[occt.git] / src / BRepOffset / BRepOffset.cxx

// Created on: 1995-10-25
// Created by: Bruno DUMORTIER
// Copyright (c) 1995-1999 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 License 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 <BRepOffset.hxx>
#include <BRep_Tool.hxx>
#include <Geom_BSplineSurface.hxx>
#include <Geom_ConicalSurface.hxx>
#include <Geom_CylindricalSurface.hxx>
#include <Geom_OffsetSurface.hxx>
#include <Geom_Plane.hxx>
#include <Geom_RectangularTrimmedSurface.hxx>
#include <Geom_SphericalSurface.hxx>
#include <Geom_Surface.hxx>
#include <Geom_SurfaceOfLinearExtrusion.hxx>
#include <Geom_SurfaceOfRevolution.hxx>
#include <Geom_ToroidalSurface.hxx>
#include <gp_Ax1.hxx>
#include <gp_Ax3.hxx>
#include <gp_Dir.hxx>
#include <gp_Vec.hxx>
#include <NCollection_LocalArray.hxx>
#include <Precision.hxx>
#include <TopExp.hxx>
#include <TopExp_Explorer.hxx>
#include <TopoDS.hxx>
#include <TopoDS_Edge.hxx>
#include <TopoDS_Face.hxx>
#include <TopoDS_ListOfShape.hxx>
#include <TopoDS_Vertex.hxx>

//=======================================================================
//function : Surface
//purpose  : 
//=======================================================================
Handle(Geom_Surface) BRepOffset::Surface(const Handle(Geom_Surface)& Surface,
					                     const Standard_Real Offset,
                                         BRepOffset_Status& theStatus,
                                         Standard_Boolean allowC0)
{
  Standard_Real Tol = Precision::Confusion();

  theStatus = BRepOffset_Good;
  Handle(Geom_Surface) Result;
  
  Handle(Standard_Type) TheType = Surface->DynamicType();

