[occt.git] / src / BRepTools / BRepTools_WireExplorer.cxx

// Created on: 1993-01-21
// Created by: Remi LEQUETTE
// Copyright (c) 1993-1999 Matra Datavision
// Copyright (c) 1999-2014 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and / or modify it
// under the terms of the GNU Lesser General Public version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#include <BRepTools_WireExplorer.ixx>
#include <TopExp.hxx>
#include <TopoDS.hxx>
#include <TopoDS_Iterator.hxx>
#include <TopTools_MapOfShape.hxx>
#include <TopTools_MapIteratorOfMapOfShape.hxx>
#include <TopTools_ListOfShape.hxx>
#include <TopTools_ListIteratorOfListOfShape.hxx>
#include <TopTools_DataMapIteratorOfDataMapOfShapeListOfShape.hxx>
#include <BRep_Tool.hxx>
#include <gp_Pnt2d.hxx>
#include <Precision.hxx>
#include <BRepTools.hxx>
#include <Geom2d_Curve.hxx>
#include <GeomAdaptor_Surface.hxx>
#include <TopExp_Explorer.hxx>
#include <Geom_Surface.hxx>

//=======================================================================
// forward declarations of aux functions
//=======================================================================
static Standard_Boolean SelectDouble(TopTools_MapOfShape& Doubles,
				     TopTools_ListOfShape& L,
				     TopoDS_Edge&          E);

static Standard_Boolean SelectDegenerated(TopTools_ListOfShape& L,
					  TopoDS_Edge&          E);

static Standard_Real GetNextParamOnPC(const Handle(Geom2d_Curve)& aPC,
				      const gp_Pnt2d& aPRef,
				      const Standard_Real& fP,
				      const Standard_Real& lP,
				      const Standard_Real& tolU,
				      const Standard_Real& tolV,
				      const Standard_Boolean& reverse);

//=======================================================================
//function : BRepTools_WireExplorer
//purpose  : 
//=======================================================================
BRepTools_WireExplorer::BRepTools_WireExplorer() 
{
}

//=======================================================================
//function : BRepTools_WireExplorer
//purpose  : 
//=======================================================================
BRepTools_WireExplorer::BRepTools_WireExplorer(const TopoDS_Wire& W)
{
  TopoDS_Face F = TopoDS_Face();
  Init(W,F);
}

//=======================================================================
//function : BRepTools_WireExplorer
//purpose  : 
//=======================================================================
BRepTools_WireExplorer::BRepTools_WireExplorer(const TopoDS_Wire& W,
					       const TopoDS_Face& F)
{
  Init(W,F);
}

//=======================================================================
//function : Init
//purpose  : 
//=======================================================================
void  BRepTools_WireExplorer::Init(const TopoDS_Wire& W)
{  
  TopoDS_Face F = TopoDS_Face();
  Init(W,F);
}

//=======================================================================
//function : Init
//purpose  : 
//=======================================================================
void  BRepTools_WireExplorer::Init(const TopoDS_Wire& W,
				   const TopoDS_Face& F)
{
  myEdge = TopoDS_Edge();
  myVertex = TopoDS_Vertex();
  myMap.Clear();
  myDoubles.Clear();

  if( W.IsNull() )
    return;

  myFace = F;
  Standard_Real dfVertToler = 0.;
  myReverse = Standard_False;

  if (!myFace.IsNull())
    {
      BRepTools::Update(myFace);
      TopLoc_Location aL;  
      const Handle(Geom_Surface)& aSurf = BRep_Tool::Surface(myFace, aL);
      GeomAdaptor_Surface aGAS(aSurf);
      TopExp_Explorer anExp(W, TopAbs_VERTEX);
      for(; anExp.More(); anExp.Next())
	{
	  const TopoDS_Vertex& aV = TopoDS::Vertex(anExp.Current());
	  dfVertToler = Max(BRep_Tool::Tolerance(aV), dfVertToler);
	}
      myTolU = 2. * aGAS.UResolution(dfVertToler);
      myTolV = 2. * aGAS.VResolution(dfVertToler);
      
      // uresolution for cone with infinite vmin vmax is too small.
      if(aGAS.GetType() == GeomAbs_Cone)
	{
	  Standard_Real u1, u2, v1, v2;
	  BRepTools::UVBounds(myFace, u1, u2, v1, v2);
	  gp_Pnt aP;
	  gp_Vec aD1U, aD1V;
	  aGAS.D1(u1, v1, aP, aD1U, aD1V);
	  Standard_Real tol1, tol2, maxtol = .0005*(u2-u1);
	  Standard_Real a = aD1U.Magnitude();

	  if(a <= Precision::Confusion())
	    tol1 = maxtol;
	  else
	    tol1 = Min(maxtol, dfVertToler/a);

	  aGAS.D1(u1, v2, aP, aD1U, aD1V);
	  a = aD1U.Magnitude();
	  if(a <= Precision::Confusion())
	    tol2 = maxtol;
	  else
	    tol2 = Min(maxtol, dfVertToler/a);

	  myTolU = 2. * Max(tol1, tol2);
	}

      if( aGAS.GetType() == GeomAbs_BSplineSurface || 
	  aGAS.GetType() == GeomAbs_BezierSurface )
	{
	  Standard_Real maxTol = Max(myTolU,myTolV);
	  myTolU = maxTol;
	  myTolV = maxTol;
	}

      myReverse = (myFace.Orientation() == TopAbs_REVERSED);
    }
      
  // map of vertices to know if the wire is open
  TopTools_MapOfShape vmap;
  //  Modified by Sergey KHROMOV - Mon May 13 11:50:48 2002 Begin
  //  map of infinite edges
  TopTools_MapOfShape anInfEmap;
  //  Modified by Sergey KHROMOV - Mon May 13 11:50:49 2002 End

  // list the vertices
  TopoDS_Vertex V1,V2;
  TopTools_ListOfShape empty;

  TopoDS_Iterator it(W);
  while (it.More())
    {
      const TopoDS_Edge& E = TopoDS::Edge(it.Value());
      TopAbs_Orientation Eori = E.Orientation();
      if (Eori == TopAbs_INTERNAL || Eori == TopAbs_EXTERNAL)
	{
	  it.Next();
	  continue;
	}
      TopExp::Vertices(E,V1,V2,Standard_True);

      if( !V1.IsNull() )
	{
	  if( !myMap.IsBound(V1) )
	    myMap.Bind(V1,empty);
	  myMap(V1).Append(E);

