MaillerParallel.cpp

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#include <MaillerParallel.h>
#include <Domaine.h>
#include <Motcle.h>
#include <Scatter.h>
#include <Param.h>
#include <TRUSTArrays.h>
#include <Parser_U.h>
#include <Reordonner_faces_periodiques.h>
#include <EFichier.h>
#include <Schema_Comm.h>
#include <Octree_Double.h>
#include <Faces_builder.h>
#include <Connectivite_som_elem.h>
#include <Static_Int_Lists.h>
#include <communications.h>
#include <ArrOfBit.h>
#include <Array_tools.h>
#include <TRUST_Ref.h>
#include <Joint.h>
#include <Perf_counters.h>
 
Implemente_instanciable(MaillerParallel, "MaillerParallel", Interprete);
// XD maillerparallel interprete maillerparallel BRACE creates a parallel distributed hexaedral mesh of a
// XD_CONT parallelipipedic box. It is equivalent to creating a mesh with a single Pave, splitting it with Decouper and
// XD_CONT reloading it in parallel with Scatter. It only works in 3D at this time. It can also be used for a sequential
// XD_CONT computation (with all NPARTS=1)}
 
Entree& MaillerParallel::readOn(Entree& is)
{
  return is;
}
 
Sortie& MaillerParallel::printOn(Sortie& os) const
{
  return os;
}
 
struct BlocData
{
  void add_bloc(Domaine& domaine, const ArrsOfDouble& coord_ijk) const;
  // xmin_tot = 0 implicitly
  // xmax_tot = total number of vertices in the mesh
  // xmax = index of the last vertex + 1
  // xmin = index of the first vertex (so xmax - xmin = number of vertices in the current block)
  ArrOfInt xmax_tot_;
  ArrOfInt xmin_, xmax_;
  Noms bord_xmin_, bord_xmax_;
  inline int nb_som(int i)  const
  {
    return xmax_[i] - xmin_[i];
  }
  inline int nb_elem(int i)  const
  {
    return xmax_[i] - xmin_[i] - 1;
  }
  void add_faces(Domaine& domaine, const Nom& nombord, int offset_sommets, int dir, int cote_max) const;
};
 
void BlocData::add_bloc(Domaine& domaine, const ArrsOfDouble& coord_ijk) const
{
  if (nb_elem(0) < 1 || nb_elem(1) < 1 || nb_elem(2) < 1)
    {
      Cerr << "Error : not enough nodes in a block, increase mesh size or decrease processor count" << finl;
      Process::exit();
    }
  const int dim = 3;
  // Vertices
  const int old_nb_som = domaine.les_sommets().dimension(0);
  {
    DoubleTab& sommets = domaine.les_sommets();
    const int nsom = nb_som(0) * nb_som(1) * nb_som(2);
    sommets.resize(old_nb_som + nsom, dim);
 
    int index = old_nb_som;
    int i, j, k;
    for (k = xmin_[2]; k < xmax_[2]; k++)
      {
        for (j = xmin_[1]; j < xmax_[1]; j++)
          {
            for (i = xmin_[0]; i < xmax_[0]; i++)
              {
                sommets(index, 0) = coord_ijk[0][i];
                sommets(index, 1) = coord_ijk[1][j];
                if (dim==3)
                  sommets(index, 2) = coord_ijk[2][k];
                index++;
              }
          }
      }
  }
  // Elements
  {
    assert(dim==3);
    IntTab& elements = domaine.les_elems();
    const int nb_som_par_element = 8;
 
    // vertex index strides:
    const int dx = 1;
    const int dy = nb_som(0);
    const int dz = dy * nb_som(1);
    // number of elements in each direction
    const int nx = nb_elem(0);
    const int ny = nb_elem(1);
    const int nz = nb_elem(2);
    const int nb_elem_old = domaine.les_elems().dimension(0);
    const int nbelem = nx * ny * nz;
    elements.resize(nb_elem_old + nbelem, nb_som_par_element);
 
