smesh/src/StdMeshers/StdMeshers_Regular_1D.cxx

//  SMESH SMESH : implementaion of SMESH idl descriptions
//
//  Copyright (C) 2003  OPEN CASCADE, EADS/CCR, LIP6, CEA/DEN,
//  CEDRAT, EDF R&D, LEG, PRINCIPIA R&D, BUREAU VERITAS 
// 
//  This library is free software; you can redistribute it and/or 
//  modify it under the terms of the GNU Lesser General Public 
//  License as published by the Free Software Foundation; either 
//  version 2.1 of the License. 
// 
//  This library is distributed in the hope that it will be useful, 
//  but WITHOUT ANY WARRANTY; without even the implied warranty of 
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU 
//  Lesser General Public License for more details. 
// 
//  You should have received a copy of the GNU Lesser General Public 
//  License along with this library; if not, write to the Free Software 
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA 
// 
//  See http://www.opencascade.org/SALOME/ or email : webmaster.salome@opencascade.org 
//
//
//
//  File   : StdMeshers_Regular_1D.cxx
//           Moved here from SMESH_Regular_1D.cxx
//  Author : Paul RASCLE, EDF
//  Module : SMESH
//  $Header$

using namespace std;

#include "StdMeshers_Regular_1D.hxx"
#include "SMESH_Gen.hxx"
#include "SMESH_Mesh.hxx"

#include "StdMeshers_LocalLength.hxx"
#include "StdMeshers_NumberOfSegments.hxx"
#include "StdMeshers_Arithmetic1D.hxx"
#include "StdMeshers_StartEndLength.hxx"
#include "StdMeshers_Deflection1D.hxx"

#include "SMDS_MeshElement.hxx"
#include "SMDS_MeshNode.hxx"
#include "SMDS_EdgePosition.hxx"
#include "SMESH_subMesh.hxx"

#include "Utils_SALOME_Exception.hxx"
#include "utilities.h"

#include <BRep_Tool.hxx>
#include <TopoDS_Edge.hxx>
#include <TopoDS_Shape.hxx>
#include <TopTools_ListIteratorOfListOfShape.hxx>
#include <GeomAdaptor_Curve.hxx>
#include <GCPnts_AbscissaPoint.hxx>
#include <GCPnts_UniformAbscissa.hxx>
#include <GCPnts_UniformDeflection.hxx>
#include <Standard_ErrorHandler.hxx>
#include <Precision.hxx>
#include <Expr_GeneralExpression.hxx>
#include <Expr_NamedUnknown.hxx>
#include <Expr_Array1OfNamedUnknown.hxx>
#include <TColStd_Array1OfReal.hxx>
#include <ExprIntrp_GenExp.hxx>

#include <string>
#include <math.h>

//=============================================================================
/*!
 *  
 */
//=============================================================================

StdMeshers_Regular_1D::StdMeshers_Regular_1D(int hypId, int studyId,
	SMESH_Gen * gen):SMESH_1D_Algo(hypId, studyId, gen)
{
	MESSAGE("StdMeshers_Regular_1D::StdMeshers_Regular_1D");
	_name = "Regular_1D";
	_shapeType = (1 << TopAbs_EDGE);

	_compatibleHypothesis.push_back("LocalLength");
	_compatibleHypothesis.push_back("NumberOfSegments");
	_compatibleHypothesis.push_back("StartEndLength");
	_compatibleHypothesis.push_back("Deflection1D");
	_compatibleHypothesis.push_back("Arithmetic1D");
}

//=============================================================================
/*!
 *  
 */
//=============================================================================

StdMeshers_Regular_1D::~StdMeshers_Regular_1D()
{
}

//=============================================================================
/*!
 *  
 */
//=============================================================================

bool StdMeshers_Regular_1D::CheckHypothesis
                         (SMESH_Mesh& aMesh,
                          const TopoDS_Shape& aShape,
                          SMESH_Hypothesis::Hypothesis_Status& aStatus)
{
  _hypType = NONE;

  const list <const SMESHDS_Hypothesis * >&hyps = GetUsedHypothesis(aMesh, aShape);
  if (hyps.size() == 0)
  {
    aStatus = SMESH_Hypothesis::HYP_MISSING;
    return false;  // can't work without a hypothesis
  }