  if (TheType == STANDARD_TYPE(Geom_Plane)) {
    Handle(Geom_Plane) P =
      Handle(Geom_Plane)::DownCast(Surface);
    gp_Vec T = P->Position().XDirection()^P->Position().YDirection();
    T *= Offset;
    Result = Handle(Geom_Plane)::DownCast(P->Translated(T));
  }
  else if (TheType == STANDARD_TYPE(Geom_CylindricalSurface)) {
    Handle(Geom_CylindricalSurface) C =
      Handle(Geom_CylindricalSurface)::DownCast(Surface);
    Standard_Real Radius = C->Radius();
    gp_Ax3 Axis = C->Position();
    if (Axis.Direct()) 
      Radius += Offset;
    else 
      Radius -= Offset;
    if ( Radius >= Tol ) {
      Result = new Geom_CylindricalSurface( Axis, Radius);
    }
    else if ( Radius <= -Tol ){
      Axis.Rotate(gp_Ax1(Axis.Location(),Axis.Direction()),M_PI);
      Result = new Geom_CylindricalSurface( Axis, Abs(Radius));
      theStatus = BRepOffset_Reversed;
    }
    else {
      theStatus = BRepOffset_Degenerated;
    }
  }
  else if (TheType == STANDARD_TYPE(Geom_ConicalSurface)) {
    Handle(Geom_ConicalSurface) C =
      Handle(Geom_ConicalSurface)::DownCast(Surface);
    Standard_Real Alpha = C->SemiAngle();
    Standard_Real Radius = C->RefRadius() + Offset * Cos(Alpha);
    gp_Ax3 Axis = C->Position();
    if ( Radius >= 0.) {
      gp_Vec Z( Axis.Direction());
      Z *= - Offset * Sin(Alpha);
      Axis.Translate(Z);
    }
    else {
      Radius = -Radius; 
      gp_Vec Z( Axis.Direction());
      Z *= - Offset * Sin(Alpha);
      Axis.Translate(Z);
      Axis.Rotate(gp_Ax1(Axis.Location(),Axis.Direction()),M_PI);
      Alpha = -Alpha; 
    }
    Result = new Geom_ConicalSurface(Axis, Alpha, Radius);
  }
  else if (TheType == STANDARD_TYPE(Geom_SphericalSurface)) {
    Handle(Geom_SphericalSurface) S = 
      Handle(Geom_SphericalSurface)::DownCast(Surface);
    Standard_Real Radius = S->Radius();
    gp_Ax3 Axis = S->Position();
    if (Axis.Direct()) 
      Radius += Offset;
    else 
      Radius -= Offset;
    if ( Radius >= Tol) {
      Result = new Geom_SphericalSurface(Axis, Radius);
    }
    else if ( Radius <= -Tol ) {
      Axis.Rotate(gp_Ax1(Axis.Location(),Axis.Direction()),M_PI);
      Axis.ZReverse();
      Result = new Geom_SphericalSurface(Axis, -Radius);
      theStatus = BRepOffset_Reversed;
    }
    else {
      theStatus = BRepOffset_Degenerated;
    }
  }
  else if (TheType == STANDARD_TYPE(Geom_ToroidalSurface)) {
    Handle(Geom_ToroidalSurface) S = 
      Handle(Geom_ToroidalSurface)::DownCast(Surface);
    Standard_Real MajorRadius = S->MajorRadius();
    Standard_Real MinorRadius = S->MinorRadius();
    gp_Ax3 Axis = S->Position();
    if (MinorRadius < MajorRadius) {  // A FINIR
      if (Axis.Direct())
	MinorRadius += Offset;
      else 
	MinorRadius -= Offset;
      if (MinorRadius >= Tol) {
	Result = new Geom_ToroidalSurface(Axis,MajorRadius,MinorRadius);
      }
      else if (MinorRadius <= -Tol) {
	theStatus = BRepOffset_Reversed;
      }
      else {
	theStatus = BRepOffset_Degenerated;
      }
    }
  }
  else if (TheType == STANDARD_TYPE(Geom_SurfaceOfRevolution)) {
  }
  else if (TheType == STANDARD_TYPE(Geom_SurfaceOfLinearExtrusion)) {
  }
  else if (TheType == STANDARD_TYPE(Geom_BSplineSurface)) {
  }
  else if (TheType == STANDARD_TYPE(Geom_RectangularTrimmedSurface)) {
    Handle(Geom_RectangularTrimmedSurface) S = 
      Handle(Geom_RectangularTrimmedSurface)::DownCast(Surface);
    Standard_Real U1,U2,V1,V2;
    S->Bounds(U1,U2,V1,V2);
    Handle(Geom_Surface) Off = BRepOffset::Surface (S->BasisSurface(), Offset, theStatus, allowC0);
    Result = new Geom_RectangularTrimmedSurface (Off,U1,U2,V1,V2);
  }
  else if (TheType == STANDARD_TYPE(Geom_OffsetSurface)) {
  }

  if ( Result.IsNull()) {
    Result = new Geom_OffsetSurface( Surface, Offset, allowC0);
  }
  
  return Result;
}

//=======================================================================
//function : CollapseSingularities
//purpose  : 
//=======================================================================
Handle(Geom_Surface) BRepOffset::CollapseSingularities (const Handle(Geom_Surface)& theSurface,
                                                        const TopoDS_Face& theFace,
                                                        Standard_Real thePrecision)
{
  // check surface type to see if it can be processed
  Handle(Standard_Type) aType = theSurface->DynamicType();
  if (aType != STANDARD_TYPE(Geom_BSplineSurface))
  {
    // for the moment, only bspline surfaces are treated;
    // in the future, bezier surfaces and surfaces of revolution can be also handled
    return theSurface;
  }

  // find singularities (vertices of degenerated edges)
  NCollection_List<gp_Pnt> aDegenPnt;
  NCollection_List<Standard_Real> aDegenTol;
  for (TopExp_Explorer anExp (theFace, TopAbs_EDGE); anExp.More(); anExp.Next())
  {
    TopoDS_Edge anEdge = TopoDS::Edge (anExp.Current());
    if (! BRep_Tool::Degenerated (anEdge))
    {
      continue;
    }
    TopoDS_Vertex aV1, aV2;
    TopExp::Vertices (anEdge, aV1, aV2);
    if (! aV1.IsSame (aV2))
    {
      continue;
    }

    aDegenPnt.Append (BRep_Tool::Pnt (aV1));
    aDegenTol.Append (BRep_Tool::Tolerance (aV1));
  }

