source: trunk/VUT/GtpVisibilityPreprocessor/src/VssPreprocessor.cpp @ 557

#include "SceneGraph.h"
#include "KdTree.h"
#include "VssPreprocessor.h"
#include "X3dExporter.h"
#include "Environment.h"
#include "MutualVisibility.h"
#include "Polygon3.h"
#include "ViewCell.h"
#include "VssRay.h"
#include "VssTree.h"
#include "ViewCellsManager.h"
#include "RenderSimulator.h"
#include "Beam.h"
#include "GlRenderer.h"

bool use2dSampling = false;
bool useViewspacePlane = false;

VssPreprocessor::VssPreprocessor():
  mPass(0),
  mVssRays()
{
  // this should increase coherence of the samples
  environment->GetIntValue("VssPreprocessor.samplesPerPass", mSamplesPerPass);
  environment->GetIntValue("VssPreprocessor.initialSamples", mInitialSamples);
  environment->GetIntValue("VssPreprocessor.vssSamples", mVssSamples);
  environment->GetIntValue("VssPreprocessor.vssSamplesPerPass", mVssSamplesPerPass);
  environment->GetBoolValue("VssPreprocessor.useImportanceSampling", mUseImportanceSampling);
  environment->GetBoolValue("ViewCells.delayedConstruction", mDelayedViewCellsConstruction);

  environment->GetBoolValue("VssPreprocessor.loadInitialSamples", mLoadInitialSamples);
  environment->GetBoolValue("VssPreprocessor.storeInitialSamples", mStoreInitialSamples);
  environment->GetBoolValue("VssPreprocessor.useViewSpaceBox", mUseViewSpaceBox);
  environment->GetBoolValue("VssPreprocessor.testBeamSampling", mTestBeamSampling);

  useViewspacePlane = mUseViewSpaceBox; //hack

  mStats.open("stats.log");
}

VssPreprocessor::~VssPreprocessor()
{
  CLEAR_CONTAINER(mVssRays);
}

void
VssPreprocessor::SetupRay(Ray &ray,
                                                  const Vector3 &point,
                                                  const Vector3 &direction
                                                  )
{
  ray.Clear();
  // do not store anything else then intersections at the ray
  ray.Init(point, direction, Ray::LOCAL_RAY);
}

int
VssPreprocessor::CastRay(
                                                 Vector3 &viewPoint,
                                                 Vector3 &direction,
                                                 VssRayContainer &vssRays
                                                 )
{

    int hits = 0;
  static Ray ray;
  AxisAlignedBox3 box = mKdTree->GetBox();

  AxisAlignedBox3 sbox = box;
  sbox.Enlarge(Vector3(-Limits::Small));
  if (!sbox.IsInside(viewPoint))
        return 0;
        
  SetupRay(ray, viewPoint, direction);
  // cast ray to KD tree to find intersection with other objects
  Intersectable *objectA, *objectB;
  Vector3 pointA, pointB;
  float bsize = Magnitude(box.Size());


        if (!mDetectEmptyViewSpace)
          ray.mFlags &= ~Ray::CULL_BACKFACES;
        else
          ray.mFlags |= Ray::CULL_BACKFACES;

  if (mKdTree->CastRay(ray)) {
        objectA = ray.intersections[0].mObject;
        pointA = ray.Extrap(ray.intersections[0].mT);
  } else {
        objectA = NULL;
        // compute intersection with the scene bounding box
        float tmin, tmax;
        if (box.ComputeMinMaxT(ray, &tmin, &tmax) && tmin < tmax)
          pointA = ray.Extrap(tmax);
        else
          return 0;
  }

        
  if (mDetectEmptyViewSpace) {
        SetupRay(ray, pointA, -direction);
  } else
        SetupRay(ray, viewPoint, -direction);
  
  if (!mDetectEmptyViewSpace)
        ray.mFlags &= ~Ray::CULL_BACKFACES;
                                                           else
                                                                 ray.mFlags |= Ray::CULL_BACKFACES;

  if (mKdTree->CastRay(ray)) {
        objectB = ray.intersections[0].mObject;
        pointB = ray.Extrap(ray.intersections[0].mT);
  } else {
        objectB = NULL;
        float tmin, tmax;
        if (box.ComputeMinMaxT(ray, &tmin, &tmax) && tmin < tmax)
          pointB = ray.Extrap(tmax);
        else
          return 0;
  }
  