  // use only the first hypothesis
  const SMESHDS_Hypothesis *theHyp = hyps.front();

  string hypName = theHyp->GetName();

  if (hypName == "LocalLength")
  {
    const StdMeshers_LocalLength * hyp =
      dynamic_cast <const StdMeshers_LocalLength * >(theHyp);
    ASSERT(hyp);
    _value[ BEG_LENGTH_IND ] = _value[ END_LENGTH_IND ] = hyp->GetLength();
    ASSERT( _value[ BEG_LENGTH_IND ] > 0 );
    _hypType = LOCAL_LENGTH;
    aStatus = SMESH_Hypothesis::HYP_OK;
  }

  else if (hypName == "NumberOfSegments")
  {
    const StdMeshers_NumberOfSegments * hyp =
      dynamic_cast <const StdMeshers_NumberOfSegments * >(theHyp);
    ASSERT(hyp);
    _ivalue[ NB_SEGMENTS_IND  ] = hyp->GetNumberOfSegments();
    ASSERT( _ivalue[ NB_SEGMENTS_IND ] > 0 );
    _ivalue[ DISTR_TYPE_IND ] = (int) hyp->GetDistrType();
    switch (_ivalue[ DISTR_TYPE_IND ])
    {
    case StdMeshers_NumberOfSegments::DT_Scale:
      _value[ SCALE_FACTOR_IND ] = hyp->GetScaleFactor();
      break;
    case StdMeshers_NumberOfSegments::DT_TabFunc:
      _vvalue[ TAB_FUNC_IND ] = hyp->GetTableFunction();
      break;
    case StdMeshers_NumberOfSegments::DT_ExprFunc:
      _svalue[ EXPR_FUNC_IND ] = hyp->GetExpressionFunction();
      break;
    case StdMeshers_NumberOfSegments::DT_Regular:
      break;
    default:
      ASSERT(0);
      break;
    }
    if (_ivalue[ DISTR_TYPE_IND ] == StdMeshers_NumberOfSegments::DT_TabFunc ||
        _ivalue[ DISTR_TYPE_IND ] == StdMeshers_NumberOfSegments::DT_ExprFunc)
      _ivalue[ EXP_MODE_IND ] = (int) hyp->IsExponentMode();
    _hypType = NB_SEGMENTS;
    aStatus = SMESH_Hypothesis::HYP_OK;
  }

  else if (hypName == "Arithmetic1D")
  {
    const StdMeshers_Arithmetic1D * hyp =
      dynamic_cast <const StdMeshers_Arithmetic1D * >(theHyp);
    ASSERT(hyp);
    _value[ BEG_LENGTH_IND ] = hyp->GetLength( true );
    _value[ END_LENGTH_IND ] = hyp->GetLength( false );
    ASSERT( _value[ BEG_LENGTH_IND ] > 0 && _value[ END_LENGTH_IND ] > 0 );
    _hypType = ARITHMETIC_1D;
    aStatus = SMESH_Hypothesis::HYP_OK;
  }

  else if (hypName == "StartEndLength")
  {
    const StdMeshers_StartEndLength * hyp =
      dynamic_cast <const StdMeshers_StartEndLength * >(theHyp);
    ASSERT(hyp);
    _value[ BEG_LENGTH_IND ] = hyp->GetLength( true );
    _value[ END_LENGTH_IND ] = hyp->GetLength( false );
    ASSERT( _value[ BEG_LENGTH_IND ] > 0 && _value[ END_LENGTH_IND ] > 0 );
    _hypType = BEG_END_LENGTH;
    aStatus = SMESH_Hypothesis::HYP_OK;
  }

  else if (hypName == "Deflection1D")
  {
    const StdMeshers_Deflection1D * hyp =
      dynamic_cast <const StdMeshers_Deflection1D * >(theHyp);
    ASSERT(hyp);
    _value[ DEFLECTION_IND ] = hyp->GetDeflection();
    ASSERT( _value[ DEFLECTION_IND ] > 0 );
    _hypType = DEFLECTION;
    aStatus = SMESH_Hypothesis::HYP_OK;
  }
  else
    aStatus = SMESH_Hypothesis::HYP_INCOMPATIBLE;

  return ( _hypType != NONE );
}

//=======================================================================
//function : compensateError
//purpose  : adjust theParams so that the last segment length == an
//=======================================================================