    int index = nb_elem_old;
    int i, j, k;
    for (k = 0; k < nz; k++)
      {
        for (j = 0; j < ny; j++)
          {
            for (i = 0; i < nx; i++)
              {
                int n = old_nb_som + k * dz + j * dy + i * dx;
                elements(index, 0) = n;
                elements(index, 1) = n + dx;
                elements(index, 2) = n + dy;
                elements(index, 3) = n + dx + dy;
                elements(index, 4) = n + dz;
                elements(index, 5) = n + dz + dx;
                elements(index, 6) = n + dz + dy;
                elements(index, 7) = n + dz + dx + dy;
                index++;
              }
          }
      }
  }
  // Boundaries
  for (int dir = 0; dir < 3; dir++)
    {
      if (xmin_[dir] == 0)
        add_faces(domaine, bord_xmin_[dir], old_nb_som, dir, 0);
      if (xmax_[dir] == xmax_tot_[dir])
        add_faces(domaine, bord_xmax_[dir], old_nb_som, dir, 1);
    }
}
 
void BlocData::add_faces(Domaine& domaine, const Nom& nombord, int offset_sommets, int dir, int cote_max) const
{
  int nfaces1, nfaces2;
  int increment1, increment2;
  int increment_dir;
  switch(dir)
    {
    case 0:
      nfaces1 = nb_elem(1);
      nfaces2 = nb_elem(2);
      increment1 = nb_som(0);
      increment2 = nb_som(0) * nb_som(1);
      increment_dir = 1;
      break;
    case 1:
      nfaces1 = nb_elem(0);
      nfaces2 = nb_elem(2);
      increment1 = 1;
      increment2 = nb_som(0) * nb_som(1);
      increment_dir = nb_som(0);
      break;
    default:
      nfaces1 = nb_elem(0);
      nfaces2 = nb_elem(1);
      increment1 = 1;
      increment2 = nb_som(0);
      increment_dir = nb_som(0)*nb_som(1);
      break;
    }
  if (cote_max)
    offset_sommets += increment_dir * (nb_som(dir)-1);
 
  IntTab& faces = domaine.frontiere(nombord).faces().les_sommets();
  int count = faces.dimension(0);
  domaine.frontiere(nombord).faces().dimensionner(count + nfaces1 * nfaces2);
  for (int i = 0; i < nfaces2; i++)
    {
      int sommet = offset_sommets;
      for (int j = 0; j < nfaces1; j++)
        {
          faces(count, 0) = sommet;
          faces(count, 1) = sommet + increment1;
          faces(count, 2) = sommet + increment2;
          faces(count, 3) = sommet + increment1 + increment2;
          sommet += increment1;
          count++;
        }
      offset_sommets += increment2;
    }
}
 
static int bbox_intersection(const DoubleTab& bboxes, int i, int j, double epsilon)
{
  const int dim = bboxes.dimension(1) / 2;
  for (int k = 0; k < dim; k++)
    {
      double min1 = bboxes(i, k) - epsilon;
      double max1 = bboxes(i, dim+k) + epsilon;
      double min2 = bboxes(j, k);
      double max2 = bboxes(j, dim+k);
      if (min1 > max2 || max1 < min2)
        return 0;
    }
  return 1;
}
 
/*! @brief for a given set of local coordinates, finds which other processors share the same nodes.
 *
 *   match must be sized to Process::nproc() and will be filled with, for each processor,
 *   the indexes of coordinates that the corresponding processor shares with me.
 *   Nodes are listed in the same order on couples of processors sharing a list of nodes
 *   match[Process::me()] will be left empty.
 *
 */
void find_matching_coordinates(const DoubleTab& coords,
                               ArrsOfInt& match,
                               double epsilon)
{
  int i, j;
  const int dim = coords.dimension(1);
  const int ncoord = coords.dimension(0);
  const int nproc = Process::nproc();
  const int moi = Process::me();
  // Fill nodes coordinates and bounding boxes
  DoubleTab bounding_boxes(nproc, dim*2);
  {
    const double big_val = 1.e36;
    ArrOfDouble min_coord(dim);
    min_coord= big_val;
    ArrOfDouble max_coord(dim);
    max_coord= -big_val;
 
    for (i = 0; i < ncoord; i++)
      {
        for (j = 0; j < dim; j++)
          {
            const double x = coords(i, j);
            if (x > max_coord[j])
              max_coord[j] = x;
            if (x < min_coord[j])
              min_coord[j] = x;
          }
      }
    // broadcast to all processors
    for (i = 0; i < nproc; i++)
      {
        for (j = 0; j < dim; j++)
          {
            bounding_boxes(i, j) = min_coord[j];
            bounding_boxes(i, j+dim) = max_coord[j];
          }
      }
    envoyer_all_to_all(bounding_boxes, bounding_boxes);
  }
  // Exchange boundary nodes coordinates with other processors
  ArrOfInt all_pe;
 
  for (i = 0; i < nproc; i++)
    if (i != moi && bbox_intersection(bounding_boxes, moi, i, epsilon))
      all_pe.append_array(i);
 