  // iterate by sides of the surface
  if (aType == STANDARD_TYPE(Geom_BSplineSurface))
  {
    Handle(Geom_BSplineSurface) aBSpline = Handle(Geom_BSplineSurface)::DownCast (theSurface);
    const TColgp_Array2OfPnt& aPoles = aBSpline->Poles();
    
    Handle(Geom_BSplineSurface) aCopy;

    // iterate by sides: {U=0; V=0; U=1; V=1}
    Standard_Integer RowStart[4] = {aPoles.LowerRow(), aPoles.LowerRow(), aPoles.UpperRow(), aPoles.LowerRow()};
    Standard_Integer ColStart[4] = {aPoles.LowerCol(), aPoles.LowerCol(), aPoles.LowerCol(), aPoles.UpperCol()};
    Standard_Integer RowStep[4]  = {0, 1, 0, 1};
    Standard_Integer ColStep[4]  = {1, 0, 1, 0};
    Standard_Integer NbSteps[4]  = {aPoles.RowLength(), aPoles.ColLength(), aPoles.RowLength(), aPoles.ColLength()};
    for (Standard_Integer iSide = 0; iSide < 4; iSide++)
    {
      // compute center of gravity of side poles
      gp_XYZ aSum;
      for (int iPole = 0; iPole < NbSteps[iSide]; iPole++)
      {
        aSum += aPoles (RowStart[iSide] + iPole * RowStep[iSide], ColStart[iSide] + iPole * ColStep[iSide]).XYZ();
      }
      gp_Pnt aCenter (aSum / NbSteps[iSide]);

      // determine if all poles of the side fit into:
      Standard_Boolean isCollapsed = Standard_True; // aCenter precisely (with gp::Resolution())
      Standard_Boolean isSingular = Standard_True;  // aCenter with thePrecision
      NCollection_LocalArray<Standard_Boolean,4> isDegenerated (aDegenPnt.Extent()); // degenerated vertex
      for (size_t iDegen = 0; iDegen < isDegenerated.Size(); ++iDegen) isDegenerated[iDegen] = Standard_True;
      for (int iPole = 0; iPole < NbSteps[iSide]; iPole++)
      {
        const gp_Pnt& aPole = aPoles (RowStart[iSide] + iPole * RowStep[iSide], ColStart[iSide] + iPole * ColStep[iSide]);

        // distance from CG
        Standard_Real aDistCG = aCenter.Distance (aPole);
        if (aDistCG > gp::Resolution())
          isCollapsed = Standard_False;
        if (aDistCG > thePrecision)
          isSingular = Standard_False;

        // distances from degenerated points
        NCollection_List<gp_Pnt>::Iterator aDegPntIt (aDegenPnt);
        NCollection_List<Standard_Real>::Iterator aDegTolIt(aDegenTol);
        for (size_t iDegen = 0; iDegen < isDegenerated.Size(); aDegPntIt.Next(), aDegTolIt.Next(), ++iDegen)
        {
          if (isDegenerated[iDegen] && aDegPntIt.Value().Distance (aPole) >= aDegTolIt.Value())
          {
            isDegenerated[iDegen] = Standard_False;
          }
        }
      }
      if (isCollapsed)
      {
        continue; // already Ok, nothing to be done
      }

      // decide to collapse the side: either if it is singular with thePrecision,
      // or if it fits into one (and only one) degenerated point
      if (! isSingular)
      {
        Standard_Integer aNbFit = 0;
        NCollection_List<gp_Pnt>::Iterator aDegPntIt (aDegenPnt);
        NCollection_List<Standard_Real>::Iterator aDegTolIt(aDegenTol);
        for (size_t iDegen = 0; iDegen < isDegenerated.Size(); ++iDegen)
        {
          if (isDegenerated[iDegen])
          {
            // remove degenerated point as soon as it fits at least one side, to prevent total collapse
            aDegenPnt.Remove (aDegPntIt);
            aDegenTol.Remove (aDegTolIt);
            aNbFit++;
          }
          else
          {
            aDegPntIt.Next();
            aDegTolIt.Next();
          }
        }