static void compensateError(double a1, double an,
                            double U1, double Un,
                            double             length,
                            GeomAdaptor_Curve& C3d,
                            list<double> &     theParams)
{
  int i, nPar = theParams.size();
  if ( a1 + an < length && nPar > 1 )
  {
    list<double>::reverse_iterator itU = theParams.rbegin();
    double Ul = *itU++;
    // dist from the last point to the edge end <Un>, it should be equal <an>
    double Ln = GCPnts_AbscissaPoint::Length( C3d, Ul, Un );
    double dLn = an - Ln; // error of <an>
    if ( Abs( dLn ) <= Precision::Confusion() )
      return;
    double dU = Abs( Ul - *itU ); // parametric length of the last but one segment
    double dUn = dLn * Abs( Un - U1 ) / length; // parametric error of <an>
    if ( dUn < 0.5 * dU ) { // last segment is a bit shorter than it should
      dUn = -dUn; // move the last parameter to the edge beginning
    }
    else {  // last segment is much shorter than it should -> remove the last param and
      theParams.pop_back(); nPar--; // move the rest points toward the edge end
      Ln = GCPnts_AbscissaPoint::Length( C3d, theParams.back(), Un );
      dUn = ( an - Ln ) * Abs( Un - U1 ) / length;
      if ( dUn < 0.5 * dU )
        dUn = -dUn;
    }
    if ( U1 > Un )
      dUn = -dUn;
    double q  = dUn / ( nPar - 1 );
    for ( itU = theParams.rbegin(), i = 1; i < nPar; itU++, i++ ) {
      (*itU) += dUn;
      dUn -= q;
    }
  }
}

/*!
 * \brief This class provides interface for a density function
 */
class Function
{
public:
  Function(bool expMode) : _expMode(expMode) {}
  double operator() (double t) const;
  virtual bool IsReady() const = 0;
protected:
  virtual double compute(double t) const = 0;
private:
  bool _expMode;
};

/*!
 * \brief This class provides computation of density function given by a table
 */
class TabFunction: public Function
{
public:
  TabFunction(const vector<double>& table, bool expMode);
  virtual bool IsReady() const;
protected:
  virtual double compute(double t) const;
private:
  const vector<double>& _table;
};

/*!
 * \brief This class provides computation of density function given by an expression
 */
class ExprFunction: public Function
{
public:
  ExprFunction(const char* expr, bool expMode);
  virtual bool IsReady() const;
protected:
  virtual double compute(double t) const;
private:
  Handle(Expr_GeneralExpression) _expression;
  Expr_Array1OfNamedUnknown _var;
  mutable TColStd_Array1OfReal _val;
};

double Function::operator() (double t) const
{
  double res = compute(t);
  if (_expMode)
    res = pow(10, res);
  return res;
}

TabFunction::TabFunction(const vector<double>& table, bool expMode)
  : Function(expMode),
    _table(table)
{
}

bool TabFunction::IsReady() const
{
  return true;
}

double TabFunction::compute (double t) const
{
  //find place of <t> in table
  int i;
  for (i=0; i < _table.size()/2; i++)
    if (_table[i*2] > t)
      break;
  if (i >= _table.size()/2)
    i = _table.size()/2 - 1;

  if (i == 0)
    return _table[1];

  // interpolate function value on found interval
  // (t - x[i-1]) / (x[i] - x[i-1]) = (y - f[i-1]) / (f[i] - f[i-1])
  // => y = f[i-1] + (f[i] - f[i-1]) * (t - x[i-1]) / (x[i] - x[i-1])
  double x1 = _table[(i-1)*2];
  double x2 = _table[i*2];
  double y1 = _table[(i-1)*2+1];
  double y2 = _table[i*2+1];
  if (x2 - x1 < Precision::Confusion())
    throw SALOME_Exception("TabFunction::compute : confused points");
  return y1 + (y2 - y1) * ((t - x1) / (x2 - x1));
}

