source: GTP/trunk/Lib/Vis/Preprocessing/src/Preprocessor.cpp @ 1251

#include "SceneGraph.h"
#include "Exporter.h"
#include "UnigraphicsParser.h"
#include "X3dParser.h"
#include "Preprocessor.h"
#include "ViewCell.h"
#include "Environment.h"
#include "ViewCellsManager.h"
#include "ViewCellBsp.h"
#include "VspBspTree.h"
#include "RenderSimulator.h"
#include "GlRenderer.h"
#include "PlyParser.h"
#include "SamplingStrategy.h"
#include "VspTree.h"
#include "OspTree.h"
#include "ObjParser.h"
#ifdef GTP_INTERNAL
#include "ArchModeler2MLRT.hxx"
#endif

namespace GtpVisibilityPreprocessor {

const static bool ADDITIONAL_GEOMETRY_HACK = false;

//Preprocessor *preprocessor;


// HACK: Artificially modify scene to watch rendercost changes
static void AddGeometry(SceneGraph *scene)
{
        scene->mRoot->UpdateBox();

        AxisAlignedBox3 sceneBox = scene->GetBox();

        int n = 200;

        if (0){
        // form grid of boxes
        for (int i = 0; i < n; ++ i)
        {
                for (int j = 0; j < n; ++ j)
                {
                        const Vector3 scale2((float)j * 0.8f / n + 0.1f,  0.05f, (float)i * 0.8f  / (float)n + 0.1f);
                
                        const Vector3 pt2 = sceneBox.Min() + scale2 * (sceneBox.Max() - sceneBox.Min());
                
                        const Vector3 boxSize = sceneBox.Size() * Vector3(0.0025f, 0.01f, 0.0025f);
                        AxisAlignedBox3 box(pt2, pt2 + boxSize);
                        Mesh *mesh = CreateMeshFromBox(box);

                        mesh->Preprocess();
                
                        MeshInstance *mi = new MeshInstance(mesh);
                        scene->mRoot->mGeometry.push_back(mi);
                }
        }

        for (int i = 0; i < n; ++ i)
        {
                for (int j = 0; j < n; ++ j)
                {
                        const Vector3 scale2(0.15f, (float)j * 0.8f / n + 0.1f, (float)i * 0.8f  / (float)n + 0.1f);
                
                        Vector3 pt2 = sceneBox.Min() + scale2 * (sceneBox.Max() - sceneBox.Min());
                
                        Vector3 boxSize = sceneBox.Size() * Vector3(0.0025f, 0.01f, 0.0025f);
                        AxisAlignedBox3 box(pt2, pt2 + boxSize);
                        Mesh *mesh = CreateMeshFromBox(box);

                        mesh->Preprocess();
                
                        MeshInstance *mi = new MeshInstance(mesh);
                        scene->mRoot->mGeometry.push_back(mi);
                }
        }

        for (int i = 0; i < n; ++ i)
        {
                const Vector3 scale2(2, 0.2f, (float)i * 0.8f  / (float)n + 0.1f);
                
                Vector3 pt2 = sceneBox.Min() + scale2 * (sceneBox.Max() - sceneBox.Min());
                
                //Vector3 boxSize = sceneBox.Size() * Vector3(0.0025, 0.01, 0.0025);
                Vector3 boxSize = sceneBox.Size() * Vector3(0.005f, 0.02f, 0.005f);

                AxisAlignedBox3 box(pt2 + 0.1f, pt2 + boxSize);
                Mesh *mesh = CreateMeshFromBox(box);

                mesh->Preprocess();
                
                MeshInstance *mi = new MeshInstance(mesh);
                scene->mRoot->mGeometry.push_back(mi);
        }
        
        scene->mRoot->UpdateBox();
        }
                
        if (1)
        {
                // plane separating view space regions
                const Vector3 scale(1.0f, 0.0, 0);

                Vector3 pt = sceneBox.Min() + scale * (sceneBox.Max() - sceneBox.Min());

                Plane3 cuttingPlane(Vector3(1, 0, 0), pt);
                Mesh *planeMesh = new Mesh();
                
                Polygon3 *poly = sceneBox.CrossSection(cuttingPlane);
                IncludePolyInMesh(*poly, *planeMesh);
                
                planeMesh->Preprocess();
                