        // if side fits more than one degenerated vertex, do not collapse it
        // to be on the safe side
        isSingular = (aNbFit == 1);
      }
      
      // do collapse
      if (isSingular)
      {
        if (aCopy.IsNull())
        {
          aCopy = Handle(Geom_BSplineSurface)::DownCast (theSurface->Copy());
        }
        for (int iPole = 0; iPole < NbSteps[iSide]; iPole++)
        {
          aCopy->SetPole (RowStart[iSide] + iPole * RowStep[iSide], ColStart[iSide] + iPole * ColStep[iSide], aCenter);
        }
      }
    }

    if (! aCopy.IsNull())
      return aCopy;
  }

  return theSurface;
}
Commit	Line	Data
b311480e	1	// Created on: 1995-10-25
	2	// Created by: Bruno DUMORTIER
	3	// Copyright (c) 1995-1999 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	//
d5f74e42	8	// This library is free software; you can redistribute it and/or modify it under
d5f74e42	9	// the terms of the GNU Lesser General Public License version 2.1 as published
973c2be1	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
7fd59977	17
42cf5bc1	18	#include <BRepOffset.hxx>
8574e329	19	#include <BRep_Tool.hxx>
42cf5bc1	20	#include <Geom_BSplineSurface.hxx>
7fd59977	21	#include <Geom_ConicalSurface.hxx>
42cf5bc1	22	#include <Geom_CylindricalSurface.hxx>
	23	#include <Geom_OffsetSurface.hxx>
	24	#include <Geom_Plane.hxx>
	25	#include <Geom_RectangularTrimmedSurface.hxx>
7fd59977	26	#include <Geom_SphericalSurface.hxx>
42cf5bc1	27	#include <Geom_Surface.hxx>
7fd59977	28	#include <Geom_SurfaceOfLinearExtrusion.hxx>
42cf5bc1	29	#include <Geom_SurfaceOfRevolution.hxx>
42cf5bc1	30	#include <Geom_ToroidalSurface.hxx>
7fd59977	31	#include <gp_Ax1.hxx>
42cf5bc1	32	#include <gp_Ax3.hxx>
	33	#include <gp_Dir.hxx>
	34	#include <gp_Vec.hxx>
8574e329	35	#include <NCollection_LocalArray.hxx>
7fd59977	36	#include <Precision.hxx>
8574e329	37	#include <TopExp.hxx>
	38	#include <TopExp_Explorer.hxx>
	39	#include <TopoDS.hxx>
	40	#include <TopoDS_Edge.hxx>
	41	#include <TopoDS_Face.hxx>
	42	#include <TopoDS_ListOfShape.hxx>
	43	#include <TopoDS_Vertex.hxx>
7fd59977	44
	45	//=======================================================================
	46	//function : Surface
	47	//purpose :
	48	//=======================================================================
7fd59977	49	Handle(Geom_Surface) BRepOffset::Surface(const Handle(Geom_Surface)& Surface,
8574e329	50	const Standard_Real Offset,
	51	BRepOffset_Status& theStatus,
	52	Standard_Boolean allowC0)
7fd59977	53	{
	54	Standard_Real Tol = Precision::Confusion();
	55
9fd2d2c3	56	theStatus = BRepOffset_Good;
7fd59977	57	Handle(Geom_Surface) Result;
	58
	59	Handle(Standard_Type) TheType = Surface->DynamicType();
	60
	61	if (TheType == STANDARD_TYPE(Geom_Plane)) {
	62	Handle(Geom_Plane) P =
	63	Handle(Geom_Plane)::DownCast(Surface);
	64	gp_Vec T = P->Position().XDirection()^P->Position().YDirection();