ExprFunction::ExprFunction(const char* expr, bool expMode)
  : Function(expMode),
    _var(1,1),
    _val(1,1)
{
  Handle( ExprIntrp_GenExp ) gen = ExprIntrp_GenExp::Create();
  gen->Process(TCollection_AsciiString((char*)expr));
  if (gen->IsDone())
  {
    _expression = gen->Expression();
    _var(1) = new Expr_NamedUnknown("t");
  }
}

bool ExprFunction::IsReady() const
{
  return !_expression.IsNull();
}

double ExprFunction::compute (double t) const
{
  ASSERT(!_expression.IsNull());
  _val(1) = t;
  return _expression->Evaluate(_var, _val);
}

//================================================================================
/*!
 * \brief Compute next abscissa when two previous ones are given
  * \param sm2 - before previous abscissa
  * \param sm1 - previous abscissa
  * \param func - function of density
  * \param reverse - the direction of next abscissa, increase (0) or decrease (1)
  * \retval double - the new abscissa
 * 
 * The abscissa s is given by the formulae
 *
 * ....|--------|----------------|.....
 *    sm2      sm1               s
 *
 *    func(sm2) / func(sm1)  = (sm1-sm2) / (s-sm1)
 * => (s-sm1) * func(sm2) = (sm1-sm2) * func(sm1)
 * => s = sm1 + (sm1-sm2) * func(sm1) / func(sm2)
 */
//================================================================================

static double nextAbscissa(double sm2, double sm1, const Function& func, int reverse)
{
  if (reverse)
  {
    sm1 = 1.0 - sm1;
    sm2 = 1.0 - sm2;
  }
  return sm1 + (sm1-sm2) * func(sm1) / func(sm2);
}

//================================================================================
/*!
 * \brief Compute distribution of points on a curve following the law of a function
  * \param C3d - the curve to discretize
  * \param first - the first parameter on the curve 
  * \param last - the last parameter on the curve 
  * \param theReverse - flag indicating that the curve must be reversed
  * \param nbSeg - number of output segments
  * \param func - the function f(t)
  * \param theParams - output points
  * \retval bool  - true if success
 */
//================================================================================

static bool computeParamByFunc(Adaptor3d_Curve& C3d, double first, double last,
                               double length, bool theReverse, 
                               int nbSeg, const Function& func,
                               list<double>& theParams)
{
  if (!func.IsReady())
    return false;
  vector<double> xxx[2];
  int nbPnt = 1 + nbSeg;
  int rev, i;
  for (rev=0; rev < 2; rev++)
  {
    // curv abscisses initialisation
    vector<double> x(nbPnt, 0.);
    // the first abscissa is 0.0

    // The aim of the algorithm is to find a second abscisse x[1] such as the last
    // one x[nbSeg] is very close to 1.0 with the epsilon precision

    double x1_too_small = 0.0;
    double x1_too_large = RealLast();
    double x1 = 1.0/nbSeg;
    while (1)
    {
      x[1] = x1;

      // Check if the abscissa of the point 2 to N-1
      // are in the segment ...

      bool ok = true;
      for (i=2; i <= nbSeg; i++)
      {
        x[i] = nextAbscissa(x[i-2], x[i-1], func, rev);
        if (x[i] - 1.0 > Precision::Confusion())
        {
          x[nbSeg] = x[i];
          ok = false;
          break;
        }
      }
      if (!ok)
      {
        // The segments are to large
        // Decrease x1 ...
        x1_too_large = x1;
        x1 = (x1_too_small+x1_too_large)/2;
        continue;
      }

      // Look at the abscissa of the point N
      // which is to be close to 1.0

      // break condition --> algo converged !!

      if (1.0 - x[nbSeg] < Precision::Confusion())
        break;

      // not ok ...

      x1_too_small = x1;

      // Modify x1 value

      if (x1_too_large > 1e100)
        x1 = 2*x1;
      else
        x1 = (x1_too_small+x1_too_large)/2;
    }
    xxx[rev] = x;
  }

  // average
  vector<double> x(nbPnt, 0.);
  for (i=0; i < nbPnt; i++)
    x[i] = (xxx[0][i] + (1.0 - xxx[1][nbPnt-i])) / 2;

  // apply parameters in range [0,1] to the space of the curve
  double prevU = first;
  double sign = 1.;
  if (theReverse)
  {
    prevU = last;
    sign = -1.;
  }
  for (i = 1; i < nbSeg; i++)
  {
    double curvLength = length * (x[i] - x[i-1]) * sign;
    GCPnts_AbscissaPoint Discret( C3d, curvLength, prevU );
    if ( !Discret.IsDone() )
      return false;
    double U = Discret.Parameter();
    if ( U > first && U < last )
      theParams.push_back( U );
    else
      return false;
    prevU = U;
  }
  return false;
}