  //  if (objectA == NULL && objectB != NULL) {
  if (mDetectEmptyViewSpace) {
        // cast again to ensure that there is no objectA
        SetupRay(ray, pointB, direction);
          ray.mFlags |= Ray::CULL_BACKFACES;
        if (mKdTree->CastRay(ray)) {
          objectA = ray.intersections[0].mObject;
          pointA = ray.Extrap(ray.intersections[0].mT);
        }
  }

  
  VssRay *vssRay  = NULL;

  bool validSample = (objectA != objectB);
  if (0 && mDetectEmptyViewSpace) {   // consider all samples valid
        // check if the viewpoint lies on the line segment AB
        if (Distance(pointA, pointB) <
                Distance(viewPoint, pointA) + Distance(viewPoint, pointB) - Limits::Small) {
          validSample = false;
        }
  }
        
  if (validSample) {
        if (objectA) {
          vssRay = new VssRay(pointB,
                                                  pointA,
                                                  objectB,
                                                  objectA,
                                                  mPass
                                                  );
          vssRays.push_back(vssRay);
          hits ++;
        }
        
        if (objectB) {
          vssRay = new VssRay(pointA,
                                                  pointB,
                                                  objectA,
                                                  objectB,
                                                  mPass
                                                  );
          vssRays.push_back(vssRay);
          hits ++;
        }
  }
        
  return hits;
}


Vector3
VssPreprocessor::GetViewpoint(AxisAlignedBox3 *viewSpaceBox)
{
  AxisAlignedBox3 box;

  if (viewSpaceBox)
        box =*viewSpaceBox;
  else
        box = mKdTree->GetBox();

  // shrink the box in the y direction
  return box.GetRandomPoint();
}

Vector3
VssPreprocessor::GetDirection(const Vector3 &viewpoint,
                                                          AxisAlignedBox3 *viewSpaceBox
                                                          )
{
  Vector3 point;
  if (!use2dSampling) {
        if (0) {
          Vector3 normal;
          int i = Random((int)mObjects.size());
          Intersectable *object = mObjects[i];
          object->GetRandomSurfacePoint(point, normal);
        } else
          point = mKdTree->GetBox().GetRandomPoint();
        //        point = viewpoint + UniformRandomVector();

  } else {
        AxisAlignedBox3 box;

        if (viewSpaceBox)
          box =*viewSpaceBox;
        else
          box = mKdTree->GetBox();

        point = box.GetRandomPoint();
        point.y = viewpoint.y;
  }

  return point - viewpoint;
}

int
VssPreprocessor::GenerateImportanceRays(VssTree *vssTree,
                                                                                const int desiredSamples,
                                                                                SimpleRayContainer &rays
                                                                                )
{
  int num;
  if (0) {
        float minRayContribution;
        float maxRayContribution;
        float avgRayContribution;

        vssTree->GetRayContributionStatistics(minRayContribution,
                                                                                  maxRayContribution,
                                                                                  avgRayContribution);

        cout<<
          "#MIN_RAY_CONTRIB\n"<<minRayContribution<<endl<<
          "#MAX_RAY_CONTRIB\n"<<maxRayContribution<<endl<<
          "#AVG_RAY_CONTRIB\n"<<avgRayContribution<<endl;

        float p = desiredSamples/(float)(avgRayContribution*vssTree->stat.Leaves());
        num = vssTree->GenerateRays(p, rays);
  } else {
        int leaves = vssTree->stat.Leaves();
        num = vssTree->GenerateRays(desiredSamples, leaves, rays);
  }

  cout<<"Generated "<<num<<" rays."<<endl;

  return num;
}


bool
VssPreprocessor::ExportRays(const char *filename,
                                                        const VssRayContainer &vssRays,
                                                        const int number
                                                        )
{
  cout<<"Exporting vss rays..."<<endl<<flush;

  Exporter *exporter = NULL;
  exporter = Exporter::GetExporter(filename);
  //    exporter->SetWireframe();
  //    exporter->ExportKdTree(*mKdTree);
  exporter->SetFilled();
  exporter->ExportScene(mSceneGraph->mRoot);
  exporter->SetWireframe();

  if (mViewSpaceBox) {
        exporter->SetForcedMaterial(RgbColor(1,0,1));
        exporter->ExportBox(*mViewSpaceBox);
        exporter->ResetForcedMaterial();
  }

