path: root/inc/AppBlend_AppSurf.gxx

#include <AppDef_MultiLine.hxx>
#include <AppDef_MultiPointConstraint.hxx>
#include <AppParCurves_MultiBSpCurve.hxx>
#include <AppParCurves_MultiCurve.hxx>
#include <AppDef_BSplineCompute.hxx>
#include <AppDef_Compute.hxx>
#include <AppParCurves_Constraint.hxx>
#include <Approx_MCurvesToBSpCurve.hxx>
#include <TColgp_Array1OfPnt.hxx>
#include <TColgp_Array1OfPnt2d.hxx>
#include <TColgp_Array1OfVec.hxx>
#include <TColgp_Array1OfVec2d.hxx>
#include <gp_Vec.hxx>
#include <gp_Vec2d.hxx>
#include <gp_Pnt.hxx>
#include <gp_Pnt2d.hxx>
#include <math_Vector.hxx>
#include <BSplCLib.hxx>

#include <StdFail_NotDone.hxx>
#include <AppParCurves_HArray1OfConstraintCouple.hxx>
#include <AppDef_TheVariational.hxx>

static   Standard_Boolean scal = 1;
#ifdef DEB
extern Standard_Boolean AppBlend_GetContextSplineApprox(); 
extern Standard_Boolean AppBlend_GetContextApproxWithNoTgt(); 
#endif

//  modified by EAP (Edward AGAPOV) Fri Jan 4 2002, bug OCC9
//  --- keep pipe parametrized like path


//=======================================================================
//function : AppBlend_AppSurf
//purpose  : 
//=======================================================================

AppBlend_AppSurf::AppBlend_AppSurf ():done(Standard_False) {}


//=======================================================================
//function : AppBlend_AppSurf
//purpose  : 
//=======================================================================

AppBlend_AppSurf::AppBlend_AppSurf (const Standard_Integer Degmin,
				    const Standard_Integer Degmax,
				    const Standard_Real Tol3d,
				    const Standard_Real Tol2d,
				    const Standard_Integer NbIt,
				    const Standard_Boolean KnownParameters):
       done(Standard_False),dmin(Degmin),dmax(Degmax),
       tol3d(Tol3d),tol2d(Tol2d),nbit(NbIt),knownp(KnownParameters)
{
  continuity = GeomAbs_C2;
  paramtype = Approx_ChordLength;
  critweights[0]=0.4;
  critweights[1]=0.2;
  critweights[2]=0.4;
}

//=======================================================================
//function : Init
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::Init (const Standard_Integer Degmin,
			     const Standard_Integer Degmax,
			     const Standard_Real Tol3d,
			     const Standard_Real Tol2d,
			     const Standard_Integer NbIt,
			     const Standard_Boolean KnownParameters)
{
  done  = Standard_False;
  dmin  = Degmin;
  dmax  = Degmax;
  tol3d = Tol3d;
  tol2d = Tol2d;
  nbit  = NbIt;
  knownp = KnownParameters;
  continuity = GeomAbs_C2;
  paramtype = Approx_ChordLength;
  critweights[0]=0.4;
  critweights[1]=0.2;
  critweights[2]=0.4;
}

//=======================================================================
//function : CriteriumWeight
//purpose  : returns the Weights associed  to the criterium used in
//           the  optimization.
//=======================================================================
//
void AppBlend_AppSurf::CriteriumWeight(Standard_Real& W1, Standard_Real& W2, Standard_Real& W3) const 
{
  W1 = critweights[0];
  W2 = critweights[1];
  W3 = critweights[2] ;
}
//=======================================================================
//function : SetCriteriumWeight
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::SetCriteriumWeight(const Standard_Real W1, const Standard_Real W2, const Standard_Real W3)
{
  if (W1 < 0 || W2 < 0 || W3 < 0 ) Standard_DomainError::Raise();
  critweights[0] = W1;
  critweights[1] = W2;
  critweights[2] = W3;
}
//=======================================================================
//function : SetContinuity
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::SetContinuity (const GeomAbs_Shape TheCont)
{
  continuity = TheCont;
}

//=======================================================================
//function : Continuity
//purpose  : 
//=======================================================================

GeomAbs_Shape AppBlend_AppSurf::Continuity () const
{
  return continuity;
}

//=======================================================================
//function : SetParType
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::SetParType (const Approx_ParametrizationType ParType)
{
  paramtype = ParType;
}

//=======================================================================
//function : ParType
//purpose  : 
//=======================================================================

Approx_ParametrizationType AppBlend_AppSurf::ParType () const
{
  return paramtype;
}


//=======================================================================
//function : Perform
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::Perform(const Handle(TheLine)& Lin,
			       TheSectionGenerator& F,
			       const Standard_Boolean SpApprox)

{
  InternalPerform(Lin, F, SpApprox, Standard_False);
}

//=======================================================================
//function : PerformSmoothing
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::PerformSmoothing(const Handle(TheLine)& Lin,
					  TheSectionGenerator& F)