  Schema_Comm schema;
  schema.set_send_recv_pe_list(all_pe, all_pe);
  schema.begin_comm();
  Octree_Double octree;
  octree.build_nodes(coords, 0 /* do not include virtual nodes */);
 
  // Send nodes coordinates to processors with non empty intersection
  // temporary array for octree functions:
  ArrOfInt nodes_list;
 
  int ipe;
  for (ipe = 0; ipe < all_pe.size_array(); ipe++)
    {
      // Search nodes within the bounding box of the other processor:
      const int pe = all_pe[ipe]; // processor number
      const double xmin = bounding_boxes(pe, 0) - epsilon;
      const double ymin = bounding_boxes(pe, 1) - epsilon;
      const double zmin = (dim == 3) ? bounding_boxes(pe, 2) - epsilon : -epsilon;
      const double xmax = bounding_boxes(pe, dim) + epsilon;
      const double ymax = bounding_boxes(pe, dim+1) + epsilon;
      const double zmax = (dim == 3) ? bounding_boxes(pe, dim+2) + epsilon : epsilon;
      octree.search_elements_box(xmin, ymin, zmin, xmax, ymax, zmax, nodes_list);
 
      Sortie& buffer = schema.send_buffer(pe);
      const int n = nodes_list.size_array();
      for (i = 0; i < n; i++)
        {
          const int som = nodes_list[i];
          const double x = coords(som, 0);
          const double y = coords(som, 1);
          const double z = (dim==3) ? coords(som, 2) : 0;
          // test again if inside bounding box (octree test gives more nodes)
          if (x>=xmin && x<=xmax && y>=ymin && y<=ymax && z>=zmin && z<=zmax)
            {
              buffer << x << y << z;
            }
        }
    }
  schema.echange_taille_et_messages();
  for (ipe = 0; ipe < all_pe.size_array(); ipe++)
    {
      const int pe = all_pe[ipe]; // processor number
      Entree& buffer = schema.recv_buffer(pe);
      ArrOfInt& resu = match[pe];
 
      resu.resize_array(0);
      while(1)
        {
          double x, y, z;
          buffer >> x >> y >> z;
          if (buffer.eof())
            break;
          // Seach for this node in my list
          octree.search_elements_box(x-epsilon, y-epsilon, z-epsilon,
                                     x+epsilon, y+epsilon, z+epsilon, nodes_list);
          // Refine search to keep only matching nodes:
          octree.search_nodes_close_to(x, y, z, coords, nodes_list, epsilon);
          const int n = nodes_list.size_array();
          if (n > 1)
            {
              Cerr << "Error in automatic joint builder: more than one node within epsilon tolerance\n"
                   << " node coord = " << x << " " << y << " " << z << " tolerance= " << epsilon << finl;
              Process::exit();
            }
          if (n == 1)
            resu.append_array(nodes_list[0]);
        }
    }
  schema.end_comm();
}
 
/*! @brief finds all faces of all elements that - have only one neighbour elements
 *
 *   - and do not belong to a boundary
 *  (these are joint faces)
 *  Fills "faces" with the local node numbers of the faces that have been found.
 *
 */
static void find_joint_faces(const Domaine& domaine, IntTab& faces)
{
  Static_Int_Lists som_elem;
  const IntTab& elements = domaine.les_elems();
  const int nb_som = domaine.nb_som();
  construire_connectivite_som_elem(nb_som, elements, som_elem, 0 /* do not include virtual elements */);
  const int nb_som_faces = domaine.type_elem()->nb_som_face();
  faces.resize(0, nb_som_faces);
 