	65	T *= Offset;
	66	Result = Handle(Geom_Plane)::DownCast(P->Translated(T));
	67	}
	68	else if (TheType == STANDARD_TYPE(Geom_CylindricalSurface)) {
	69	Handle(Geom_CylindricalSurface) C =
	70	Handle(Geom_CylindricalSurface)::DownCast(Surface);
	71	Standard_Real Radius = C->Radius();
	72	gp_Ax3 Axis = C->Position();
	73	if (Axis.Direct())
	74	Radius += Offset;
	75	else
	76	Radius -= Offset;
	77	if ( Radius >= Tol ) {
	78	Result = new Geom_CylindricalSurface( Axis, Radius);
	79	}
	80	else if ( Radius <= -Tol ){
c6541a0c	81	Axis.Rotate(gp_Ax1(Axis.Location(),Axis.Direction()),M_PI);
7fd59977	82	Result = new Geom_CylindricalSurface( Axis, Abs(Radius));
9fd2d2c3	83	theStatus = BRepOffset_Reversed;
7fd59977	84	}
7fd59977	85	else {
9fd2d2c3	86	theStatus = BRepOffset_Degenerated;
7fd59977	87	}
	88	}
	89	else if (TheType == STANDARD_TYPE(Geom_ConicalSurface)) {
	90	Handle(Geom_ConicalSurface) C =
	91	Handle(Geom_ConicalSurface)::DownCast(Surface);
	92	Standard_Real Alpha = C->SemiAngle();
	93	Standard_Real Radius = C->RefRadius() + Offset * Cos(Alpha);
	94	gp_Ax3 Axis = C->Position();
	95	if ( Radius >= 0.) {
	96	gp_Vec Z( Axis.Direction());
	97	Z = - Offset Sin(Alpha);
	98	Axis.Translate(Z);
	99	}
	100	else {
	101	Radius = -Radius;
	102	gp_Vec Z( Axis.Direction());
	103	Z = - Offset Sin(Alpha);
	104	Axis.Translate(Z);
c6541a0c	105	Axis.Rotate(gp_Ax1(Axis.Location(),Axis.Direction()),M_PI);
7fd59977	106	Alpha = -Alpha;
	107	}
	108	Result = new Geom_ConicalSurface(Axis, Alpha, Radius);
	109	}
	110	else if (TheType == STANDARD_TYPE(Geom_SphericalSurface)) {
	111	Handle(Geom_SphericalSurface) S =
	112	Handle(Geom_SphericalSurface)::DownCast(Surface);
	113	Standard_Real Radius = S->Radius();
	114	gp_Ax3 Axis = S->Position();
	115	if (Axis.Direct())
	116	Radius += Offset;
	117	else
	118	Radius -= Offset;
	119	if ( Radius >= Tol) {
	120	Result = new Geom_SphericalSurface(Axis, Radius);
	121	}
	122	else if ( Radius <= -Tol ) {
c6541a0c	123	Axis.Rotate(gp_Ax1(Axis.Location(),Axis.Direction()),M_PI);
7fd59977	124	Axis.ZReverse();
7fd59977	125	Result = new Geom_SphericalSurface(Axis, -Radius);
9fd2d2c3	126	theStatus = BRepOffset_Reversed;
7fd59977	127	}
7fd59977	128	else {
9fd2d2c3	129	theStatus = BRepOffset_Degenerated;
7fd59977	130	}
	131	}
	132	else if (TheType == STANDARD_TYPE(Geom_ToroidalSurface)) {
	133	Handle(Geom_ToroidalSurface) S =
	134	Handle(Geom_ToroidalSurface)::DownCast(Surface);
	135	Standard_Real MajorRadius = S->MajorRadius();
	136	Standard_Real MinorRadius = S->MinorRadius();
	137	gp_Ax3 Axis = S->Position();
	138	if (MinorRadius < MajorRadius) { // A FINIR
	139	if (Axis.Direct())
	140	MinorRadius += Offset;
	141	else
	142	MinorRadius -= Offset;
	143	if (MinorRadius >= Tol) {
	144	Result = new Geom_ToroidalSurface(Axis,MajorRadius,MinorRadius);
	145	}
	146	else if (MinorRadius <= -Tol) {
9fd2d2c3	147	theStatus = BRepOffset_Reversed;
