TNodeColumn* StdMeshers_RadialPrism_3D::makeNodeColumn( TNode2ColumnMap&     n2ColMap,
                                                        const SMDS_MeshNode* outNode,
                                                        const SMDS_MeshNode* inNode)
{
  SMESHDS_Mesh * meshDS = myHelper->GetMeshDS();
  int shapeID = myHelper->GetSubShapeID();

  if ( myLayerPositions.empty() ) {
    gp_Pnt pIn = gpXYZ( inNode ), pOut = gpXYZ( outNode );
    computeLayerPositions( pIn, pOut );
  }
  int nbSegments = myLayerPositions.size() + 1;

  TNode2ColumnMap::iterator n_col =
    n2ColMap.insert( make_pair( outNode, TNodeColumn() )).first;
  TNodeColumn & column = n_col->second;
  column.resize( nbSegments + 1 );
  column.front() = outNode;
  column.back() =  inNode;

  gp_XYZ p1 = gpXYZ( outNode );
  gp_XYZ p2 = gpXYZ( inNode );
  for ( int z = 1; z < nbSegments; ++z )
  {
    double r = myLayerPositions[ z - 1 ];
    gp_XYZ p = ( 1 - r ) * p1 + r * p2;
    SMDS_MeshNode* n = meshDS->AddNode( p.X(), p.Y(), p.Z() );
    meshDS->SetNodeInVolume( n, shapeID );
    column[ z ] = n;
  }

  return & column;
}
Example #2
0
SMDS_MeshNode* SMESH_MesherHelper::AddNode(double x, double y, double z, int ID)
{
  SMESHDS_Mesh * meshDS = GetMeshDS();
  SMDS_MeshNode* node = 0;
  if ( ID )
    node = meshDS->AddNodeWithID( x, y, z, ID );
  else
    node = meshDS->AddNode( x, y, z );
  if ( mySetElemOnShape && myShapeID > 0 ) {
    switch ( myShape.ShapeType() ) {
    case TopAbs_SOLID:  meshDS->SetNodeInVolume( node, myShapeID); break;
    case TopAbs_SHELL:  meshDS->SetNodeInVolume( node, myShapeID); break;
    case TopAbs_FACE:   meshDS->SetNodeOnFace(   node, myShapeID); break;
    case TopAbs_EDGE:   meshDS->SetNodeOnEdge(   node, myShapeID); break;
    case TopAbs_VERTEX: meshDS->SetNodeOnVertex( node, myShapeID); break;
    default: ;
    }
  }
  return node;
}
//=============================================================================
bool NETGENPlugin_Mesher::Compute()
{
#ifdef WNT
  netgen::MeshingParameters& mparams = netgen::GlobalMeshingParameters();
#else
  netgen::MeshingParameters& mparams = netgen::mparam;
#endif  
  MESSAGE("Compute with:\n"
          " max size = " << mparams.maxh << "\n"
          " segments per edge = " << mparams.segmentsperedge);
  MESSAGE("\n"
          " growth rate = " << mparams.grading << "\n"
          " elements per radius = " << mparams.curvaturesafety << "\n"
          " second order = " << mparams.secondorder << "\n"
          " quad allowed = " << mparams.quad);

  SMESH_ComputeErrorPtr error = SMESH_ComputeError::New();
  nglib::Ng_Init();

  // -------------------------
  // Prepare OCC geometry
  // -------------------------

  netgen::OCCGeometry occgeo;
  list< SMESH_subMesh* > meshedSM;
  PrepareOCCgeometry( occgeo, _shape, *_mesh, &meshedSM );

  // -------------------------
  // Generate the mesh
  // -------------------------

  netgen::Mesh *ngMesh = NULL;

  SMESH_Comment comment;
  int err = 0;
  int nbInitNod = 0;
  int nbInitSeg = 0;
  int nbInitFac = 0;
  // vector of nodes in which node index == netgen ID
  vector< SMDS_MeshNode* > nodeVec;
  try
  {
    // ----------------
    // compute 1D mesh
    // ----------------
    // pass 1D simple parameters to NETGEN
    if ( _simpleHyp ) {
      if ( int nbSeg = _simpleHyp->GetNumberOfSegments() ) {
        // nb of segments
        mparams.segmentsperedge = nbSeg + 0.1;
        mparams.maxh = occgeo.boundingbox.Diam();
        mparams.grading = 0.01;
      }
      else {
        // segment length
        mparams.segmentsperedge = 1;
        mparams.maxh = _simpleHyp->GetLocalLength();
      }
    }
    // let netgen create ngMesh and calculate element size on not meshed shapes
    char *optstr = 0;
    int startWith = netgen::MESHCONST_ANALYSE;
    int endWith   = netgen::MESHCONST_ANALYSE;
    err = netgen::OCCGenerateMesh(occgeo, ngMesh, startWith, endWith, optstr);
    if (err) comment << "Error in netgen::OCCGenerateMesh() at MESHCONST_ANALYSE step";

    // fill ngMesh with nodes and elements of computed submeshes
    err = ! fillNgMesh(occgeo, *ngMesh, nodeVec, meshedSM);
    nbInitNod = ngMesh->GetNP();
    nbInitSeg = ngMesh->GetNSeg();
    nbInitFac = ngMesh->GetNSE();

    // compute mesh
    if (!err)
    {
      startWith = endWith = netgen::MESHCONST_MESHEDGES;
      err = netgen::OCCGenerateMesh(occgeo, ngMesh, startWith, endWith, optstr);
      if (err) comment << "Error in netgen::OCCGenerateMesh() at 1D mesh generation";
    }
    // ---------------------
    // compute surface mesh
    // ---------------------
    if (!err)
    {
      // pass 2D simple parameters to NETGEN
      if ( _simpleHyp ) {
        if ( double area = _simpleHyp->GetMaxElementArea() ) {
          // face area
          mparams.maxh = sqrt(2. * area/sqrt(3.0));
          mparams.grading = 0.4; // moderate size growth
        }
        else {
          // length from edges
          double length = 0;
          TopTools_MapOfShape tmpMap;
          for ( TopExp_Explorer exp( _shape, TopAbs_EDGE ); exp.More(); exp.Next() )
            if( tmpMap.Add(exp.Current()) )
              length += SMESH_Algo::EdgeLength( TopoDS::Edge( exp.Current() ));

          if ( ngMesh->GetNSeg() ) {
            // we have to multiply length by 2 since for each TopoDS_Edge there
            // are double set of NETGEN edges or, in other words, we have to
            // divide ngMesh->GetNSeg() on 2.
            mparams.maxh = 2*length / ngMesh->GetNSeg();
          }
          else
            mparams.maxh = 1000;
          mparams.grading = 0.2; // slow size growth
        }
        mparams.maxh = min( mparams.maxh, occgeo.boundingbox.Diam()/2 );
        ngMesh->SetGlobalH (mparams.maxh);
        netgen::Box<3> bb = occgeo.GetBoundingBox();
        bb.Increase (bb.Diam()/20);
        ngMesh->SetLocalH (bb.PMin(), bb.PMax(), mparams.grading);
      }
      // let netgen compute 2D mesh
      startWith = netgen::MESHCONST_MESHSURFACE;
      endWith = _optimize ? netgen::MESHCONST_OPTSURFACE : netgen::MESHCONST_MESHSURFACE;
      err = netgen::OCCGenerateMesh(occgeo, ngMesh, startWith, endWith, optstr);
      if (err) comment << "Error in netgen::OCCGenerateMesh() at surface mesh generation";
    }
    // ---------------------
    // generate volume mesh
    // ---------------------
    if (!err && _isVolume)
    {
      // add ng face descriptors of meshed faces
      std::map< int, std::pair<int,int> >::iterator fId_soIds = _faceDescriptors.begin();
      for ( ; fId_soIds != _faceDescriptors.end(); ++fId_soIds ) {
        int faceID   = fId_soIds->first;
        int solidID1 = fId_soIds->second.first;
        int solidID2 = fId_soIds->second.second;
        ngMesh->AddFaceDescriptor (netgen::FaceDescriptor(faceID, solidID1, solidID2, 0));
      }
      // pass 3D simple parameters to NETGEN
      const NETGENPlugin_SimpleHypothesis_3D* simple3d =
        dynamic_cast< const NETGENPlugin_SimpleHypothesis_3D* > ( _simpleHyp );
      if ( simple3d ) {
        if ( double vol = simple3d->GetMaxElementVolume() ) {
          // max volume
          mparams.maxh = pow( 72, 1/6. ) * pow( vol, 1/3. );
          mparams.maxh = min( mparams.maxh, occgeo.boundingbox.Diam()/2 );
        }
        else {
          // length from faces
          mparams.maxh = ngMesh->AverageH();
        }
//      netgen::ARRAY<double> maxhdom;
//      maxhdom.SetSize (occgeo.NrSolids());
//      maxhdom = mparams.maxh;
//      ngMesh->SetMaxHDomain (maxhdom);
        ngMesh->SetGlobalH (mparams.maxh);
        mparams.grading = 0.4;
        ngMesh->CalcLocalH();
      }
      // let netgen compute 3D mesh
      startWith = netgen::MESHCONST_MESHVOLUME;
      endWith = _optimize ? netgen::MESHCONST_OPTVOLUME : netgen::MESHCONST_MESHVOLUME;
      err = netgen::OCCGenerateMesh(occgeo, ngMesh, startWith, endWith, optstr);
      if (err) comment << "Error in netgen::OCCGenerateMesh()";
    }
    if (!err && mparams.secondorder > 0)
    {
      netgen::OCCRefinementSurfaces ref (occgeo);
      ref.MakeSecondOrder (*ngMesh);
    }
  }
  catch (netgen::NgException exc)
  {
    error->myName = err = COMPERR_ALGO_FAILED;
    comment << exc.What();
  }

  int nbNod = ngMesh->GetNP();
  int nbSeg = ngMesh->GetNSeg();
  int nbFac = ngMesh->GetNSE();
  int nbVol = ngMesh->GetNE();