  IntTab faces_element_reference;
  domaine.type_elem()->get_tab_faces_sommets_locaux(faces_element_reference);
  const int nb_faces_elem = faces_element_reference.dimension(0);
  // Mark faces of elements that are on a boundary
  const int nb_elem = elements.dimension(0);
  ArrOfBit boundary_faces(nb_elem * nb_faces_elem);
  boundary_faces = 0;
  ArrOfInt une_face(nb_som_faces);
  ArrOfInt liste_elements;
 
  const int nb_boundaries = domaine.nb_front_Cl();
  for (int i_boundary = 0; i_boundary < nb_boundaries; i_boundary++)
    {
      const IntTab& faces_front = domaine.frontiere(i_boundary).faces().les_sommets();
      const int nb_faces_bord = faces_front.dimension(0);
      for (int j = 0; j < nb_faces_bord; j++)
        {
          for (int k = 0; k < nb_som_faces; k++)
            une_face[k] = faces_front(j, k);
          find_adjacent_elements(som_elem, une_face, liste_elements);
          if (liste_elements.size_array() != 1)
            {
              Cerr << "Error in MaillerParallel::find_joint_faces: boundary face ArrOfInt=" << une_face
                   << " does not have exactly 1 neighbour element: " << liste_elements;
              Process::exit();
            }
          const int elem = liste_elements[0];
          const int face_locale = Faces_builder::chercher_face_element(elements, faces_element_reference, une_face, elem);
          boundary_faces.setbit(elem * nb_faces_elem + face_locale);
        }
    }
  // Browse all faces of all elements, find faces with only one neighbour
  for (int elem = 0; elem < nb_elem; elem++)
    {
      for (int face_locale = 0; face_locale < nb_faces_elem; face_locale++)
        {
          if (boundary_faces[elem * nb_faces_elem + face_locale])
            continue;
          int i;
          for (i = 0; i < nb_som_faces; i++)
            {
              const int sommet_local = faces_element_reference(face_locale, i);
              une_face[i] = elements(elem, sommet_local);
            }
          find_adjacent_elements(som_elem, une_face, liste_elements);
          if (liste_elements.size_array() == 1)
            {
              const int n = faces.dimension(0);
              faces.resize_dim0(n+1);
              for (i = 0; i < nb_som_faces; i++)
                faces(n, i) = une_face[i];
            }
        }
    }
  Process::Journal() << "Domain " << domaine.le_nom() << " has " << faces.dimension(0) << " undeclared boundary faces candidates for joint faces" << finl;
}
 
static void auto_build_joints(Domaine& domaine, const int epaisseur_joint)
{
  const double epsilon = 1e-10;
  int i, j;
  // Find joint faces (faces with 1 neighbour element not registered in boundary faces)
  IntTab faces;
  find_joint_faces(domaine, faces);
 
  const DoubleTab& sommets = domaine.les_sommets();
  // List of unique local boundary node numbers
  const int dim = sommets.dimension(1);
 
  {
    ArrOfInt boundary_nodes_index;
    boundary_nodes_index = faces; // copy of the array
    array_trier_retirer_doublons(boundary_nodes_index);
    const int ncoord = boundary_nodes_index.size_array();
    // Fill nodes coordinates and bounding boxes
    DoubleTab coord;
    coord.resize(ncoord, dim, RESIZE_OPTIONS::NOCOPY_NOINIT);
    for (i = 0; i < ncoord; i++)
      {
        const int som = boundary_nodes_index[i];
        for (j = 0; j < dim; j++)
          coord(i, j) = sommets(som, j);
      }
    ArrsOfInt match(Process::nproc());
    find_matching_coordinates(coord, match, epsilon);
 
    for (int pe = 0; pe < match.size(); pe++)
      {
        const ArrOfInt& list = match[pe];
        const int n = list.size_array();
        if (n > 0)
          {
            Joint& joint = domaine.faces_joint().add(Joint());
            joint.nommer("Joint_i");
            joint.associer_domaine(domaine);
            joint.affecte_epaisseur(epaisseur_joint);
            joint.affecte_PEvoisin(pe);
            joint.faces().typer(domaine.type_elem()->type_face());
            ArrOfInt& sommets_joint = joint.set_joint_item(JOINT_ITEM::SOMMET).set_items_communs();
            sommets_joint.resize_array(n, RESIZE_OPTIONS::NOCOPY_NOINIT);
            for (i = 0; i < n; i++)
              sommets_joint[i] = boundary_nodes_index[list[i]];
            sommets_joint.ordonne_array();
            Process::Journal() << "Joint sommets with pe " << pe << " has " << n << " nodes" << finl;
          }
      }
  }
 