	  // add or remove in the vertex map
	  V1.Orientation(TopAbs_FORWARD);
	  if( !vmap.Add(V1) )
	    vmap.Remove(V1);
	}

      if( !V2.IsNull() )
	{
	  V2.Orientation(TopAbs_REVERSED);
	  if(!vmap.Add(V2))
	    vmap.Remove(V2);
	}

      //  Modified by Sergey KHROMOV - Mon May 13 11:52:20 2002 Begin
      if (V1.IsNull() || V2.IsNull())
	{
	  Standard_Real aF = 0., aL = 0.;
	  BRep_Tool::Range(E, aF, aL);
	  
	  if(Eori == TopAbs_FORWARD)
	    {
	      if (aF == -Precision::Infinite())
		anInfEmap.Add(E);
	    }
	  else
	    { // Eori == TopAbs_REVERSED
	      if (aL == Precision::Infinite())
		anInfEmap.Add(E);
	    }
	}
      //  Modified by Sergey KHROMOV - Mon May 13 11:52:20 2002 End
      it.Next();
    }

  //Construction of the set of double edges.
  TopoDS_Iterator it2(W);  
  TopTools_MapOfShape emap;
  while (it2.More()) {
    if (!emap.Add(it2.Value())) 
      myDoubles.Add(it2.Value());
    it2.Next();
  }

  // if vmap is not empty the wire is open, let us find the first vertex
  if (!vmap.IsEmpty()) {
    TopTools_MapIteratorOfMapOfShape itt(vmap); // skl : I change "it" to "itt"
    while (itt.Key().Orientation() != TopAbs_FORWARD) {
      itt.Next();
      if (!itt.More()) break;
    }
    if (itt.More()) V1 = TopoDS::Vertex(itt.Key());
  }
  else {
//  Modified by Sergey KHROMOV - Mon May 13 12:05:30 2002 Begin
//   The wire is infinite Try to find the first vertex. It may be NULL.
    if (!anInfEmap.IsEmpty()) {
      TopTools_MapIteratorOfMapOfShape itt(anInfEmap);

      for (; itt.More(); itt.Next()) {
	TopoDS_Edge        anEdge = TopoDS::Edge(itt.Key());
	TopAbs_Orientation anOri  = anEdge.Orientation();
	Standard_Real      aF;
	Standard_Real      aL;

	BRep_Tool::Range(anEdge, aF, aL);
	if ((anOri == TopAbs_FORWARD  && aF == -Precision::Infinite()) ||
	    (anOri == TopAbs_REVERSED && aL ==  Precision::Infinite())) {
	  myEdge   = anEdge;
	  myVertex = TopoDS_Vertex();

	  return;
	}
      }
    }
//  Modified by Sergey KHROMOV - Mon May 13 12:05:31 2002 End


    // use the first vertex in iterator
    it.Initialize(W);
    while (it.More()) {
      const TopoDS_Edge& E = TopoDS::Edge(it.Value());
      TopAbs_Orientation Eori = E.Orientation();
      if (Eori == TopAbs_INTERNAL || Eori == TopAbs_EXTERNAL) {
	// JYL 10-03-97 : waiting for correct processing 
	// of INTERNAL/EXTERNAL edges
	it.Next();
	continue;
      }
      TopExp::Vertices(E,V1,V2,Standard_True);
      break;
    }
  }

  if (V1.IsNull() ) return;
  if (!myMap.IsBound(V1)) return;
  
  TopTools_ListOfShape& l = myMap(V1);
  myEdge = TopoDS::Edge(l.First());
  l.RemoveFirst();
  myVertex = TopExp::FirstVertex (myEdge, Standard_True);

}

//=======================================================================
//function : More
//purpose  : 
//=======================================================================
Standard_Boolean  BRepTools_WireExplorer::More()const 
{
  return !myEdge.IsNull();
}

//=======================================================================
//function : Next
//purpose  : 
//=======================================================================
void  BRepTools_WireExplorer::Next()
{
  myVertex = TopExp::LastVertex (myEdge, Standard_True);

  if (myVertex.IsNull()) {
     myEdge = TopoDS_Edge();
     return;
  }
  if (!myMap.IsBound(myVertex)) {
     myEdge = TopoDS_Edge();
     return;
  }

  TopTools_ListOfShape& l = myMap(myVertex);

  if (l.IsEmpty()) {
    myEdge = TopoDS_Edge();
  }
  else if (l.Extent() == 1) {
//  Modified by Sergey KHROMOV - Fri Jun 21 10:28:01 2002 OCC325 Begin
    TopoDS_Vertex aV1;
    TopoDS_Vertex aV2;
    TopoDS_Edge   aNextEdge = TopoDS::Edge(l.First());

    TopExp::Vertices(aNextEdge, aV1, aV2, Standard_True);

    if (!aV1.IsSame(myVertex)) {
      myEdge = TopoDS_Edge();
      return;
    }
    if (!myFace.IsNull() && aV1.IsSame(aV2)) {
      Handle(Geom2d_Curve) aPrevPC;
      Handle(Geom2d_Curve) aNextPC;
      Standard_Real        aPar11, aPar12;
      Standard_Real        aPar21, aPar22;
      Standard_Real        aPrevPar;
      Standard_Real        aNextFPar;
      Standard_Real        aNextLPar;

      aPrevPC = BRep_Tool::CurveOnSurface(myEdge, myFace, aPar11, aPar12);
      aNextPC = BRep_Tool::CurveOnSurface(aNextEdge, myFace, aPar21, aPar22);

      if (aPrevPC.IsNull() || aNextPC.IsNull()) {
	      myEdge = TopoDS_Edge();
	      return;
      }

      if (myEdge.Orientation() == TopAbs_FORWARD)
	      aPrevPar = aPar12;
      else
	      aPrevPar = aPar11;

      if (aNextEdge.Orientation() == TopAbs_FORWARD) {
	      aNextFPar = aPar21;
	      aNextLPar = aPar22;
      } else {
	      aNextFPar = aPar22;
	      aNextLPar = aPar21;
      }

      gp_Pnt2d aPPrev  = aPrevPC->Value(aPrevPar);
      gp_Pnt2d aPNextF = aNextPC->Value(aNextFPar);
      gp_Pnt2d aPNextL = aNextPC->Value(aNextLPar);

      if (aPPrev.SquareDistance(aPNextF) > aPPrev.SquareDistance(aPNextL)) {
	      myEdge = TopoDS_Edge();
	      return;
      }
    }
//  Modified by Sergey KHROMOV - Fri Jun 21 11:08:16 2002 End
    myEdge = TopoDS::Edge(l.First());
    l.Clear();
  }
  else {
    if (myFace.IsNull()) {
      // Without Face - try to return edges
      // as logically as possible
      // At first degenerated edges.
      TopoDS_Edge E = myEdge;
      if (SelectDegenerated(l,E)) {
	      myEdge = E;
	      return;
      }
      // At second double edges.
      E = myEdge;
      if (SelectDouble(myDoubles,l,E)) {
	      myEdge = E;
	      return;
      }

