path: root/inc/IntWalk_IWalking_2.gxx

//-- IntWalk_IWalking_2.gxx

#ifndef DEB
#define No_Standard_RangeError
#define No_Standard_OutOfRange
#endif


// _______________________________________________
//
// Cadrage d un point (u, v) dans le domaine naturel d une surface ET mise 
// a jour du couple (u, v) pour le calcul du point suivant.
//
Standard_Boolean IntWalk_IWalking::Cadrage 
  (math_Vector& BornInf,
   math_Vector& BornSup,
   math_Vector& UVap,
   Standard_Real& Step,
//   Standard_Real& StepV,
   const Standard_Integer StepSign) const 

// on a toujours :
// BorInf(1) <= UVap(1) <= BornSup(1) et BorInf(2) <= UVap(2) <= BornSup(2)
// 1) on verifier si le point approche ne depasse pas le domaine naturel de 
//  la surface
// 2) si c est le cas on cadre le point approche sur frontiere en prenant la
//  meilleure direction. On MODIFIE alors le pas d avancement et une des 
//  bornes bloquer un des parametres lors du prochain appel a FunctionSetRoot;
// 3) on recalcule couple (u, v) approche pour le le calcul du point suivant.
// 4) return Standard_True si cadrage, Standard_False si pas de cadrage.
{
  Standard_Real Duvx = previousd2d.X();
  Standard_Real Duvy = previousd2d.Y();

  if (!reversed) {
    previousPoint.ParametersOnS2(UVap(1),UVap(2));
  }
  else {
    previousPoint.ParametersOnS1(UVap(1),UVap(2));
  }

  Standard_Real U1 = UVap(1) + Step * Duvx * StepSign;
  Standard_Real V1 = UVap(2) + Step * Duvy * StepSign;


  Standard_Boolean infu = (U1 <= BornInf(1)+Precision::PConfusion());
  Standard_Boolean supu = (U1 >= BornSup(1)-Precision::PConfusion());
  Standard_Boolean infv = (V1 <= BornInf(2)+Precision::PConfusion());
  Standard_Boolean supv = (V1 >= BornSup(2)-Precision::PConfusion());

  Standard_Real theStepU,theStepV;

  if (!infu && !supu && !infv && !supv) {
    UVap(1) = U1;
    UVap(2) = V1;
    return Standard_False;
  }

  if ((infu || supu) && (infv || supv)) {
    if (infu) { // jag 940616
      if(Duvx) { 
	theStepU = Abs((BornInf(1) - UVap(1)) / Duvx);  // iso U =BornInf(1)
      }
      else { 
	theStepU = Step; 
      }
    }
    else {
      if(Duvx) { 
	theStepU = Abs((BornSup(1) - UVap(1)) / Duvx);  // iso U =BornSup(1)
      }
      else { 
	theStepU = Step;
      }
    }
    if (infv) { // jag 940616
      if(Duvy) { 
	theStepV = Abs((BornInf(2) - UVap(2)) / Duvy);  // iso V =BornInf(2)
      }
      else { 
	theStepV = Step;
      }
    }
    else {
      if(Duvy) { 
	theStepV = Abs((BornSup(2) - UVap(2)) / Duvy);  // iso V =BornSup(2)
      }
      else { 
	theStepV = Step; 
      }
    }


    if (theStepU <= theStepV) {
      Step = theStepU;
      if (infu) {
	UVap(1) = BornInf(1);
	BornSup(1) = BornInf(1);
      }
      else {
	UVap(1) = BornSup(1);
	BornInf(1) = BornSup(1);
      }
      UVap(2) += Step*Duvy*StepSign;
    }
    else {
      Step = theStepV;
      if (infv) {
	UVap(2) = BornInf(2);
	BornSup(2) = BornInf(2); 
      }
      else {
	UVap(2) = BornSup(2);
	BornInf(2) = BornSup(2); 
      }
      UVap(1) += Step*Duvx*StepSign;
    }
    return Standard_True;
  }