                MeshInstance *planeMi = new MeshInstance(planeMesh);
                scene->mRoot->mGeometry.push_back(planeMi);
        }       
}


Preprocessor::Preprocessor():
mKdTree(NULL),
mBspTree(NULL),
mVspBspTree(NULL),
mViewCellsManager(NULL),
mRenderSimulator(NULL),
mPass(0)
{
        Environment::GetSingleton()->GetBoolValue("Preprocessor.useGlRenderer", mUseGlRenderer);
  
        // renderer will be constructed when the scene graph and viewcell manager will be known
        renderer = NULL;
  
        Environment::GetSingleton()->GetBoolValue("Preprocessor.useGlDebugger", mUseGlDebugger);
        Environment::GetSingleton()->GetBoolValue("Preprocessor.loadPolygonsAsMeshes", mLoadPolygonsAsMeshes);
        Environment::GetSingleton()->GetBoolValue("Preprocessor.quitOnFinish", mQuitOnFinish);
        Environment::GetSingleton()->GetBoolValue("Preprocessor.computeVisibility", mComputeVisibility);
        Environment::GetSingleton()->GetBoolValue("Preprocessor.detectEmptyViewSpace", mDetectEmptyViewSpace);
        Environment::GetSingleton()->GetBoolValue("Preprocessor.exportVisibility", mExportVisibility );
        Environment::GetSingleton()->GetIntValue("Preprocessor.rayCastMethod", mRayCastMethod);

        char buffer[256];
        Environment::GetSingleton()->GetStringValue("Preprocessor.visibilityFile",  buffer);
        mVisibilityFileName = buffer;
        Environment::GetSingleton()->GetBoolValue("Preprocessor.applyVisibilityFilter", mApplyVisibilityFilter );
        Environment::GetSingleton()->GetBoolValue("Preprocessor.applyVisibilitySpatialFilter",
                                                          mApplyVisibilitySpatialFilter );
        Environment::GetSingleton()->GetFloatValue("Preprocessor.visibilityFilterWidth", mVisibilityFilterWidth);

        Debug << "detect empty view space=" << mDetectEmptyViewSpace << endl;
        Debug << "load polygons as meshes: " << mLoadPolygonsAsMeshes << endl;
}


Preprocessor::~Preprocessor()
{
  cout << "cleaning up" << endl;

  cout << "Deleting view cells manager ... \n";
  DEL_PTR(mViewCellsManager);
  cout << "done.\n";

  cout << "Deleting bsp tree ... \n";
  DEL_PTR(mBspTree);
  cout << "done.\n";

  cout << "Deleting kd tree...\n";
  DEL_PTR(mKdTree);
  cout << "done.\n";
 
  cout << "Deleting vsp tree...\n";
  DEL_PTR(mVspTree);
  cout << "done.\n";

  cout << "Deleting osp tree...\n";
  DEL_PTR(mOspTree);
  cout << "done.\n";

  cout << "Deleting vspbsp tree...\n";
  DEL_PTR(mVspBspTree);
  cout << "done.\n";

   cout << "Deleting scene graph...\n";
  DEL_PTR(mSceneGraph);
  cout << "done.\n";

  DEL_PTR(mRenderSimulator);
  DEL_PTR(renderer);
}

int
SplitFilenames(const string str, vector<string> &filenames)
{
        int pos = 0;

        while(1) {
                int npos = (int)str.find(';', pos);
                
                if (npos < 0 || npos - pos < 1)
                        break;
                filenames.push_back(string(str, pos, npos - pos));
                pos = npos + 1;
        }
        
        filenames.push_back(string(str, pos, str.size() - pos));
        return (int)filenames.size();
}


bool
Preprocessor::LoadScene(const string filename)
{
        // use leaf nodes of the original spatial hierarchy as occludees
        mSceneGraph = new SceneGraph;
  