      TopTools_ListIteratorOfListOfShape it(l); 
      Standard_Boolean notfound = Standard_True;
      while (it.More()) {
	      if (!it.Value().IsSame(myEdge)) {
	        myEdge = TopoDS::Edge(it.Value());
	        l.Remove(it);
	        notfound = Standard_False;
	        break;
	      }
	      it.Next();
      }
      
      if(notfound) {
	      myEdge = TopoDS_Edge();
	      return;
      }

    }
    else
    {
      // If we have more than one edge attached to the list
      // probably wire that we explore contains a loop or loops.
      Standard_Real dfFPar = 0., dfLPar = 0.;
      Handle(Geom2d_Curve) aPCurve = BRep_Tool::CurveOnSurface (myEdge, myFace, dfFPar, dfLPar);
      if(aPCurve.IsNull())
      {
        myEdge = TopoDS_Edge();
        return;
      }
      // Note: current < myVertex > which is last on < myEdge >
      //       equals in 2D to following 2D points:
      //       edge is FORWARD  - point with MAX parameter on PCurve;
      //       edge is REVERSED - point with MIN parameter on PCurve.

      // Get 2D point equals to < myVertex > in 2D for current edge.
      gp_Pnt2d PRef;
      if( myEdge.Orientation() == TopAbs_REVERSED )
        aPCurve->D0(dfFPar, PRef);
      else 
        aPCurve->D0(dfLPar, PRef);

      // Get next 2D point from current edge's PCurve with parameter
      // F + dP (REV) or L - dP (FOR)
      Standard_Boolean isrevese = ( myEdge.Orientation() == TopAbs_REVERSED );
      Standard_Real dfMPar = GetNextParamOnPC(aPCurve,PRef,dfFPar,dfLPar,myTolU,myTolV,isrevese);

      gp_Pnt2d PRefm;
      aPCurve->D0(dfMPar, PRefm);
      // Get vector from PRef to PRefm
      gp_Vec2d anERefDir(PRef,PRefm);
      // Search the list of edges looking for the edge having hearest
      // 2D point of connected vertex to current one and smallest angle.
      // First process all degenerated edges, then - all others.

      TopTools_ListIteratorOfListOfShape it;
      Standard_Integer k = 1, kMin = 0, iDone = 0;
      Standard_Boolean isDegenerated = Standard_True;
      Standard_Real dmin = RealLast();
      Standard_Real dfMinAngle = 3.0*M_PI, dfCurAngle = 3.0*M_PI;

      for(iDone = 0; iDone < 2; iDone++)
      {
        it.Initialize(l);
        while( it.More() )
        {
	        const TopoDS_Edge& E = TopoDS::Edge(it.Value());
	        if( E.IsSame(myEdge) )
	        {
	          it.Next();
	          k++;
	          continue;
	        }
  		
	        TopoDS_Vertex aVert1, aVert2;
	        TopExp::Vertices (E, aVert1, aVert2, Standard_True);
	        if( aVert1.IsNull() || aVert2.IsNull() )
          {
            it.Next();
            k++;
            continue;
          }
  		
	        aPCurve = BRep_Tool::CurveOnSurface (E, myFace, dfFPar, dfLPar);
	        if( aPCurve.IsNull() )
          {
            it.Next();
            k++;
            continue;
          }
    		
	        gp_Pnt2d aPEb, aPEe;
	        if( aVert1.IsSame(aVert2) == isDegenerated )
	        {
	          if( E.Orientation() == TopAbs_REVERSED )
	            aPCurve->D0(dfLPar, aPEb);
	          else	
	            aPCurve->D0(dfFPar, aPEb);

	          if( Abs(dfLPar-dfFPar) > Precision::PConfusion() )
	          {
		          isrevese = ( E.Orientation() == TopAbs_REVERSED );
		          isrevese = !isrevese;
		          Standard_Real aEPm = GetNextParamOnPC(aPCurve,aPEb,dfFPar,dfLPar,myTolU,myTolV,isrevese);
        			
		          aPCurve->D0 (aEPm, aPEe);
              if(aPEb.SquareDistance(aPEe) <= gp::Resolution())
              {
                //seems to be very short curve
                gp_Vec2d aD;
                aPCurve->D1(aEPm, aPEe, aD);
	              if( E.Orientation() == TopAbs_REVERSED )
                  aPEe.SetXY(aPEb.XY()-aD.XY());
	              else	
                  aPEe.SetXY(aPEb.XY()+aD.XY());

                if(aPEb.SquareDistance(aPEe) <= gp::Resolution())
                {
                  it.Next();
                  k++;
                  continue;
                }
              }
		          gp_Vec2d anEDir(aPEb, aPEe);
		          dfCurAngle = Abs( anEDir.Angle(anERefDir) );
	          }

	          if( dfCurAngle <= dfMinAngle )
	          {
		          Standard_Real d = PRef.SquareDistance(aPEb);
		          if( d <= Precision::PConfusion() )
		            d = 0.;
		          if( Abs(aPEb.X()-PRef.X()) < myTolU  &&  Abs(aPEb.Y()-PRef.Y()) < myTolV )
		          {
		            if( d <= dmin )
		            {
			            dfMinAngle = dfCurAngle;
			            kMin = k;
			            dmin = d;
		            }
		          }
	          }
	        }
	        it.Next();
	        k++;
        }// while it

        if( kMin == 0 )
        {
	        isDegenerated = Standard_False;
	        k = 1;
	        dmin = RealLast();
        }
        else
          break;
      }// for iDone

      if(kMin == 0)
      {
        // probably unclosed in 2d space wire
        myEdge = TopoDS_Edge();
        return;
      }