  VssRayContainer rays;
  vssRays.SelectRays(number, rays);
  
  exporter->ExportRays(rays, RgbColor(1, 0, 0));

  delete exporter;

  cout<<"done."<<endl<<flush;

  return true;
}


bool
VssPreprocessor::ExportVssTree(char *filename,
                                                           VssTree *tree,
                                                           const Vector3 &dir
                                                           )
{
  Exporter *exporter = Exporter::GetExporter(filename);
  exporter->SetFilled();
  exporter->ExportScene(mSceneGraph->mRoot);
  //  exporter->SetWireframe();
  bool result = exporter->ExportVssTree2( *tree, dir );
  delete exporter;
  return result;
}

bool
VssPreprocessor::ExportVssTreeLeaf(char *filename,
                                                                   VssTree *tree,
                                                                   VssTreeLeaf *leaf)
{
  Exporter *exporter = NULL;
  exporter = Exporter::GetExporter(filename);
  exporter->SetWireframe();
  exporter->ExportKdTree(*mKdTree);

  if (mViewSpaceBox) {
        exporter->SetForcedMaterial(RgbColor(1,0,0));
        exporter->ExportBox(*mViewSpaceBox);
        exporter->ResetForcedMaterial();
  }

  exporter->SetForcedMaterial(RgbColor(0,0,1));
  exporter->ExportBox(tree->GetBBox(leaf));
  exporter->ResetForcedMaterial();

  VssRayContainer rays[4];
  for (int i=0; i < leaf->rays.size(); i++) {
        int k = leaf->rays[i].GetRayClass();
        rays[k].push_back(leaf->rays[i].mRay);
  }

  // SOURCE RAY
  exporter->ExportRays(rays[0], RgbColor(1, 0, 0));
  // TERMINATION RAY
  exporter->ExportRays(rays[1], RgbColor(1, 1, 1));
  // PASSING_RAY
  exporter->ExportRays(rays[2], RgbColor(1, 1, 0));
  // CONTAINED_RAY
  exporter->ExportRays(rays[3], RgbColor(0, 0, 1));

  delete exporter;
  return true;
}

void
VssPreprocessor::ExportVssTreeLeaves(VssTree *tree, const int number)
{
  vector<VssTreeLeaf *> leaves;
  tree->CollectLeaves(leaves);

  int num = 0;
  int i;
  float p = number / (float)leaves.size();
  for (i=0; i < leaves.size(); i++) {
        if (RandomValue(0,1) < p) {
          char filename[64];
          sprintf(filename, "vss-leaf-%04d.x3d", num);
          ExportVssTreeLeaf(filename, tree, leaves[i]);
          num++;
        }
        if (num >= number)
          break;
  }
}
#include "ViewCellBsp.h"

void VssPreprocessor::TestBeamCasting(VssTree *tree, 
                                                                          ViewCellsManager *vm, 
                                                                          const ObjectContainer &objects)
{
        //debuggerWidget = new GlDebuggerWidget(renderer);
        //  renderer->resize(640, 480);
        //debuggerWidget->resize(640, 480);

        vector<VssTreeLeaf *> leaves;
        tree->CollectLeaves(leaves);

        Exporter *exporter = Exporter::GetExporter("shafts.x3d");

        exporter->SetWireframe();
        exporter->ExportGeometry(objects);
        exporter->SetFilled();
        //Randomize();
        debuggerWidget = new GlDebuggerWidget(renderer);

        /*debuggerWidget->mBeam = beam;
        debuggerWidget->mSourceObject = sourceObj;
        debuggerWidget->mSamples = 10000;
        
        Debug << "showing window" << endl;
        debuggerWidget->show();*/
        
        renderer->makeCurrent();

        for (int i = 0; i < 10; ++ i)
        {
                Beam beam;
                Intersectable *sourceObj = mObjects[5];

                const int index = (int)RandomValue(0, (Real)((int)leaves.size() - 1));
                VssTreeLeaf *leaf = leaves[index];

                AxisAlignedBox3 dirBox = tree->GetDirBBox(leaf);
                AxisAlignedBox3 box = tree->GetBBox(leaf);
                
                beam.Construct(box, dirBox);

                // collect kd leaves and view cells
                mKdTree->CastBeam(beam);
                vm->CastBeam(beam);

                Debug << "found " << beam.mViewCells.size() << " view cells and " 
                          << beam.mKdNodes.size() << " kd nodes" << endl;

                BeamSampleStatistics stats;

                renderer->SampleBeamContributions(sourceObj,
                                                                                  beam,
                                                                                  200000,
                                                                                  stats);

                char s[64]; sprintf(s, "shaft%04d.png", i);