{
  InternalPerform(Lin, F, Standard_True, Standard_True);
}

//=======================================================================
//function : InternalPerform
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::InternalPerform(const Handle(TheLine)& Lin,
				       TheSectionGenerator& F,
				       const Standard_Boolean SpApprox,
				       const Standard_Boolean UseSmoothing)

{
  done = Standard_False;
  if (Lin.IsNull()) {return;}
  Standard_Integer i,j,k,NbPoint;
  Standard_Integer NbUPoles,NbUKnots,NbPoles2d,NbVPoles;
  Standard_Boolean withderiv;
  AppParCurves_Constraint Cfirst,Clast;

  Standard_Real mytol3d,mytol2d;
  gp_XYZ newDv;

  seqPoles2d.Clear();

  NbPoint=Lin->NbPoints();
  AppDef_MultiPointConstraint multP;
  AppDef_MultiLine multL(NbPoint);

  F.GetShape(NbUPoles,NbUKnots,udeg,NbPoles2d);

  tabUKnots  = new TColStd_HArray1OfReal (1,NbUKnots);
  tabUMults  = new TColStd_HArray1OfInteger (1,NbUKnots);

  F.Knots(tabUKnots->ChangeArray1());
  F.Mults(tabUMults->ChangeArray1());

  TColgp_Array1OfPnt tabAppP(1,NbUPoles);
  TColgp_Array1OfVec tabAppV(1,NbUPoles);

  TColgp_Array1OfPnt2d tabP2d(1,Max(1,NbPoles2d));
  TColgp_Array1OfVec2d tabV2d(1,Max(1,NbPoles2d));

  TColStd_Array1OfReal tabW(1,NbUPoles),tabDW(1,NbUPoles);

  TColgp_Array1OfPnt2d tabAppP2d(1,NbPoles2d+NbUPoles); // points2d + poids
  TColgp_Array1OfVec2d tabAppV2d(1,NbPoles2d+NbUPoles); 


  AppParCurves_MultiBSpCurve multC;

//  Standard_Boolean SpApprox = Standard_False;

  withderiv = F.Section(Lin->Point(1),tabAppP,tabAppV,tabP2d,tabV2d,
			tabW,tabDW);

#if DEB
//  SpApprox = AppBlend_GetContextSplineApprox();
  if(AppBlend_GetContextApproxWithNoTgt()) withderiv = Standard_False;
#endif


  for (j=1; j<=NbPoles2d; j++) {
    tabAppP2d(j) = tabP2d(j);
    if (withderiv) {
      tabAppV2d(j) = tabV2d(j);
    }
  }
  for (j=1; j<=NbUPoles; j++) {
    // pour les courbes rationnelles il faut multiplier les poles par
    // leurs poids respectifs
    if (withderiv) {
      tabAppV2d(NbPoles2d+j).SetCoord(tabDW(j),0.);
      newDv.SetLinearForm(tabDW(j),tabAppP(j).XYZ(),tabW(j),tabAppV(j).XYZ());
      tabAppV(j).SetXYZ(newDv);
    }
    tabAppP(j).SetXYZ(tabAppP(j).XYZ() * tabW(j));
    tabAppP2d(NbPoles2d+j).SetCoord(tabW(j),0.);
  }
    
  if (withderiv) {
    multP = AppDef_MultiPointConstraint(tabAppP,tabAppP2d,tabAppV,tabAppV2d);
    Cfirst = AppParCurves_TangencyPoint;
  }
  else {
    multP = AppDef_MultiPointConstraint(tabAppP,tabAppP2d);
    Cfirst = AppParCurves_PassPoint;
  }
  multL.SetValue(1,multP);

  for (i=2; i<=NbPoint-1; i++) {
    if (SpApprox) {
      F.Section(Lin->Point(i),tabAppP,tabP2d,tabW);
      for (j=1; j<=NbPoles2d; j++) {
	tabAppP2d(j) = tabP2d(j);
      }
      for (j=1; j<=NbUPoles; j++) {
	// pour les courbes rationnelles il faut multiplier les poles par
	// leurs poids respectifs
	tabAppP(j).SetXYZ(tabAppP(j).XYZ() * tabW(j));
	tabAppP2d(NbPoles2d+j).SetCoord(tabW(j),0.);
      }
      multP = AppDef_MultiPointConstraint(tabAppP,tabAppP2d);
      multL.SetValue(i,multP);
    }
// ***********************
    else {
      withderiv = F.Section(Lin->Point(i),tabAppP,tabAppV,tabP2d,tabV2d,
			    tabW,tabDW);
#if DEB
      if(AppBlend_GetContextApproxWithNoTgt()) withderiv = Standard_False;
#endif
      