  MESSAGE((err ? "Mesh Generation failure" : "End of Mesh Generation") <<
          ", nb nodes: " << nbNod <<
          ", nb segments: " << nbSeg <<
          ", nb faces: " << nbFac <<
          ", nb volumes: " << nbVol);

  // -----------------------------------------------------------
  // Feed back the SMESHDS with the generated Nodes and Elements
  // -----------------------------------------------------------

  SMESHDS_Mesh* meshDS = _mesh->GetMeshDS();
  bool isOK = ( !err && (_isVolume ? (nbVol > 0) : (nbFac > 0)) );
  if ( true /*isOK*/ ) // get whatever built
  {
    // map of nodes assigned to submeshes
    NCollection_Map<int> pindMap;
    // create and insert nodes into nodeVec
    nodeVec.resize( nbNod + 1 );
    int i;
    for (i = nbInitNod+1; i <= nbNod /*&& isOK*/; ++i )
    {
      const netgen::MeshPoint& ngPoint = ngMesh->Point(i);
      SMDS_MeshNode* node = NULL;
      bool newNodeOnVertex = false;
      TopoDS_Vertex aVert;
      if (i-nbInitNod <= occgeo.vmap.Extent())
      {
        // point on vertex
        aVert = TopoDS::Vertex(occgeo.vmap(i-nbInitNod));
        SMESHDS_SubMesh * submesh = meshDS->MeshElements(aVert);
        if (submesh)
        {
          SMDS_NodeIteratorPtr it = submesh->GetNodes();
          if (it->more())
          {
            node = const_cast<SMDS_MeshNode*> (it->next());
            pindMap.Add(i);
          }
        }
        if (!node)
          newNodeOnVertex = true;
      }
      if (!node)
        node = meshDS->AddNode(ngPoint.X(), ngPoint.Y(), ngPoint.Z());
      if (!node)
      {
        MESSAGE("Cannot create a mesh node");
        if ( !comment.size() ) comment << "Cannot create a mesh node";
        nbSeg = nbFac = nbVol = isOK = 0;
        break;
      }
      nodeVec.at(i) = node;
      if (newNodeOnVertex)
      {
        // point on vertex
        meshDS->SetNodeOnVertex(node, aVert);
        pindMap.Add(i);
      }
    }

    // create mesh segments along geometric edges
    NCollection_Map<Link> linkMap;
    for (i = nbInitSeg+1; i <= nbSeg/* && isOK*/; ++i )
    {
      const netgen::Segment& seg = ngMesh->LineSegment(i);
      Link link(seg.p1, seg.p2);
      if (linkMap.Contains(link))
        continue;
      linkMap.Add(link);
      TopoDS_Edge aEdge;
      int pinds[3] = { seg.p1, seg.p2, seg.pmid };
      int nbp = 0;
      double param2 = 0;
      for (int j=0; j < 3; ++j)
      {
        int pind = pinds[j];
        if (pind <= 0) continue;
        ++nbp;
        double param;
        if (j < 2)
        {
          if (aEdge.IsNull())
          {
            int aGeomEdgeInd = seg.epgeominfo[j].edgenr;
            if (aGeomEdgeInd > 0 && aGeomEdgeInd <= occgeo.emap.Extent())
              aEdge = TopoDS::Edge(occgeo.emap(aGeomEdgeInd));
          }
          param = seg.epgeominfo[j].dist;
          param2 += param;
        }
        else
          param = param2 * 0.5;
        if (pind <= nbInitNod || pindMap.Contains(pind))
          continue;
        if (!aEdge.IsNull())
        {
          meshDS->SetNodeOnEdge(nodeVec.at(pind), aEdge, param);
          pindMap.Add(pind);
        }
      }
      SMDS_MeshEdge* edge;
      if (nbp < 3) // second order ?
        edge = meshDS->AddEdge(nodeVec.at(pinds[0]), nodeVec.at(pinds[1]));
      else
        edge = meshDS->AddEdge(nodeVec.at(pinds[0]), nodeVec.at(pinds[1]),
                                nodeVec.at(pinds[2]));
      if (!edge)
      {
        if ( !comment.size() ) comment << "Cannot create a mesh edge";
        MESSAGE("Cannot create a mesh edge");
        nbSeg = nbFac = nbVol = isOK = 0;
        break;
      }
      if (!aEdge.IsNull())
        meshDS->SetMeshElementOnShape(edge, aEdge);
    }

    // create mesh faces along geometric faces
    for (i = nbInitFac+1; i <= nbFac/* && isOK*/; ++i )
    {
      const netgen::Element2d& elem = ngMesh->SurfaceElement(i);
      int aGeomFaceInd = elem.GetIndex();
      TopoDS_Face aFace;
      if (aGeomFaceInd > 0 && aGeomFaceInd <= occgeo.fmap.Extent())
        aFace = TopoDS::Face(occgeo.fmap(aGeomFaceInd));
      vector<SMDS_MeshNode*> nodes;
      for (int j=1; j <= elem.GetNP(); ++j)
      {
        int pind = elem.PNum(j);
        SMDS_MeshNode* node = nodeVec.at(pind);
        nodes.push_back(node);
        if (pind <= nbInitNod || pindMap.Contains(pind))
          continue;
        if (!aFace.IsNull())
        {
          const netgen::PointGeomInfo& pgi = elem.GeomInfoPi(j);
          meshDS->SetNodeOnFace(node, aFace, pgi.u, pgi.v);
          pindMap.Add(pind);
        }
      }
      SMDS_MeshFace* face = NULL;
      switch (elem.GetType())
      {
      case netgen::TRIG:
        face = meshDS->AddFace(nodes[0],nodes[1],nodes[2]);
        break;
      case netgen::QUAD:
        face = meshDS->AddFace(nodes[0],nodes[1],nodes[2],nodes[3]);
        break;
      case netgen::TRIG6:
        face = meshDS->AddFace(nodes[0],nodes[1],nodes[2],nodes[5],nodes[3],nodes[4]);
        break;
      case netgen::QUAD8:
        face = meshDS->AddFace(nodes[0],nodes[1],nodes[2],nodes[3],
                               nodes[4],nodes[7],nodes[5],nodes[6]);
        break;
      default:
        MESSAGE("NETGEN created a face of unexpected type, ignoring");
        continue;
      }
      if (!face)
      {
        if ( !comment.size() ) comment << "Cannot create a mesh face";
        MESSAGE("Cannot create a mesh face");
        nbSeg = nbFac = nbVol = isOK = 0;
        break;
      }
      if (!aFace.IsNull())
        meshDS->SetMeshElementOnShape(face, aFace);
    }

    // create tetrahedra
    for (i = 1; i <= nbVol/* && isOK*/; ++i)
    {
      const netgen::Element& elem = ngMesh->VolumeElement(i);      
      int aSolidInd = elem.GetIndex();
      TopoDS_Solid aSolid;
      if (aSolidInd > 0 && aSolidInd <= occgeo.somap.Extent())
        aSolid = TopoDS::Solid(occgeo.somap(aSolidInd));
      vector<SMDS_MeshNode*> nodes;
      for (int j=1; j <= elem.GetNP(); ++j)
      {
        int pind = elem.PNum(j);
        SMDS_MeshNode* node = nodeVec.at(pind);
        nodes.push_back(node);
        if (pind <= nbInitNod || pindMap.Contains(pind))
          continue;
        if (!aSolid.IsNull())
        {
          // point in solid
          meshDS->SetNodeInVolume(node, aSolid);
          pindMap.Add(pind);
        }
      }
      SMDS_MeshVolume* vol = NULL;
      switch (elem.GetType())
      {
      case netgen::TET:
        vol = meshDS->AddVolume(nodes[0],nodes[1],nodes[2],nodes[3]);
        break;
      case netgen::TET10:
        vol = meshDS->AddVolume(nodes[0],nodes[1],nodes[2],nodes[3],
                                nodes[4],nodes[7],nodes[5],nodes[6],nodes[8],nodes[9]);
        break;
      default:
        MESSAGE("NETGEN created a volume of unexpected type, ignoring");
        continue;
      }
      if (!vol)
      {
        if ( !comment.size() ) comment << "Cannot create a mesh volume";
        MESSAGE("Cannot create a mesh volume");
        nbSeg = nbFac = nbVol = isOK = 0;
        break;
      }
      if (!aSolid.IsNull())
        meshDS->SetMeshElementOnShape(vol, aSolid);
    }
  }

  if ( error->IsOK() && ( !isOK || comment.size() > 0 ))
    error->myName = COMPERR_ALGO_FAILED;
  if ( !comment.empty() )
    error->myComment = comment;

  // set bad compute error to subshapes of all failed subshapes shapes
  if ( !error->IsOK() && err )
  {
    for (int i = 1; i <= occgeo.fmap.Extent(); i++) {
      int status = occgeo.facemeshstatus[i-1];
      if (status == 1 ) continue;
      if ( SMESH_subMesh* sm = _mesh->GetSubMeshContaining( occgeo.fmap( i ))) {
        SMESH_ComputeErrorPtr& smError = sm->GetComputeError();
        if ( !smError || smError->IsOK() ) {
          if ( status == -1 )
            smError.reset( new SMESH_ComputeError( error->myName, error->myComment ));
          else
            smError.reset( new SMESH_ComputeError( COMPERR_ALGO_FAILED, "Ignored" ));
        }
      }
    }
  }

  nglib::Ng_DeleteMesh((nglib::Ng_Mesh*)ngMesh);
  nglib::Ng_Exit();