  else if (infu) { // jag 940616
    if(Duvx) { 
      Standard_Real aStep = Abs((BornInf(1) - UVap(1)) / Duvx);  // iso U =BornInf(1)
      if(aStep<Step) Step=aStep;
    }
    BornSup(1) = BornInf(1);                     // on bloque le parametre
    UVap(1) = BornInf(1);
    UVap(2) += Step*Duvy*StepSign;;
    return Standard_True;
  }
  else if (supu) { // jag 940616
    if(Duvx) { 
      Standard_Real aStep = Abs((BornSup(1) - UVap(1)) / Duvx);  // iso U =BornSup(1)
      if(aStep<Step) Step=aStep;
    }
    BornInf(1) = BornSup(1);                    // on bloque le parametre
    UVap(1) = BornSup(1);
    UVap(2) += Step*Duvy*StepSign;
    return Standard_True;
  }
  else if (infv) { // jag 940616
    if(Duvy) { 
      Standard_Real aStep = Abs((BornInf(2) - UVap(2)) / Duvy);  // iso V =BornInf(2) 
      if(aStep<Step) Step=aStep;
    }
    BornSup(2) = BornInf(2);
    UVap(1) += Step*Duvx*StepSign;
    UVap(2) = BornInf(2);
    return Standard_True;
  }
  else if (supv) { // jag 940616
    if(Duvy) { 
      Standard_Real aStep = Abs((BornSup(2) - UVap(2)) / Duvy);  // iso V =BornSup(2)
      if(aStep<Step) Step=aStep;
    }
    BornInf(2) = BornSup(2);
    UVap(1) += Step*Duvx*StepSign;
    UVap(2) = BornSup(2);
    return Standard_True;
  }
  return Standard_True;
}


Standard_Boolean IntWalk_IWalking::TestArretPassage
  (const TColStd_SequenceOfReal& Umult,
   const TColStd_SequenceOfReal& Vmult,
   TheIWFunction& sp,
   math_Vector& UV,
   Standard_Integer& Irang)

// Umult et Vmult : tableau des points d arret (ou passant) sur frontiere, ici
//          on ne s interesse qu aux points passant.
// UV     : le point courant.
// Irang  : en sortie : donne l index du point d arret dans uvstart1 ou 0.
//          on considere qu on ne risque de passer que sur un seul point
//          passant.


// test d arret pour une ligne d intersection OUVERTE
// 1) test de passage sur l ensemble des points interieur
// 2) test d arret sur l ensemble des points depart
// si on detecte un arret on renvoie l index du point d arret (Irang) dans 
// l iterateur des points de depart et les parametres associes dans 
// l espace UV.
{
  Standard_Real Up, Vp, Du, Dv, Dup, Dvp, Utest,Vtest; 
  Standard_Integer i, j, k, N, ind;
  Standard_Real tolu = tolerance(1);
  Standard_Real tolv = tolerance(2);
  Standard_Real tolu2 = 10.*tolerance(1);
  Standard_Real tolv2 = 10.*tolerance(2);
  
  Standard_Boolean Arrive = Standard_False;
  
  // test de passage sur point pouvant demarrer une boucle;les marquer traites
  // si passe sur la ligne ouverte
  
  if (!reversed) {
    previousPoint.ParametersOnS2(Up,Vp);
  }
  else {
    previousPoint.ParametersOnS1(Up,Vp);
  }

  for (i = 1; i <= etat2.Length(); i++) { 
    if (etat2(i) > 0) { 
      // debug jag 05.04.94

//      if ((Up-ustart2(i))*(UV(1)-ustart2(i)) +
//	  (Vp-vstart2(i))*(UV(2)-vstart2(i)) <= 0)
      Utest = ustart2(i);
      Vtest = vstart2(i);

      Du  = UV(1)-Utest;
      Dv  = UV(2)-Vtest;
      Dup = Up - Utest;
      Dvp = Vp - Vtest;
      