      // Selection the edge.
      it.Initialize(l);
      k = 1;
      while( it.More() )
      {
        if( k == kMin )
        {
          myEdge = TopoDS::Edge(it.Value());
          l.Remove(it);
          break;
        }
        it.Next();
        k++;
      }
    }//else face != NULL && l > 1
  }//else l > 1
}

//=======================================================================
//function : Current
//purpose  : 
//=======================================================================
const TopoDS_Edge&  BRepTools_WireExplorer::Current()const 
{
  return myEdge;
}

//=======================================================================
//function : Orientation
//purpose  : 
//=======================================================================
TopAbs_Orientation BRepTools_WireExplorer::Orientation() const
{
  TopoDS_Iterator it(myEdge,Standard_False);
  while (it.More()) {
    if (myVertex.IsSame(it.Value()))
      return it.Value().Orientation();
    it.Next();
  }
  Standard_NoSuchObject::Raise("BRepTools_WireExplorer::Orientation");
  return TopAbs_FORWARD;
}

//=======================================================================
//function : CurrentVertex
//purpose  : 
//=======================================================================
const TopoDS_Vertex& BRepTools_WireExplorer::CurrentVertex() const
{
  return myVertex;
}

//=======================================================================
//function : Clear
//purpose  : 
//=======================================================================

void BRepTools_WireExplorer::Clear()
{
  myMap.Clear();
  myDoubles.Clear();
  myEdge = TopoDS_Edge();
  myFace = TopoDS_Face();
  myVertex = TopoDS_Vertex();
}


//=======================================================================
//function : SelectDouble
//purpose  : 
//=======================================================================

Standard_Boolean SelectDouble(TopTools_MapOfShape& Doubles,
			      TopTools_ListOfShape& L,
			      TopoDS_Edge&          E)
{
  TopTools_ListIteratorOfListOfShape it(L);
  
  for (; it.More(); it.Next()) {
    const TopoDS_Shape& CE = it.Value();
    if (Doubles.Contains(CE) && (!E.IsSame(CE))) {
      E = TopoDS::Edge(CE);
      L.Remove(it);
      return 1;
    }
  }
  return 0;
}

//=======================================================================
//function : SelectDegenerated
//purpose  : 
//=======================================================================

Standard_Boolean SelectDegenerated(TopTools_ListOfShape& L,
				   TopoDS_Edge&          E)
{
  TopTools_ListIteratorOfListOfShape it(L);
  while (it.More()) {
    if (!it.Value().IsSame(E)) {
      E = TopoDS::Edge(it.Value());
      if (BRep_Tool::Degenerated(E)) {
	L.Remove(it);
	return 1;
      }
    }
    it.Next();
  } 
  return 0;
}

//=======================================================================
//function : GetNextParamOnPC
//purpose  : 
//=======================================================================
Standard_Real GetNextParamOnPC(const Handle(Geom2d_Curve)& aPC,
			       const gp_Pnt2d& aPRef,
			       const Standard_Real& fP,
			       const Standard_Real& lP,
			       const Standard_Real& tolU,
			       const Standard_Real& tolV,
			       const Standard_Boolean& reverse)
{
  Standard_Real result = ( reverse ) ? fP : lP;
  Standard_Real dP = Abs( lP - fP ) / 1000.; // was / 16.;
  if( reverse )
    {
      Standard_Real startPar = fP;
      Standard_Boolean nextPntOnEdge = Standard_False;
      while( !nextPntOnEdge && startPar < lP )
	{
	  gp_Pnt2d pnt;
	  startPar += dP;
	  aPC->D0(startPar, pnt);
	  if( Abs( aPRef.X() - pnt.X() ) < tolU && Abs( aPRef.Y() - pnt.Y() ) < tolV )
	    continue;
	  else
	    {
	      result = startPar;
	      nextPntOnEdge = Standard_True;
	      break;
	    }
	}
      
      if( !nextPntOnEdge )
	result = lP;

      if( result > lP )
	result = lP;
    }
  else
    {
      Standard_Real startPar = lP;
      Standard_Boolean nextPntOnEdge = Standard_False;
      while( !nextPntOnEdge && startPar > fP )
	{
	  gp_Pnt2d pnt;
	  startPar -= dP;
	  aPC->D0(startPar, pnt);
	  if( Abs( aPRef.X() - pnt.X() ) < tolU && Abs( aPRef.Y() - pnt.Y() ) < tolV )
	    continue;
	  else
	    {
	      result = startPar;
	      nextPntOnEdge = Standard_True;
	      break;
	    }
	}
      
      if( !nextPntOnEdge )
	result = fP;