  RemoveTmpFiles();

  return error->IsOK();
}
bool NETGENPlugin_NETGEN_3D::Compute(SMESH_Mesh&         aMesh,
                                     const TopoDS_Shape& aShape)
{
    MESSAGE("NETGENPlugin_NETGEN_3D::Compute with maxElmentsize = " << _maxElementVolume);

    SMESHDS_Mesh* meshDS = aMesh.GetMeshDS();

    const int invalid_ID = -1;

    SMESH::Controls::Area areaControl;
    SMESH::Controls::TSequenceOfXYZ nodesCoords;

    // -------------------------------------------------------------------
    // get triangles on aShell and make a map of nodes to Netgen node IDs
    // -------------------------------------------------------------------

    SMESH_MesherHelper helper(aMesh);
    SMESH_MesherHelper* myTool = &helper;
    bool _quadraticMesh = myTool->IsQuadraticSubMesh(aShape);

    typedef map< const SMDS_MeshNode*, int, TIDCompare > TNodeToIDMap;
    TNodeToIDMap nodeToNetgenID;
    list< const SMDS_MeshElement* > triangles;
    list< bool >                    isReversed; // orientation of triangles

    TopAbs_ShapeEnum mainType = aMesh.GetShapeToMesh().ShapeType();
    bool checkReverse = ( mainType == TopAbs_COMPOUND || mainType == TopAbs_COMPSOLID );

    // for the degeneraged edge: ignore all but one node on it;
    // map storing ids of degen edges and vertices and their netgen id:
    map< int, int* > degenShapeIdToPtrNgId;
    map< int, int* >::iterator shId_ngId;
    list< int > degenNgIds;

    StdMeshers_QuadToTriaAdaptor Adaptor;
    Adaptor.Compute(aMesh,aShape);

    for (TopExp_Explorer exp(aShape,TopAbs_FACE); exp.More(); exp.Next())
    {
        const TopoDS_Shape& aShapeFace = exp.Current();
        const SMESHDS_SubMesh * aSubMeshDSFace = meshDS->MeshElements( aShapeFace );
        if ( aSubMeshDSFace )
        {
            bool isRev = false;
            if ( checkReverse && helper.NbAncestors(aShapeFace, aMesh, aShape.ShapeType()) > 1 )
                // IsReversedSubMesh() can work wrong on strongly curved faces,
                // so we use it as less as possible
                isRev = SMESH_Algo::IsReversedSubMesh( TopoDS::Face(aShapeFace), meshDS );

            SMDS_ElemIteratorPtr iteratorElem = aSubMeshDSFace->GetElements();
            while ( iteratorElem->more() ) // loop on elements on a face
            {
                // check element
                const SMDS_MeshElement* elem = iteratorElem->next();
                if ( !elem )
                    return error( COMPERR_BAD_INPUT_MESH, "Null element encounters");
                bool isTraingle = ( elem->NbNodes()==3 || (_quadraticMesh && elem->NbNodes()==6 ));
                if ( !isTraingle ) {
                    //return error( COMPERR_BAD_INPUT_MESH,
                    //              SMESH_Comment("Not triangle element ")<<elem->GetID());
                    // using adaptor
                    const list<const SMDS_FaceOfNodes*>* faces = Adaptor.GetTriangles(elem);
                    if(faces==0) {
                        return error( COMPERR_BAD_INPUT_MESH,
                                      SMESH_Comment("Not triangles in adaptor for element ")<<elem->GetID());
                    }
                    list<const SMDS_FaceOfNodes*>::const_iterator itf = faces->begin();
                    for(; itf!=faces->end(); itf++ ) {
                        triangles.push_back( (*itf) );
                        isReversed.push_back( isRev );
                        // put triange's nodes to nodeToNetgenID map
                        SMDS_ElemIteratorPtr triangleNodesIt = (*itf)->nodesIterator();
                        while ( triangleNodesIt->more() ) {
                            const SMDS_MeshNode * node =
                                static_cast<const SMDS_MeshNode *>(triangleNodesIt->next());
                            if(myTool->IsMedium(node))
                                continue;
                            nodeToNetgenID.insert( make_pair( node, invalid_ID ));
                        }
                    }
                }
                else {
                    // keep a triangle
                    triangles.push_back( elem );
                    isReversed.push_back( isRev );
                    // put elem nodes to nodeToNetgenID map
                    SMDS_ElemIteratorPtr triangleNodesIt = elem->nodesIterator();
                    while ( triangleNodesIt->more() ) {
                        const SMDS_MeshNode * node =
                            static_cast<const SMDS_MeshNode *>(triangleNodesIt->next());
                        if(myTool->IsMedium(node))
                            continue;
                        nodeToNetgenID.insert( make_pair( node, invalid_ID ));
                    }
                }
#ifdef _DEBUG_
                // check if a trainge is degenerated
                areaControl.GetPoints( elem, nodesCoords );
                double area = areaControl.GetValue( nodesCoords );
                if ( area <= DBL_MIN ) {
                    MESSAGE( "Warning: Degenerated " << elem );
                }
#endif
            }
            // look for degeneraged edges and vetices
            for (TopExp_Explorer expE(aShapeFace,TopAbs_EDGE); expE.More(); expE.Next())
            {
                TopoDS_Edge aShapeEdge = TopoDS::Edge( expE.Current() );
                if ( BRep_Tool::Degenerated( aShapeEdge ))
                {
                    degenNgIds.push_back( invalid_ID );
                    int* ptrIdOnEdge = & degenNgIds.back();
                    // remember edge id
                    int edgeID = meshDS->ShapeToIndex( aShapeEdge );
                    degenShapeIdToPtrNgId.insert( make_pair( edgeID, ptrIdOnEdge ));
                    // remember vertex id
                    int vertexID = meshDS->ShapeToIndex( TopExp::FirstVertex( aShapeEdge ));
                    degenShapeIdToPtrNgId.insert( make_pair( vertexID, ptrIdOnEdge ));
                }
            }
        }
    }
    // ---------------------------------
    // Feed the Netgen with surface mesh
    // ---------------------------------

    int Netgen_NbOfNodes = 0;
    int Netgen_param2ndOrder = 0;
    double Netgen_paramFine = 1.;
    double Netgen_paramSize = pow( 72, 1/6. ) * pow( _maxElementVolume, 1/3. );

    double Netgen_point[3];
    int Netgen_triangle[3];
    int Netgen_tetrahedron[4];

    Ng_Init();

    Ng_Mesh * Netgen_mesh = Ng_NewMesh();

    // set nodes and remember thier netgen IDs
    bool isDegen = false, hasDegen = !degenShapeIdToPtrNgId.empty();
    TNodeToIDMap::iterator n_id = nodeToNetgenID.begin();
    for ( ; n_id != nodeToNetgenID.end(); ++n_id )
    {
        const SMDS_MeshNode* node = n_id->first;

        // ignore nodes on degenerated edge
        if ( hasDegen ) {
            int shapeId = node->GetPosition()->GetShapeId();
            shId_ngId = degenShapeIdToPtrNgId.find( shapeId );
            isDegen = ( shId_ngId != degenShapeIdToPtrNgId.end() );
            if ( isDegen && *(shId_ngId->second) != invalid_ID ) {
                n_id->second = *(shId_ngId->second);
                continue;
            }
        }
        Netgen_point [ 0 ] = node->X();
        Netgen_point [ 1 ] = node->Y();
        Netgen_point [ 2 ] = node->Z();
        Ng_AddPoint(Netgen_mesh, Netgen_point);
        n_id->second = ++Netgen_NbOfNodes; // set netgen ID

        if ( isDegen ) // all nodes on a degen edge get one netgen ID
            *(shId_ngId->second) = n_id->second;
    }

    // set triangles
    list< const SMDS_MeshElement* >::iterator tria = triangles.begin();
    list< bool >::iterator                 reverse = isReversed.begin();
    for ( ; tria != triangles.end(); ++tria, ++reverse )
    {
        int i = 0;
        SMDS_ElemIteratorPtr triangleNodesIt = (*tria)->nodesIterator();
        while ( triangleNodesIt->more() ) {
            const SMDS_MeshNode * node =
                static_cast<const SMDS_MeshNode *>(triangleNodesIt->next());
            if(myTool->IsMedium(node))
                continue;
            Netgen_triangle[ *reverse ? 2 - i : i ] = nodeToNetgenID[ node ];
            ++i;
        }
        if ( !hasDegen ||
                // ignore degenerated triangles, they have 2 or 3 same ids
                (Netgen_triangle[0] != Netgen_triangle[1] &&
                 Netgen_triangle[0] != Netgen_triangle[2] &&
                 Netgen_triangle[2] != Netgen_triangle[1] ))
        {
            Ng_AddSurfaceElement(Netgen_mesh, NG_TRIG, Netgen_triangle);
        }
    }

    // -------------------------
    // Generate the volume mesh
    // -------------------------

    Ng_Meshing_Parameters Netgen_param;

    Netgen_param.secondorder = Netgen_param2ndOrder;
    Netgen_param.fineness = Netgen_paramFine;
    Netgen_param.maxh = Netgen_paramSize;

