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41 results

gmm_interface_bgeot.h

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  • GModel.cpp 23.31 KiB
    // Gmsh - Copyright (C) 1997-2008 C. Geuzaine, J.-F. Remacle
    //
    // See the LICENSE.txt file for license information. Please report all
    // bugs and problems to <gmsh@geuz.org>.
    
    #include <sstream>
    #include "GModel.h"
    #include "MElement.h"
    #include "discreteRegion.h"
    #include "discreteFace.h"
    #include "discreteEdge.h"
    #include "discreteVertex.h"
    #include "Message.h"
    
    #if defined(HAVE_GMSH_EMBEDDED)
    #include "GmshEmbedded.h"
    #else
    #include "gmshSurface.h"
    #include "Octree.h"
    #include "SmoothData.h"
    #include "Field.h"
    #include "Generator.h"
    #include "Context.h"
    #endif
    
    extern Context_T CTX;
    
    std::vector<GModel*> GModel::list;
    int GModel::_current = -1;
    
    GModel::GModel(std::string name)
      : _octree(0), _geo_internals(0), _occ_internals(0), _fm_internals(0), 
        _fields(0), _currentMeshEntity(0), modelName(name), normals(0)
    {
      partitionSize[0] = 0; partitionSize[1] = 0;
      list.push_back(this);
    
    #if !defined(HAVE_GMSH_EMBEDDED)
      // at the moment we always create (at least an empty) GEO model
      _createGEOInternals();
      _fields = new FieldManager();
    #endif
    }
    
    GModel::~GModel()
    {
      std::vector<GModel*>::iterator it = std::find(list.begin(), list.end(), this);
      if(it != list.end()) list.erase(it);
    
      destroy();
    
    #if !defined(HAVE_GMSH_EMBEDDED)
      _deleteGEOInternals();
      _deleteOCCInternals();
      delete _fields;
    #endif
    }
    
    GModel *GModel::current(int index)
    {
      if(index >= 0) _current = index;
      if(list.empty()) return 0; // not an error
    
      if(_current < 0 || _current >= (int)list.size()) return list.back();
      return list[_current];
    }
    
    GModel *GModel::findByName(std::string name)
    {
      // return last mesh with given name
      for(int i = list.size() - 1; i >= 0; i--)
        if(list[i]->getName() == name) return list[i];
      return 0;
    }
    
    void GModel::destroy()
    {
      for(riter it = firstRegion(); it != lastRegion(); ++it)
        delete *it;
      regions.clear();
    
      std::vector<GFace*> to_keep;
      for(fiter it = firstFace(); it != lastFace(); ++it){
        // projection faces are persistent
        if((*it)->getNativeType() == GEntity::UnknownModel &&
           (*it)->geomType() == GEntity::ProjectionFace)
          to_keep.push_back(*it);
        else
          delete *it;
      }
      faces.clear();
      faces.insert(to_keep.begin(), to_keep.end());
    
      for(eiter it = firstEdge(); it != lastEdge(); ++it)
        delete *it;
      edges.clear();
    
      for(viter it = firstVertex(); it != lastVertex(); ++it)
        delete *it;
      vertices.clear();
    
      destroyMeshCaches();
    
      MVertex::resetGlobalNumber();
      MElement::resetGlobalNumber();
    
    #if !defined(HAVE_GMSH_EMBEDDED)
      if(normals) delete normals;
      normals = 0;
    
      _fields->reset();
      gmshSurface::reset();
    #endif
    }
    
    void GModel::destroyMeshCaches()
    {
      _vertexVectorCache.clear();
      _vertexMapCache.clear();
    #if !defined(HAVE_GMSH_EMBEDDED)
      if(_octree) Octree_Delete(_octree);
      _octree = 0;
    #endif
    }
    
    GRegion *GModel::getRegionByTag(int n) const
    {
      GEntity tmp((GModel*)this, n);
      std::set<GRegion*, GEntityLessThan>::const_iterator it = regions.find((GRegion*)&tmp);
      if(it != regions.end())
        return *it;
      else
        return 0;
    }
    