                QImage image = renderer->toImage();
                image.save(s, "PNG");
                Debug << "beam statistics: " << stats << endl << endl;

                if (1)
                {
                        AxisAlignedBox3 sbox = mSceneGraph->GetBox();
                        Vector3 bmin = sbox.Min() - 150.0f;
                        Vector3 bmax = sbox.Max() + 150.0f;
                        AxisAlignedBox3 vbox(bmin, bmax);
                
                        exporter->ExportBeam(beam, vbox);
                }

                bool exportViewCells = false;
                
                if (exportViewCells)
                {
                        ViewCellContainer::const_iterator it, it_end = beam.mViewCells.end();
                        
                        for (it = beam.mViewCells.begin(); it != beam.mViewCells.end(); ++ it)
                        {
                                BspNodeGeometry geom;
                                AxisAlignedBox3 vbox;
                                vbox.Initialize();
                                vbox.Include((*it)->GetMesh());
                        
                                exporter->SetWireframe();
                                exporter->ExportBox(vbox);
                                exporter->SetFilled();
                                exporter->ExportViewCell(*it);
                        }

                        /*vector<KdNode *>::const_iterator it, it_end = beam.mKdNodes.end();
                        
                        for (it = beam.mKdNodes.begin(); it != beam.mKdNodes.end(); ++ it)
                        {
                                exporter->ExportBox(mKdTree->GetBox((*it)));
                        }*/
                }
        }
        /*while (1)
        { debuggerWidget->repaint();
        };*/
        delete exporter;
}


float
VssPreprocessor::GetAvgPvsSize(VssTree *tree,
                                                           const vector<AxisAlignedBox3> &viewcells
                                                           )
{
  vector<AxisAlignedBox3>::const_iterator it, it_end = viewcells.end();

  int sum = 0;
  for (it = viewcells.begin(); it != it_end; ++ it)
        sum += tree->GetPvsSize(*it);

  return sum/(float)viewcells.size();
}

bool
VssPreprocessor::ComputeVisibility()
{


  long startTime = GetTime();

  int totalSamples = 0;


  AxisAlignedBox3 *box = new AxisAlignedBox3(mKdTree->GetBox());
  
  if (!useViewspacePlane) {
        float size = 0.05f;
        float s = 0.5f - size;
        float olds = Magnitude(box->Size());
        box->Enlarge(box->Size()*Vector3(-s));
        Vector3 translation = Vector3(-olds*0.1f, 0, 0);
        box->SetMin(box->Min() + translation);
        box->SetMax(box->Max() + translation);
  } else {

        // sample city like heights
        box->SetMin(1, box->Min(1) + box->Size(1)*0.2f);
        box->SetMax(1, box->Min(1) + box->Size(1)*0.3f);
  }

  if (use2dSampling)
        box->SetMax(1, box->Min(1));

  cout<<"mUseViewSpaceBox="<<mUseViewSpaceBox<<endl;
  Debug << "use view space box=" << mUseViewSpaceBox << endl;
  if (mUseViewSpaceBox)
  {
        mViewSpaceBox = box;
        mViewCellsManager->SetViewSpaceBox(*box);
  }
  else
  {
        mViewSpaceBox = NULL;
        mViewCellsManager->SetViewSpaceBox(mKdTree->GetBox());
  }
  
  //-- load view cells from file if requested
  if (mLoadViewCells)
  {     
          // load now because otherwise bounding box not correct
          mViewCellsManager->LoadViewCells(mViewCellsFilename, &mObjects);
  }


  VssTree *vssTree = NULL;

  mSceneGraph->CollectObjects(&mObjects);

  long initialTime = GetTime();

  if (mLoadInitialSamples)
  {
          cout << "Loading samples from file ... ";
          LoadSamples(mVssRays, mObjects);
          cout << "finished\n" << endl;
          totalSamples = (int)mVssRays.size();
  }
  else
  {
        
        while (totalSamples < mInitialSamples) {
                int passContributingSamples = 0;
                int passSampleContributions = 0;
                int passSamples = 0;

                int index = 0;

                int sampleContributions;

                int s = Min(mSamplesPerPass, mInitialSamples);
                for (int k=0; k < s; k++) {
                        // changed by matt
                        Vector3 viewpoint; 
                        //                      viewpoint = GetViewpoint(mViewSpaceBox);
                        mViewCellsManager->GetViewPoint(viewpoint);
                        Vector3 direction = GetDirection(viewpoint, mViewSpaceBox);

                        sampleContributions = CastRay(viewpoint, direction, mVssRays);