  {
    // Find matching faces (match the coordinates of the centers)
    const int nfaces = faces.dimension(0);
    const int nb_som_faces = faces.dimension(1);
    DoubleTab coord(nfaces, dim); // init with 0.
    const double facteur = 1. / (double)nb_som_faces;
    for (i = 0; i < nfaces; i++)
      {
        for (j = 0; j < nb_som_faces; j++)
          {
            const int som = faces(i,j);
            for (int k = 0; k < dim; k++)
              coord(i, k) += sommets(som, k) * facteur;
          }
      }
    ArrsOfInt match(Process::nproc());
    find_matching_coordinates(coord, match, epsilon);
 
    for (int pe = 0; pe < match.size(); pe++)
      {
        const ArrOfInt& list = match[pe];
        const int n = list.size_array();
        if (n > 0)
          {
            OBS_PTR(Joint) ref_joint;
            int ii;
            for (ii = 0; ii < domaine.faces_joint().size(); ii++)
              {
                Joint& joint = domaine.faces_joint()[ii];
                if (joint.PEvoisin() == pe)
                  {
                    ref_joint = joint;
                    break;
                  }
              }
            if (!ref_joint)
              {
                Joint& joint = domaine.faces_joint().add(Joint());
                joint.nommer("Joint_i");
                joint.associer_domaine(domaine);
                joint.affecte_epaisseur(epaisseur_joint);
                joint.affecte_PEvoisin(pe);
                joint.faces().typer(domaine.type_elem()->type_face());
                ref_joint = joint;
              }
            Faces& les_faces = ref_joint->faces();
            les_faces.dimensionner(n);
            IntTab& faces_sommets = les_faces.les_sommets();
            for (ii = 0; ii < n; ii++)
              {
                const int num_face = list[ii];
                for (j = 0; j < nb_som_faces; j++)
                  faces_sommets(ii, j) = faces(num_face, j);
              }
            Process::Journal() << "Joint faces with pe " << pe << " has " << n << " faces" << finl;
          }
      }
  }
  // Sort the joints in ascending order of processor rank
  Scatter::trier_les_joints(domaine.faces_joint());
}
 
Entree& MaillerParallel::interpreter(Entree& is)
{
  if (dimension != 3)
    {
      Cerr << "Error: MaillerParallel is only coded for dimension 3" << finl;
      barrier();
      exit();
    }
 
  Nom      nom_domaine;
  ArrOfInt nb_noeuds;
  ArrOfInt decoupage;
  int   epaisseur_joint = -1;
  bool perio[3] = {false, false, false};
  Noms fonctions_coord(3);
  Noms nom_bords_min(3);
  Noms nom_bords_max(3);
  nom_bords_min[0] = "xmin";
  nom_bords_min[1] = "ymin";
  nom_bords_min[2] = "zmin";
  nom_bords_max[0] = "xmax";
  nom_bords_max[1] = "ymax";
  nom_bords_max[2] = "zmax";
  Noms fichier_coord(3);
  IntTab mapping;
 