    GFace *GModel::getFaceByTag(int n) const
    {
      GEntity tmp((GModel*)this, n);
      std::set<GFace*, GEntityLessThan>::const_iterator it = faces.find((GFace*)&tmp);
      if(it != faces.end())
        return *it;
      else
        return 0;
    }
    
    GEdge *GModel::getEdgeByTag(int n) const
    {
      GEntity tmp((GModel*)this, n);
      std::set<GEdge*, GEntityLessThan>::const_iterator it = edges.find((GEdge*)&tmp);
      if(it != edges.end())
        return *it;
      else
        return 0;
    }
    
    GVertex *GModel::getVertexByTag(int n) const
    {
      GEntity tmp((GModel*)this, n);
      std::set<GVertex*, GEntityLessThan>::const_iterator it = vertices.find((GVertex*)&tmp);
      if(it != vertices.end())
        return *it;
      else
        return 0;
    }
    
    void GModel::remove(GRegion *r)
    {
      riter it = std::find(firstRegion(), lastRegion(), r);
      if(it != (riter)regions.end()) regions.erase(it);
    }
    
    void GModel::remove(GFace *f)
    {
      fiter it = std::find(firstFace(), lastFace(), f);
      if(it != faces.end()) faces.erase(it);
    }
    
    void GModel::remove(GEdge *e)
    {
      eiter it = std::find(firstEdge(), lastEdge(), e);
      if(it != edges.end()) edges.erase(it);
    }
    
    void GModel::remove(GVertex *v)
    {
      viter it = std::find(firstVertex(), lastVertex(), v);
      if(it != vertices.end()) vertices.erase(it);
    }
    
    void GModel::snapVertices()
    {
      viter vit = firstVertex();
    
      double tol = CTX.geom.tolerance;
    
      while (vit != lastVertex()){
        std::list<GEdge*> edges = (*vit)->edges();
        for (std::list<GEdge*>::iterator it = edges.begin(); it != edges.end(); ++it){
          Range<double> parb = (*it)->parBounds(0);
          double t;
          if ((*it)->getBeginVertex() == *vit){
            t = parb.low();
          }
          else if ((*it)->getEndVertex() == *vit){
            t = parb.high();
          }
          else{
    	Msg::Error("Weird vertex: impossible to snap");
    	break;
          }
          GPoint gp = (*it)->point(t);
          double d = sqrt((gp.x() - (*vit)->x()) * (gp.x() - (*vit)->x()) +
                          (gp.y() - (*vit)->y()) * (gp.y() - (*vit)->y()) +
                          (gp.z() - (*vit)->z()) * (gp.z() - (*vit)->z()));
          if (d > tol){
            (*vit)->setPosition(gp);
            Msg::Warning("Geom Vertex %d Corrupted (%12.5E)... Snap performed",
    		     (*vit)->tag(), d);
          }
        }
        vit++;
      }
    }
    
    void GModel::getEntities(std::vector<GEntity*> &entities)
    {
      entities.clear();
      entities.insert(entities.end(), vertices.begin(), vertices.end());
      entities.insert(entities.end(), edges.begin(), edges.end());
      entities.insert(entities.end(), faces.begin(), faces.end());
      entities.insert(entities.end(), regions.begin(), regions.end());
    }
    
    bool GModel::noPhysicalGroups()
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
      for(unsigned int i = 0; i < entities.size(); i++)
        if(entities[i]->physicals.size()) return false;
      return true;
    }
    
    void GModel::getPhysicalGroups(std::map<int, std::vector<GEntity*> > groups[4])
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
      for(unsigned int i = 0; i < entities.size(); i++){
        std::map<int, std::vector<GEntity*> > &group(groups[entities[i]->dim()]);
        for(unsigned int j = 0; j < entities[i]->physicals.size(); j++){
          // physicals can be stored with negative signs when the entity
          // should be "reversed"
          int p = std::abs(entities[i]->physicals[j]);
          if(std::find(group[p].begin(), group[p].end(), entities[i]) == group[p].end())
    	group[p].push_back(entities[i]);
        }
      }
    }
    
    void GModel::deletePhysicalGroups()
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
      for(unsigned int i = 0; i < entities.size(); i++)
        entities[i]->physicals.clear();
    }
    