    Ng_Result status;

    try {
#if (OCC_VERSION_MAJOR << 16 | OCC_VERSION_MINOR << 8 | OCC_VERSION_MAINTENANCE) > 0x060100
        OCC_CATCH_SIGNALS;
#endif
        status = Ng_GenerateVolumeMesh(Netgen_mesh, &Netgen_param);
    }
    catch (Standard_Failure& exc) {
        error(COMPERR_OCC_EXCEPTION, exc.GetMessageString());
        status = NG_VOLUME_FAILURE;
    }
    catch (...) {
        error("Exception in Ng_GenerateVolumeMesh()");
        status = NG_VOLUME_FAILURE;
    }
    if ( GetComputeError()->IsOK() ) {
        switch ( status ) {
        case NG_SURFACE_INPUT_ERROR:
            error( status, "NG_SURFACE_INPUT_ERROR");
        case NG_VOLUME_FAILURE:
            error( status, "NG_VOLUME_FAILURE");
        case NG_STL_INPUT_ERROR:
            error( status, "NG_STL_INPUT_ERROR");
        case NG_SURFACE_FAILURE:
            error( status, "NG_SURFACE_FAILURE");
        case NG_FILE_NOT_FOUND:
            error( status, "NG_FILE_NOT_FOUND");
        };
    }

    int Netgen_NbOfNodesNew = Ng_GetNP(Netgen_mesh);

    int Netgen_NbOfTetra = Ng_GetNE(Netgen_mesh);

    MESSAGE("End of Volume Mesh Generation. status=" << status <<
            ", nb new nodes: " << Netgen_NbOfNodesNew - Netgen_NbOfNodes <<
            ", nb tetra: " << Netgen_NbOfTetra);

    // -------------------------------------------------------------------
    // Feed back the SMESHDS with the generated Nodes and Volume Elements
    // -------------------------------------------------------------------

    bool isOK = ( /*status == NG_OK &&*/ Netgen_NbOfTetra > 0 );// get whatever built
    if ( isOK )
    {
        // vector of nodes in which node index == netgen ID
        vector< const SMDS_MeshNode* > nodeVec ( Netgen_NbOfNodesNew + 1 );
        // insert old nodes into nodeVec
        for ( n_id = nodeToNetgenID.begin(); n_id != nodeToNetgenID.end(); ++n_id ) {
            nodeVec.at( n_id->second ) = n_id->first;
        }
        // create and insert new nodes into nodeVec
        int nodeIndex = Netgen_NbOfNodes + 1;
        int shapeID = meshDS->ShapeToIndex( aShape );
        for ( ; nodeIndex <= Netgen_NbOfNodesNew; ++nodeIndex )
        {
            Ng_GetPoint( Netgen_mesh, nodeIndex, Netgen_point );
            SMDS_MeshNode * node = meshDS->AddNode(Netgen_point[0],
                                                   Netgen_point[1],
                                                   Netgen_point[2]);
            meshDS->SetNodeInVolume(node, shapeID);
            nodeVec.at(nodeIndex) = node;
        }

        // create tetrahedrons
        for ( int elemIndex = 1; elemIndex <= Netgen_NbOfTetra; ++elemIndex )
        {
            Ng_GetVolumeElement(Netgen_mesh, elemIndex, Netgen_tetrahedron);
            SMDS_MeshVolume * elt = myTool->AddVolume (nodeVec.at( Netgen_tetrahedron[0] ),
                                    nodeVec.at( Netgen_tetrahedron[1] ),
                                    nodeVec.at( Netgen_tetrahedron[2] ),
                                    nodeVec.at( Netgen_tetrahedron[3] ));
            meshDS->SetMeshElementOnShape(elt, shapeID );
        }
    }

    Ng_DeleteMesh(Netgen_mesh);
    Ng_Exit();

    NETGENPlugin_Mesher::RemoveTmpFiles();

    return (status == NG_OK);
}
Example #5
0
/*!
 * Special function for search or creation medium node
 */
const SMDS_MeshNode* SMESH_MesherHelper::GetMediumNode(const SMDS_MeshNode* n1,
                                                       const SMDS_MeshNode* n2,
                                                       bool force3d)
{
  TopAbs_ShapeEnum shapeType = myShape.IsNull() ? TopAbs_SHAPE : myShape.ShapeType();

  NLink link(( n1 < n2 ? n1 : n2 ), ( n1 < n2 ? n2 : n1 ));
  ItNLinkNode itLN = myNLinkNodeMap.find( link );
  if ( itLN != myNLinkNodeMap.end() ) {
    return (*itLN).second;
  }
  else {
    // create medium node
    SMDS_MeshNode* n12;
    SMESHDS_Mesh* meshDS = GetMeshDS();
    int faceID = -1, edgeID = -1;
    const SMDS_PositionPtr Pos1 = n1->GetPosition();
    const SMDS_PositionPtr Pos2 = n2->GetPosition();
  
    if( myShape.IsNull() )
    {
      if( Pos1->GetTypeOfPosition()==SMDS_TOP_FACE ) {
        faceID = Pos1->GetShapeId();
      }
      else if( Pos2->GetTypeOfPosition()==SMDS_TOP_FACE ) {
        faceID = Pos2->GetShapeId();
      }

      if( Pos1->GetTypeOfPosition()==SMDS_TOP_EDGE ) {
        edgeID = Pos1->GetShapeId();
      }
      if( Pos2->GetTypeOfPosition()==SMDS_TOP_EDGE ) {
        edgeID = Pos2->GetShapeId();
      }
    }

    if(!force3d) {
      // we try to create medium node using UV parameters of
      // nodes, else - medium between corresponding 3d points
      if(faceID>-1 || shapeType == TopAbs_FACE) {
	// obtaining a face and 2d points for nodes
	TopoDS_Face F;
	if( myShape.IsNull() )
          F = TopoDS::Face(meshDS->IndexToShape(faceID));
	else {
          F = TopoDS::Face(myShape);
          faceID = myShapeID;
        }

	gp_XY p1 = GetNodeUV(F,n1,n2);
        gp_XY p2 = GetNodeUV(F,n2,n1);

	if ( IsDegenShape( Pos1->GetShapeId() ))
	  p1.SetCoord( myParIndex, p2.Coord( myParIndex ));
	else if ( IsDegenShape( Pos2->GetShapeId() ))
	  p2.SetCoord( myParIndex, p1.Coord( myParIndex ));

	//checking if surface is periodic
	Handle(Geom_Surface) S = BRep_Tool::Surface(F);
	Standard_Real UF,UL,VF,VL;
	S->Bounds(UF,UL,VF,VL);

	Standard_Real u,v;
	Standard_Boolean isUPeriodic = S->IsUPeriodic();
	if(isUPeriodic) {
	  Standard_Real UPeriod = S->UPeriod();
	  Standard_Real p2x = p2.X()+ShapeAnalysis::AdjustByPeriod(p2.X(),p1.X(),UPeriod);
	  Standard_Real pmid = (p1.X()+p2x)/2.;
	  u = pmid+ShapeAnalysis::AdjustToPeriod(pmid,UF,UL);
	}
	else 
	  u= (p1.X()+p2.X())/2.;

	Standard_Boolean isVPeriodic = S->IsVPeriodic();
	if(isVPeriodic) {
	  Standard_Real VPeriod = S->VPeriod();
	  Standard_Real p2y = p2.Y()+ShapeAnalysis::AdjustByPeriod(p2.Y(),p1.Y(),VPeriod);
	  Standard_Real pmid = (p1.Y()+p2y)/2.;
	  v = pmid+ShapeAnalysis::AdjustToPeriod(pmid,VF,VL);
	}
	else
	  v = (p1.Y()+p2.Y())/2.;

        gp_Pnt P = S->Value(u, v);
        n12 = meshDS->AddNode(P.X(), P.Y(), P.Z());
        meshDS->SetNodeOnFace(n12, faceID, u, v);
        myNLinkNodeMap.insert(NLinkNodeMap::value_type(link,n12));
        return n12;
      }
      if (edgeID>-1 || shapeType == TopAbs_EDGE) {

	TopoDS_Edge E;
	if( myShape.IsNull() )
          E = TopoDS::Edge(meshDS->IndexToShape(edgeID));
	else {
          E = TopoDS::Edge(myShape);
          edgeID = myShapeID;
        }

	double p1 = GetNodeU(E,n1);
	double p2 = GetNodeU(E,n2);

	double f,l;
	Handle(Geom_Curve) C = BRep_Tool::Curve(E, f, l);
	if(!C.IsNull()) {

	  Standard_Boolean isPeriodic = C->IsPeriodic();
	  double u;
	  if(isPeriodic) {
	    Standard_Real Period = C->Period();
	    Standard_Real p = p2+ShapeAnalysis::AdjustByPeriod(p2,p1,Period);
	    Standard_Real pmid = (p1+p)/2.;
	    u = pmid+ShapeAnalysis::AdjustToPeriod(pmid,C->FirstParameter(),C->LastParameter());
	  }
	  else
	    u = (p1+p2)/2.;

          gp_Pnt P = C->Value( u );
          n12 = meshDS->AddNode(P.X(), P.Y(), P.Z());
          meshDS->SetNodeOnEdge(n12, edgeID, u);
          myNLinkNodeMap.insert(NLinkNodeMap::value_type(link,n12));
          return n12;
	}
      }
    }
    // 3d variant
    double x = ( n1->X() + n2->X() )/2.;
    double y = ( n1->Y() + n2->Y() )/2.;
    double z = ( n1->Z() + n2->Z() )/2.;
    n12 = meshDS->AddNode(x,y,z);
    if(edgeID>-1)
        meshDS->SetNodeOnEdge(n12, edgeID);
    else if(faceID>-1)
        meshDS->SetNodeOnFace(n12, faceID);
    else
      meshDS->SetNodeInVolume(n12, myShapeID);
    myNLinkNodeMap.insert(NLinkNodeMap::value_type(link,n12));
    return n12;
  }
}
bool StdMeshers_Projection_3D::Compute(SMESH_Mesh& aMesh, const TopoDS_Shape& aShape)
{
  if ( !_sourceHypo )
    return false;