  Param param(que_suis_je());
  param.ajouter("domain", &nom_domaine, Param::REQUIRED); // XD_ADD_P ref_domaine
  // XD_CONT the name of the domain to mesh (it must be an empty domain object).
  param.ajouter("nb_nodes", &nb_noeuds, Param::REQUIRED); // XD_ADD_P listentier
  // XD_CONT dimension defines the spatial dimension (currently only dimension=3 is supported), and nX, nY and nZ
  // XD_CONT defines the total number of nodes in the mesh in each direction.
  param.ajouter("splitting", &decoupage, Param::REQUIRED); // XD_ADD_P listentier
  // XD_CONT dimension is the spatial dimension and npartsX, npartsY and npartsZ are the number of parts created. The
  // XD_CONT product of the number of parts must be equal to the number of processors used for the computation.
  param.ajouter("ghost_thickness", &epaisseur_joint, Param::REQUIRED); // XD_ADD_P entier
  // XD_CONT the number of ghost cells (equivalent to the epaisseur_joint parameter of Decouper.
  param.ajouter_flag("perio_x", &perio[0]); // XD_ADD_P rien
  // XD_CONT change the splitting method to provide a valid mesh for periodic boundary conditions. Register the
  // XD_CONT corresponding boundary in the list of periodic boundaries for the domain.
  param.ajouter_flag("perio_y", &perio[1]); // XD_ADD_P rien
  // XD_CONT change the splitting method to provide a valid mesh for periodic boundary conditions. Register the
  // XD_CONT corresponding boundary in the list of periodic boundaries for the domain.
  param.ajouter_flag("perio_z", &perio[2]); // XD_ADD_P rien
  // XD_CONT change the splitting method to provide a valid mesh for periodic boundary conditions. Register the
  // XD_CONT corresponding boundary in the list of periodic boundaries for the domain.
  param.ajouter("function_coord_x", &fonctions_coord[0]); // XD_ADD_P chaine
  // XD_CONT By default, the meshing algorithm creates nX nY nZ coordinates ranging between 0 and 1 (eg a unity size
  // XD_CONT box). If function_coord_x} is specified, it is used to transform the [0,1] segment to the coordinates of
  // XD_CONT the nodes. funcX must be a function of the x variable only.
  param.ajouter("function_coord_y", &fonctions_coord[1]); // XD_ADD_P chaine
  // XD_CONT like function_coord_x for y
  param.ajouter("function_coord_z", &fonctions_coord[2]); // XD_ADD_P chaine
  // XD_CONT like function_coord_x for z
  param.ajouter("file_coord_x", &fichier_coord[0]); // XD_ADD_P chaine
  // XD_CONT Keyword to read the Nx floating point values used as nodes coordinates in the file.
  param.ajouter("file_coord_y", &fichier_coord[1]); // XD_ADD_P chaine
  // XD_CONT idem file_coord_x for y
  param.ajouter("file_coord_z", &fichier_coord[2]); // XD_ADD_P chaine
  // XD_CONT idem file_coord_x for z
  param.ajouter("boundary_xmin", &nom_bords_min[0]); // XD_ADD_P chaine
  // XD_CONT the name of the boundary at the minimum X direction. If it not provided, the default boundary names are
  // XD_CONT xmin, xmax, ymin, ymax, zmin and zmax. If the mesh is periodic in a given direction, only the MIN boundary
  // XD_CONT name is used, for both sides of the box.
  param.ajouter("boundary_xmax", &nom_bords_max[0]); // XD_ADD_P chaine
  // XD_CONT not_set
  param.ajouter("boundary_ymin", &nom_bords_min[1]); // XD_ADD_P chaine
  // XD_CONT not_set
  param.ajouter("boundary_ymax", &nom_bords_max[1]); // XD_ADD_P chaine
  // XD_CONT not_set
  param.ajouter("boundary_zmin", &nom_bords_min[2]); // XD_ADD_P chaine
  // XD_CONT not_set
  param.ajouter("boundary_zmax", &nom_bords_max[2]); // XD_ADD_P chaine
  // XD_CONT not_set
  param.ajouter("mapping", &mapping);
  param.lire_avec_accolades(is);
 
 
  ArrsOfDouble coord_ijk(3);
  for (int dir=0; dir<3; dir++)
    {
      const int n = nb_noeuds[dir];
      ArrOfDouble& coord = coord_ijk[dir];
      coord.resize_array(n);
      Cerr << "Building coordinates for direction " << dir << finl;
      if (fonctions_coord[dir] != "??")
        {
          Nom chaine = fonctions_coord[dir];
          Cerr << " Interpreting expression " << chaine << finl;
          Parser_U p;
          Noms noms_dir(3);
          noms_dir[0]="X";
          noms_dir[1]="Y";
          noms_dir[2]="Z";
          p.setNbVar(1);
          p.setString(chaine);
          p.addVar(noms_dir[dir]);
          p.parseString();
          for (int i = 0; i < n; i++)
            {
              p.setVar(0, (double) i / (double) (nb_noeuds[dir]-1));
              coord[i] = p.eval();
              if (i > 0 && coord[i] <= coord[i-1])
                {
                  Cerr << "Error in fonctions_coord parameter " << chaine << " : must be strictly increasing" << finl;
                  Process::exit();
                }
            }
          Cerr << " Build mesh covering [ " << coord[0] << " , " << coord[n-1] << " ]" << finl;
        }
      else if (fichier_coord[dir] != "??")
        {
          Cerr << " Reading file " << fichier_coord[dir] << finl;
          if (Process::je_suis_maitre())
            {
              EFichier f(fichier_coord[dir]);
              for (int i = 0; i < n; i++)
                f >> coord[i];
            }
          envoyer_broadcast(coord, 0);
          Cerr << " Found mesh covering [ " << coord[0] << " , " << coord[n-1] << " ]" << finl;
        }
      else
        {
          Cerr << " Uniform mesh covering [0,1]" << finl;
          for (int i = 0; i < n; i++)
            {
              coord[i] = (double) i / (double)(n-1);
            }
        }
    }
 