//-- lbr le 30 oct 97 

      //IFV for OCC20285


 
      if ((Abs(Du) < tolu2 && Abs(Dv) < tolv2) ||
	  (Abs(Dup) < tolu2 && Abs(Dvp) < tolv2)) { 
	    
	etat2(i) = -etat2(i);
      }
      else {
	Standard_Real DDu = (UV(1)-Up);
	Standard_Real DDv = (UV(2)-Vp);
	Standard_Real DDD = DDu*DDu+DDv*DDv;
	Standard_Real DD1 = Du*Du+Dv*Dv;
	if(DD1<=DDD) { 
	  Standard_Real DD2 = Dup*Dup+Dvp*Dvp;
	  if(DD2<=DDD && ((Du*Dup) + (Dv*Dvp*tolu/tolv) <= 0.)) { 	
	    etat2(i) = -etat2(i);
	  }
	}
      }
    }
  }

  // test d arret sur point donne en entree et non encore traite

//  Modified by Sergey KHROMOV - Tue Nov 20 10:55:01 2001 Begin
// Check of all path points in the following order:
//   * First check all not treated points;
//   * After that check of already treated ones.
  Standard_Integer l;

  //// Modified by jgv, 28.07.2010 for OCC21914 ////
  // There are several path points between (Up,Vp) and UV
  // So several path points satisfy the condition
  // Dup*UV1mUtest + Dvp*UV2mVtest) < 0
  // We choose from them the path point with
  // minimum distance to (Up,Vp)
  TColStd_SequenceOfInteger i_candidates;
  TColStd_SequenceOfReal    SqDist_candidates;

  for (l = 1; l <= 2 && !Arrive; l++) {
    Standard_Boolean isToCheck;

    for (i = 1; i <= etat1.Length(); i++) {
      if (l == 1)
	isToCheck = (etat1(i) > 0);
      else
	isToCheck = (etat1(i) < 0);
	
      if (isToCheck) {
//  Modified by Sergey KHROMOV - Tue Nov 20 11:03:16 2001 End

	// debug jag voir avec isg

	Utest = ustart1(i);
	Vtest = vstart1(i);
	Dup = Up - Utest;
	Dvp = Vp - Vtest;
	if (Abs(Dup) >= tolu || Abs(Dvp) >= tolv) {
	  Standard_Real UV1mUtest = UV(1)-Utest;
	  Standard_Real UV2mVtest = UV(2)-Vtest;
	  if(( (Dup*UV1mUtest + Dvp*UV2mVtest) < 0) ||
	     (   Abs(UV1mUtest) < tolu 
	      && Abs(UV2mVtest) < tolv)) {
	    i_candidates.Append(i);
	    SqDist_candidates.Append(Dup*Dup + Dvp*Dvp);
	    /*
	    Irang=i;
	    Arrive = Standard_True;
	    UV(1) = Utest;
	    UV(2) = Vtest;
	    */
	  }
	  else if (nbMultiplicities(i) > 0 && i_candidates.IsEmpty()) {
	    N=0;
	    for (k = 1; k < i; k++) { 
	      N+=nbMultiplicities(k);
	    }
	    for (j = N + 1; j <= N + nbMultiplicities(i); j++) {
	      if (((Up-Umult(j))*(UV(1)-Umult(j)) +
		   (Vp-Vmult(j))*(UV(2)-Vmult(j)) < 0) ||
		  (Abs(UV(1)-Umult(j)) < tolu &&
		   Abs(UV(2)-Vmult(j)) < tolv)) {
		Irang=i;
		Arrive = Standard_True;
		UV(1) = Utest;
		UV(2) = Vtest;
		break;
	      }
	    }
	  }
	  if (Arrive) {
	    static math_Vector bidF(1,1);
	    static math_Matrix bidD(1,1,1,2);
	    sp.Values(UV,bidF,bidD);
	    break;
	  }
	}
      }
    } //end of for (i = 1; i <= etat1.Length(); i++)
    if (!i_candidates.IsEmpty())
      {
	Standard_Real MinSqDist = RealLast();
	for (ind = 1; ind <= i_candidates.Length(); ind++)
	  if (SqDist_candidates(ind) < MinSqDist)
	    {
	      MinSqDist = SqDist_candidates(ind);
	      Irang = i_candidates(ind);
	    }
	Arrive = Standard_True;
	UV(1) = ustart1(Irang);
	UV(2) = vstart1(Irang);
      }
  } //end of for (l = 1; l <= 2 && !Arrive; l++)
  return  Arrive;
}