  SMESH_Mesh * srcMesh = _sourceHypo->GetSourceMesh();
  SMESH_Mesh * tgtMesh = & aMesh;
  if ( !srcMesh )
    srcMesh = tgtMesh;

  SMESHDS_Mesh * srcMeshDS = srcMesh->GetMeshDS();
  SMESHDS_Mesh * tgtMeshDS = tgtMesh->GetMeshDS();

  // get shell from shape3D
  TopoDS_Shell srcShell, tgtShell;
  TopExp_Explorer exp( _sourceHypo->GetSource3DShape(), TopAbs_SHELL );
  int nbShell;
  for ( nbShell = 0; exp.More(); exp.Next(), ++nbShell )
    srcShell = TopoDS::Shell( exp.Current() );
  if ( nbShell != 1 )
    return error(COMPERR_BAD_SHAPE,
                 SMESH_Comment("Source shape must have 1 shell but not ") << nbShell);

  exp.Init( aShape, TopAbs_SHELL );
  for ( nbShell = 0; exp.More(); exp.Next(), ++nbShell )
    tgtShell = TopoDS::Shell( exp.Current() );
  if ( nbShell != 1 )
    return error(COMPERR_BAD_SHAPE,
                 SMESH_Comment("Target shape must have 1 shell but not ") << nbShell);

  // Check that shapes are blocks
  if ( TAssocTool::Count( tgtShell, TopAbs_FACE , 1 ) != 6 ||
       TAssocTool::Count( tgtShell, TopAbs_EDGE , 1 ) != 12 ||
       TAssocTool::Count( tgtShell, TopAbs_WIRE , 1 ) != 6 )
    return error(COMPERR_BAD_SHAPE, "Target shape is not a block");
  if ( TAssocTool::Count( srcShell, TopAbs_FACE , 1 ) != 6 ||
       TAssocTool::Count( srcShell, TopAbs_EDGE , 1 ) != 12 ||
       TAssocTool::Count( srcShell, TopAbs_WIRE , 1 ) != 6 )
    return error(COMPERR_BAD_SHAPE, "Source shape is not a block");

  // Assure that mesh on a source shape is computed

  SMESH_subMesh* srcSubMesh = srcMesh->GetSubMesh( _sourceHypo->GetSource3DShape() );
  //SMESH_subMesh* tgtSubMesh = tgtMesh->GetSubMesh( aShape );

  if ( tgtMesh == srcMesh && !aShape.IsSame( _sourceHypo->GetSource3DShape() )) {
    if ( !TAssocTool::MakeComputed( srcSubMesh ))
      return error(COMPERR_BAD_INPUT_MESH,"Source mesh not computed");
  }
  else {
    if ( !srcSubMesh->IsMeshComputed() )
      return error(COMPERR_BAD_INPUT_MESH,"Source mesh not computed");
  }

  // Find 2 pairs of corresponding vertices

  TopoDS_Vertex tgtV000, tgtV100, srcV000, srcV100;
  TAssocTool::TShapeShapeMap shape2ShapeMap;

  if ( _sourceHypo->HasVertexAssociation() )
  {
    tgtV000 = _sourceHypo->GetTargetVertex(1);
    tgtV100 = _sourceHypo->GetTargetVertex(2);
    srcV000 = _sourceHypo->GetSourceVertex(1);
    srcV100 = _sourceHypo->GetSourceVertex(2);
  }
  else
  {
    if ( !TAssocTool::FindSubShapeAssociation( tgtShell, tgtMesh, srcShell, srcMesh,
                                               shape2ShapeMap) )
      return error(COMPERR_BAD_SHAPE,"Topology of source and target shapes seems different" );

    exp.Init( tgtShell, TopAbs_EDGE );
    TopExp::Vertices( TopoDS::Edge( exp.Current() ), tgtV000, tgtV100 );

    if ( !shape2ShapeMap.IsBound( tgtV000 ) || !shape2ShapeMap.IsBound( tgtV100 ))
      return error("Association of subshapes failed" );
    srcV000 = TopoDS::Vertex( shape2ShapeMap( tgtV000 ));
    srcV100 = TopoDS::Vertex( shape2ShapeMap( tgtV100 ));
    if ( !TAssocTool::IsSubShape( srcV000, srcShell ) ||
         !TAssocTool::IsSubShape( srcV100, srcShell ))
      return error("Incorrect association of subshapes" );
  }

  // Load 2 SMESH_Block's with src and tgt shells

  SMESH_Block srcBlock, tgtBlock;
  TopTools_IndexedMapOfOrientedShape scrShapes, tgtShapes;
  if ( !tgtBlock.LoadBlockShapes( tgtShell, tgtV000, tgtV100, tgtShapes ))
    return error(COMPERR_BAD_SHAPE, "Can't detect block subshapes. Not a block?");

  if ( !srcBlock.LoadBlockShapes( srcShell, srcV000, srcV100, scrShapes ))
    return error(COMPERR_BAD_SHAPE, "Can't detect block subshapes. Not a block?");

  // Find matching nodes of src and tgt shells

  TNodeNodeMap src2tgtNodeMap;
  for ( int fId = SMESH_Block::ID_FirstF; fId < SMESH_Block::ID_Shell; ++fId )
  {
    // Corresponding subshapes
    TopoDS_Face srcFace = TopoDS::Face( scrShapes( fId ));
    TopoDS_Face tgtFace = TopoDS::Face( tgtShapes( fId ));
    if ( _sourceHypo->HasVertexAssociation() ) { // associate face subshapes
      shape2ShapeMap.Clear();
      vector< int > edgeIdVec;
      SMESH_Block::GetFaceEdgesIDs( fId, edgeIdVec );
      for ( int i = 0; i < edgeIdVec.size(); ++i ) {
        int eID = edgeIdVec[ i ];
        shape2ShapeMap.Bind( tgtShapes( eID ), scrShapes( eID ));
        if ( i < 2 ) {
          vector< int > vertexIdVec;
          SMESH_Block::GetEdgeVertexIDs( eID, vertexIdVec );
          shape2ShapeMap.Bind( tgtShapes( vertexIdVec[0] ), scrShapes( vertexIdVec[0] ));
          shape2ShapeMap.Bind( tgtShapes( vertexIdVec[1] ), scrShapes( vertexIdVec[1] ));
        }
      }
    }
    // Find matching nodes of tgt and src faces
    TNodeNodeMap faceMatchingNodes;
    if ( ! TAssocTool::FindMatchingNodesOnFaces( srcFace, srcMesh, tgtFace, tgtMesh, 
                                                 shape2ShapeMap, faceMatchingNodes ))
    return error(COMPERR_BAD_INPUT_MESH,SMESH_Comment("Mesh on faces #")
                 << srcMeshDS->ShapeToIndex( srcFace ) << " and "
                 << tgtMeshDS->ShapeToIndex( tgtFace ) << " seems different" );

    // put found matching nodes of 2 faces to the global map
    src2tgtNodeMap.insert( faceMatchingNodes.begin(), faceMatchingNodes.end() );
  }

  // ------------------
  // Make mesh
  // ------------------

  SMDS_VolumeTool volTool;
  SMESH_MesherHelper helper( *tgtMesh );
  helper.IsQuadraticSubMesh( aShape );

  SMESHDS_SubMesh* srcSMDS = srcSubMesh->GetSubMeshDS();
  SMDS_ElemIteratorPtr volIt = srcSMDS->GetElements();
  while ( volIt->more() ) // loop on source volumes
  {
    const SMDS_MeshElement* srcVol = volIt->next();
    if ( !srcVol || srcVol->GetType() != SMDSAbs_Volume )
        continue;
    int nbNodes = srcVol->NbNodes();
    SMDS_VolumeTool::VolumeType  volType = volTool.GetType( nbNodes );
    if ( srcVol->IsQuadratic() )
      nbNodes = volTool.NbCornerNodes( volType );

    // Find or create a new tgt node for each node of a src volume

    vector< const SMDS_MeshNode* > nodes( nbNodes );
    for ( int i = 0; i < nbNodes; ++i )
    {
      const SMDS_MeshNode* srcNode = srcVol->GetNode( i );
      const SMDS_MeshNode* tgtNode = 0;
      TNodeNodeMap::iterator sN_tN = src2tgtNodeMap.find( srcNode );
      if ( sN_tN != src2tgtNodeMap.end() ) // found
      {
        tgtNode = sN_tN->second;
      }
      else // Create a new tgt node
      {
        // compute normalized parameters of source node in srcBlock
        gp_Pnt srcCoord = gpXYZ( srcNode );
        gp_XYZ srcParam;
        if ( !srcBlock.ComputeParameters( srcCoord, srcParam ))
          return error(SMESH_Comment("Can't compute normalized parameters ")
                       << "for source node " << srcNode->GetID());
        // compute coordinates of target node by srcParam
        gp_XYZ tgtXYZ;
        if ( !tgtBlock.ShellPoint( srcParam, tgtXYZ ))
          return error("Can't compute coordinates by normalized parameters");
        // add node
        SMDS_MeshNode* newNode = tgtMeshDS->AddNode( tgtXYZ.X(), tgtXYZ.Y(), tgtXYZ.Z() );
        tgtMeshDS->SetNodeInVolume( newNode, helper.GetSubShapeID() );
        tgtNode = newNode;
        src2tgtNodeMap.insert( make_pair( srcNode, tgtNode ));
      }
      nodes[ i ] = tgtNode;
    }