  Objet_U& obj = objet(nom_domaine);
  if(!sub_type(Domaine, obj))
    {
      Cerr << "obj : " << nom_domaine << " is not an object of type Domaine !" << finl;
      exit();
    }
 
  Domaine& domaine = ref_cast(Domaine, obj);
 
  const int numproc = Process::me();
 
  const int dim = Objet_U::dimension;
  if (nb_noeuds.size_array() != dim)
    {
      Cerr << "MaillerParallel::construire_domaine wrong dimension for nb_noeuds : nb_noeuds=" << nb_noeuds << finl;
      barrier();
      exit();
    }
 
  if (decoupage.size_array() != dim)
    {
      Cerr << "MaillerParallel::construire_domaine wrong dimension for nb_noeuds : nb_noeuds=" << nb_noeuds << finl;
      barrier();
      exit();
    }
 
  {
    int n = 1;
    for (int i = 0; i < dim; i++)
      n *= decoupage[i];
    if (n != Process::nproc())
      {
        Cerr << "MaillerParallel::construire_domaine decoupage does not match nproc" << finl;
        barrier();
        exit();
      }
  }
  statistics().begin_count(STD_COUNTERS::parallel_meshing,statistics().get_last_opened_counter_level()+1);
  // Position of the block corresponding to numproc in the i,j,k partition:
  ArrOfInt i_proc(dim);
  if (mapping.dimension(0) == 0)
    {
      // No mapping provided, using default partition
      int i;
      int reste = numproc;
 
      for (i = 0; i < dim; i++)
        {
          // Number of parts in direction dim_2:
          const int n_parties = decoupage[i];
          // Position of the current processor in this direction:
          i_proc[i] = reste % n_parties;
          reste = reste / n_parties;
        }
    }
  else
    {
      if (mapping.dimension(0) != Process::nproc() || mapping.dimension(1) != 3)
        {
          Cerr << "Error: processor mapping should be of dimension " << Process::nproc() <<  " x 3" << finl;
          Process::exit();
        }
      i_proc[0] = mapping(numproc,0);
      i_proc[1] = mapping(numproc,1);
      i_proc[2] = mapping(numproc,2);
    }
  // Index of the first element of the block associated with the processor in direction i:
  // Warning, in the case of periodicity, i_premier_element will be negative.
  ArrOfInt i_premier_element(dim);
  // Size of the block associated with the processor
  ArrOfInt nb_elements(dim);
  {
    int i;
    for (i = 0; i < dim; i++)
      {
        const int nb_elem_tot = nb_noeuds[i] - 1; // Total number of nodes in direction i
        i_premier_element[i] = nb_elem_tot * i_proc[i] / decoupage[i];
        const int i_dernier_element = nb_elem_tot * (i_proc[i] + 1) / decoupage[i] - 1;
        nb_elements[i] = i_dernier_element - i_premier_element[i] + 1;
 
        if (perio[i] && decoupage[i] > 1)
          {
            int decalage = nb_elem_tot / decoupage[i] / 2;
            i_premier_element[i] -= decalage;
          }
      }
  }
 
  Elem_geom& elem = domaine.type_elem();
  switch(dim)
    {
    case 3:
      elem.typer("Hexaedre");
      break;
    default:
      Cerr << "MaillerParallel::construire_domaine  error" << finl;
      exit();
    }
  elem->associer_domaine(domaine);
 
  BlocData data;
  Bords& bords = domaine.faces_bord();
  data.bord_xmin_ = nom_bords_min;
  data.bord_xmax_ = nom_bords_max;
  for (int dir = 0; dir < 3; dir++)
    {
      Nom nomdir;
      if (dir == 0) nomdir = "x";
      else if (dir == 1) nomdir = "y";
      else nomdir = "z";
      if (perio[dir])
        {
          // In case of a periodic boundary only 'min' should be named:
          data.bord_xmax_[dir] = data.bord_xmin_[dir];
          bords.add(Bord()).nommer(data.bord_xmin_[dir]);
          // And the name is added to the list of periodic boundaries in the domain:
          domaine.bords_perio().add(data.bord_xmin_[dir]);
        }
      else
        {
          bords.add(Bord()).nommer(data.bord_xmin_[dir]);
          bords.add(Bord()).nommer(data.bord_xmax_[dir]);
        }
    }
  data.xmax_tot_ = nb_noeuds;
 