        Parser *parser;
        vector<string> filenames;
        int files = SplitFilenames(filename, filenames);
        cout << "number of input files: " << files << endl;
        bool result = false;
        if (files == 1) {
                
                if (strstr(filename.c_str(), ".x3d"))
                  parser = new X3dParser;
                else
                  if (strstr(filename.c_str(), ".ply") || strstr(filename.c_str(), ".plb"))
                        parser = new PlyParser;
                  else if (strstr(filename.c_str(), ".obj"))
                          parser = new ObjParser;
                  else 
                          parser = new UnigraphicsParser;

                cout<<filename<<endl;

                if (mRayCastMethod == Preprocessor::INTEL_RAYCASTER)
                        result = parser->ParseFile(filename, &mSceneGraph->mRoot, mLoadPolygonsAsMeshes, &mFaceParents);
                else
                        result = parser->ParseFile(filename, &mSceneGraph->mRoot, mLoadPolygonsAsMeshes);

                delete parser;

        } else {
                // root for different files
                mSceneGraph->mRoot = new SceneGraphNode;
                for (int i= 0; i < filenames.size(); i++) {
                        if (strstr(filenames[i].c_str(), ".x3d"))
                                parser = new X3dParser;
                        else 
                                parser = new UnigraphicsParser;
                                                
                        SceneGraphNode *node;
                        if (parser->ParseFile(filenames[i], &node)) {
                                mSceneGraph->mRoot->mChildren.push_back(node);
                                // at least one file parsed
                                result = true;
                        }
                        delete parser;
                }
        }
        

        if (result) 
        {
                // HACK 
                if (ADDITIONAL_GEOMETRY_HACK)
                        AddGeometry(mSceneGraph);
                
                mSceneGraph->AssignObjectIds();
        
                int intersectables, faces;
                mSceneGraph->GetStatistics(intersectables, faces);
        
                cout<<filename<<" parsed successfully."<<endl;
                cout<<"#NUM_OBJECTS (Total numner of objects)\n"<<intersectables<<endl;
                cout<<"#NUM_FACES (Total numner of faces)\n"<<faces<<endl;
                mSceneGraph->CollectObjects(&mObjects);
                mSceneGraph->mRoot->UpdateBox();

                if (0)
                {
                        Exporter *exporter = Exporter::GetExporter("testload.x3d");

                        if (exporter)
                        {
                                exporter->ExportGeometry(mObjects);
                                delete exporter;
                        }
                }
        }
        
        
        return result;
}

bool
Preprocessor::ExportPreprocessedData(const string filename)
{
  
  mViewCellsManager->ExportViewCells(filename, true, mObjects);
  
  return true;
}

bool
Preprocessor::PostProcessVisibility()
{
  
  if (mApplyVisibilityFilter || mApplyVisibilitySpatialFilter) {
        cout<<"Applying visibility filter ...";
        cout<<"filter width = " << mVisibilityFilterWidth << endl;
        
        if (!mViewCellsManager)
          return false;
        
        mViewCellsManager->ApplyFilter(mKdTree,
                                                                   mApplyVisibilityFilter ? mVisibilityFilterWidth : -1.0f,
                                                                   mApplyVisibilitySpatialFilter ? mVisibilityFilterWidth : -1.0f);
        cout << "done." << endl;
  }
  
  // export the preprocessed information to a file
  if (mExportVisibility)
        ExportPreprocessedData(mVisibilityFileName);
  
  return true;
}


bool
Preprocessor::BuildKdTree()
{
  mKdTree = new KdTree;
  // add mesh instances of the scene graph to the root of the tree
  KdLeaf *root = (KdLeaf *)mKdTree->GetRoot();
  mSceneGraph->CollectObjects(&root->mObjects);
  
  long startTime = GetTime();

  cout << "building kd tree ... " << endl;
  mKdTree->Construct();
  cout << "construction finished in " << TimeDiff(startTime, GetTime()) * 1e-3 << " secs " << endl;
  return true;
}

void
Preprocessor::KdTreeStatistics(ostream &s)
{
  s<<mKdTree->GetStatistics();
}

void
Preprocessor::BspTreeStatistics(ostream &s)
{
        s << mBspTree->GetStatistics();
}

bool
Preprocessor::Export( const string filename,
                                          const bool scene,
                                          const bool kdtree,
                                          const bool bsptree
                                          )
{
  Exporter *exporter = Exporter::GetExporter(filename);
        
  if (exporter) {
    if (scene)
      exporter->ExportScene(mSceneGraph->mRoot);

    if (kdtree) {
      exporter->SetWireframe();
      exporter->ExportKdTree(*mKdTree);
    }

        if (bsptree) {
                //exporter->SetWireframe();
                exporter->ExportBspTree(*mBspTree);
        }