      if( result < fP )
	result = fP;
    }

  return result;
}
Commit	Line	Data
b311480e	1	// Created on: 1993-01-21
	2	// Created by: Remi LEQUETTE
	3	// Copyright (c) 1993-1999 Matra Datavision
973c2be1	4	// Copyright (c) 1999-2014 OPEN CASCADE SAS
b311480e	5	//
973c2be1	6	// This file is part of Open CASCADE Technology software library.
b311480e	7	//
973c2be1	8	// This library is free software; you can redistribute it and / or modify it
	9	// under the terms of the GNU Lesser General Public version 2.1 as published
	10	// by the Free Software Foundation, with special exception defined in the file
	11	// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
	12	// distribution for complete text of the license and disclaimer of any warranty.
b311480e	13	//
973c2be1	14	// Alternatively, this file may be used under the terms of Open CASCADE
973c2be1	15	// commercial license or contractual agreement.
7fd59977	16
	17	#include <BRepTools_WireExplorer.ixx>
	18	#include <TopExp.hxx>
	19	#include <TopoDS.hxx>
	20	#include <TopoDS_Iterator.hxx>
	21	#include <TopTools_MapOfShape.hxx>
	22	#include <TopTools_MapIteratorOfMapOfShape.hxx>
	23	#include <TopTools_ListOfShape.hxx>
	24	#include <TopTools_ListIteratorOfListOfShape.hxx>
	25	#include <TopTools_DataMapIteratorOfDataMapOfShapeListOfShape.hxx>
	26	#include <BRep_Tool.hxx>
	27	#include <gp_Pnt2d.hxx>
	28	#include <Precision.hxx>
	29	#include <BRepTools.hxx>
	30	#include <Geom2d_Curve.hxx>
	31	#include <GeomAdaptor_Surface.hxx>
	32	#include <TopExp_Explorer.hxx>
	33	#include <Geom_Surface.hxx>
	34
	35	//=======================================================================
	36	// forward declarations of aux functions
	37	//=======================================================================
	38	static Standard_Boolean SelectDouble(TopTools_MapOfShape& Doubles,
	39	TopTools_ListOfShape& L,
	40	TopoDS_Edge& E);
	41
	42	static Standard_Boolean SelectDegenerated(TopTools_ListOfShape& L,
	43	TopoDS_Edge& E);
	44
	45	static Standard_Real GetNextParamOnPC(const Handle(Geom2d_Curve)& aPC,
	46	const gp_Pnt2d& aPRef,
	47	const Standard_Real& fP,
	48	const Standard_Real& lP,
	49	const Standard_Real& tolU,
	50	const Standard_Real& tolV,
	51	const Standard_Boolean& reverse);
	52
	53	//=======================================================================
	54	//function : BRepTools_WireExplorer
	55	//purpose :
	56	//=======================================================================
	57	BRepTools_WireExplorer::BRepTools_WireExplorer()
	58	{
	59	}
	60
	61	//=======================================================================
	62	//function : BRepTools_WireExplorer
	63	//purpose :
	64	//=======================================================================
	65	BRepTools_WireExplorer::BRepTools_WireExplorer(const TopoDS_Wire& W)
	66	{
	67	TopoDS_Face F = TopoDS_Face();
	68	Init(W,F);
	69	}
	70
	71	//=======================================================================
	72	//function : BRepTools_WireExplorer
	73	//purpose :
	74	//=======================================================================
	75	BRepTools_WireExplorer::BRepTools_WireExplorer(const TopoDS_Wire& W,
	76	const TopoDS_Face& F)
	77	{
	78	Init(W,F);
	79	}
80
81	//=======================================================================
82	//function : Init
83	//purpose :
84	//=======================================================================
85	void BRepTools_WireExplorer::Init(const TopoDS_Wire& W)
86	{
87	TopoDS_Face F = TopoDS_Face();
88	Init(W,F);
89	}
90
91	//=======================================================================
92	//function : Init
93	//purpose :
94	//=======================================================================
95	void BRepTools_WireExplorer::Init(const TopoDS_Wire& W,
96	const TopoDS_Face& F)
97	{
98	myEdge = TopoDS_Edge();
99	myVertex = TopoDS_Vertex();
100	myMap.Clear();
101	myDoubles.Clear();
102
103	if( W.IsNull() )
104	return;
105
106	myFace = F;
107	Standard_Real dfVertToler = 0.;
108	myReverse = Standard_False;
109
110	if (!myFace.IsNull())
111	{
112	BRepTools::Update(myFace);
113	TopLoc_Location aL;
114	const Handle(Geom_Surface)& aSurf = BRep_Tool::Surface(myFace, aL);
115	GeomAdaptor_Surface aGAS(aSurf);
116	TopExp_Explorer anExp(W, TopAbs_VERTEX);
117	for(; anExp.More(); anExp.Next())
118	{
119	const TopoDS_Vertex& aV = TopoDS::Vertex(anExp.Current());
120	dfVertToler = Max(BRep_Tool::Tolerance(aV), dfVertToler);
121	}
122	myTolU = 2. * aGAS.UResolution(dfVertToler);
123	myTolV = 2. * aGAS.VResolution(dfVertToler);
124
125	// uresolution for cone with infinite vmin vmax is too small.
126	if(aGAS.GetType() == GeomAbs_Cone)
127	{
128	Standard_Real u1, u2, v1, v2;
129	BRepTools::UVBounds(myFace, u1, u2, v1, v2);
130	gp_Pnt aP;
131	gp_Vec aD1U, aD1V;
132	aGAS.D1(u1, v1, aP, aD1U, aD1V);
133	Standard_Real tol1, tol2, maxtol = .0005*(u2-u1);
134	Standard_Real a = aD1U.Magnitude();
135
136	if(a <= Precision::Confusion())
137	tol1 = maxtol;
138	else
139	tol1 = Min(maxtol, dfVertToler/a);
140
141	aGAS.D1(u1, v2, aP, aD1U, aD1V);
142	a = aD1U.Magnitude();
143	if(a <= Precision::Confusion())
144	tol2 = maxtol;
145	else
146	tol2 = Min(maxtol, dfVertToler/a);
147
148	myTolU = 2. * Max(tol1, tol2);
149	}
150
151	if( aGAS.GetType() == GeomAbs_BSplineSurface \|\|