  ArrOfInt nblocs(3);
  nblocs= 1;
  for (int i = 0; i < 3; i++)
    {
      if (i_premier_element[i] < 0)
        nblocs[i] = 2;
    }
 
  int num_bord;
  for (num_bord = 0; num_bord < bords.size(); num_bord++)
    {
      Bord& bord = bords[num_bord];
      bord.associer_domaine(domaine);
      bord.faces().typer(domaine.type_elem()->type_face());
      // important for sizing the linesize of the face array for empty boundaries
      bord.faces().dimensionner(0);
    }
 
  ArrOfInt ibloc(3);
  for (ibloc[0] = 0; ibloc[0] < nblocs[0]; ibloc[0]++)
    {
      for (ibloc[1] = 0; ibloc[1]  < nblocs[1]; ibloc[1]++)
        {
          for (ibloc[2] = 0; ibloc[2]  < nblocs[2]; ibloc[2]++)
            {
 
              data.xmin_.resize_array(3);
              data.xmax_.resize_array(3);
              for (int dir = 0; dir < 3; dir++)
                {
                  data.xmin_[dir] = i_premier_element[dir];
                  data.xmax_[dir] = i_premier_element[dir] + nb_elements[dir] + 1;
 
                  if (nblocs[dir] > 1)
                    {
                      if (ibloc[dir] == 0)
                        data.xmin_[dir] = 0;
                      else
                        {
                          data.xmin_[dir] += data.xmax_tot_[dir] - 1;
                          data.xmax_[dir] = data.xmax_tot_[dir];
                        }
                    }
                }
              Process::Journal() << "add bloc xmin=" << data.xmin_ << "xmax=" << data.xmax_ << "xtot=" << data.xmax_tot_;
              data.add_bloc(domaine, coord_ijk);
            }
        }
    }
 
  {
    for (int d = 0; d < 3; d++)
      {
        if (perio[d])
          {
            ArrOfDouble dir(3);
            dir[d] = coord_ijk[d][nb_noeuds[d]-1] - coord_ijk[d][0];
            IntTab& faces = domaine.bord(nom_bords_min[d]).faces().les_sommets();
            double epsilon = precision_geom;
            Reordonner_faces_periodiques::reordonner_faces_periodiques(domaine, faces, dir, epsilon);
          }
      }
  }
 
 
  auto_build_joints(domaine, epaisseur_joint);
 
  double maxtime = mp_max(statistics().get_time_since_last_open(STD_COUNTERS::parallel_meshing));
  statistics().end_count(STD_COUNTERS::parallel_meshing);
  if (Process::je_suis_maitre())
    Cerr << "Ending of the construction of the domaines, time:" << maxtime << finl;
 
  if (nproc() > 1)
    {
      statistics().begin_count(STD_COUNTERS::parallel_meshing,statistics().get_last_opened_counter_level()+1);
      Scatter::construire_correspondance_sommets_par_coordonnees(domaine);
      Scatter::calculer_renum_items_communs(domaine.faces_joint(), JOINT_ITEM::SOMMET);
      maxtime = mp_max(statistics().get_time_since_last_open(STD_COUNTERS::parallel_meshing));
      statistics().end_count(STD_COUNTERS::parallel_meshing);
      Cerr << "Scatter::construire_correspondance_sommets_par_coordonnees fin, time:"
           << maxtime << finl;
      statistics().begin_count(STD_COUNTERS::parallel_meshing,statistics().get_last_opened_counter_level()+1);
      Scatter::construire_structures_paralleles(domaine);
 
      maxtime = mp_max(statistics().get_time_since_last_open(STD_COUNTERS::parallel_meshing));
      statistics().end_count(STD_COUNTERS::parallel_meshing);
      Cerr << "Scatter::construire_structures_paralleles, time:" << maxtime << finl;
    }
  else
    {
      Scatter::init_sequential_domain(domaine);
    }
 
  domaine.nommer(domaine.le_nom());
 
  Cerr << "MaillerParallel::construire_domaine : end" << finl;
 
  return is;
}