    delete exporter;
    return true;
  }

  return false;
}


bool Preprocessor::PrepareViewCells()
{
        //-- parse view cells construction method
        Environment::GetSingleton()->GetBoolValue("ViewCells.loadFromFile", mLoadViewCells);
        char buf[100];
        
        if (mLoadViewCells)
        {       
                Environment::GetSingleton()->GetStringValue("ViewCells.filename", buf);
                mViewCellsManager = ViewCellsManager::LoadViewCells(buf, &mObjects, true);
        }
        else
        {
                //-- parse type of view cell container
                Environment::GetSingleton()->GetStringValue("ViewCells.type", buf);             
            mViewCellsManager = CreateViewCellsManager(buf);

                // default view space is the extent of the scene
                mViewCellsManager->SetViewSpaceBox(mSceneGraph->GetBox());


        }
        
        //-- parameters for render heuristics evaluation
        float objRenderCost = 0, vcOverhead = 0, moveSpeed = 0;

        Environment::GetSingleton()->GetFloatValue("Simulation.objRenderCost",objRenderCost);
        Environment::GetSingleton()->GetFloatValue("Simulation.vcOverhead", vcOverhead);
        Environment::GetSingleton()->GetFloatValue("Simulation.moveSpeed", moveSpeed);
        
        mRenderSimulator = 
                new RenderSimulator(mViewCellsManager, objRenderCost, vcOverhead, moveSpeed);

        mViewCellsManager->SetRenderer(mRenderSimulator);


        if (mUseGlRenderer || mUseGlDebugger)
        {
                // NOTE: render texture should be power of 2 and square
                // renderer must be initialised
                // $$matt
//              renderer = new GlRendererBuffer(1024, 768, mSceneGraph, mViewCellsManager, mKdTree);
                //              renderer->makeCurrent();
                
        }
        
        return true;
}


ViewCellsManager *Preprocessor::CreateViewCellsManager(const char *name)
{
        if (strcmp(name, "kdTree") == 0)
        {
                mViewCellsManager = new KdViewCellsManager(mKdTree);
        }
        else if (strcmp(name, "bspTree") == 0)
        {
                Debug << "view cell type: Bsp" << endl;

                mBspTree = new BspTree();
                mViewCellsManager = new BspViewCellsManager(mBspTree);
        }
        else if (strcmp(name, "vspBspTree") == 0)
        {
                Debug << "view cell type: VspBsp" << endl;

                mVspBspTree = new VspBspTree();
                mViewCellsManager = new VspBspViewCellsManager(mVspBspTree);
        }
        else if (strcmp(name, "vspOspTree") == 0)
        {
                mVspTree = new VspTree();
                mOspTree = new OspTree();
                
                // HACK for testing if per kd evaluation works!!
                mOspTree = new OspTree(*mKdTree);

                mViewCellsManager = new VspOspViewCellsManager(mVspTree, mOspTree);
        }
        else if (strcmp(name, "sceneDependent") == 0)
        {
                Debug << "view cell type: Bsp" << endl;

                //TODO
                mBspTree = new BspTree();
                mViewCellsManager = new BspViewCellsManager(mBspTree);
        }
        else
        {
                cerr << "Wrong view cells type " << name << "!!!" << endl;
                exit(1);
        }

        return mViewCellsManager;
}


// use ascii format to store rays
#define USE_ASCII 0


static inline bool ilt(Intersectable *obj1, Intersectable *obj2)
{
        return obj1->mId < obj2->mId;
}


bool Preprocessor::LoadKdTree()
{
        return true;
}

bool Preprocessor::ExportKdTree()
{
        return true;
}


bool Preprocessor::LoadSamples(VssRayContainer &samples, 
                                                           ObjectContainer &objects) const
{
        std::stable_sort(objects.begin(), objects.end(), ilt);
        char fileName[100];
        Environment::GetSingleton()->GetStringValue("Preprocessor.samplesFilename", fileName);
        
    Vector3 origin, termination;
        // HACK: needed only for lower_bound algorithm to find the 
        // intersected objects
        MeshInstance sObj(NULL);
        MeshInstance tObj(NULL);