    void GModel::deletePhysicalGroup(int dim, int num)
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
      for(unsigned int i = 0; i < entities.size(); i++){
        if(dim == entities[i]->dim()){
          std::vector<int> p;
          for(unsigned int j = 0; j < entities[i]->physicals.size(); j++)
            if(entities[i]->physicals[j] != num) 
    	  p.push_back(entities[i]->physicals[j]);
          entities[i]->physicals = p;
        }
      }
    }
    
    int GModel::getMaxPhysicalNumber()
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
      int num = 0;
      for(unsigned int i = 0; i < entities.size(); i++)
        for(unsigned int j = 0; j < entities[i]->physicals.size(); j++)
          num = std::max(num, std::abs(entities[i]->physicals[j]));
      return num;
    }
    
    int GModel::setPhysicalName(std::string name, int number)
    {
      // check if the name is already used
      std::map<int, std::string>::iterator it = physicalNames.begin();
      while(it != physicalNames.end()){
        if(it->second == name) return it->first;
        ++it;
      }
      // if no number is given, find the next available one
      if(!number) number = getMaxPhysicalNumber() + 1;
      physicalNames[number] = name;
      return number;
    }
    
    std::string GModel::getPhysicalName(int number)
    {
      return physicalNames[number];
    }
    
    SBoundingBox3d GModel::bounds()
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
      // using the mesh vertices for now; should use entities[i]->bounds() instead
      SBoundingBox3d bb;
      for(unsigned int i = 0; i < entities.size(); i++)
        for(unsigned int j = 0; j < entities[i]->mesh_vertices.size(); j++)
          bb += entities[i]->mesh_vertices[j]->point();
      return bb;
    }
    
    int GModel::mesh(int dimension)
    {
    #if !defined(HAVE_GMSH_EMBEDDED)
      GenerateMesh(this, dimension);
      return true;
    #else
      Msg::Error("Embedded Gmsh cannot do mesh generation");
      return false;
    #endif
    }
    
    int GModel::getMeshStatus(bool countDiscrete)
    {
      for(riter it = firstRegion(); it != lastRegion(); ++it)
        if((countDiscrete || ((*it)->geomType() != GEntity::DiscreteVolume &&
    			  (*it)->meshAttributes.Method != MESH_NONE)) &&
           ((*it)->tetrahedra.size() ||(*it)->hexahedra.size() ||
            (*it)->prisms.size() || (*it)->pyramids.size())) return 3;
      for(fiter it = firstFace(); it != lastFace(); ++it)
        if((countDiscrete || ((*it)->geomType() != GEntity::DiscreteSurface &&
    			  (*it)->meshAttributes.Method != MESH_NONE)) &&
           ((*it)->triangles.size() || (*it)->quadrangles.size())) return 2;
      for(eiter it = firstEdge(); it != lastEdge(); ++it)
        if((countDiscrete || ((*it)->geomType() != GEntity::DiscreteCurve &&
    			  (*it)->meshAttributes.Method != MESH_NONE)) &&
           (*it)->lines.size()) return 1;
      for(viter it = firstVertex(); it != lastVertex(); ++it)
        if((*it)->mesh_vertices.size()) return 0;
      return -1;
    }
    
    int GModel::getNumMeshVertices()
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
      unsigned int n = 0;
      for(unsigned int i = 0; i < entities.size(); i++)
        n += entities[i]->mesh_vertices.size();
      return n;
    }
    
    int GModel::getNumMeshElements()
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
      unsigned int n = 0;
      for(unsigned int i = 0; i < entities.size(); i++)
        n += entities[i]->getNumMeshElements();
      return n;
    }
    
    int GModel::getNumMeshElements(unsigned c[4])
    {
      c[0] = 0; c[1] = 0; c[2] = 0; c[3] = 0;
      for(riter it = firstRegion(); it != lastRegion(); ++it)
        (*it)->getNumMeshElements(c);
      if(c[0] + c[1] + c[2] + c[3]) return 3;
      for(fiter it = firstFace(); it != lastFace(); ++it)
        (*it)->getNumMeshElements(c);
      if(c[0] + c[1]) return 2;
      for(eiter it = firstEdge(); it != lastEdge(); ++it)
        (*it)->getNumMeshElements(c);
      if(c[0]) return 1;
      return 0;
    }
    