      for (j=1; j<=NbPoles2d; j++) {
	tabAppP2d(j) = tabP2d(j);
	if (withderiv) {
	  tabAppV2d(j) = tabV2d(j);
	}
      }
      for (j=1; j<=NbUPoles; j++) {
	// pour les courbes rationnelles il faut multiplier les poles par
	// leurs poids respectifs
	if (withderiv) {
	  tabAppV2d(NbPoles2d+j).SetCoord(tabDW(j),0.);
	  newDv.SetLinearForm(tabDW(j),tabAppP(j).XYZ(),tabW(j),tabAppV(j).XYZ());
	  tabAppV(j).SetXYZ(newDv);
	}
	tabAppP(j).SetXYZ(tabAppP(j).XYZ() * tabW(j));
	tabAppP2d(NbPoles2d+j).SetCoord(tabW(j),0.);
      }
      if (withderiv) {
	multP = AppDef_MultiPointConstraint(tabAppP,tabAppP2d,tabAppV,tabAppV2d);
      }
      else {
	multP = AppDef_MultiPointConstraint(tabAppP,tabAppP2d);
      }
      multL.SetValue(i,multP);
    }
// ******************************
  }
  
  withderiv = F.Section(Lin->Point(NbPoint),tabAppP,tabAppV,tabP2d,tabV2d,
			tabW,tabDW);
#if DEB
      if(AppBlend_GetContextApproxWithNoTgt()) withderiv = Standard_False;
#endif

  for (j=1; j<=NbPoles2d; j++) {
    tabAppP2d(j) = tabP2d(j);
    if (withderiv) {
      tabAppV2d(j) = tabV2d(j);
    }
  }
  for (j=1; j<=NbUPoles; j++) {
    // pour les courbes rationnelles il faut multiplier les poles par
    // leurs poids respectifs
    if (withderiv) {
      tabAppV2d(NbPoles2d+j).SetCoord(tabDW(j),0.);
      newDv.SetLinearForm(tabDW(j),tabAppP(j).XYZ(),tabW(j),tabAppV(j).XYZ());
      tabAppV(j).SetXYZ(newDv);
    }
    tabAppP(j).SetXYZ(tabAppP(j).XYZ() * tabW(j));
    tabAppP2d(NbPoles2d+j).SetCoord(tabW(j),0.);
  }

  if (withderiv) {
    multP = AppDef_MultiPointConstraint(tabAppP,tabAppP2d,tabAppV,tabAppV2d);
    Clast = AppParCurves_TangencyPoint;
  }
  else {
    multP = AppDef_MultiPointConstraint(tabAppP,tabAppP2d);
    Clast = AppParCurves_PassPoint;
  }
  multL.SetValue(NbPoint,multP);

  //IFV 04.06.07 occ13904
  if(NbPoint == 2) {
    dmin = 1;
    if(Cfirst == AppParCurves_PassPoint && Clast == AppParCurves_PassPoint) {
      dmax = 1;
    }
  }


  if (!SpApprox) {
    AppDef_Compute theapprox (dmin,dmax,tol3d,tol2d,nbit, Standard_True, paramtype);
    if (knownp) {
      math_Vector theParams(1,NbPoint);

      // On recale les parametres entre 0 et 1.
      theParams(1) = 0.;
      theParams(NbPoint) = 1.;
      Standard_Real Uf = F.Parameter(Lin->Point(1));
      Standard_Real Ul = F.Parameter(Lin->Point(NbPoint))-Uf;
      for (i=2; i<NbPoint; i++) {
	theParams(i) = (F.Parameter(Lin->Point(i))-Uf)/Ul;;
      }
      AppDef_Compute theAppDef(theParams,dmin,dmax,tol3d,tol2d,nbit,
				 Standard_True, Standard_True);
      theapprox = theAppDef;
    }
    theapprox.SetConstraints(Cfirst,Clast);
    theapprox.Perform(multL);

    Standard_Real TheTol3d, TheTol2d;
    mytol3d = mytol2d = 0.0;
    for (Standard_Integer Index=1; Index<=theapprox.NbMultiCurves(); Index++) {
      theapprox.Error(Index, TheTol3d, TheTol2d);
      mytol3d = Max(TheTol3d, mytol3d);
      mytol2d = Max(TheTol2d, mytol2d);
    }
#ifdef DEB
    cout << " Tolerances obtenues  --> 3d : "<< mytol3d << endl;
    cout << "                      --> 2d : "<< mytol2d << endl;
#endif
    multC = theapprox.SplineValue();
  }  

  else {
    if(!UseSmoothing) {
      Standard_Boolean UseSquares = Standard_False;
      if(nbit == 0) UseSquares = Standard_True;
      AppDef_BSplineCompute theapprox (dmin,dmax,tol3d,tol2d,nbit,Standard_True, paramtype,
				       UseSquares);
      if(continuity == GeomAbs_C0) {
	theapprox.SetContinuity(0);
      }
      if(continuity == GeomAbs_C1) {
	theapprox.SetContinuity(1);
      }
      else if(continuity == GeomAbs_C2) {
	theapprox.SetContinuity(2);
      }
      else {
	theapprox.SetContinuity(3);
      }

      theapprox.SetConstraints(Cfirst,Clast);