Standard_Boolean IntWalk_IWalking::TestArretPassage
  (const TColStd_SequenceOfReal& Umult,
   const TColStd_SequenceOfReal& Vmult,
   const math_Vector& UV, 
   const Standard_Integer Index, 
   Standard_Integer& Irang)
{
// Umult, Vmult : tableau des points d arret (ou passant) sur frontiere, ici
//          on ne s interesse qu aux points passant.
// UV     : le point courant.
// Index  : l index du point de demarrage dans uvstart2 de la ligne en cours
//          (c est un point interieur).
// Irang  : en sortie : donne l index du point passant dans uvstart1 ou 0.
//          on considere qu on ne risque de passer que sur un seul point
//          passant.

// test d arret pour une ligne d intersection FERMEE.
// 1) test de passage sur l ensemble des points interieur
// 2) test de passage sur les points passant.

  Standard_Real Up, Vp, Scal;
  Standard_Boolean Arrive = Standard_False;
  Standard_Integer N, k, i;
  Standard_Real Utest,Vtest;
  Standard_Real tolu = tolerance(1);
  Standard_Real tolv = tolerance(2);

  
  // tests d arret et de passage sur points interieurs.

  if (!reversed) {
    previousPoint.ParametersOnS2(Up,Vp);
  }
  else {
    previousPoint.ParametersOnS1(Up,Vp);
  }

  Standard_Real UV1=UV(1);
  Standard_Real UV2=UV(2);


  //-- On met tout le monde ds une boite 0 1  x 0 1 
  //-- en tourte rigueur il faudrait faire les test en 3d

  Standard_Real deltau=UM-Um;
  Standard_Real deltav=VM-Vm;

  Up/=deltau; UV1/=deltau; 
  Vp/=deltav; UV2/=deltav;

  tolu/=deltau;
  tolv/=deltav;

  Standard_Real tolu2=tolu+tolu;
  Standard_Real tolv2=tolv+tolv;

  
  Standard_Real dPreviousCurrent = (Up-UV1)*(Up-UV1)+(Vp-UV2)*(Vp-UV2);
  for (k = 1; k <= etat2.Length(); k++) { 
    if (etat2(k) > 0) {
      Utest = ustart2(k);
      Vtest = vstart2(k);
      
      Utest/=deltau;
      Vtest/=deltav;
      
      Standard_Real UV1mUtest=UV1-Utest;
      Standard_Real UV2mVtest=UV2-Vtest;
      if(   (UV1mUtest<tolu2 && UV1mUtest>-tolu2)
	 && (UV2mVtest<tolv2 && UV2mVtest>-tolv2)) { 
	if(Index!=k) { 
	  //-- cout<<"* etat2 : ("<<k<<")"<<endl;
	  etat2(k)=-etat2(k); //-- marque le point comme point de passage 
	}
	else {  //-- Index == k
	  //-- cout<<"* Arrive"<<endl;
	  Arrive=Standard_True;
	}
      }
      else { 
	Standard_Real UpmUtest = (Up-Utest);
	Standard_Real VpmVtest = (Vp-Vtest);
	Standard_Real dPreviousStart = (UpmUtest)*(UpmUtest)+(VpmVtest)*(VpmVtest);
	Standard_Real dCurrentStart  = UV1mUtest * UV1mUtest + UV2mVtest * UV2mVtest;