152	aGAS.GetType() == GeomAbs_BezierSurface )
153	{
154	Standard_Real maxTol = Max(myTolU,myTolV);
155	myTolU = maxTol;
156	myTolV = maxTol;
157	}
158
159	myReverse = (myFace.Orientation() == TopAbs_REVERSED);
160	}
161
162	// map of vertices to know if the wire is open
163	TopTools_MapOfShape vmap;
164	// Modified by Sergey KHROMOV - Mon May 13 11:50:48 2002 Begin
165	// map of infinite edges
166	TopTools_MapOfShape anInfEmap;
167	// Modified by Sergey KHROMOV - Mon May 13 11:50:49 2002 End
168
169	// list the vertices
170	TopoDS_Vertex V1,V2;
171	TopTools_ListOfShape empty;
172
173	TopoDS_Iterator it(W);
174	while (it.More())
175	{
176	const TopoDS_Edge& E = TopoDS::Edge(it.Value());
177	TopAbs_Orientation Eori = E.Orientation();
178	if (Eori == TopAbs_INTERNAL \|\| Eori == TopAbs_EXTERNAL)
179	{
180	it.Next();
181	continue;
182	}
183	TopExp::Vertices(E,V1,V2,Standard_True);
184
185	if( !V1.IsNull() )
186	{
187	if( !myMap.IsBound(V1) )
188	myMap.Bind(V1,empty);
189	myMap(V1).Append(E);
190
191	// add or remove in the vertex map
192	V1.Orientation(TopAbs_FORWARD);
193	if( !vmap.Add(V1) )
194	vmap.Remove(V1);
195	}
196
197	if( !V2.IsNull() )
198	{
199	V2.Orientation(TopAbs_REVERSED);
200	if(!vmap.Add(V2))
201	vmap.Remove(V2);
202	}
203
204	// Modified by Sergey KHROMOV - Mon May 13 11:52:20 2002 Begin
205	if (V1.IsNull() \|\| V2.IsNull())
206	{
207	Standard_Real aF = 0., aL = 0.;
208	BRep_Tool::Range(E, aF, aL);
209
210	if(Eori == TopAbs_FORWARD)
211	{
212	if (aF == -Precision::Infinite())
213	anInfEmap.Add(E);
214	}
215	else
216	{ // Eori == TopAbs_REVERSED
217	if (aL == Precision::Infinite())
218	anInfEmap.Add(E);
219	}
220	}
221	// Modified by Sergey KHROMOV - Mon May 13 11:52:20 2002 End
222	it.Next();
223	}
224
0d969553	225	//Construction of the set of double edges.
7fd59977	226	TopoDS_Iterator it2(W);
	227	TopTools_MapOfShape emap;
	228	while (it2.More()) {
	229	if (!emap.Add(it2.Value()))
	230	myDoubles.Add(it2.Value());
	231	it2.Next();
	232	}
	233
	234	// if vmap is not empty the wire is open, let us find the first vertex
	235	if (!vmap.IsEmpty()) {
	236	TopTools_MapIteratorOfMapOfShape itt(vmap); // skl : I change "it" to "itt"
	237	while (itt.Key().Orientation() != TopAbs_FORWARD) {
	238	itt.Next();
	239	if (!itt.More()) break;
	240	}
	241	if (itt.More()) V1 = TopoDS::Vertex(itt.Key());
	242	}
	243	else {
	244	// Modified by Sergey KHROMOV - Mon May 13 12:05:30 2002 Begin
	245	// The wire is infinite Try to find the first vertex. It may be NULL.
	246	if (!anInfEmap.IsEmpty()) {
	247	TopTools_MapIteratorOfMapOfShape itt(anInfEmap);
	248
	249	for (; itt.More(); itt.Next()) {
	250	TopoDS_Edge anEdge = TopoDS::Edge(itt.Key());
	251	TopAbs_Orientation anOri = anEdge.Orientation();
	252	Standard_Real aF;
	253	Standard_Real aL;
	254
	255	BRep_Tool::Range(anEdge, aF, aL);
	256	if ((anOri == TopAbs_FORWARD && aF == -Precision::Infinite()) \|\|
	257	(anOri == TopAbs_REVERSED && aL == Precision::Infinite())) {
	258	myEdge = anEdge;
	259	myVertex = TopoDS_Vertex();
	260
	261	return;
	262	}
	263	}
	264	}
	265	// Modified by Sergey KHROMOV - Mon May 13 12:05:31 2002 End
	266
	267
	268	// use the first vertex in iterator
	269	it.Initialize(W);
	270	while (it.More()) {
	271	const TopoDS_Edge& E = TopoDS::Edge(it.Value());
	272	TopAbs_Orientation Eori = E.Orientation();
	273	if (Eori == TopAbs_INTERNAL \|\| Eori == TopAbs_EXTERNAL) {
0d969553 Y	274	// JYL 10-03-97 : waiting for correct processing
0d969553 Y	275	// of INTERNAL/EXTERNAL edges
7fd59977	276	it.Next();
	277	continue;
	278	}
	279	TopExp::Vertices(E,V1,V2,Standard_True);
	280	break;
	281	}
	282	}
	283
	284	if (V1.IsNull() ) return;
	285	if (!myMap.IsBound(V1)) return;
	286
	287	TopTools_ListOfShape& l = myMap(V1);
	288	myEdge = TopoDS::Edge(l.First());
	289	l.RemoveFirst();
	290	myVertex = TopExp::FirstVertex (myEdge, Standard_True);
	291
	292	}
	293
	294	//=======================================================================
	295	//function : More
	296	//purpose :
	297	//=======================================================================
	298	Standard_Boolean BRepTools_WireExplorer::More()const
	299	{
	300	return !myEdge.IsNull();
	301	}
	302
	303	//=======================================================================
	304	//function : Next
	305	//purpose :
	306	//=======================================================================
	307	void BRepTools_WireExplorer::Next()
	308	{
	309	myVertex = TopExp::LastVertex (myEdge, Standard_True);
	310
	311	if (myVertex.IsNull()) {
	312	myEdge = TopoDS_Edge();
	313	return;
	314	}
	315	if (!myMap.IsBound(myVertex)) {
	316	myEdge = TopoDS_Edge();
	317	return;
	318	}
	319
	320	TopTools_ListOfShape& l = myMap(myVertex);
	321
	322	if (l.IsEmpty()) {
	323	myEdge = TopoDS_Edge();
	324	}
	325	else if (l.Extent() == 1) {
	326	// Modified by Sergey KHROMOV - Fri Jun 21 10:28:01 2002 OCC325 Begin
	327	TopoDS_Vertex aV1;
	328	TopoDS_Vertex aV2;
	329	TopoDS_Edge aNextEdge = TopoDS::Edge(l.First());
	330
	331	TopExp::Vertices(aNextEdge, aV1, aV2, Standard_True);
	332
	333	if (!aV1.IsSame(myVertex)) {
	334	myEdge = TopoDS_Edge();
	335	return;
	336	}
	337	if (!myFace.IsNull() && aV1.IsSame(aV2)) {
	338	Handle(Geom2d_Curve) aPrevPC;
	339	Handle(Geom2d_Curve) aNextPC;
340	Standard_Real aPar11, aPar12;
341	Standard_Real aPar21, aPar22;
342	Standard_Real aPrevPar;