                        if (sampleContributions) {
                                passContributingSamples ++;
                                passSampleContributions += sampleContributions;
                        }
                        passSamples++;
                        totalSamples++;
                }

                mPass++;
                int pvsSize = 0;
                float avgRayContrib = (passContributingSamples > 0) ?
                        passSampleContributions/(float)passContributingSamples : 0;

                cout << "#Pass " << mPass << " : t = " << TimeDiff(startTime, GetTime())*1e-3 << "s" << endl;
                cout << "#TotalSamples=" << totalSamples/1000
                        << "k   #SampleContributions=" << passSampleContributions << " ("
                        << 100*passContributingSamples/(float)passSamples<<"%)" << " avgPVS="
                        << pvsSize/(float)mObjects.size() << endl
                        << "avg ray contrib=" << avgRayContrib << endl;

                mStats <<
                        "#Pass\n" <<mPass<<endl<<
                        "#Time\n" << TimeDiff(startTime, GetTime())*1e-3 << endl<<
                        "#TotalSamples\n" << totalSamples<< endl<<
                        "#SampleContributions\n" << passSampleContributions << endl <<
                        "#PContributingSamples\n"<<100*passContributingSamples/(float)passSamples<<endl <<
                        "#AvgPVS\n"<< pvsSize/(float)mObjects.size() << endl <<
                        "#AvgRayContrib\n" << avgRayContrib << endl;
          }
 
          cout << "#totalPvsSize=" << mKdTree->CollectLeafPvs() << endl;


          
  }
  
  cout << "#totalRayStackSize=" << (int)mVssRays.size() << endl << flush;
  Debug << (int)mVssRays.size() << " rays generated in " 
            << TimeDiff(initialTime, GetTime()) * 1e-3 << " seconds" << endl;

  if (mStoreInitialSamples)
  {
          cout << "Writing " << (int)mVssRays.size() << " samples to file ... ";
          ExportSamples(mVssRays);
          cout << "finished\n" << endl;

          /*VssRayContainer dummyRays;
          LoadSamples(dummyRays, mObjects);
          Debug << "rays " << (int)mVssRays.size() << " " << dummyRays.size() << endl;

          for (int i = 0; i < (int)mVssRays.size(); ++ i)
          {
                  Debug << mVssRays[i]->GetOrigin() << " " << mVssRays[i]->GetTermination() << " " << mVssRays[i]->mOriginObject << " " << mVssRays[i]->mTerminationObject << endl;
                  Debug << dummyRays[i]->GetOrigin() << " " << dummyRays[i]->GetTermination() << " " << dummyRays[i]->mOriginObject << " " << dummyRays[i]->mTerminationObject << endl << endl;
          }*/
  }

  
  //int numExportRays = 5000;
  int numExportRays = 0;

  if (numExportRays) {
        char filename[64];
        sprintf(filename, "vss-rays-initial.x3d");
        ExportRays(filename, mVssRays, numExportRays);
  }

  /// compute view cell contribution of rays if view cells manager already constructed
  mViewCellsManager->ComputeSampleContributions(mVssRays);

  // construct view cells
  if (!mDelayedViewCellsConstruction)
        mViewCellsManager->Construct(mObjects, mVssRays);
 
  vssTree = new VssTree;
  // viewcells = Construct(mVssRays);

  vssTree->Construct(mVssRays, mViewSpaceBox);
  cout<<"VssTree root PVS size = "<<vssTree->GetRootPvsSize()<<endl;

  if (0)
  {
          ExportVssTree("vss-tree-100.x3d", vssTree, Vector3(1,0,0));
          ExportVssTree("vss-tree-001.x3d", vssTree, Vector3(0,0,1));
          ExportVssTree("vss-tree-101.x3d", vssTree, Vector3(1,0,1));
          ExportVssTree("vss-tree-101m.x3d", vssTree, Vector3(-1,0,-1));
          ExportVssTreeLeaves(vssTree, 10);
  }

  // viewcells->UpdatePVS(newVssRays);
  // get viewcells as kd tree boxes
  vector<AxisAlignedBox3> kdViewcells;
  if (0) {
        vector<KdLeaf *> leaves;
        mKdTree->CollectLeaves(leaves);
        vector<KdLeaf *>::const_iterator it;
        int targetLeaves = 50;
        float prob = targetLeaves/(float)leaves.size();
        for (it = leaves.begin(); it != leaves.end(); ++it)
          if (RandomValue(0.0f,1.0f) < prob)
                kdViewcells.push_back(mKdTree->GetBox(*it));

        float avgPvs = GetAvgPvsSize(vssTree, kdViewcells);
        cout<<"Initial average PVS size = "<<avgPvs<<endl;
  }


  int samples = 0;
  int pass = 0;