#if USE_ASCII
        ifstream samplesIn(fileName);
        if (!samplesIn.is_open())
                return false;

        string buf;
        while (!(getline(samplesIn, buf)).eof())
        {
                sscanf(buf.c_str(), "%f %f %f %f %f %f %d %d", 
                           &origin.x, &origin.y, &origin.z,
                           &termination.x, &termination.y, &termination.z, 
                           &(sObj.mId), &(tObj.mId));
                
                Intersectable *sourceObj = NULL;
                Intersectable *termObj = NULL;
                
                if (sObj.mId >= 0)
                {
                        ObjectContainer::iterator oit =
                                lower_bound(objects.begin(), objects.end(), &sObj, ilt);
                        sourceObj = *oit;
                }
                
                if (tObj.mId >= 0)
                {
                        ObjectContainer::iterator oit =
                                lower_bound(objects.begin(), objects.end(), &tObj, ilt);
                        termObj = *oit;
                }

                samples.push_back(new VssRay(origin, termination, sourceObj, termObj));
        }
#else
        ifstream samplesIn(fileName, ios::binary);
        if (!samplesIn.is_open())
                return false;

        while (1)
        {
                 samplesIn.read(reinterpret_cast<char *>(&origin), sizeof(Vector3));
                 samplesIn.read(reinterpret_cast<char *>(&termination), sizeof(Vector3));
                 samplesIn.read(reinterpret_cast<char *>(&(sObj.mId)), sizeof(int));
                 samplesIn.read(reinterpret_cast<char *>(&(tObj.mId)), sizeof(int));
                
                 if (samplesIn.eof())
                        break;

                Intersectable *sourceObj = NULL;
                Intersectable *termObj = NULL;
                
                if (sObj.mId >= 0)
                {
                        ObjectContainer::iterator oit =
                                lower_bound(objects.begin(), objects.end(), &sObj, ilt);
                        sourceObj = *oit;
                }
                
                if (tObj.mId >= 0)
                {
                        ObjectContainer::iterator oit =
                                lower_bound(objects.begin(), objects.end(), &tObj, ilt);
                        termObj = *oit;
                }

                samples.push_back(new VssRay(origin, termination, sourceObj, termObj));
        }

#endif
        samplesIn.close();

        return true;
}


bool Preprocessor::ExportSamples(const VssRayContainer &samples) const
{
        char fileName[100];
        Environment::GetSingleton()->GetStringValue("Preprocessor.samplesFilename", fileName);
        

        VssRayContainer::const_iterator it, it_end = samples.end();
        
#if USE_ASCII
        ofstream samplesOut(fileName);
        if (!samplesOut.is_open())
                return false;

        for (it = samples.begin(); it != it_end; ++ it)
        {
                VssRay *ray = *it;
                int sourceid = ray->mOriginObject ? ray->mOriginObject->mId : -1;               
                int termid = ray->mTerminationObject ? ray->mTerminationObject->mId : -1;       

                samplesOut << ray->GetOrigin().x << " " << ray->GetOrigin().y << " " << ray->GetOrigin().z << " " 
                                   << ray->GetTermination().x << " " << ray->GetTermination().y << " " << ray->GetTermination().z << " " 
                                   << sourceid << " " << termid << "\n";
        }
#else
        ofstream samplesOut(fileName, ios::binary);
        if (!samplesOut.is_open())
                return false;

        for (it = samples.begin(); it != it_end; ++ it)
        {       
                VssRay *ray = *it;
                Vector3 origin(ray->GetOrigin());
                Vector3 termination(ray->GetTermination());
                
                int sourceid = ray->mOriginObject ? ray->mOriginObject->mId : -1;               
                int termid = ray->mTerminationObject ? ray->mTerminationObject->mId : -1;               

                samplesOut.write(reinterpret_cast<char *>(&origin), sizeof(Vector3));
                samplesOut.write(reinterpret_cast<char *>(&termination), sizeof(Vector3));
                samplesOut.write(reinterpret_cast<char *>(&sourceid), sizeof(int));
                samplesOut.write(reinterpret_cast<char *>(&termid), sizeof(int));
    }
#endif
        samplesOut.close();