      if (knownp) {
	math_Vector theParams(1,NbPoint);
	// On recale les parametres entre 0 et 1.
	theParams(1) = 0.;
	theParams(NbPoint) = 1.;
	Standard_Real Uf = F.Parameter(Lin->Point(1));
	Standard_Real Ul = F.Parameter(Lin->Point(NbPoint))-Uf;
	for (i=2; i<NbPoint; i++) {
	  theParams(i) = (F.Parameter(Lin->Point(i))-Uf)/Ul;;
	}

	theapprox.Init(dmin,dmax,tol3d,tol2d,nbit,Standard_True,
		       Approx_IsoParametric,Standard_True);
	theapprox.SetParameters(theParams);
      }
      theapprox.Perform(multL);
      theapprox.Error(mytol3d,mytol2d);
#ifdef DEB
      cout << " Tolerances obtenues  --> 3d : "<< mytol3d << endl;
      cout << "                      --> 2d : "<< mytol2d << endl;
#endif    
      tol3dreached = mytol3d;
      tol2dreached = mytol2d;
      multC = theapprox.Value();
    }
    else {
      //Variational algo
      Handle(AppParCurves_HArray1OfConstraintCouple) TABofCC = 
	new AppParCurves_HArray1OfConstraintCouple(1, NbPoint);
      AppParCurves_Constraint  Constraint=AppParCurves_NoConstraint;

      for(i = 1; i <= NbPoint; ++i) {
	AppParCurves_ConstraintCouple ACC(i,Constraint);
	TABofCC->SetValue(i,ACC);
      }
      
      TABofCC->ChangeValue(1).SetConstraint(Cfirst);
      TABofCC->ChangeValue(NbPoint).SetConstraint(Clast);

      AppDef_TheVariational Variation(multL, 1, NbPoint, TABofCC);

//===================================
      Standard_Integer theMaxSegments = 1000;
      Standard_Boolean theWithMinMax = Standard_False;
      Standard_Boolean theWithCutting = Standard_True;
//===================================      

      Variation.SetMaxDegree(dmax);
      Variation.SetContinuity(continuity);
      Variation.SetMaxSegment(theMaxSegments);

      Variation.SetTolerance(tol3d);
      Variation.SetWithMinMax(theWithMinMax);
      Variation.SetWithCutting(theWithCutting);
      Variation.SetNbIterations(nbit);

      Variation.SetCriteriumWeight(critweights[0], critweights[1], critweights[2]);

      if(!Variation.IsCreated()) {
	return;
      }
  
      if(Variation.IsOverConstrained()) {
	return;
      }

      try {
	Variation.Approximate();
      }
      catch (Standard_Failure) {
	return;
      }

      if(!Variation.IsDone()) {
	return;
      }

      mytol3d = Variation.MaxError();
      mytol2d = 0.;
#ifdef DEB
      cout << " Tolerances obtenues  --> 3d : "<< mytol3d << endl;
      cout << "                      --> 2d : "<< mytol2d << endl;
#endif    
      tol3dreached = mytol3d;
      tol2dreached = mytol2d;
      multC = Variation.Value();
    }
  }

  vdeg = multC.Degree();
  NbVPoles = multC.NbPoles();
  
  tabPoles   = new TColgp_HArray2OfPnt (1,NbUPoles,1,NbVPoles);
  tabWeights = new TColStd_HArray2OfReal (1,NbUPoles,1,NbVPoles);
  tabVKnots  = new TColStd_HArray1OfReal (multC.Knots().Lower(),
					  multC.Knots().Upper());
  tabVKnots->ChangeArray1() = multC.Knots();

  if (knownp && !UseSmoothing) {
    BSplCLib::Reparametrize(F.Parameter(Lin->Point(1)),
			    F.Parameter(Lin->Point(NbPoint)),
			    tabVKnots->ChangeArray1());
  }

  tabVMults  = new TColStd_HArray1OfInteger (multC.Multiplicities().Lower(),
					     multC.Multiplicities().Upper());
  tabVMults->ChangeArray1() = multC.Multiplicities();

  
  TColgp_Array1OfPnt newtabP(1,NbVPoles);
  Handle(TColgp_HArray1OfPnt2d) newtabP2d = 
    new TColgp_HArray1OfPnt2d(1,NbVPoles);
  for (j=1; j <=NbUPoles; j++) {
    multC.Curve(j,newtabP);
    multC.Curve(j+NbUPoles+NbPoles2d,newtabP2d->ChangeArray1());
    for (k=1; k<=NbVPoles; k++) {
      // pour les courbes rationnelles il faut maintenant diviser
      // les poles par leurs poids respectifs
      tabPoles->ChangeValue(j,k).
	SetXYZ(newtabP(k).XYZ()/newtabP2d->Value(k).X());
      tabWeights->SetValue(j,k,newtabP2d->Value(k).X());
    }
  }