    // Create a new volume

    SMDS_MeshVolume * tgtVol = 0;
    int id = 0, force3d = false;
    switch ( volType ) {
    case SMDS_VolumeTool::TETRA     :
    case SMDS_VolumeTool::QUAD_TETRA:
      tgtVol = helper.AddVolume( nodes[0],
                                 nodes[1],
                                 nodes[2],
                                 nodes[3], id, force3d); break;
    case SMDS_VolumeTool::PYRAM     :
    case SMDS_VolumeTool::QUAD_PYRAM:
      tgtVol = helper.AddVolume( nodes[0],
                                 nodes[1],
                                 nodes[2],
                                 nodes[3],
                                 nodes[4], id, force3d); break;
    case SMDS_VolumeTool::PENTA     :
    case SMDS_VolumeTool::QUAD_PENTA:
      tgtVol = helper.AddVolume( nodes[0],
                                 nodes[1],
                                 nodes[2],
                                 nodes[3],
                                 nodes[4],
                                 nodes[5], id, force3d); break;
    case SMDS_VolumeTool::HEXA      :
    case SMDS_VolumeTool::QUAD_HEXA :
      tgtVol = helper.AddVolume( nodes[0],
                                 nodes[1],
                                 nodes[2],
                                 nodes[3],
                                 nodes[4],
                                 nodes[5],
                                 nodes[6],
                                 nodes[7], id, force3d); break;
    default: // polyhedron
      const SMDS_PolyhedralVolumeOfNodes * poly =
        dynamic_cast<const SMDS_PolyhedralVolumeOfNodes*>( srcVol );
      if ( !poly )
        RETURN_BAD_RESULT("Unexpected volume type");
      tgtVol = tgtMeshDS->AddPolyhedralVolume( nodes, poly->GetQuanities() );
    }
    if ( tgtVol ) {
      tgtMeshDS->SetMeshElementOnShape( tgtVol, helper.GetSubShapeID() );
    }
  } // loop on volumes of src shell

  return true;
}
bool StdMeshers_Hexa_3D::Compute(SMESH_Mesh &         aMesh,
                                 const TopoDS_Shape & aShape)// throw(SALOME_Exception)
{
  // PAL14921. Enable catching std::bad_alloc and Standard_OutOfMemory outside
  //Unexpect aCatch(SalomeException);
  MESSAGE("StdMeshers_Hexa_3D::Compute");
  SMESHDS_Mesh * meshDS = aMesh.GetMeshDS();

  // 0.  - shape and face mesh verification
  // 0.1 - shape must be a solid (or a shell) with 6 faces

  vector < SMESH_subMesh * >meshFaces;
  for (TopExp_Explorer exp(aShape, TopAbs_FACE); exp.More(); exp.Next()) {
    SMESH_subMesh *aSubMesh = aMesh.GetSubMeshContaining(exp.Current());
    ASSERT(aSubMesh);
    meshFaces.push_back(aSubMesh);
  }
  if (meshFaces.size() != 6) {
    //return error(COMPERR_BAD_SHAPE, TComm(meshFaces.size())<<" instead of 6 faces in a block");
    static StdMeshers_CompositeHexa_3D compositeHexa(-10, 0, aMesh.GetGen());
    if ( !compositeHexa.Compute( aMesh, aShape ))
      return error( compositeHexa.GetComputeError() );
    return true;
  }

  // 0.2 - is each face meshed with Quadrangle_2D? (so, with a wire of 4 edges)

  // tool for working with quadratic elements
  SMESH_MesherHelper aTool (aMesh);
  _quadraticMesh = aTool.IsQuadraticSubMesh(aShape);

  // cube structure
  typedef struct cubeStruct
  {
    TopoDS_Vertex V000;
    TopoDS_Vertex V001;
    TopoDS_Vertex V010;
    TopoDS_Vertex V011;
    TopoDS_Vertex V100;
    TopoDS_Vertex V101;
    TopoDS_Vertex V110;
    TopoDS_Vertex V111;
    faceQuadStruct* quad_X0;
    faceQuadStruct* quad_X1;
    faceQuadStruct* quad_Y0;
    faceQuadStruct* quad_Y1;
    faceQuadStruct* quad_Z0;
    faceQuadStruct* quad_Z1;
    Point3DStruct* np; // normalised 3D coordinates
  } CubeStruct;

  CubeStruct aCube;

  // bounding faces
  FaceQuadStruct* aQuads[6];
  for (int i = 0; i < 6; i++)
    aQuads[i] = 0;

  for (int i = 0; i < 6; i++)
  {
    TopoDS_Shape aFace = meshFaces[i]->GetSubShape();
    SMESH_Algo *algo = _gen->GetAlgo(aMesh, aFace);
    string algoName = algo->GetName();
    bool isAllQuad = false;
    if (algoName == "Quadrangle_2D") {
      SMESHDS_SubMesh * sm = meshDS->MeshElements( aFace );
      if ( sm ) {
        isAllQuad = true;
        SMDS_ElemIteratorPtr eIt = sm->GetElements();
        while ( isAllQuad && eIt->more() ) {
          const SMDS_MeshElement* elem =  eIt->next();
          isAllQuad = ( elem->NbNodes()==4 ||(_quadraticMesh && elem->NbNodes()==8) );
        }
      }
    }
    if ( ! isAllQuad ) {
      SMESH_ComputeErrorPtr err = ComputePentahedralMesh(aMesh, aShape);
      return ClearAndReturn( aQuads, error(err));
    }
    StdMeshers_Quadrangle_2D *quadAlgo =
      dynamic_cast < StdMeshers_Quadrangle_2D * >(algo);
    ASSERT(quadAlgo);
    try {
      aQuads[i] = quadAlgo->CheckAnd2Dcompute(aMesh, aFace, _quadraticMesh);
      if(!aQuads[i]) {
        return error( quadAlgo->GetComputeError());
      }
    }
    catch(SALOME_Exception & S_ex) {
      return ClearAndReturn( aQuads, error(COMPERR_SLM_EXCEPTION,TComm(S_ex.what()) <<
                                           " Raised by StdMeshers_Quadrangle_2D "
                                           " on face #" << meshDS->ShapeToIndex( aFace )));
    }

    // 0.2.1 - number of points on the opposite edges must be the same
    if (aQuads[i]->side[0]->NbPoints() != aQuads[i]->side[2]->NbPoints() ||
        aQuads[i]->side[1]->NbPoints() != aQuads[i]->side[3]->NbPoints()
        /*aQuads[i]->side[0]->NbEdges() != 1 ||
        aQuads[i]->side[1]->NbEdges() != 1 ||
        aQuads[i]->side[2]->NbEdges() != 1 ||
        aQuads[i]->side[3]->NbEdges() != 1*/) {
      MESSAGE("different number of points on the opposite edges of face " << i);
      // Try to go into penta algorithm 'cause it has been improved.
      SMESH_ComputeErrorPtr err = ComputePentahedralMesh(aMesh, aShape);
      return ClearAndReturn( aQuads, error(err));
    }
  }

  // 1.  - identify faces and vertices of the "cube"
  // 1.1 - ancestor maps vertex->edges in the cube

//   TopTools_IndexedDataMapOfShapeListOfShape MS;
//   TopExp::MapShapesAndAncestors(aShape, TopAbs_VERTEX, TopAbs_EDGE, MS);

  // 1.2 - first face is choosen as face Y=0 of the unit cube

  const TopoDS_Shape & aFace = meshFaces[0]->GetSubShape();
  //const TopoDS_Face & F = TopoDS::Face(aFace);

  // 1.3 - identify the 4 vertices of the face Y=0: V000, V100, V101, V001

  aCube.V000 = aQuads[0]->side[0]->FirstVertex(); // will be (0,0,0) on the unit cube
  aCube.V100 = aQuads[0]->side[0]->LastVertex();  // will be (1,0,0) on the unit cube
  aCube.V001 = aQuads[0]->side[2]->FirstVertex(); // will be (0,0,1) on the unit cube
  aCube.V101 = aQuads[0]->side[2]->LastVertex();  // will be (1,0,1) on the unit cube

  TopTools_IndexedMapOfShape MV0;
  TopExp::MapShapes(aFace, TopAbs_VERTEX, MV0);

  aCube.V010 = OppositeVertex( aCube.V000, MV0, aQuads);
  aCube.V110 = OppositeVertex( aCube.V100, MV0, aQuads);
  aCube.V011 = OppositeVertex( aCube.V001, MV0, aQuads);
  aCube.V111 = OppositeVertex( aCube.V101, MV0, aQuads);

  // 1.6 - find remaining faces given 4 vertices

  int _indY0 = 0;
  int _indY1 = GetFaceIndex(aMesh, aShape, meshFaces,
                            aCube.V010, aCube.V011, aCube.V110, aCube.V111);
  int _indZ0 = GetFaceIndex(aMesh, aShape, meshFaces,
                            aCube.V000, aCube.V010, aCube.V100, aCube.V110);
  int _indZ1 = GetFaceIndex(aMesh, aShape, meshFaces,
                            aCube.V001, aCube.V011, aCube.V101, aCube.V111);
  int _indX0 = GetFaceIndex(aMesh, aShape, meshFaces,
                            aCube.V000, aCube.V001, aCube.V010, aCube.V011);
  int _indX1 = GetFaceIndex(aMesh, aShape, meshFaces,
                            aCube.V100, aCube.V101, aCube.V110, aCube.V111);

  // IPAL21120: SIGSEGV on Meshing attached Compound with Automatic Hexadralization
  if ( _indY1 < 1 || _indZ0 < 1 || _indZ1 < 1 || _indX0 < 1 || _indX1 < 1 )
    return error(COMPERR_BAD_SHAPE);

  aCube.quad_Y0 = aQuads[_indY0];
  aCube.quad_Y1 = aQuads[_indY1];
  aCube.quad_Z0 = aQuads[_indZ0];
  aCube.quad_Z1 = aQuads[_indZ1];
  aCube.quad_X0 = aQuads[_indX0];
  aCube.quad_X1 = aQuads[_indX1];