//=============================================================================
/*!
 *  
 */
//=============================================================================
bool StdMeshers_Regular_1D::computeInternalParameters(const TopoDS_Edge& theEdge,
                                                      list<double> &     theParams,
                                                      const bool         theReverse) const
{
  theParams.clear();

  double f, l;
  Handle(Geom_Curve) Curve = BRep_Tool::Curve(theEdge, f, l);
  GeomAdaptor_Curve C3d(Curve);

  double length = EdgeLength(theEdge);

  switch( _hypType )
  {
  case LOCAL_LENGTH:
  case NB_SEGMENTS: {

    double eltSize = 1;
    if ( _hypType == LOCAL_LENGTH )
    {
      // Local Length hypothesis
      double nbseg = ceil(length / _value[ BEG_LENGTH_IND ]); // integer sup
      if (nbseg <= 0)
        nbseg = 1;                        // degenerated edge
      eltSize = length / nbseg;
    }
    else
    {
      // Number Of Segments hypothesis
      switch (_ivalue[ DISTR_TYPE_IND ])
      {
      case StdMeshers_NumberOfSegments::DT_Scale:
        {
          double scale = _value[ SCALE_FACTOR_IND ];
          if ( theReverse )
            scale = 1. / scale;
          double alpha = pow( scale , 1.0 / (_ivalue[ NB_SEGMENTS_IND ] - 1));
          double factor = (l - f) / (1 - pow( alpha,_ivalue[ NB_SEGMENTS_IND ]));

          int i, NbPoints = 1 + _ivalue[ NB_SEGMENTS_IND ];
          for ( i = 2; i < NbPoints; i++ )
          {
            double param = f + factor * (1 - pow(alpha, i - 1));
            theParams.push_back( param );
          }
          return true;
        }
        break;
      case StdMeshers_NumberOfSegments::DT_TabFunc:
        {
          TabFunction func(_vvalue[ TAB_FUNC_IND ], (bool)_ivalue[ EXP_MODE_IND ]);
          return computeParamByFunc(C3d, f, l, length, theReverse,
                                    _ivalue[ NB_SEGMENTS_IND ], func,
                                    theParams);
        }
        break;
      case StdMeshers_NumberOfSegments::DT_ExprFunc:
        {
          ExprFunction func(_svalue[ EXPR_FUNC_IND ].c_str(), (bool)_ivalue[ EXP_MODE_IND ]);
          return computeParamByFunc(C3d, f, l, length, theReverse,
                                    _ivalue[ NB_SEGMENTS_IND ], func,
                                    theParams);
        }
        break;
      case StdMeshers_NumberOfSegments::DT_Regular:
        eltSize = length / _ivalue[ NB_SEGMENTS_IND ];
        break;
      default:
        return false;
      }
    }

    GCPnts_UniformAbscissa Discret(C3d, eltSize, f, l);
    if ( !Discret.IsDone() )
      return false;

    int NbPoints = Discret.NbPoints();
    for ( int i = 2; i < NbPoints; i++ )
    {
      double param = Discret.Parameter(i);
      theParams.push_back( param );
    }
    return true;
  }

  case BEG_END_LENGTH: {

    // geometric progression: SUM(n) = ( a1 - an * q ) / ( 1 - q ) = length

    double a1 = _value[ BEG_LENGTH_IND ];
    double an = _value[ END_LENGTH_IND ];
    double q  = ( length - a1 ) / ( length - an );

    double U1 = theReverse ? l : f;
    double Un = theReverse ? f : l;
    double param = U1;
    double eltSize = theReverse ? -a1 : a1;
    while ( 1 ) {
      // computes a point on a curve <C3d> at the distance <eltSize>
      // from the point of parameter <param>.
      GCPnts_AbscissaPoint Discret( C3d, eltSize, param );
      if ( !Discret.IsDone() ) break;
      param = Discret.Parameter();
      if ( param > f && param < l )
        theParams.push_back( param );
      else
        break;
      eltSize *= q;
    }
    compensateError( a1, an, U1, Un, length, C3d, theParams );
    return true;
  }