    static void MElementBB(void *a, double *min, double *max)
    {
      MElement *e = (MElement*)a;
      MVertex *v = e->getVertex(0);
      min[0] = max[0] = v->x(); 
      min[1] = max[1] = v->y(); 
      min[2] = max[2] = v->z();
      for(int i = 1; i < e->getNumVertices(); i++){
        v = e->getVertex(i);
        min[0] = std::min(min[0], v->x()); max[0] = std::max(max[0], v->x());
        min[1] = std::min(min[1], v->y()); max[1] = std::max(max[1], v->y());
        min[2] = std::min(min[2], v->z()); max[2] = std::max(max[2], v->z());
      }
    }
    
    static void MElementCentroid(void *a, double *x)
    {
      MElement *e = (MElement*)a;
      MVertex *v = e->getVertex(0);
      int n = e->getNumVertices();
      x[0] = v->x(); x[1] = v->y(); x[2] = v->z();
      for(int i = 1; i < n; i++) {
        v = e->getVertex(i);
        x[0] += v->x(); x[1] += v->y(); x[2] += v->z();
      }
      double oc = 1. / (double)n;
      x[0] *= oc;
      x[1] *= oc;
      x[2] *= oc;
    }
    
    static int MElementInEle(void *a, double *x)
    {
      MElement *e = (MElement*)a;
      double uvw[3];
      e->xyz2uvw(x, uvw);
      return e->isInside(uvw[0], uvw[1], uvw[2]) ? 1 : 0;
    }
    
    MElement *GModel::getMeshElementByCoord(SPoint3 &p)
    {
    #if !defined(HAVE_GMSH_EMBEDDED)
      if(!_octree){
        Msg::Debug("Rebuilding mesh element octree");
        SBoundingBox3d bb = bounds();
        double min[3] = {bb.min().x(), bb.min().y(), bb.min().z()};
        double size[3] = {bb.max().x() - bb.min().x(),
    		      bb.max().y() - bb.min().y(),
    		      bb.max().z() - bb.min().z()};                   
        const int maxElePerBucket = 100; // memory vs. speed trade-off
        _octree = Octree_Create(maxElePerBucket, min, size, 
    			    MElementBB, MElementCentroid, MElementInEle);
        std::vector<GEntity*> entities;
        getEntities(entities);
        for(unsigned int i = 0; i < entities.size(); i++)
          for(unsigned int j = 0; j < entities[i]->getNumMeshElements(); j++)
    	Octree_Insert(entities[i]->getMeshElement(j), _octree);
        Octree_Arrange(_octree);
      }
      double P[3] = {p.x(), p.y(), p.z()};
      return (MElement*)Octree_Search(P, _octree);
    #else
      Msg::Error("Embedded Gmsh cannot perform octree-based element searches");
      return 0;
    #endif
    }
    
    MVertex *GModel::getMeshVertexByTag(int n)
    {
      if(_vertexVectorCache.empty() && _vertexMapCache.empty()){
        Msg::Debug("Rebuilding mesh vertex cache");
        _vertexVectorCache.clear();
        _vertexMapCache.clear();
        bool dense = (getNumMeshVertices() == MVertex::getGlobalNumber());
        std::vector<GEntity*> entities;
        getEntities(entities);
        if(dense){
          Msg::Debug("Good: we have a dense vertex numbering in the cache");
          // numbering starts at 1
          _vertexVectorCache.resize(MVertex::getGlobalNumber() + 1);
          for(unsigned int i = 0; i < entities.size(); i++)
    	for(unsigned int j = 0; j < entities[i]->mesh_vertices.size(); j++)
    	  _vertexVectorCache[entities[i]->mesh_vertices[j]->getNum()] = 
    	    entities[i]->mesh_vertices[j];
        }
        else{
          for(unsigned int i = 0; i < entities.size(); i++)
    	for(unsigned int j = 0; j < entities[i]->mesh_vertices.size(); j++)
    	  _vertexMapCache[entities[i]->mesh_vertices[j]->getNum()] = 
    	    entities[i]->mesh_vertices[j];
        }
      }
      