	Scal=(UpmUtest)*(UV1mUtest)+(VpmVtest)*(UV2mVtest);
	if( (Abs(UpmUtest)<tolu && Abs(VpmVtest)<tolv)) { 
	  if(Index != k ) { 
	    //-- cout<<"** etat2 : ("<<k<<")"<<endl;
	    etat2(k) = -etat2(k);
	  }
	}
	else if(Scal<0 && (dPreviousStart+dCurrentStart < dPreviousCurrent)) { 
	  if (Index == k ) { // on a boucle.
	    Arrive = Standard_True;
	    //-- cout<<"** Arrive  : k="<<k<<endl;
	  }
	  else {
	    //-- cout<<"*** etat2 : ("<<k<<")"<<endl;
	    etat2(k) = -etat2(k); // marque le point point de passage 
	  }
	}
	else if(k!=Index) {
	  if(dPreviousStart < dPreviousCurrent*0.25) { 
	    etat2(k) = -etat2(k); // marque le point point de passage 
	    //-- cout<<"**** etat2 : ("<<k<<")"<<endl;
	  }
	  else { 
	    if(dCurrentStart < dPreviousCurrent*0.25) {
	      //-- cout<<"***** etat2 : ("<<k<<")"<<endl;
	      etat2(k) = -etat2(k); // marque le point point de passage 
	    }
	    else { 
	      Standard_Real UMidUtest = 0.5*(UV1+Up)-Utest;
	      Standard_Real VMidVtest = 0.5*(UV2+Vp)-Vtest;	    
	      Standard_Real dMiddleStart =  UMidUtest* UMidUtest+VMidVtest*VMidVtest;

	      if(dMiddleStart < dPreviousCurrent*0.5) { 
		//-- cout<<"*********** etat2 : ("<<k<<")"<<endl;
		etat2(k) = -etat2(k); // marque le point point de passage 
	      }
	    }
	  }
	}
      }
    }
  }

  // test de passage sur points passant.
  
  Irang =0;
  for (i = 1; i <= etat1.Length(); i++) {
    if (etat1(i) > 0 && etat1(i) < 11) { //test des points passant
      Utest = ustart1(i);
      Vtest = vstart1(i);
      Utest/=deltau;
      Vtest/=deltav;
      
      if (((Up-Utest) * (UV1-Utest) + (Vp-Vtest) * (UV2-Vtest) < 0) ||
	  (Abs(UV1-Utest) < tolu &&  Abs(UV2-Vtest) < tolv)) 
	Irang = i;
      else if (nbMultiplicities(i) > 0) {
	N=0;
	for (k = 1; k < i; k++) N = N + nbMultiplicities(k);
	for (Standard_Integer j = N + 1; j <= N + nbMultiplicities(i); j++) {
	  Standard_Real Umultj = Umult(j)/deltau;
	  Standard_Real Vmultj = Vmult(j)/deltav;	  
          if (((Up-Umultj)*(UV1-Umultj) +
	       (Vp-Vmultj)*(UV2-Vmultj) < 0) ||
	      (Abs(UV1-Umultj) < tolu &&
	       Abs(UV2-Vmultj) < tolv)) {
	    Irang=i;
	    break;
          }
	}
      }
    }    
  }
  return Arrive;
}


Standard_Boolean IntWalk_IWalking::TestArretAjout
  (TheIWFunction& sp,
   math_Vector& UV, 
   Standard_Integer& Irang,
   IntSurf_PntOn2S& Psol) 

// test d arret sur les points rajoutes 
// ces points sont des points sur frontiere naturelle qui n ont pas ete 
// donnes en entree
// on renvoit : Psol,  le point rajoute.
//              Irang, l index dans l iterateur des points rajoutes.
//              UV,     parametre du point rajoute.
//
{
  Standard_Boolean Arrive = Standard_False;
  Standard_Real U1,V1;
  Standard_Real Up,Vp; 

  if (!reversed) {
    previousPoint.ParametersOnS2(Up,Vp);
  }
  else {
    previousPoint.ParametersOnS1(Up,Vp);
  }

  Standard_Integer nbAjout = seqAjout.Length();
  for (Standard_Integer i = 1; i <= nbAjout; i++) {
    Irang = seqAjout.Value(i);