  for (j=1; j<=NbPoles2d; j++) {
    newtabP2d = new TColgp_HArray1OfPnt2d(1,NbVPoles);
    multC.Curve(NbUPoles+j,newtabP2d->ChangeArray1());
    seqPoles2d.Append(newtabP2d);
  }
  
  done = Standard_True;
}


//=======================================================================
//function : Perform
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::Perform(const Handle(TheLine)& Lin,
			       TheSectionGenerator& F,
			       const Standard_Integer NbMaxP)
{
  done = Standard_False;
  if (Lin.IsNull()) {return;}
  Standard_Integer i,j,k;
  Standard_Integer NbUPoles,NbUKnots,NbPoles2d,NbVPoles;
  Standard_Boolean withderiv;
  AppParCurves_Constraint Cfirst=AppParCurves_NoConstraint,Clast=AppParCurves_NoConstraint;

  Standard_Real mytol3d = 0.0, mytol2d = 0.0;
  gp_XYZ newDv;

  seqPoles2d.Clear();

  Standard_Integer NbPointTot = Lin->NbPoints();

  F.GetShape(NbUPoles,NbUKnots,udeg,NbPoles2d);

  tabUKnots  = new TColStd_HArray1OfReal (1,NbUKnots);
  tabUMults  = new TColStd_HArray1OfInteger (1,NbUKnots);

  F.Knots(tabUKnots->ChangeArray1());
  F.Mults(tabUMults->ChangeArray1());

  TColgp_Array1OfPnt tabAppP(1,NbUPoles);
  TColgp_Array1OfVec tabAppV(1,NbUPoles);
  Standard_Real X,Y,Z,DX,DY,DZ;
  X = Y = Z = RealLast();
  DX = DY = DZ = RealFirst();

  TColgp_Array1OfPnt2d tabP2d(1,Max(1,NbPoles2d));
  TColgp_Array1OfVec2d tabV2d(1,Max(1,NbPoles2d));
  TColStd_Array1OfReal X2d(1,Max(1,NbPoles2d));X2d.Init(RealLast());
  TColStd_Array1OfReal Y2d(1,Max(1,NbPoles2d));Y2d.Init(RealLast());
  TColStd_Array1OfReal DX2d(1,Max(1,NbPoles2d));DX2d.Init(RealFirst());
  TColStd_Array1OfReal DY2d(1,Max(1,NbPoles2d));DY2d.Init(RealFirst());

  TColStd_Array1OfReal tabW(1,NbUPoles),tabDW(1,NbUPoles);

  TColgp_Array1OfPnt2d tabAppP2d(1,NbPoles2d+NbUPoles); // points2d + poids
  TColgp_Array1OfVec2d tabAppV2d(1,NbPoles2d+NbUPoles); 

  // On calcule les boites de chaque ligne (box for all lines)
  for(i = 1; i <= NbPointTot; i++){
    F.Section(Lin->Point(i),tabAppP,tabAppV,tabP2d,tabV2d,tabW,tabDW);
    Standard_Real x,y,z;
    for(j = 1; j <= NbUPoles; j++){
      tabAppP(j).Coord(x,y,z);
      if(x < X) X = x; if(x > DX) DX = x;
      if(y < Y) Y = y; if(y > DY) DY = y;
      if(z < Z) Z = z; if(z > DZ) DZ = z;
    }
    for(j = 1; j <= NbPoles2d; j++){
      tabP2d(j).Coord(x,y);
      if(x < X2d(j)) X2d(j) = x; if(x > DX2d(j)) DX2d(j) = x;
      if(y < Y2d(j)) Y2d(j) = y; if(y > DY2d(j)) DY2d(j) = y;
    }
  }
  // On calcule pour chaque ligne la transformation vers 0 1.
  Standard_Real seuil = 1000.*tol3d;
  Standard_Real seuil2d = 1000.*tol2d;
  if((DX - X) < seuil ){ DX = 1.; X = 0.; }
  else{ DX = 1./(DX - X); X *= -DX; }
  if((DY - Y) < seuil){ DY = 1.; Y = 0.; }
  else{ DY = 1./(DY - Y); Y *= -DY; }
  if((DZ - Z) < seuil){ DZ = 1.; Z = 0.; }
  else{ DZ = 1./(DZ - Z); Z *= -DZ; }
  for(j = 1; j <= NbPoles2d; j++){
    if((DX2d(j) - X2d(j)) < seuil2d){ DX2d(j) = 1.; X2d(j) = 0.; }
    else{ DX2d(j) = 1./(DX2d(j) - X2d(j)); X2d(j) *= -DX2d(j); }
    if((DY2d(j) - Y2d(j)) < seuil2d){ DY2d(j) = 1.; Y2d(j) = 0.; }
    else{ DY2d(j) = 1./(DY2d(j) - Y2d(j)); Y2d(j) *= -DY2d(j); }
  }
  if(!scal){
    DX = 1.; X = 0.;
    DY = 1.; Y = 0.;
    DZ = 1.; Z = 0.;
    for(j = 1; j <= NbPoles2d; j++){
      DX2d(j) = 1.; X2d(j) = 0.;
      DY2d(j) = 1.; Y2d(j) = 0.;
    }
  }
//  modified by eap Thu Jan  3 14:45:22 2002 ___BEGIN___
  // Keep "inter-troncons" parameters, not only first and last
//  Standard_Real Ufirst=0,Ulast=0;
  TColStd_SequenceOfReal aParamSeq;
   if (knownp) {
//     Ufirst = F.Parameter(Lin->Point(1));
//     Ulast = F.Parameter(Lin->Point(NbPointTot));
     aParamSeq.Append( F.Parameter (Lin->Point(1)) );
  }    
//  modified by EAP Thu Jan  3 14:45:41 2002 ___END___