  
  // cast view cell samples
  while (samples < mVssSamples) 
  {
        
        int num = mVssSamplesPerPass;
        SimpleRayContainer rays;
        VssRayContainer vssRays;

        if (!mUseImportanceSampling) {
          for (int j=0; j < num; j++) {
            // changed by matt
                //Vector3 viewpoint = GetViewpoint(mViewSpaceBox);
                Vector3 viewpoint; 
                mViewCellsManager->GetViewPoint(viewpoint);
                Vector3 direction = GetDirection(viewpoint, mViewSpaceBox);
                rays.push_back(SimpleRay(viewpoint, direction));
          }
        } else {
          num = GenerateImportanceRays(vssTree, num, rays);
        }

        for (int i=0; i < rays.size(); i++)
          CastRay(rays[i].mOrigin, rays[i].mDirection, vssRays);

        vssTree->AddRays(vssRays);

        if (0) {
          int subdivided = vssTree->UpdateSubdivision();
          cout<<"subdivided leafs = "<<subdivided<<endl;
        }

        float avgPvs = GetAvgPvsSize(vssTree, kdViewcells);
        cout<<"Average PVS size = "<<avgPvs<<endl;

        // construct view cells after vss
        if (!mViewCellsManager->ViewCellsConstructed() && 
                (samples + mInitialSamples >= mViewCellsManager->GetConstructionSamples()))
        {
                Debug << "samples " << samples << " initial " << mInitialSamples << " " << samples + mInitialSamples << endl;
                VssRayContainer constructionRays;
                vssTree->CollectRays(constructionRays, mViewCellsManager->GetConstructionSamples());

                Debug << "collected rays: " << constructionRays.size() << endl;

                // test if we really have enough rays
                //if (constructionRays.size() >= nSamples) 
                mViewCellsManager->Construct(mObjects, constructionRays);
        }

        /// compute view cell contribution of rays
        mViewCellsManager->ComputeSampleContributions(vssRays);
        
        if (numExportRays) {
          char filename[64];
          if (mUseImportanceSampling)
                sprintf(filename, "vss-rays-i%04d.x3d", pass);
          else
                sprintf(filename, "vss-rays-%04d.x3d", pass);

          ExportRays(filename, vssRays, numExportRays);
        }

        samples+=num;
        float pvs = vssTree->GetAvgPvsSize();
        cout<<"*****************************\n";
        cout<<samples<<" avgPVS ="<<pvs<<endl;
        cout<<"VssTree root PVS size = "<<vssTree->GetRootPvsSize()<<endl;
        cout<<"*****************************\n";
//      if (samples >= mVssSamples) break;
        pass ++;
  }


  // at the latest create view cells here
  if (!mViewCellsManager->ViewCellsConstructed())
  {
          VssRayContainer constructionRays;

          vssTree->CollectRays(constructionRays, 
                                                   mViewCellsManager->GetConstructionSamples());
          Debug << "collected rays: " << constructionRays.size() << endl;

          mViewCellsManager->Construct(mObjects, constructionRays);
  }

  Debug << vssTree->stat << endl;
  VssRayContainer viewCellRays;
  
  // compute rays used for view cells construction
  int numRays = Max(mViewCellsManager->GetPostProcessSamples(),
                                        mViewCellsManager->GetVisualizationSamples());

  vssTree->CollectRays(viewCellRays, numRays);
  
  //-- post process view cells
  mViewCellsManager->PostProcess(mObjects, viewCellRays);

  if (mTestBeamSampling && mUseGlRenderer)
  {     
          TestBeamCasting(vssTree, mViewCellsManager, mObjects);
  }

  //-- several visualizations and statistics
  Debug << "\nview cells after post processing: " << endl;
  mViewCellsManager->PrintStatistics(Debug);

  mViewCellsManager->Visualize(mObjects, viewCellRays);
  
  //-- render simulation after merge
  cout << "\nevaluating bsp view cells render time after merge ... ";
  mRenderSimulator->RenderScene();
  SimulationStatistics ss;
  mRenderSimulator->GetStatistics(ss);
  
  cout << " finished" << endl;
  cout << ss << endl;
  Debug << ss << endl;

  delete vssTree;
  
  return true;
}