// on rajoute le test Abs(Irang) <= lines.Length() pour le cas ou
// on ouvre une ligne fermee suite a l ajout 1 point sur cette meme
// ligne. De toute facon on a un gros pb , car on va avoir 2 points
// rajoutes sur cette ligne...

    if (Abs(Irang) <= lines.Length()) {

      const Handle(IntWalk_TheIWLine)& Line = lines.Value(Abs(Irang));
      if (Irang>0) 
	Psol = Line->Value(Line->NbPoints()); 
      else 
	Psol = Line->Value(1);
      if (!reversed) {
	Psol.ParametersOnS2(U1, V1);
      }
      else {
	Psol.ParametersOnS1(U1, V1);
      }
      if (((Up-U1) * (UV(1)-U1) + 
	   (Vp-V1) * (UV(2)-V1)) < 0 ||
	  (Abs(UV(1)-U1) < tolerance(1) &&  
	   Abs(UV(2)-V1) < tolerance(2))) {
//jag 940615	Irang= -Abs(Irang); 
	Arrive = Standard_True; 
	UV(1) = U1;
	UV(2) = V1;
	static math_Vector bidF(1,1);
	static math_Matrix bidD(1,1,1,2);
	sp.Values(UV,bidF,bidD);
	break;
      }
    }
  }
  return Arrive;
}

void IntWalk_IWalking::TestArretCadre
  (const TColStd_SequenceOfReal& Umult,
   const TColStd_SequenceOfReal& Vmult,
   const Handle(IntWalk_TheIWLine)& Line,
   TheIWFunction& sp,
   math_Vector& UV,
   Standard_Integer& Irang)

// test d arret alors qu on est sur frontiere.
// on a essaye tous les tests d  arret et on est arrive.
// test d  arret sur les points donne au depart deja marques et sur 
// l  ensemble de la ligne courante. Cette ligne peut etre racourcie si
// on trouve in point d arret.
// Abs(Irang) = index dans l  iterateur des points de depart ou 0
//  si Irang <0 , il faut ajouter ce point a la ligne ( pas de Line->Cut)
// UV = parametre du point de depart
{
  Standard_Real Scal, Up, Vp, Uc, Vc;
  Standard_Integer N;
  Standard_Boolean Found = Standard_False;


  Irang =0;
  for (Standard_Integer i = 1; i <= etat1.Length(); i++) {
    if (etat1(i) < 0) {
      N=0; // rang dans UVMult.
      if (nbMultiplicities(i) > 0) {
	for (Standard_Integer k = 1; k < i; k++) 
	  N+=nbMultiplicities(k);
      }
      if (!reversed) {
	Line->Value(1).ParametersOnS2(Up,Vp);
      }
      else {
	Line->Value(1).ParametersOnS1(Up,Vp);
      }
      Standard_Integer nbp= Line->NbPoints();
      for (Standard_Integer j = 2; j <= nbp; j++) {
	if (!reversed) {
	  Line->Value(j).ParametersOnS2(Uc,Vc);
	}
	else {
	  Line->Value(j).ParametersOnS1(Uc,Vc);
	}