  Approx_MCurvesToBSpCurve concat;

  //On calcule le nombre de troncons.
  Standard_Integer nbtronc = NbPointTot/NbMaxP;
  Standard_Integer reste = NbPointTot - (nbtronc * NbMaxP);
  // On regarde si il faut prendre un troncon de plus.
  Standard_Integer nmax = NbMaxP;
  if(nbtronc > 0 && reste > 0){
    nmax = NbPointTot/(nbtronc + 1);
    if(nmax > (2*NbMaxP)/3) {
      nbtronc++;
      reste = NbPointTot - (nbtronc * nmax);
    }
    else nmax = NbMaxP;
  }
  else if(nbtronc == 0){
    nbtronc = 1;
    nmax = reste;
    reste = 0;
  }

  // Approximate each "troncon" with nb of Bezier's using AppDef_Compute
  // and concat them into BSpline with Approx_MCurvesToBSpCurve 

  TColStd_Array1OfInteger troncsize(1,nbtronc);
  TColStd_Array1OfInteger troncstart(1,nbtronc);

  Standard_Integer rab = reste/nbtronc + 1;
  Standard_Integer start = 1;
  Standard_Integer itronc ;
  for( itronc = 1; itronc <= nbtronc; itronc++){
    troncstart(itronc) = start;
    Standard_Integer rabrab = Min(rab,reste);
    if(reste > 0){ reste -= rabrab; }
    troncsize(itronc) = nmax + rabrab + 1;
    start += (nmax + rabrab);
  }
  troncsize(nbtronc) = troncsize(nbtronc) - 1;
  for(itronc = 1; itronc <= nbtronc; itronc++){
    Standard_Integer NbPoint = troncsize(itronc); 
    Standard_Integer StPoint = troncstart(itronc);
    AppDef_MultiPointConstraint multP;
    AppDef_MultiLine multL(NbPoint);
    
    for (i=1; i<=NbPoint; i++) {
      Standard_Integer iLin = StPoint + i - 1;
      Standard_Real x,y,z;
      withderiv = F.Section(Lin->Point(iLin),tabAppP,tabAppV,tabP2d,tabV2d,
			    tabW,tabDW);
#if DEB
      if(AppBlend_GetContextApproxWithNoTgt()) withderiv = Standard_False;
#endif
      
      for (j=1; j<=NbPoles2d; j++) {
	tabP2d(j).Coord(x,y);
	tabAppP2d(j).SetCoord(DX2d(j)*x+X2d(j),DY2d(j)*y+Y2d(j));
	if (withderiv) {
	  tabV2d(j).Coord(x,y);
	  tabAppV2d(j).SetCoord(DX2d(j)*x,DY2d(j)*y);
	}
      }
      for (j=1; j<=NbUPoles; j++) {
	// pour les courbes rationnelles il faut multiplier les poles par
	// leurs poids respectifs
	if (withderiv) {
	  tabAppV2d(NbPoles2d+j).SetCoord(tabDW(j),0.);
	  newDv.SetLinearForm(tabDW(j),tabAppP(j).XYZ(),tabW(j),tabAppV(j).XYZ());
	  tabAppV(j).SetCoord(DX*newDv.X(),DY*newDv.Y(),DZ*newDv.Z());
	}
	tabAppP(j).SetXYZ(tabAppP(j).XYZ() * tabW(j));
	tabAppP2d(NbPoles2d+j).SetCoord(tabW(j),0.);
	tabAppP(j).Coord(x,y,z);
	tabAppP(j).SetCoord(DX*x+X,DY*y+Y,DZ*z+Z);
      }
      if (withderiv) {
	multP = AppDef_MultiPointConstraint(tabAppP,tabAppP2d,tabAppV,tabAppV2d);
	if(i == 1) Cfirst = AppParCurves_TangencyPoint;
	else if(i == NbPoint) Clast = AppParCurves_TangencyPoint;
      }
      else {
	multP = AppDef_MultiPointConstraint(tabAppP,tabAppP2d);
	if(i == 1) Cfirst = AppParCurves_PassPoint;
	else if(i == NbPoint) Clast = AppParCurves_PassPoint;
      }
      multL.SetValue(i,multP);
    }
    