      if(n < (int)_vertexVectorCache.size())
        return _vertexVectorCache[n];
      else
        return _vertexMapCache[n];
    }
    
    void GModel::getMeshVertices(int number, int dim, std::vector<MVertex*> &v)
    {
      v.clear();
      std::map<int, std::vector<GEntity*> > groups[4];
      getPhysicalGroups(groups);
      std::map<int, std::vector<GEntity*> >::const_iterator it = groups[dim].find(number);
      if(it == groups[dim].end()) return;
      const std::vector<GEntity *> &entities = it->second;
      std::set<MVertex*> sv;
      for(unsigned int i = 0; i < entities.size(); i++){
        if(dim == 0){
          GVertex *g = (GVertex*)entities[i];
          sv.insert(g->mesh_vertices[0]);
        }
        else{
          for(unsigned int j = 0; j < entities[i]->getNumMeshElements(); j++){
    	MElement *e = entities[i]->getMeshElement(j);
    	for(int k = 0; k < e->getNumVertices(); k++)
    	  sv.insert(e->getVertex(k));
          }
        }
      }
      v.insert(v.begin(), sv.begin(), sv.end());
    }
    
    template <class T>
    static void removeInvisible(std::vector<T*> &elements, bool all)
    {
      std::vector<T*> tmp;
      for(unsigned int i = 0; i < elements.size(); i++){
        if(all || !elements[i]->getVisibility())
          delete elements[i];
        else
          tmp.push_back(elements[i]);
      }
      elements.clear();
      elements = tmp;
    }
    
    void GModel::removeInvisibleElements()
    {
      for(riter it = firstRegion(); it != lastRegion(); ++it){
        bool all = !(*it)->getVisibility();
        removeInvisible((*it)->tetrahedra, all);
        removeInvisible((*it)->hexahedra, all);
        removeInvisible((*it)->prisms, all);
        removeInvisible((*it)->pyramids, all);
        (*it)->deleteVertexArrays();
      }
      for(fiter it = firstFace(); it != lastFace(); ++it){
        bool all = !(*it)->getVisibility();
        removeInvisible((*it)->triangles, all);
        removeInvisible((*it)->quadrangles, all);
        (*it)->deleteVertexArrays();
      }
      for(eiter it = firstEdge(); it != lastEdge(); ++it){
        bool all = !(*it)->getVisibility();
        removeInvisible((*it)->lines, all);
        (*it)->deleteVertexArrays();
      }
    }
    
    int GModel::indexMeshVertices(bool all)
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
    
      // tag all mesh vertices with -1 (negative vertices will not be
      // saved)
      for(unsigned int i = 0; i < entities.size(); i++)
        for(unsigned int j = 0; j < entities[i]->mesh_vertices.size(); j++)
          entities[i]->mesh_vertices[j]->setIndex(-1);
      
      // tag all mesh vertices belonging to elements that need to be saved
      // with 0
      for(unsigned int i = 0; i < entities.size(); i++)
        if(all || entities[i]->physicals.size())
          for(unsigned int j = 0; j < entities[i]->getNumMeshElements(); j++)
    	for(int k = 0; k < entities[i]->getMeshElement(j)->getNumVertices(); k++)
    	  entities[i]->getMeshElement(j)->getVertex(k)->setIndex(0);
    
      // renumber all the mesh vertices tagged with 0
      int numVertices = 0;
      for(unsigned int i = 0; i < entities.size(); i++)
        for(unsigned int j = 0; j < entities[i]->mesh_vertices.size(); j++)
          if(!entities[i]->mesh_vertices[j]->getIndex())
            entities[i]->mesh_vertices[j]->setIndex(++numVertices);
      
      return numVertices;
    }
    
    void GModel::scaleMesh(double factor)
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
      for(unsigned int i = 0; i < entities.size(); i++)
        for(unsigned int j = 0; j < entities[i]->mesh_vertices.size(); j++){
          MVertex *v = entities[i]->mesh_vertices[j];
          v->x() *= factor;
          v->y() *= factor;
          v->z() *= factor;
        }
    }
    