  case ARITHMETIC_1D: {

    // arithmetic progression: SUM(n) = ( an - a1 + q ) * ( a1 + an ) / ( 2 * q ) = length

    double a1 = _value[ BEG_LENGTH_IND ];
    double an = _value[ END_LENGTH_IND ];

    double  q = ( an - a1 ) / ( 2 *length/( a1 + an ) - 1 );
    int     n = int( 1 + ( an - a1 ) / q );

    double U1 = theReverse ? l : f;
    double Un = theReverse ? f : l;
    double param = U1;
    double eltSize = a1;
    if ( theReverse ) {
      eltSize = -eltSize;
      q = -q;
    }
    while ( n-- > 0 && eltSize * ( Un - U1 ) > 0 ) {
      // computes a point on a curve <C3d> at the distance <eltSize>
      // from the point of parameter <param>.
      GCPnts_AbscissaPoint Discret( C3d, eltSize, param );
      if ( !Discret.IsDone() ) break;
      param = Discret.Parameter();
      if ( param > f && param < l )
        theParams.push_back( param );
      else
        break;
      eltSize += q;
    }
    compensateError( a1, an, U1, Un, length, C3d, theParams );

    return true;
  }

  case DEFLECTION: {

    GCPnts_UniformDeflection Discret(C3d, _value[ DEFLECTION_IND ], true);
    if ( !Discret.IsDone() )
      return false;

    int NbPoints = Discret.NbPoints();
    for ( int i = 2; i < NbPoints; i++ )
    {
      double param = Discret.Parameter(i);
      theParams.push_back( param );
    }
    return true;
    
  }

  default:;
  }

  return false;
}

//=============================================================================
/*!
 *  
 */
//=============================================================================

bool StdMeshers_Regular_1D::Compute(SMESH_Mesh & aMesh, const TopoDS_Shape & aShape)
{
  MESSAGE("StdMeshers_Regular_1D::Compute");

  if ( _hypType == NONE )
    return false;

  SMESHDS_Mesh * meshDS = aMesh.GetMeshDS();
  aMesh.GetSubMesh(aShape);

  const TopoDS_Edge & EE = TopoDS::Edge(aShape);
  TopoDS_Edge E = TopoDS::Edge(EE.Oriented(TopAbs_FORWARD));

  double f, l;
  Handle(Geom_Curve) Curve = BRep_Tool::Curve(E, f, l);

  TopoDS_Vertex VFirst, VLast;
  TopExp::Vertices(E, VFirst, VLast);   // Vfirst corresponds to f and Vlast to l

  ASSERT(!VFirst.IsNull());
  SMDS_NodeIteratorPtr lid= aMesh.GetSubMesh(VFirst)->GetSubMeshDS()->GetNodes();
  if (!lid->more())
  {
    MESSAGE (" NO NODE BUILT ON VERTEX ");
    return false;
  }
  const SMDS_MeshNode * idFirst = lid->next();

  ASSERT(!VLast.IsNull());
  lid=aMesh.GetSubMesh(VLast)->GetSubMeshDS()->GetNodes();
  if (!lid->more())
  {
    MESSAGE (" NO NODE BUILT ON VERTEX ");
    return false;
  }
  const SMDS_MeshNode * idLast = lid->next();

  if (!Curve.IsNull())
  {
    list< double > params;
    bool reversed = false;
    if ( !_mainEdge.IsNull() )
      reversed = aMesh.IsReversedInChain( EE, _mainEdge );
    try {
      if ( ! computeInternalParameters( E, params, reversed ))
        return false;
    }
    catch ( Standard_Failure ) {
      return false;
    }

    // edge extrema (indexes : 1 & NbPoints) already in SMDS (TopoDS_Vertex)
    // only internal nodes receive an edge position with param on curve

    const SMDS_MeshNode * idPrev = idFirst;
    
    for (list<double>::iterator itU = params.begin(); itU != params.end(); itU++)
    {
      double param = *itU;
      gp_Pnt P = Curve->Value(param);

      //Add the Node in the DataStructure
      SMDS_MeshNode * node = meshDS->AddNode(P.X(), P.Y(), P.Z());
      meshDS->SetNodeOnEdge(node, E);