        return true;
}

#if 0 // matt: implemented interface samplestrategy
bool
Preprocessor::GenerateRays(
                                                   const int number,
                                                   const int sampleType,
                                                   SimpleRayContainer &rays
                                                   )
{
  Vector3 origin, direction; 
  int startSize = (int)rays.size();
  for (int i=0; (int)rays.size() - startSize  < number; i ++) {
        // now get the direction
        switch (sampleType) {
        case OBJECT_BASED_DISTRIBUTION: {
          mViewCellsManager->GetViewPoint(origin);
          Vector3 point;
          Vector3 normal;
          int i = RandomValue(0, mObjects.size() - 1);
          Intersectable *object = mObjects[i];
          object->GetRandomSurfacePoint(point, normal);
          direction = point - origin;
        }
          break;
        case OBJECT_DIRECTION_BASED_DISTRIBUTION: {
          int i = RandomValue(0, mObjects.size() - 1);
          Intersectable *object = mObjects[i];
          Vector3 normal;
          object->GetRandomSurfacePoint(origin, normal);
          direction = UniformRandomVector(normal);
          origin += 0.1f*direction;
        }
          break;
        case DIRECTION_BASED_DISTRIBUTION:
          mViewCellsManager->GetViewPoint(origin);
          direction = UniformRandomVector();
          break;
        case DIRECTION_BOX_BASED_DISTRIBUTION: {
          mViewCellsManager->GetViewPoint(origin);
          float alpha = RandomValue(0.0f, 2*M_PI);
          float beta = RandomValue(-M_PI/2, M_PI/2);
          direction = VssRay::GetDirection(alpha, beta);
          break;
        }
        case SPATIAL_BOX_BASED_DISTRIBUTION:
          mViewCellsManager->GetViewPoint(origin);
          direction = mKdTree->GetBox().GetRandomPoint() - origin;
          break;
        default:
          // unsuported distribution type
          return false;
        }
        // $$ jb the pdf is yet not correct for all sampling methods!
        float pdf = 1.0f;
        float c = Magnitude(direction);
        if (c > Limits::Small) {
          direction*=1.0f/c;
          rays.AddRay(SimpleRay(origin, direction, pdf));
        }
  }
  return true;
}
#endif
bool Preprocessor::GenerateRays(const int number,
                                                                const int sampleType,
                                                                SimpleRayContainer &rays)
{
        Vector3 origin, direction; 
        
        const int startSize = (int)rays.size();
        SamplingStrategy *strategy = GenerateSamplingStrategy(sampleType);

        if (!strategy)
                return false;

        for (int i=0; (int)rays.size() - startSize < number; ++ i) 
        {
                SimpleRay newRay;
                bool success = strategy->GenerateSample(newRay);

                if (success)
                        rays.AddRay(newRay);
        }

        delete strategy;

    return true;
}


SamplingStrategy *Preprocessor::GenerateSamplingStrategy(const int strategyId) const
{
        switch (strategyId)
        {
        case OBJECT_BASED_DISTRIBUTION: 
                return new ObjectBasedDistribution(*this);
        case OBJECT_DIRECTION_BASED_DISTRIBUTION:
                return new ObjectDirectionBasedDistribution(*this);
        case DIRECTION_BASED_DISTRIBUTION:
                return new DirectionBasedDistribution(*this);
        case DIRECTION_BOX_BASED_DISTRIBUTION: 
                return new DirectionBoxBasedDistribution(*this);
        case SPATIAL_BOX_BASED_DISTRIBUTION:
                return new SpatialBoxBasedDistribution(*this);
        //case OBJECTS_INTERIOR_DISTRIBUTION:
        //      return new ObjectsInteriorDistribution(*this);
        default: // no valid strategy
                return NULL;
        }

        // should never come here
        return NULL;
}


bool Preprocessor::InitRayCast(const string externKdTree)
{
        switch (mRayCastMethod) // use intel ray tracing
        {
        case INTEL_RAYCASTER:
#ifdef GTP_INTERNAL
                return mlrtaLoadAS(externKdTree.c_str());
#endif
        case INTERNAL_RAYCASTER:
        default:
                break;
        }

        return true;
}


int Preprocessor::CastIntelDoubleRay(
                                                                         const Vector3 &viewPoint,
                                                                         const Vector3 &direction,
                                                                         const float probability,
                                                                         VssRayContainer &vssRays,
                                                                         const AxisAlignedBox3 &box
                                                                         )
{
        VssRay *vssRay  = NULL;
        int hits = 0;

        Vector3 pointA, pointB;
        