343	Standard_Real aNextFPar;
344	Standard_Real aNextLPar;
345
346	aPrevPC = BRep_Tool::CurveOnSurface(myEdge, myFace, aPar11, aPar12);
347	aNextPC = BRep_Tool::CurveOnSurface(aNextEdge, myFace, aPar21, aPar22);
348
349	if (aPrevPC.IsNull() \|\| aNextPC.IsNull()) {
a0f8845f	350	myEdge = TopoDS_Edge();
a0f8845f	351	return;
7fd59977	352	}
	353
	354	if (myEdge.Orientation() == TopAbs_FORWARD)
a0f8845f	355	aPrevPar = aPar12;
7fd59977	356	else
a0f8845f	357	aPrevPar = aPar11;
7fd59977	358
7fd59977	359	if (aNextEdge.Orientation() == TopAbs_FORWARD) {
a0f8845f	360	aNextFPar = aPar21;
a0f8845f	361	aNextLPar = aPar22;
7fd59977	362	} else {
a0f8845f	363	aNextFPar = aPar22;
a0f8845f	364	aNextLPar = aPar21;
7fd59977	365	}
	366
	367	gp_Pnt2d aPPrev = aPrevPC->Value(aPrevPar);
	368	gp_Pnt2d aPNextF = aNextPC->Value(aNextFPar);
	369	gp_Pnt2d aPNextL = aNextPC->Value(aNextLPar);
	370
	371	if (aPPrev.SquareDistance(aPNextF) > aPPrev.SquareDistance(aPNextL)) {
a0f8845f	372	myEdge = TopoDS_Edge();
a0f8845f	373	return;
7fd59977	374	}
	375	}
	376	// Modified by Sergey KHROMOV - Fri Jun 21 11:08:16 2002 End
	377	myEdge = TopoDS::Edge(l.First());
	378	l.Clear();
	379	}
	380	else {
	381	if (myFace.IsNull()) {
0d969553 Y	382	// Without Face - try to return edges
	383	// as logically as possible
	384	// At first degenerated edges.
7fd59977	385	TopoDS_Edge E = myEdge;
7fd59977	386	if (SelectDegenerated(l,E)) {
a0f8845f	387	myEdge = E;
a0f8845f	388	return;
7fd59977	389	}
0d969553	390	// At second double edges.
7fd59977	391	E = myEdge;
7fd59977	392	if (SelectDouble(myDoubles,l,E)) {
a0f8845f	393	myEdge = E;
a0f8845f	394	return;
7fd59977	395	}
	396
	397	TopTools_ListIteratorOfListOfShape it(l);
	398	Standard_Boolean notfound = Standard_True;
	399	while (it.More()) {
a0f8845f	400	if (!it.Value().IsSame(myEdge)) {
	401	myEdge = TopoDS::Edge(it.Value());
	402	l.Remove(it);
	403	notfound = Standard_False;
	404	break;
	405	}
	406	it.Next();
7fd59977	407	}
	408
	409	if(notfound) {
a0f8845f	410	myEdge = TopoDS_Edge();
a0f8845f	411	return;
7fd59977	412	}
	413
	414	}
	415	else
a0f8845f	416	{
	417	// If we have more than one edge attached to the list
	418	// probably wire that we explore contains a loop or loops.
	419	Standard_Real dfFPar = 0., dfLPar = 0.;
	420	Handle(Geom2d_Curve) aPCurve = BRep_Tool::CurveOnSurface (myEdge, myFace, dfFPar, dfLPar);
	421	if(aPCurve.IsNull())
7fd59977	422	{
a0f8845f	423	myEdge = TopoDS_Edge();
	424	return;
	425	}
	426	// Note: current < myVertex > which is last on < myEdge >
	427	// equals in 2D to following 2D points:
	428	// edge is FORWARD - point with MAX parameter on PCurve;
	429	// edge is REVERSED - point with MIN parameter on PCurve.
	430
	431	// Get 2D point equals to < myVertex > in 2D for current edge.
	432	gp_Pnt2d PRef;
	433	if( myEdge.Orientation() == TopAbs_REVERSED )
	434	aPCurve->D0(dfFPar, PRef);
	435	else
	436	aPCurve->D0(dfLPar, PRef);
	437
	438	// Get next 2D point from current edge's PCurve with parameter
	439	// F + dP (REV) or L - dP (FOR)
	440	Standard_Boolean isrevese = ( myEdge.Orientation() == TopAbs_REVERSED );
	441	Standard_Real dfMPar = GetNextParamOnPC(aPCurve,PRef,dfFPar,dfLPar,myTolU,myTolV,isrevese);
	442
	443	gp_Pnt2d PRefm;
	444	aPCurve->D0(dfMPar, PRefm);
	445	// Get vector from PRef to PRefm
	446	gp_Vec2d anERefDir(PRef,PRefm);
	447	// Search the list of edges looking for the edge having hearest
	448	// 2D point of connected vertex to current one and smallest angle.
	449	// First process all degenerated edges, then - all others.
	450
	451	TopTools_ListIteratorOfListOfShape it;
	452	Standard_Integer k = 1, kMin = 0, iDone = 0;
	453	Standard_Boolean isDegenerated = Standard_True;
	454	Standard_Real dmin = RealLast();
	455	Standard_Real dfMinAngle = 3.0M_PI, dfCurAngle = 3.0M_PI;
	456
	457	for(iDone = 0; iDone < 2; iDone++)
	458	{
	459	it.Initialize(l);
	460	while( it.More() )
	461	{
	462	const TopoDS_Edge& E = TopoDS::Edge(it.Value());
	463	if( E.IsSame(myEdge) )
	464	{
	465	it.Next();
	466	k++;
	467	continue;
	468	}
	469
	470	TopoDS_Vertex aVert1, aVert2;
	471	TopExp::Vertices (E, aVert1, aVert2, Standard_True);
	472	if( aVert1.IsNull() \|\| aVert2.IsNull() )
	473	{
	474	it.Next();
	475	k++;
	476	continue;
	477	}
	478
	479	aPCurve = BRep_Tool::CurveOnSurface (E, myFace, dfFPar, dfLPar);
	480	if( aPCurve.IsNull() )
	481	{
	482	it.Next();
	483	k++;
	484	continue;
	485	}
	486
487	gp_Pnt2d aPEb, aPEe;
488	if( aVert1.IsSame(aVert2) == isDegenerated )
489	{
490	if( E.Orientation() == TopAbs_REVERSED )
491	aPCurve->D0(dfLPar, aPEb);
492	else
493	aPCurve->D0(dfFPar, aPEb);
494
495	if( Abs(dfLPar-dfFPar) > Precision::PConfusion() )
496	{
497	isrevese = ( E.Orientation() == TopAbs_REVERSED );
498	isrevese = !isrevese;
499	Standard_Real aEPm = GetNextParamOnPC(aPCurve,aPEb,dfFPar,dfLPar,myTolU,myTolV,isrevese);
500
501	aPCurve->D0 (aEPm, aPEe);
502	if(aPEb.SquareDistance(aPEe) <= gp::Resolution())
503	{
504	//seems to be very short curve
505	gp_Vec2d aD;
506	aPCurve->D1(aEPm, aPEe, aD);
507	if( E.Orientation() == TopAbs_REVERSED )
508	aPEe.SetXY(aPEb.XY()-aD.XY());
509	else
510	aPEe.SetXY(aPEb.XY()+aD.XY());
511
512	if(aPEb.SquareDistance(aPEe) <= gp::Resolution())
513	{
514	it.Next();
515	k++;
516	continue;
517	}
518	}
519	gp_Vec2d anEDir(aPEb, aPEe);
520	dfCurAngle = Abs( anEDir.Angle(anERefDir) );