      // **** edgePosition associe au point = param. 
      SMDS_EdgePosition* epos =
        dynamic_cast<SMDS_EdgePosition *>(node->GetPosition().get());
      epos->SetUParameter(param);

      SMDS_MeshEdge * edge = meshDS->AddEdge(idPrev, node);
      meshDS->SetMeshElementOnShape(edge, E);
      idPrev = node;
    }
    SMDS_MeshEdge* edge = meshDS->AddEdge(idPrev, idLast);
    meshDS->SetMeshElementOnShape(edge, E);
  }
  else
  {
    // Edge is a degenerated Edge : We put n = 5 points on the edge.
    int NbPoints = 5;
    BRep_Tool::Range(E, f, l);
    double du = (l - f) / (NbPoints - 1);
    //MESSAGE("************* Degenerated edge! *****************");

    TopoDS_Vertex V1, V2;
    TopExp::Vertices(E, V1, V2);
    gp_Pnt P = BRep_Tool::Pnt(V1);

    const SMDS_MeshNode * idPrev = idFirst;
    for (int i = 2; i < NbPoints; i++)
    {
      double param = f + (i - 1) * du;
      SMDS_MeshNode * node = meshDS->AddNode(P.X(), P.Y(), P.Z());
      meshDS->SetNodeOnEdge(node, E);

      SMDS_EdgePosition* epos =
        dynamic_cast<SMDS_EdgePosition*>(node->GetPosition().get());
      epos->SetUParameter(param);

      SMDS_MeshEdge * edge = meshDS->AddEdge(idPrev, node);
      meshDS->SetMeshElementOnShape(edge, E);
      idPrev = node;
    }
    SMDS_MeshEdge * edge = meshDS->AddEdge(idPrev, idLast);
    meshDS->SetMeshElementOnShape(edge, E);
  }
  return true;
}

//=============================================================================
/*!
 *  See comments in SMESH_Algo.cxx
 */
//=============================================================================

const list <const SMESHDS_Hypothesis *> & StdMeshers_Regular_1D::GetUsedHypothesis(
	SMESH_Mesh & aMesh, const TopoDS_Shape & aShape)
{
  _usedHypList.clear();
  _usedHypList = GetAppliedHypothesis(aMesh, aShape);	// copy
  int nbHyp = _usedHypList.size();
  _mainEdge.Nullify();
  if (nbHyp == 0)
  {
    // Check, if propagated from some other edge
    if (aShape.ShapeType() == TopAbs_EDGE &&
        aMesh.IsPropagatedHypothesis(aShape, _mainEdge))
    {
      // Propagation of 1D hypothesis from <aMainEdge> on this edge
      //_usedHypList = GetAppliedHypothesis(aMesh, _mainEdge);	// copy
      // use a general method in order not to nullify _mainEdge
      _usedHypList = SMESH_Algo::GetUsedHypothesis(aMesh, _mainEdge);	// copy
      nbHyp = _usedHypList.size();
    }
  }
  if (nbHyp == 0)
  {
    TopTools_ListIteratorOfListOfShape ancIt( aMesh.GetAncestors( aShape ));
    for (; ancIt.More(); ancIt.Next())
    {
      const TopoDS_Shape& ancestor = ancIt.Value();
      _usedHypList = GetAppliedHypothesis(aMesh, ancestor);	// copy
      nbHyp = _usedHypList.size();
      if (nbHyp == 1)
        break;
    }
  }
  if (nbHyp > 1)
    _usedHypList.clear();	//only one compatible hypothesis allowed
  return _usedHypList;
}

//=============================================================================
/*!
 *  
 */
//=============================================================================

ostream & StdMeshers_Regular_1D::SaveTo(ostream & save)
{
  return save;
}

//=============================================================================
/*!
 *  
 */
//=============================================================================

istream & StdMeshers_Regular_1D::LoadFrom(istream & load)
{
  return load;
}

//=============================================================================
/*!
 *  
 */
//=============================================================================

ostream & operator <<(ostream & save, StdMeshers_Regular_1D & hyp)
{
  return hyp.SaveTo( save );
}

//=============================================================================
/*!
 *  
 */
//=============================================================================

istream & operator >>(istream & load, StdMeshers_Regular_1D & hyp)
{
  return hyp.LoadFrom( load );
}