    void GModel::recomputeMeshPartitions()
    {
      meshPartitions.clear();
      std::vector<GEntity*> entities;
      getEntities(entities);
      for(unsigned int i = 0; i < entities.size(); i++){
        for(unsigned int j = 0; j < entities[i]->getNumMeshElements(); j++){
          int part = entities[i]->getMeshElement(j)->getPartition();
          if(part) meshPartitions.insert(part);
        }
      }
    }
    
    void GModel::deleteMeshPartitions()
    {
      std::vector<GEntity*> entities;
      getEntities(entities);
      for(unsigned int i = 0; i < entities.size(); i++)
        for(unsigned int j = 0; j < entities[i]->getNumMeshElements(); j++)
          entities[i]->getMeshElement(j)->setPartition(0);
      meshPartitions.clear();
    }
    
    void GModel::checkMeshCoherence()
    {
      int numEle = getNumMeshElements();
      if(!numEle) return;
    
      Msg::Info("Checking mesh coherence (%d elements)", numEle);
    
      SBoundingBox3d bb = bounds();
      double lc = bb.empty() ? 1. : norm(SVector3(bb.max(), bb.min()));
      double tol = CTX.geom.tolerance * lc;
    
      std::vector<GEntity*> entities;
      getEntities(entities);
    
      // check for duplicate mesh vertices
      {
        double old_tol = MVertexLessThanLexicographic::tolerance;
        MVertexLessThanLexicographic::tolerance = tol;
        std::set<MVertex*, MVertexLessThanLexicographic> pos;
        int num = 0;
        for(unsigned int i = 0; i < entities.size(); i++){
          for(unsigned int j = 0; j < entities[i]->mesh_vertices.size(); j++){
    	MVertex *v = entities[i]->mesh_vertices[j];
    	std::set<MVertex*, MVertexLessThanLexicographic>::iterator it = pos.find(v);
    	if(it == pos.end()){
    	  pos.insert(v);
    	}
    	else{
    	  Msg::Info("Vertices %d and %d have identical position (%g, %g, %g)",
    		    (*it)->getNum(), v->getNum(), v->x(), v->y(), v->z());
    	  num++;
    	}
          }
        }
        if(num) Msg::Warning("%d duplicate vertices", num);
        MVertexLessThanLexicographic::tolerance = old_tol;
      }
    
      // check for duplicate elements
      {
        double old_tol = MElementLessThanLexicographic::tolerance;
        MElementLessThanLexicographic::tolerance = tol;
        std::set<MElement*, MElementLessThanLexicographic> pos;
        int num = 0;
        for(unsigned int i = 0; i < entities.size(); i++){
          for(unsigned int j = 0; j < entities[i]->getNumMeshElements(); j++){
    	MElement *e = entities[i]->getMeshElement(j);
    	std::set<MElement*, MElementLessThanLexicographic>::iterator it = pos.find(e);
    	if(it == pos.end()){
    	  pos.insert(e);
    	}
    	else{
    	  std::ostringstream sstream;
    	  sstream << "Element " << e->getNum() << " [ ";
    	  for (int k = 0; k < e->getNumVertices(); k++)
    	    sstream << e->getVertex(k)->getNum() << " ";
    	  sstream << "] on entity " << entities[i]->tag() 
    		  << " has same barycenter as element " << (*it)->getNum() 
    		  << " [ ";
    	  for (int k = 0; k < (*it)->getNumVertices(); k++)
    	    sstream << (*it)->getVertex(k)->getNum() << " ";
    	  sstream << "]";
    	  Msg::Info("%s", sstream.str().c_str());
    	  num++;
    	}
          }
        }
        if(num) Msg::Warning("%d duplicate elements", num);
        MElementLessThanLexicographic::tolerance = old_tol;
      }
    }
    
    template<class T>
    static void _addElements(std::vector<T*> &dst, const std::vector<MElement*> &src)
    {
      for(unsigned int i = 0; i < src.size(); i++) dst.push_back((T*)src[i]);
    }
    