	Scal = (Up-ustart1(i)) * (Uc-ustart1(i)) +
	       (Vp-vstart1(i)) * (Vc-vstart1(i));
        // si on a trouve un point d arret : on arrete la ligne sur ce point.
	if (Scal < 0) { 
          Line->Cut(j);  nbp= Line->NbPoints();
          Irang = i;
	  UV(1) = ustart1(Irang);
	  UV(2) = vstart1(Irang);
          Found = Standard_True;
	}
	else if (Abs(Uc-ustart1(i)) < tolerance(1) &&
		 Abs(Vc-vstart1(i)) < tolerance(2) ) {
          Line->Cut(j);  nbp= Line->NbPoints();
          Irang=i; 
	  UV(1) = ustart1(Irang);
	  UV(2) = vstart1(Irang);
          Found = Standard_True;
	}
	else if (nbMultiplicities(i) > 0) {
          for (Standard_Integer k = N+1; k <= N + nbMultiplicities(i); k++) {
	    Scal = (Up-Umult(k)) * (Uc-Umult(k)) +
	           (Vp-Vmult(k)) * (Vc-Vmult(k));
	    if (Scal < 0) { 
	      Line->Cut(j);  nbp= Line->NbPoints();
	      Irang=i;
	      UV(1) = ustart1(Irang);
	      UV(2) = vstart1(Irang);
	      Found = Standard_True;
	      break;
	    }
	    else if (Abs(Uc-Umult(k)) < tolerance(1) &&
		     Abs(Vc-Vmult(k)) < tolerance(2)) {
	      Line->Cut(j);  nbp= Line->NbPoints();
	      Irang=i; 
	      UV(1) = ustart1(Irang);
	      UV(2) = vstart1(Irang);
	      Found = Standard_True;
	      break;
	    }
          }
	}
	if (Found) {
	  static math_Vector bidF(1,1);
	  static math_Matrix bidD(1,1,1,2);
	  sp.Values(UV,bidF,bidD);
	  Standard_Integer NBP =  Line->NbPoints();
	  Standard_Integer Indextg;	  
	  Line->TangentVector(Indextg);
	  if(Indextg > NBP) { 
	    if(j>3 && j<=NBP+1) { 
	      gp_Vec Dir3d = sp.Direction3d();
	      gp_Vec Dir3d1 = gp_Vec(Line->Value(j-2).Value(),Line->Value(j-1).Value());
	      Standard_Real dot = Dir3d.Dot(Dir3d1);
	      if(dot<0.0) { // Normalement on ne doit pas passer souvent ds cette Fonction !!! 
		Dir3d.Reverse();
		//-- cout<<" IntWalk_IWalking_2.gxx REVERSE "<<endl;
	      }
	      Line->SetTangentVector(previousd3d,j-1);
	    }
#ifdef DEB
	    else { 
	      cout<<" IntWalk_IWalking_2.gxx : bizarrerie 30 10 97 "<<endl;
	    }
#endif
	  }

	  return;
	}
	Up = Uc;
	Vp = Vc;
      }

      // et maintenant on compare le dernier point de la ligne et le dernier
      // point calcule.
      // il n y aura pas besoin de "Cuter"

      Scal = (Up-ustart1(i)) * (UV(1)-ustart1(i)) +
	// 	(Vp-ustart1(i)) * (UV(2)-vstart1(i));
      // modified by NIZHNY-MKK  Fri Oct 27 12:29:41 2000
	(Vp-vstart1(i)) * (UV(2)-vstart1(i));

      if (Scal < 0) { 
        Irang = i;
	UV(1) = ustart1(Irang);
	UV(2) = vstart1(Irang);
	Found = Standard_True;
      }
      else if (Abs(UV(1)-ustart1(i)) < tolerance(1) &&
	       Abs(UV(2)-vstart1(i)) < tolerance(2)) {
        Irang=i; 
	UV(1) = ustart1(Irang);
	UV(2) = vstart1(Irang);
	Found = Standard_True;
      }
      else if (nbMultiplicities(i) > 0) {
        for (Standard_Integer j = N+1; j <= N+nbMultiplicities(i); j++) {
	  Scal = (Up-Umult(j)) * (UV(1)-Umult(j)) +
                 (Vp-Vmult(j)) * (UV(2)-Vmult(j));
	  if (Scal < 0) { 
	    Irang=i;
	    UV(1) = ustart1(Irang);
	    UV(2) = vstart1(Irang);
	    Found = Standard_True;
	    break;
	  }
	  else if (Abs(UV(1)-Umult(j)) < tolerance(1) &&
		   Abs(UV(2)-Vmult(j)) < tolerance(2)) {
	    Irang=i; 
	    UV(1) = ustart1(Irang);
	    UV(2) = vstart1(Irang);
	    Found = Standard_True;
	    break;
	  }
        }
      }
      if (Found) {
	Irang = -Irang; // jag 941017
	static math_Vector bidF(1,1);
	static math_Matrix bidD(1,1,1,2);
	sp.Values(UV,bidF,bidD);
	return;
      }
    }
  } 
}