  //IFV 04.06.07 occ13904
    if(NbPoint == 2) {
      dmin = 1;
      if(Cfirst == AppParCurves_PassPoint && Clast == AppParCurves_PassPoint) {
	dmax = 1;
      }
    }

//  modified by EAP Thu Jan  3 15:44:13 2002 ___BEGIN___
    Standard_Real Ufloc=0., Ulloc=0.;
    AppDef_Compute theapprox (dmin,dmax,tol3d,tol2d,nbit);
    if (knownp) {
      math_Vector theParams(1,NbPoint);
      // On recale les parametres entre 0 et 1.
      /*Standard_Real*/ Ufloc = F.Parameter(Lin->Point(StPoint));
      /*Standard_Real*/ Ulloc = F.Parameter(Lin->Point(StPoint+NbPoint-1));
//  modified by EAP Thu Jan  3 15:45:17 2002 ___END___
      for (i=1; i <= NbPoint; i++) {
	Standard_Integer iLin = StPoint + i - 1;
	theParams(i) = (F.Parameter(Lin->Point(iLin))-Ufloc)/(Ulloc - Ufloc);
      }
      AppDef_Compute theAppDef1(theParams,dmin,dmax,tol3d,tol2d,nbit, Standard_True,Standard_True);
      theapprox = theAppDef1;
    }
    theapprox.SetConstraints(Cfirst,Clast);
    theapprox.Perform(multL);

//  modified by EAP Thu Jan  3 16:00:43 2002 ___BEGIN___
    // To know internal parameters if multicurve is approximated by several Bezier's
    TColStd_SequenceOfReal aPoleDistSeq;
    Standard_Real aWholeDist=0;
//  modified by EAP Thu Jan  3 16:45:48 2002 ___END___
    Standard_Real TheTol3d, TheTol2d;
    for (Standard_Integer Index=1; Index<=theapprox.NbMultiCurves(); Index++) {
      AppParCurves_MultiCurve& mucu = theapprox.ChangeValue(Index);
      theapprox.Error(Index, TheTol3d, TheTol2d);
      mytol3d = Max(TheTol3d/DX, mytol3d);
      mytol3d = Max(TheTol3d/DY, mytol3d);
      mytol3d = Max(TheTol3d/DZ, mytol3d);
      for(j = 1; j <= NbUPoles; j++){
	mucu.Transform(j,
		       -X/DX,1./DX,
		       -Y/DY,1./DY,
		       -Z/DZ,1./DZ);
      }
      for(j = 1; j <= NbPoles2d; j++){
	mucu.Transform2d(j + NbUPoles,
			 -X2d(j)/DX2d(j),1./DX2d(j),
			 -Y2d(j)/DY2d(j),1./DY2d(j));
	mytol2d = Max(TheTol2d/DX2d(j), mytol2d);
	mytol2d = Max(TheTol2d/DY2d(j), mytol2d);
      }
      concat.Append(mucu);
      
//  modified by EAP Thu Jan  3 15:45:23 2002 ___BEGIN___
      if (knownp && theapprox.NbMultiCurves() > 1) 
      {
	gp_Pnt aFirstPole = mucu.Pole(Index, 1);
	gp_Pnt aLastPole  = mucu.Pole(Index, mucu.NbPoles());
	aPoleDistSeq.Append (aFirstPole.Distance(aLastPole));
	aWholeDist += aPoleDistSeq.Last();
      }
    }
    if (knownp)
    {
      Standard_Integer iDist;
      Standard_Real iU = Ufloc;
      for (iDist=1; iDist<aPoleDistSeq.Length(); iDist++)
      {
	iU += aPoleDistSeq(iDist) / aWholeDist * (Ulloc - Ufloc);
	//cout << "Internal: " << iU << endl;
	aParamSeq.Append(iU);
      }
      aParamSeq.Append(Ulloc);
    }
//  modified by EAP Thu Jan  3 15:45:27 2002 ___END___
  }
#ifdef DEB
  cout << "   Tolerances obtenues  --> 3d : "<< mytol3d << endl;
  cout << "                        --> 2d : "<< mytol2d << endl;
#endif
  tol3dreached = mytol3d;
  tol2dreached = mytol2d;
  concat.Perform();
  const AppParCurves_MultiBSpCurve& multC = concat.Value();
  vdeg = multC.Degree();
  NbVPoles = multC.NbPoles();
  
  tabPoles   = new TColgp_HArray2OfPnt (1,NbUPoles,1,NbVPoles);
  tabWeights = new TColStd_HArray2OfReal (1,NbUPoles,1,NbVPoles);
  tabVKnots  = new TColStd_HArray1OfReal (multC.Knots().Lower(),
					  multC.Knots().Upper());
  tabVKnots->ChangeArray1() = multC.Knots();
  