        Intersectable *objectA = 
                CastIntelSingleRay(viewPoint, direction, pointA, box);
        
        // cast ray into other direction
        Intersectable *objectB = 
                CastIntelSingleRay(viewPoint, -direction, pointB, box);

        const bool validSample = (objectA != objectB);
        
        if (validSample) 
        {       
                if (objectA) 
                {
                        vssRay = new VssRay(pointB,
                                                                pointA,
                                                                objectB,
                                                                objectA,
                                                                probability,
                                                                mPass);

                        vssRays.push_back(vssRay);
                        hits ++;
                }

                if (objectB) 
                {
                        vssRay = new VssRay(pointA,
                                                                pointB,
                                                                objectA,
                                                                objectB,
                                                                probability,
                                                                mPass);

                        vssRays.push_back(vssRay);
                        hits ++;
                }
                //Debug << "intel ray: " << *vssRay << endl;
        }
        //cout << "a";
        return hits;
}


Intersectable *Preprocessor::CastIntelSingleRay(const Vector3 &viewPoint,
                                                                                                const Vector3 &direction,
                                                                                                //const float probability,
                                                                                                Vector3 &tPoint,
                                                                                                const AxisAlignedBox3 &box
                                                                                                )
{
        AxisAlignedBox3 sbox = box;
        sbox.Enlarge(Vector3(-Limits::Small));

        if (!sbox.IsInside(viewPoint))
                return 0;
        
        float pforg[3];
        float pfdir[3];
        double pfnorm[3];

        pforg[0] = viewPoint[0]; pforg[1] = viewPoint[1]; pforg[2] = viewPoint[2];
        pfdir[0] = direction[0]; pfdir[1] = direction[1]; pfdir[2] = direction[2];

        float dist = 0;
#ifdef GTP_INTERNAL
        const int hittriangle = mlrtaIntersectAS(pforg, pfdir, pfnorm, dist);
#else
        const int hittriangle = -1;
#endif

        if (hittriangle == -1)
        {
                static Ray ray;
                SetupRay(ray, viewPoint, direction);

                float tmin = 0, tmax;
                if (box.ComputeMinMaxT(ray, &tmin, &tmax) && tmin < tmax)
                {
                        tPoint = ray.Extrap(tmax);
                }

                return NULL;
        }
        else
        {
                tPoint[0] = pforg[0] + pfdir[0] * dist;
                tPoint[1] = pforg[1] + pfdir[1] * dist;
                tPoint[2] = pforg[2] + pfdir[2] * dist;

                return mFaceParents[hittriangle];
        }
}


int Preprocessor::CastInternalRay(
                                                                  const Vector3 &viewPoint,
                                                                  const Vector3 &direction,
                                                                  const float probability,
                                                                  VssRayContainer &vssRays,
                                                                  const AxisAlignedBox3 &box
                                                                  )
{
    int hits = 0;
        static Ray ray;

        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;
        Vector3 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;
        }

        // matt: point A could be undefined?

        // cast ray into opposite direction
        if (1 && 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;
        }
  
        //bool thesame = objectA && (objectA == objectB);
        
        //  if (objectA == NULL && objectB != NULL) {
        if (1 && 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 (validSample && thesame) Debug << "warning!!" << endl;

        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,
                                                                probability,
                                                                mPass);
                        vssRays.push_back(vssRay);
                        hits ++;
                }

                if (objectB) 
                {
                        vssRay = new VssRay(pointA,
                                                                pointB,
                                                                objectA,
                                                                objectB,
                                                                probability,
                                                                mPass);
                        vssRays.push_back(vssRay);
                        hits ++;
                }
                //Debug << "internal ray: " << *vssRay << endl << endl;
        }
//cout << "b";
        return hits;
}


int Preprocessor::CastRay(
                                                  const Vector3 &viewPoint,
                                                  const Vector3 &direction,
                                                  const float probability,
                                                  VssRayContainer &vssRays,
                                                  const AxisAlignedBox3 &box
                                                  )
{
        switch (mRayCastMethod)
        {
        case INTEL_RAYCASTER:
                return CastIntelDoubleRay(viewPoint, direction, probability, vssRays, box);
        case INTERNAL_RAYCASTER:
        default:
                return CastInternalRay(viewPoint, direction, probability, vssRays, box);
        }
}


void Preprocessor::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);
}

}