  // 1.7 - get convertion coefs from face 2D normalized to 3D normalized

  Conv2DStruct cx0;                     // for face X=0
  Conv2DStruct cx1;                     // for face X=1
  Conv2DStruct cy0;
  Conv2DStruct cy1;
  Conv2DStruct cz0;
  Conv2DStruct cz1;

  GetConv2DCoefs(*aCube.quad_X0, meshFaces[_indX0]->GetSubShape(),
                 aCube.V000, aCube.V010, aCube.V011, aCube.V001, cx0);
  GetConv2DCoefs(*aCube.quad_X1, meshFaces[_indX1]->GetSubShape(),
                 aCube.V100, aCube.V110, aCube.V111, aCube.V101, cx1);
  GetConv2DCoefs(*aCube.quad_Y0, meshFaces[_indY0]->GetSubShape(),
                 aCube.V000, aCube.V100, aCube.V101, aCube.V001, cy0);
  GetConv2DCoefs(*aCube.quad_Y1, meshFaces[_indY1]->GetSubShape(),
                 aCube.V010, aCube.V110, aCube.V111, aCube.V011, cy1);
  GetConv2DCoefs(*aCube.quad_Z0, meshFaces[_indZ0]->GetSubShape(),
                 aCube.V000, aCube.V100, aCube.V110, aCube.V010, cz0);
  GetConv2DCoefs(*aCube.quad_Z1, meshFaces[_indZ1]->GetSubShape(),
                 aCube.V001, aCube.V101, aCube.V111, aCube.V011, cz1);

  // 1.8 - create a 3D structure for normalized values
  
  int nbx = aCube.quad_Z0->side[0]->NbPoints();
  if (cz0.a1 == 0.) nbx = aCube.quad_Z0->side[1]->NbPoints();
 
  int nby = aCube.quad_X0->side[0]->NbPoints();
  if (cx0.a1 == 0.) nby = aCube.quad_X0->side[1]->NbPoints();
 
  int nbz = aCube.quad_Y0->side[0]->NbPoints();
  if (cy0.a1 != 0.) nbz = aCube.quad_Y0->side[1]->NbPoints();

  int i1, j1, nbxyz = nbx * nby * nbz;
  Point3DStruct *np = new Point3DStruct[nbxyz];

  // 1.9 - store node indexes of faces

  {
    const TopoDS_Face & F = TopoDS::Face(meshFaces[_indX0]->GetSubShape());

    faceQuadStruct *quad = aCube.quad_X0;
    int i = 0;                          // j = x/face , k = y/face
    int nbdown = quad->side[0]->NbPoints();
    int nbright = quad->side[1]->NbPoints();

    SMDS_NodeIteratorPtr itf= aMesh.GetSubMesh(F)->GetSubMeshDS()->GetNodes();
                        
    while(itf->more()) {
      const SMDS_MeshNode * node = itf->next();
      if(aTool.IsMedium(node))
        continue;
      if ( !findIJ( node, quad, i1, j1 ))
        return ClearAndReturn( aQuads, false );
      int ij1 = j1 * nbdown + i1;
      quad->uv_grid[ij1].node = node;
    }

    for (int i1 = 0; i1 < nbdown; i1++)
      for (int j1 = 0; j1 < nbright; j1++) {
        int ij1 = j1 * nbdown + i1;
        int j = cx0.ia * i1 + cx0.ib * j1 + cx0.ic;     // j = x/face
        int k = cx0.ja * i1 + cx0.jb * j1 + cx0.jc;     // k = y/face
        int ijk = k * nbx * nby + j * nbx + i;
        //MESSAGE(" "<<ij1<<" "<<i<<" "<<j<<" "<<ijk);
        np[ijk].node = quad->uv_grid[ij1].node;
        //SCRUTE(np[ijk].nodeId);
      }
  }

  {
    const TopoDS_Face & F = TopoDS::Face(meshFaces[_indX1]->GetSubShape());

    SMDS_NodeIteratorPtr itf= aMesh.GetSubMesh(F)->GetSubMeshDS()->GetNodes();

    faceQuadStruct *quad = aCube.quad_X1;
    int i = nbx - 1;            // j = x/face , k = y/face
    int nbdown = quad->side[0]->NbPoints();
    int nbright = quad->side[1]->NbPoints();

    while(itf->more()) {
      const SMDS_MeshNode * node = itf->next();
      if(aTool.IsMedium(node))
        continue;
      if ( !findIJ( node, quad, i1, j1 ))
        return ClearAndReturn( aQuads, false );
      int ij1 = j1 * nbdown + i1;
      quad->uv_grid[ij1].node = node;
    }

    for (int i1 = 0; i1 < nbdown; i1++)
      for (int j1 = 0; j1 < nbright; j1++) {
        int ij1 = j1 * nbdown + i1;
        int j = cx1.ia * i1 + cx1.ib * j1 + cx1.ic;     // j = x/face
        int k = cx1.ja * i1 + cx1.jb * j1 + cx1.jc;     // k = y/face
        int ijk = k * nbx * nby + j * nbx + i;
        //MESSAGE(" "<<ij1<<" "<<i<<" "<<j<<" "<<ijk);
        np[ijk].node = quad->uv_grid[ij1].node;
        //SCRUTE(np[ijk].nodeId);
      }
  }

  {
    const TopoDS_Face & F = TopoDS::Face(meshFaces[_indY0]->GetSubShape());

    SMDS_NodeIteratorPtr itf= aMesh.GetSubMesh(F)->GetSubMeshDS()->GetNodes();

    faceQuadStruct *quad = aCube.quad_Y0;
    int j = 0;                          // i = x/face , k = y/face
    int nbdown = quad->side[0]->NbPoints();
    int nbright = quad->side[1]->NbPoints();

    while(itf->more()) {
      const SMDS_MeshNode * node = itf->next();
      if(aTool.IsMedium(node))
        continue;
      if ( !findIJ( node, quad, i1, j1 ))
        return ClearAndReturn( aQuads, false );
      int ij1 = j1 * nbdown + i1;
      quad->uv_grid[ij1].node = node;
    }

    for (int i1 = 0; i1 < nbdown; i1++)
      for (int j1 = 0; j1 < nbright; j1++) {
        int ij1 = j1 * nbdown + i1;
        int i = cy0.ia * i1 + cy0.ib * j1 + cy0.ic;     // i = x/face
        int k = cy0.ja * i1 + cy0.jb * j1 + cy0.jc;     // k = y/face
        int ijk = k * nbx * nby + j * nbx + i;
        //MESSAGE(" "<<ij1<<" "<<i<<" "<<j<<" "<<ijk);
        np[ijk].node = quad->uv_grid[ij1].node;
        //SCRUTE(np[ijk].nodeId);
      }
  }

  {
    const TopoDS_Face & F = TopoDS::Face(meshFaces[_indY1]->GetSubShape());

    SMDS_NodeIteratorPtr itf= aMesh.GetSubMesh(F)->GetSubMeshDS()->GetNodes();

    faceQuadStruct *quad = aCube.quad_Y1;
    int j = nby - 1;            // i = x/face , k = y/face
    int nbdown = quad->side[0]->NbPoints();
    int nbright = quad->side[1]->NbPoints();

    while(itf->more()) {
      const SMDS_MeshNode * node = itf->next();
      if(aTool.IsMedium(node))
        continue;
      if ( !findIJ( node, quad, i1, j1 ))
        return ClearAndReturn( aQuads, false );
      int ij1 = j1 * nbdown + i1;
      quad->uv_grid[ij1].node = node;
    }

    for (int i1 = 0; i1 < nbdown; i1++)
      for (int j1 = 0; j1 < nbright; j1++) {
        int ij1 = j1 * nbdown + i1;
        int i = cy1.ia * i1 + cy1.ib * j1 + cy1.ic;     // i = x/face
        int k = cy1.ja * i1 + cy1.jb * j1 + cy1.jc;     // k = y/face
        int ijk = k * nbx * nby + j * nbx + i;
        //MESSAGE(" "<<ij1<<" "<<i<<" "<<j<<" "<<ijk);
        np[ijk].node = quad->uv_grid[ij1].node;
        //SCRUTE(np[ijk].nodeId);
      }
  }

  {
    const TopoDS_Face & F = TopoDS::Face(meshFaces[_indZ0]->GetSubShape());

    SMDS_NodeIteratorPtr itf= aMesh.GetSubMesh(F)->GetSubMeshDS()->GetNodes();

    faceQuadStruct *quad = aCube.quad_Z0;
    int k = 0;                          // i = x/face , j = y/face
    int nbdown = quad->side[0]->NbPoints();
    int nbright = quad->side[1]->NbPoints();

    while(itf->more()) {
      const SMDS_MeshNode * node = itf->next();
      if(aTool.IsMedium(node))
        continue;
      if ( !findIJ( node, quad, i1, j1 ))
        return ClearAndReturn( aQuads, false );
      int ij1 = j1 * nbdown + i1;
      quad->uv_grid[ij1].node = node;
    }

    for (int i1 = 0; i1 < nbdown; i1++)
      for (int j1 = 0; j1 < nbright; j1++) {
        int ij1 = j1 * nbdown + i1;
        int i = cz0.ia * i1 + cz0.ib * j1 + cz0.ic;     // i = x/face
        int j = cz0.ja * i1 + cz0.jb * j1 + cz0.jc;     // j = y/face
        int ijk = k * nbx * nby + j * nbx + i;
        //MESSAGE(" "<<ij1<<" "<<i<<" "<<j<<" "<<ijk);
        np[ijk].node = quad->uv_grid[ij1].node;
        //SCRUTE(np[ijk].nodeId);
      }
  }

