = in->GetFront();
		}
	}

	// should never come here
	return false;
}


void VspTree::PropagateUpValidity(VspNode *node)
{
	const bool isValid = node->TreeValid();

	// propagative up invalid flag until only invalid nodes exist over this node
	if (!isValid)
	{
		while (!node->IsRoot() && node->GetParent()->TreeValid())
		{
			node = node->GetParent();
			node->SetTreeValid(false);
		}
	}
	else
	{
		// propagative up valid flag until one of the subtrees is invalid
		while (!node->IsRoot() && !node->TreeValid())
		{
            node = node->GetParent();
			VspInterior *interior = dynamic_cast<VspInterior *>(node);
			
			// the parent is valid iff both leaves are valid
			node->SetTreeValid(interior->GetBack()->TreeValid() && 
							   interior->GetFront()->TreeValid());
		}
	}
}


bool VspTree::Export(OUT_STREAM &stream)
{
	ExportNode(mRoot, stream);

	return true;
}


void VspTree::ExportNode(VspNode *node, OUT_STREAM &stream)
{
	if (node->IsLeaf())
	{
		VspLeaf *leaf = dynamic_cast<VspLeaf *>(node);
		ViewCell *viewCell = mViewCellsTree->GetActiveViewCell(leaf->GetViewCell());

		int id = -1;
		if (viewCell != mOutOfBoundsCell)
			id = viewCell->GetId();

		stream << "<Leaf viewCellId=\"" << id << "\" />" << endl;
	}
	else
	{	
		VspInterior *interior = dynamic_cast<VspInterior *>(node);
	
		AxisAlignedPlane plane = interior->GetPlane();
		stream << "<Interior plane=\"" << plane.mPosition << " " 
			   << plane.mAxis << "\">" << endl;

		ExportNode(interior->GetBack(), stream);
		ExportNode(interior->GetFront(), stream);

		stream << "</Interior>" << endl;
	}
}


int VspTree::SplitRays(const AxisAlignedPlane &plane,
					   RayInfoContainer &rays,
					   RayInfoContainer &frontRays,
					   RayInfoContainer &backRays) const
{
	int splits = 0;

	RayInfoContainer::const_iterator rit, rit_end = rays.end();

	for (rit = rays.begin(); rit != rit_end; ++ rit)
	{
		RayInfo bRay = *rit;
		
		VssRay *ray = bRay.mRay;
		float t;

		// get classification and receive new t
		// test if start point behind or in front of plane
		const int side = bRay.ComputeRayIntersection(plane.mAxis, plane.mPosition, t);
			
		if (side == 0)
		{
			++ splits;

			if (ray->HasPosDir(plane.mAxis))
			{
				backRays.push_back(RayInfo(ray, bRay.GetMinT(), t));
				frontRays.push_back(RayInfo(ray, t, bRay.GetMaxT()));
			}
			else
			{
				frontRays.push_back(RayInfo(ray, bRay.GetMinT(), t));
				backRays.push_back(RayInfo(ray, t, bRay.GetMaxT()));
			}
		}
		else if (side == 1)
		{
			frontRays.push_back(bRay);
		}
		else
		{
			backRays.push_back(bRay);
		}
	}

	return splits;
}


AxisAlignedBox3 VspTree::GetBoundingBox(VspNode *node) const
{
	if (!node->GetParent())
		return mBoundingBox;

	if (!node->IsLeaf())
	{
		return (dynamic_cast<VspInterior *>(node))->GetBoundingBox();		
	}

	VspInterior *parent = dynamic_cast<VspInterior *>(node->GetParent());

	AxisAlignedBox3 box(parent->GetBoundingBox());

	if (parent->GetFront() == node)
      box.SetMin(parent->GetAxis(), parent->GetPosition());
    else
      box.SetMax(parent->GetAxis(), parent->GetPosition());

	return box;
}


int VspTree::ComputeBoxIntersections(const AxisAlignedBox3 &box,
									 ViewCellContainer &viewCells) const
{
	stack<VspNode *> nodeStack;
 
	ViewCell::NewMail();

	while (!nodeStack.empty()) 
	{
		VspNode *node = nodeStack.top();
		nodeStack.pop();

		const AxisAlignedBox3 bbox = GetBoundingBox(node);

		if (bbox.Includes(box))
		{
			// node geometry is contained in box
			CollectViewCells(node, true, viewCells, true);
		}
		else if (Overlap(bbox, box))
		{
			if (node->IsLeaf())
			{
				BspLeaf *leaf = dynamic_cast<BspLeaf *>(node);
			
				if (!leaf->GetViewCell()->Mailed() && leaf->TreeValid())
				{
					leaf->GetViewCell()->Mail();
					viewCells.push_back(leaf->GetViewCell());
				}
			}
			else 
			{
				VspInterior *interior = dynamic_cast<VspInterior *>(node);
			