  if (knownp) {
//  modified by EAP Fri Jan  4 12:07:30 2002 ___BEGIN___
    if (aParamSeq.Length() != tabVKnots->Length())
    {
      BSplCLib::Reparametrize(F.Parameter(Lin->Point(1)),
			      F.Parameter(Lin->Point(Lin->NbPoints())),
			      tabVKnots->ChangeArray1()
			      );
#ifdef DEB
      cout << "Warning: AppBlend_AppSurf::Perform(), bad length of aParamSeq: " <<
	aParamSeq.Length() << " instead of " << tabVKnots->Length() << endl;
#endif
    }
    else
    {
      Standard_Integer iKnot, iTabKnot = tabVKnots->Lower();
      for (iKnot=1; iKnot<=aParamSeq.Length(); iKnot++, iTabKnot++)
      {
	//cout << "Replace " << tabVKnots->Value(iTabKnot) << " with " << aParamSeq(iKnot) << endl;
	tabVKnots->SetValue(iTabKnot, aParamSeq(iKnot));
      }
    }
//  modified by EAP Fri Jan  4 12:07:35 2002 ___END___
  }
  
  tabVMults  = new TColStd_HArray1OfInteger (multC.Multiplicities().Lower(),
					     multC.Multiplicities().Upper());
  tabVMults->ChangeArray1() = multC.Multiplicities();
  
  
  TColgp_Array1OfPnt newtabP(1,NbVPoles);
  Handle(TColgp_HArray1OfPnt2d) newtabP2d = 
    new TColgp_HArray1OfPnt2d(1,NbVPoles);
  for (j=1; j <=NbUPoles; j++) {
    multC.Curve(j,newtabP);
    multC.Curve(j+NbUPoles+NbPoles2d,newtabP2d->ChangeArray1());
    for (k=1; k<=NbVPoles; k++) {
      // pour les courbes rationnelles il faut maintenant diviser
      // les poles par leurs poids respectifs
      tabPoles->ChangeValue(j,k).
	SetXYZ(newtabP(k).XYZ()/newtabP2d->Value(k).X());
      tabWeights->SetValue(j,k,newtabP2d->Value(k).X());
    }
  }
  
  for (j=1; j<=NbPoles2d; j++) {
    newtabP2d = new TColgp_HArray1OfPnt2d(1,NbVPoles);
    multC.Curve(NbUPoles+j,newtabP2d->ChangeArray1());
    seqPoles2d.Append(newtabP2d);
  }
  
  done = Standard_True;
}


//=======================================================================
//function : SurfShape
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::SurfShape (Standard_Integer& UDegree,
				  Standard_Integer& VDegree,
				  Standard_Integer& NbUPoles,
				  Standard_Integer& NbVPoles,
				  Standard_Integer& NbUKnots,
				  Standard_Integer& NbVKnots) const
{
  if (!done) {StdFail_NotDone::Raise();}
  UDegree  = udeg;
  VDegree  = vdeg;
  NbUPoles = tabPoles->ColLength();
  NbVPoles = tabPoles->RowLength();
  NbUKnots = tabUKnots->Length();
  NbVKnots = tabVKnots->Length();
}


void AppBlend_AppSurf::Surface(TColgp_Array2OfPnt& TPoles,
			       TColStd_Array2OfReal& TWeights,
			       TColStd_Array1OfReal& TUKnots,
			       TColStd_Array1OfReal& TVKnots,
			       TColStd_Array1OfInteger& TUMults,
			       TColStd_Array1OfInteger& TVMults) const

{
  if (!done) {StdFail_NotDone::Raise();}
  TPoles   = tabPoles->Array2();
  TWeights = tabWeights->Array2();
  TUKnots  = tabUKnots->Array1();
  TUMults  = tabUMults->Array1();
  TVKnots  = tabVKnots->Array1();
  TVMults  = tabVMults->Array1();
}

//=======================================================================
//function : Curves2dShape
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::Curves2dShape(Standard_Integer& Degree,
				     Standard_Integer& NbPoles,
				     Standard_Integer& NbKnots) const
{
  if (!done) {StdFail_NotDone::Raise();}
  if (seqPoles2d.Length() == 0) {Standard_DomainError::Raise();}
  Degree = vdeg;
  NbPoles = tabPoles->ColLength();
  NbKnots = tabVKnots->Length();
}

//=======================================================================
//function : Curve2d
//purpose  : 
//=======================================================================

void AppBlend_AppSurf::Curve2d(const Standard_Integer Index,
			       TColgp_Array1OfPnt2d& TPoles,
			       TColStd_Array1OfReal& TKnots,
			       TColStd_Array1OfInteger& TMults) const
{
  if (!done) {StdFail_NotDone::Raise();}
  if (seqPoles2d.Length() == 0) {Standard_DomainError::Raise();}
  TPoles = seqPoles2d(Index)->Array1();
  TKnots  = tabVKnots->Array1();
  TMults  = tabVMults->Array1();
}

//=======================================================================
//function : TolCurveOnSurf
//purpose  : 
//=======================================================================

Standard_Real AppBlend_AppSurf::TolCurveOnSurf(const Standard_Integer) const
{
  return tol3dreached; //On ne s'embete pas !!
}