  {
    const TopoDS_Face & F = TopoDS::Face(meshFaces[_indZ1]->GetSubShape());

    SMDS_NodeIteratorPtr itf= aMesh.GetSubMesh(F)->GetSubMeshDS()->GetNodes();

    faceQuadStruct *quad = aCube.quad_Z1;
    int k = nbz - 1;            // i = x/face , j = y/face
    int nbdown = quad->side[0]->NbPoints();
    int nbright = quad->side[1]->NbPoints();
    
    while(itf->more()) {
      const SMDS_MeshNode * node = itf->next();
      if(aTool.IsMedium(node))
        continue;
      if ( !findIJ( node, quad, i1, j1 ))
        return ClearAndReturn( aQuads, false );
      int ij1 = j1 * nbdown + i1;
      quad->uv_grid[ij1].node = node;
    }

    for (int i1 = 0; i1 < nbdown; i1++)
      for (int j1 = 0; j1 < nbright; j1++) {
        int ij1 = j1 * nbdown + i1;
        int i = cz1.ia * i1 + cz1.ib * j1 + cz1.ic;     // i = x/face
        int j = cz1.ja * i1 + cz1.jb * j1 + cz1.jc;     // j = y/face
        int ijk = k * nbx * nby + j * nbx + i;
        //MESSAGE(" "<<ij1<<" "<<i<<" "<<j<<" "<<ijk);
        np[ijk].node = quad->uv_grid[ij1].node;
        //SCRUTE(np[ijk].nodeId);
      }
  }

  // 2.0 - for each node of the cube:
  //       - get the 8 points 3D = 8 vertices of the cube
  //       - get the 12 points 3D on the 12 edges of the cube
  //       - get the 6 points 3D on the 6 faces with their ID
  //       - compute the point 3D
  //       - store the point 3D in SMESHDS, store its ID in 3D structure

  int shapeID = meshDS->ShapeToIndex( aShape );

  Pt3 p000, p001, p010, p011, p100, p101, p110, p111;
  Pt3 px00, px01, px10, px11;
  Pt3 p0y0, p0y1, p1y0, p1y1;
  Pt3 p00z, p01z, p10z, p11z;
  Pt3 pxy0, pxy1, px0z, px1z, p0yz, p1yz;

  GetPoint(p000, 0, 0, 0, nbx, nby, nbz, np, meshDS);
  GetPoint(p001, 0, 0, nbz - 1, nbx, nby, nbz, np, meshDS);
  GetPoint(p010, 0, nby - 1, 0, nbx, nby, nbz, np, meshDS);
  GetPoint(p011, 0, nby - 1, nbz - 1, nbx, nby, nbz, np, meshDS);
  GetPoint(p100, nbx - 1, 0, 0, nbx, nby, nbz, np, meshDS);
  GetPoint(p101, nbx - 1, 0, nbz - 1, nbx, nby, nbz, np, meshDS);
  GetPoint(p110, nbx - 1, nby - 1, 0, nbx, nby, nbz, np, meshDS);
  GetPoint(p111, nbx - 1, nby - 1, nbz - 1, nbx, nby, nbz, np, meshDS);

  for (int i = 1; i < nbx - 1; i++) {
    for (int j = 1; j < nby - 1; j++) {
      for (int k = 1; k < nbz - 1; k++) {
        // *** seulement maillage regulier
        // 12 points on edges
        GetPoint(px00, i, 0, 0, nbx, nby, nbz, np, meshDS);
        GetPoint(px01, i, 0, nbz - 1, nbx, nby, nbz, np, meshDS);
        GetPoint(px10, i, nby - 1, 0, nbx, nby, nbz, np, meshDS);
        GetPoint(px11, i, nby - 1, nbz - 1, nbx, nby, nbz, np, meshDS);

        GetPoint(p0y0, 0, j, 0, nbx, nby, nbz, np, meshDS);
        GetPoint(p0y1, 0, j, nbz - 1, nbx, nby, nbz, np, meshDS);
        GetPoint(p1y0, nbx - 1, j, 0, nbx, nby, nbz, np, meshDS);
        GetPoint(p1y1, nbx - 1, j, nbz - 1, nbx, nby, nbz, np, meshDS);

        GetPoint(p00z, 0, 0, k, nbx, nby, nbz, np, meshDS);
        GetPoint(p01z, 0, nby - 1, k, nbx, nby, nbz, np, meshDS);
        GetPoint(p10z, nbx - 1, 0, k, nbx, nby, nbz, np, meshDS);
        GetPoint(p11z, nbx - 1, nby - 1, k, nbx, nby, nbz, np, meshDS);

        // 12 points on faces
        GetPoint(pxy0, i, j, 0, nbx, nby, nbz, np, meshDS);
        GetPoint(pxy1, i, j, nbz - 1, nbx, nby, nbz, np, meshDS);
        GetPoint(px0z, i, 0, k, nbx, nby, nbz, np, meshDS);
        GetPoint(px1z, i, nby - 1, k, nbx, nby, nbz, np, meshDS);
        GetPoint(p0yz, 0, j, k, nbx, nby, nbz, np, meshDS);
        GetPoint(p1yz, nbx - 1, j, k, nbx, nby, nbz, np, meshDS);

        int ijk = k * nbx * nby + j * nbx + i;
        double x = double (i) / double (nbx - 1);       // *** seulement
        double y = double (j) / double (nby - 1);       // *** maillage
        double z = double (k) / double (nbz - 1);       // *** regulier

        Pt3 X;
        for (int i = 0; i < 3; i++) {
          X[i] = (1 - x) * p0yz[i] + x * p1yz[i]
                 + (1 - y) * px0z[i] + y * px1z[i]
                 + (1 - z) * pxy0[i] + z * pxy1[i]
                 - (1 - x) * ((1 - y) * p00z[i] + y * p01z[i])
                 - x * ((1 - y) * p10z[i] + y * p11z[i])
                 - (1 - y) * ((1 - z) * px00[i] + z * px01[i])
                 - y * ((1 - z) * px10[i] + z * px11[i])
                 - (1 - z) * ((1 - x) * p0y0[i] + x * p1y0[i])
                 - z * ((1 - x) * p0y1[i] + x * p1y1[i])
                 + (1 - x) * ((1 - y) * ((1 - z) * p000[i] + z * p001[i])
                 + y * ((1 - z) * p010[i] + z * p011[i]))
                 + x * ((1 - y) * ((1 - z) * p100[i] + z * p101[i])
                 + y * ((1 - z) * p110[i] + z * p111[i]));
        }

        SMDS_MeshNode * node = meshDS->AddNode(X[0], X[1], X[2]);
        np[ijk].node = node;
        meshDS->SetNodeInVolume(node, shapeID);
      }
    }
  }

  // find orientation of furute volumes according to MED convention
  vector< bool > forward( nbx * nby );
  SMDS_VolumeTool vTool;
  for (int i = 0; i < nbx - 1; i++) {
    for (int j = 0; j < nby - 1; j++) {
      int n1 = j * nbx + i;
      int n2 = j * nbx + i + 1;
      int n3 = (j + 1) * nbx + i + 1;
      int n4 = (j + 1) * nbx + i;
      int n5 = nbx * nby + j * nbx + i;
      int n6 = nbx * nby + j * nbx + i + 1;
      int n7 = nbx * nby + (j + 1) * nbx + i + 1;
      int n8 = nbx * nby + (j + 1) * nbx + i;

      SMDS_VolumeOfNodes tmpVol (np[n1].node,np[n2].node,np[n3].node,np[n4].node,
                                 np[n5].node,np[n6].node,np[n7].node,np[n8].node);
      vTool.Set( &tmpVol );
      forward[ n1 ] = vTool.IsForward();
    }
  }

  //2.1 - for each node of the cube (less 3 *1 Faces):
  //      - store hexahedron in SMESHDS
  MESSAGE("Storing hexahedron into the DS");
  for (int i = 0; i < nbx - 1; i++) {
    for (int j = 0; j < nby - 1; j++) {
      bool isForw = forward.at( j * nbx + i );
      for (int k = 0; k < nbz - 1; k++) {
        int n1 = k * nbx * nby + j * nbx + i;
        int n2 = k * nbx * nby + j * nbx + i + 1;
        int n3 = k * nbx * nby + (j + 1) * nbx + i + 1;
        int n4 = k * nbx * nby + (j + 1) * nbx + i;
        int n5 = (k + 1) * nbx * nby + j * nbx + i;
        int n6 = (k + 1) * nbx * nby + j * nbx + i + 1;
        int n7 = (k + 1) * nbx * nby + (j + 1) * nbx + i + 1;
        int n8 = (k + 1) * nbx * nby + (j + 1) * nbx + i;

        SMDS_MeshVolume * elt;
        if ( isForw ) {
          elt = aTool.AddVolume(np[n1].node, np[n2].node,
                                np[n3].node, np[n4].node,
                                np[n5].node, np[n6].node,
                                np[n7].node, np[n8].node);
        }
        else {
          elt = aTool.AddVolume(np[n1].node, np[n4].node,
                                np[n3].node, np[n2].node,
                                np[n5].node, np[n8].node,
                                np[n7].node, np[n6].node);
        }
        
        meshDS->SetMeshElementOnShape(elt, shapeID);
      }
    }
  }
  if ( np ) delete [] np;
  return ClearAndReturn( aQuads, true );
}