				VspNode *first = interior->GetFront();
				VspNode *second = interior->GetBack();
            
				nodeStack.push(first);
				nodeStack.push(second);
			}
		}	
		// default: cull
	}

	return (int)viewCells.size();
}


void VspTree::PreprocessRays(const VssRayContainer &sampleRays,
							 RayInfoContainer &rays)
{
	VssRayContainer::const_iterator rit, rit_end = sampleRays.end();

	long startTime = GetTime();

	cout << "storing rays ... ";

	Intersectable::NewMail();

	//-- store rays and objects
	for (rit = sampleRays.begin(); rit != rit_end; ++ rit)
	{
		VssRay *ray = *rit;
		float minT, maxT;
		static Ray hray;

		hray.Init(*ray);
		
		// TODO: not very efficient to implictly cast between rays types
		if (GetBoundingBox().GetRaySegment(hray, minT, maxT))
		{
			float len = ray->Length();

			if (!len)
				len = Limits::Small;

			rays.push_back(RayInfo(ray, minT / len, maxT / len));
		}
	}

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


void VspTree::GetViewCells(const VssRay &ray, ViewCellContainer &viewCells)
{
#if 0 
	// use view cells manager to compute view cells
	mViewCellsManager->ComputeSampleContribution(ray, false, true);
	viewCells = ray.mViewCells;
	ray.mViewCells.clear();
	
#else
	static Ray hray;
	hray.Init(ray);
	
	float tmin = 0, tmax = 1.0;

	if (!mBoundingBox.GetRaySegment(hray, tmin, tmax) || (tmin > tmax))
		return;

	const Vector3 origin = hray.Extrap(tmin);
	const Vector3 termination = hray.Extrap(tmax);

	// if no precomputation of view cells
	CastLineSegment(origin, termination, viewCells);
#endif
}


SubdivisionCandidate *VspTree::PrepareConstruction(const VssRayContainer &sampleRays,
									AxisAlignedBox3 *forcedViewSpace,
									RayInfoContainer &rays)
{
	// store pointer to this tree
	VspSubdivisionCandidate::sVspTree = this;
	mVspStats.nodes = 1;

	// compute view space bounding box
	ComputeBoundingBox(sampleRays, forcedViewSpace);

	// initialise termination criteria
	mTermMinProbability *= mBoundingBox.GetVolume();
	mGlobalCostMisses = 0;

	// get clipped rays
	PreprocessRays(sampleRays, rays);

	const int pvsSize = EvalPvsSize(rays);
	
	Debug <<  "pvs size: " << (int)pvsSize << endl;
	Debug <<  "rays size: " << (int)rays.size() << endl;

	//-- prepare view space partition

	// add first candidate for view space partition
	VspLeaf *leaf = new VspLeaf();
	mRoot = leaf;

	const float prop = mBoundingBox.GetVolume();

	// first vsp traversal data
	VspTraversalData vData(leaf, 0, &rays, pvsSize,	prop, mBoundingBox);

	// create first view cell
	CreateViewCell(vData, false);
		
#if WORK_WITH_VIEWCELL_PVS
	
	// add first view cell to all the objects view cell pvs
	ObjectPvsMap::const_iterator oit, 
		oit_end = leaf->GetViewCell()->GetPvs().mEntries.end();


	for (oit = leaf->GetViewCell()->GetPvs().mEntries.begin(); oit != oit_end; ++ oit)
	{
		Intersectable *obj = (*oit).first;
		obj->mViewCellPvs.AddSample(leaf->GetViewCell(), 1);
	}
#endif

	//-- compute first split candidate

	VspSubdivisionCandidate *splitCandidate = new VspSubdivisionCandidate(vData);
    EvalSubdivisionCandidate(*splitCandidate);

	mTotalCost = (float)pvsSize;
	EvalSubdivisionStats(*splitCandidate);

	return splitCandidate;
}


void VspTree::CollectDirtyCandidates(VspSubdivisionCandidate *sc, 
									 vector<SubdivisionCandidate *> &dirtyList)
{
	VspTraversalData &tData = sc->mParentData;
	VspLeaf *node = tData.mNode;
	
	KdLeaf::NewMail();

	RayInfoContainer::const_iterator rit, rit_end = tData.mRays->end();

	// add all kd nodes seen by the rays
	for (rit = tData.mRays->begin(); rit != rit_end; ++ rit)
	{
		VssRay *ray = (*rit).mRay;
	
		KdLeaf *leaf = mHierarchyManager->mOspTree->GetLeaf(ray->mOrigin, ray->mOriginNode);
	
		if (!leaf->Mailed())
		{
			leaf->Mail();
			dirtyList.push_back(leaf->mSubdivisionCandidate);
		}
		
		leaf = mHierarchyManager->mOspTree->GetLeaf(ray->mTermination, ray->mTerminationNode);
	
		if (!leaf->Mailed())
		{
			leaf->Mail();
			dirtyList.push_back(leaf->mSubdivisionCandidate);
		}
	}
}

}