    void GModel::_storeElementsInEntities(std::map<int, std::vector<MElement*> > &map)
    {
      std::map<int, std::vector<MElement*> >::const_iterator it = map.begin();
      for(; it != map.end(); ++it){
        if(!it->second.size()) continue;
        int numEdges = it->second[0]->getNumEdges();
        switch(numEdges){
        case 0: 
          {
            GVertex *v = getVertexByTag(it->first);
            if(!v){
              v = new discreteVertex(this, it->first);
              add(v);
            }
    	if(v->points.empty()) // CAD points already have one by default
    	  _addElements(v->points, it->second);
          }
          break;
        case 1: 
          {
            GEdge *e = getEdgeByTag(it->first);
            if(!e){
              e = new discreteEdge(this, it->first);
              add(e);
            }
            _addElements(e->lines, it->second);
          }
          break;
        case 3: case 4: 
          {
            GFace *f = getFaceByTag(it->first);
            if(!f){
              f = new discreteFace(this, it->first);
              add(f);
            }
            if(numEdges == 3) _addElements(f->triangles, it->second);
            else _addElements(f->quadrangles, it->second);
          }
          break;
        case 6: case 12: case 9: case 8:
          {
            GRegion *r = getRegionByTag(it->first);
            if(!r){
              r = new discreteRegion(this, it->first);
              add(r);
            }
            if(numEdges == 6) _addElements(r->tetrahedra, it->second);
            else if(numEdges == 12) _addElements(r->hexahedra, it->second);
            else if(numEdges == 9) _addElements(r->prisms, it->second);
            else _addElements(r->pyramids, it->second);
          }
          break;
        }
      }
    }
    
    template<class T>
    static void _associateEntityWithElementVertices(GEntity *ge, std::vector<T*> &elements)
    {
      for(unsigned int i = 0; i < elements.size(); i++)
        for(int j = 0; j < elements[i]->getNumVertices(); j++)
          elements[i]->getVertex(j)->setEntity(ge);
    }
    
    void GModel::_associateEntityWithMeshVertices()
    {
      // loop on regions, then on faces, edges and vertices and store the
      // entity pointer in the the elements' vertices (this way we
      // associate the entity of lowest geometrical degree with each
      // vertex)
      for(riter it = firstRegion(); it != lastRegion(); ++it){
        _associateEntityWithElementVertices(*it, (*it)->tetrahedra);
        _associateEntityWithElementVertices(*it, (*it)->hexahedra);
        _associateEntityWithElementVertices(*it, (*it)->prisms);
        _associateEntityWithElementVertices(*it, (*it)->pyramids);
      }
      for(fiter it = firstFace(); it != lastFace(); ++it){
        _associateEntityWithElementVertices(*it, (*it)->triangles);
        _associateEntityWithElementVertices(*it, (*it)->quadrangles);
      }
      for(eiter it = firstEdge(); it != lastEdge(); ++it){
        _associateEntityWithElementVertices(*it, (*it)->lines);
      }
      for(viter it = firstVertex(); it != lastVertex(); ++it){
        _associateEntityWithElementVertices(*it, (*it)->points);
      }
    }
    
    void GModel::_storeVerticesInEntities(std::map<int, MVertex*> &vertices)
    {
      std::map<int, MVertex*>::const_iterator it = vertices.begin();
      for(; it != vertices.end(); ++it){
        MVertex *v = it->second;
        GEntity *ge = v->onWhat();
        if(ge){
          if(ge->dim() || ge->mesh_vertices.empty()){ // special case for points
    	ge->mesh_vertices.push_back(v);
          }
        }
        else
          delete v; // we delete all unused vertices
      }
    }
    
    void GModel::_storeVerticesInEntities(std::vector<MVertex*> &vertices)
    {
      for(unsigned int i = 0; i < vertices.size(); i++){
        MVertex *v = vertices[i];
        if(v){ // the vector is allowed to have null entries
          GEntity *ge = v->onWhat();
          if(ge) {
    	if(ge->dim() || ge->mesh_vertices.empty()){ // special case for points
    	  ge->mesh_vertices.push_back(v);
    	}
          }
          else
            delete v; // we delete all unused vertices
        }
      }
    }