521	}
522
523	if( dfCurAngle <= dfMinAngle )
524	{
525	Standard_Real d = PRef.SquareDistance(aPEb);
526	if( d <= Precision::PConfusion() )
527	d = 0.;
528	if( Abs(aPEb.X()-PRef.X()) < myTolU && Abs(aPEb.Y()-PRef.Y()) < myTolV )
529	{
530	if( d <= dmin )
531	{
532	dfMinAngle = dfCurAngle;
533	kMin = k;
534	dmin = d;
535	}
536	}
537	}
538	}
539	it.Next();
540	k++;
541	}// while it
542
543	if( kMin == 0 )
544	{
545	isDegenerated = Standard_False;
546	k = 1;
547	dmin = RealLast();
548	}
549	else
550	break;
551	}// for iDone
552
553	if(kMin == 0)
554	{
555	// probably unclosed in 2d space wire
556	myEdge = TopoDS_Edge();
557	return;
558	}
559
560	// Selection the edge.
561	it.Initialize(l);
562	k = 1;
563	while( it.More() )
564	{
565	if( k == kMin )
566	{
567	myEdge = TopoDS::Edge(it.Value());
568	l.Remove(it);
569	break;
570	}
571	it.Next();
572	k++;
573	}
574	}//else face != NULL && l > 1
7fd59977	575	}//else l > 1
	576	}
	577
	578	//=======================================================================
	579	//function : Current
	580	//purpose :
	581	//=======================================================================
	582	const TopoDS_Edge& BRepTools_WireExplorer::Current()const
	583	{
	584	return myEdge;
	585	}
	586
	587	//=======================================================================
	588	//function : Orientation
	589	//purpose :
	590	//=======================================================================
	591	TopAbs_Orientation BRepTools_WireExplorer::Orientation() const
	592	{
	593	TopoDS_Iterator it(myEdge,Standard_False);
	594	while (it.More()) {
	595	if (myVertex.IsSame(it.Value()))
	596	return it.Value().Orientation();
	597	it.Next();
	598	}
	599	Standard_NoSuchObject::Raise("BRepTools_WireExplorer::Orientation");
	600	return TopAbs_FORWARD;
	601	}
	602
	603	//=======================================================================
	604	//function : CurrentVertex
	605	//purpose :
	606	//=======================================================================
	607	const TopoDS_Vertex& BRepTools_WireExplorer::CurrentVertex() const
	608	{
	609	return myVertex;
	610	}
	611
	612	//=======================================================================
	613	//function : Clear
	614	//purpose :
	615	//=======================================================================
	616
	617	void BRepTools_WireExplorer::Clear()
	618	{
	619	myMap.Clear();
	620	myDoubles.Clear();
	621	myEdge = TopoDS_Edge();
	622	myFace = TopoDS_Face();
	623	myVertex = TopoDS_Vertex();
	624	}
	625
	626
	627	//=======================================================================
	628	//function : SelectDouble
	629	//purpose :
	630	//=======================================================================
	631
	632	Standard_Boolean SelectDouble(TopTools_MapOfShape& Doubles,
	633	TopTools_ListOfShape& L,
	634	TopoDS_Edge& E)
	635	{
	636	TopTools_ListIteratorOfListOfShape it(L);
	637
	638	for (; it.More(); it.Next()) {
639	const TopoDS_Shape& CE = it.Value();
640	if (Doubles.Contains(CE) && (!E.IsSame(CE))) {
641	E = TopoDS::Edge(CE);
642	L.Remove(it);
643	return 1;
644	}
645	}
646	return 0;
647	}
648
649	//=======================================================================
650	//function : SelectDegenerated
651	//purpose :
652	//=======================================================================
653
654	Standard_Boolean SelectDegenerated(TopTools_ListOfShape& L,
655	TopoDS_Edge& E)
656	{
657	TopTools_ListIteratorOfListOfShape it(L);
658	while (it.More()) {
659	if (!it.Value().IsSame(E)) {
660	E = TopoDS::Edge(it.Value());
661	if (BRep_Tool::Degenerated(E)) {
662	L.Remove(it);
663	return 1;
664	}
665	}
666	it.Next();
667	}
668	return 0;
669	}
670
671	//=======================================================================
672	//function : GetNextParamOnPC
673	//purpose :
674	//=======================================================================
675	Standard_Real GetNextParamOnPC(const Handle(Geom2d_Curve)& aPC,
676	const gp_Pnt2d& aPRef,
677	const Standard_Real& fP,
678	const Standard_Real& lP,
679	const Standard_Real& tolU,
680	const Standard_Real& tolV,
681	const Standard_Boolean& reverse)
682	{
683	Standard_Real result = ( reverse ) ? fP : lP;
684	Standard_Real dP = Abs( lP - fP ) / 1000.; // was / 16.;
685	if( reverse )
686	{
687	Standard_Real startPar = fP;
688	Standard_Boolean nextPntOnEdge = Standard_False;
689	while( !nextPntOnEdge && startPar < lP )
690	{
691	gp_Pnt2d pnt;
692	startPar += dP;
693	aPC->D0(startPar, pnt);
694	if( Abs( aPRef.X() - pnt.X() ) < tolU && Abs( aPRef.Y() - pnt.Y() ) < tolV )
695	continue;
696	else
697	{
698	result = startPar;
699	nextPntOnEdge = Standard_True;
700	break;
701	}
702	}
703
704	if( !nextPntOnEdge )
705	result = lP;
706
707	if( result > lP )
708	result = lP;
709	}
710	else
711	{
712	Standard_Real startPar = lP;
713	Standard_Boolean nextPntOnEdge = Standard_False;
714	while( !nextPntOnEdge && startPar > fP )
715	{
716	gp_Pnt2d pnt;
717	startPar -= dP;
718	aPC->D0(startPar, pnt);
719	if( Abs( aPRef.X() - pnt.X() ) < tolU && Abs( aPRef.Y() - pnt.Y() ) < tolV )
720	continue;
721	else
722	{
723	result = startPar;
724	nextPntOnEdge = Standard_True;
725	break;
726	}
727	}
728
729	if( !nextPntOnEdge )
730	result = fP;
731
732	if( result < fP )
733	result = fP;
734	}
735
736	return result;
737	}