7fd59977	148	}
7fd59977	149	else {
9fd2d2c3	150	theStatus = BRepOffset_Degenerated;
7fd59977	151	}
	152	}
	153	}
	154	else if (TheType == STANDARD_TYPE(Geom_SurfaceOfRevolution)) {
	155	}
	156	else if (TheType == STANDARD_TYPE(Geom_SurfaceOfLinearExtrusion)) {
	157	}
	158	else if (TheType == STANDARD_TYPE(Geom_BSplineSurface)) {
	159	}
	160	else if (TheType == STANDARD_TYPE(Geom_RectangularTrimmedSurface)) {
	161	Handle(Geom_RectangularTrimmedSurface) S =
	162	Handle(Geom_RectangularTrimmedSurface)::DownCast(Surface);
	163	Standard_Real U1,U2,V1,V2;
	164	S->Bounds(U1,U2,V1,V2);
8574e329	165	Handle(Geom_Surface) Off = BRepOffset::Surface (S->BasisSurface(), Offset, theStatus, allowC0);
7fd59977	166	Result = new Geom_RectangularTrimmedSurface (Off,U1,U2,V1,V2);
	167	}
	168	else if (TheType == STANDARD_TYPE(Geom_OffsetSurface)) {
	169	}
	170
	171	if ( Result.IsNull()) {
8574e329	172	Result = new Geom_OffsetSurface( Surface, Offset, allowC0);
7fd59977	173	}
	174
	175	return Result;
	176	}
	177
8574e329	178	//=======================================================================
	179	//function : CollapseSingularities
	180	//purpose :
	181	//=======================================================================
	182	Handle(Geom_Surface) BRepOffset::CollapseSingularities (const Handle(Geom_Surface)& theSurface,
	183	const TopoDS_Face& theFace,
	184	Standard_Real thePrecision)
	185	{
	186	// check surface type to see if it can be processed
	187	Handle(Standard_Type) aType = theSurface->DynamicType();
	188	if (aType != STANDARD_TYPE(Geom_BSplineSurface))
	189	{
	190	// for the moment, only bspline surfaces are treated;
	191	// in the future, bezier surfaces and surfaces of revolution can be also handled
	192	return theSurface;
	193	}
	194
	195	// find singularities (vertices of degenerated edges)
	196	NCollection_List<gp_Pnt> aDegenPnt;
	197	NCollection_List<Standard_Real> aDegenTol;
	198	for (TopExp_Explorer anExp (theFace, TopAbs_EDGE); anExp.More(); anExp.Next())
	199	{
	200	TopoDS_Edge anEdge = TopoDS::Edge (anExp.Current());
	201	if (! BRep_Tool::Degenerated (anEdge))
	202	{
	203	continue;
	204	}
	205	TopoDS_Vertex aV1, aV2;
	206	TopExp::Vertices (anEdge, aV1, aV2);
	207	if (! aV1.IsSame (aV2))
	208	{
	209	continue;
	210	}
	211
	212	aDegenPnt.Append (BRep_Tool::Pnt (aV1));
	213	aDegenTol.Append (BRep_Tool::Tolerance (aV1));
	214	}
	215
	216	// iterate by sides of the surface
	217	if (aType == STANDARD_TYPE(Geom_BSplineSurface))
	218	{
	219	Handle(Geom_BSplineSurface) aBSpline = Handle(Geom_BSplineSurface)::DownCast (theSurface);
	220	const TColgp_Array2OfPnt& aPoles = aBSpline->Poles();
	221
	222	Handle(Geom_BSplineSurface) aCopy;
	223
	224	// iterate by sides: {U=0; V=0; U=1; V=1}
	225	Standard_Integer RowStart[4] = {aPoles.LowerRow(), aPoles.LowerRow(), aPoles.UpperRow(), aPoles.LowerRow()};
	226	Standard_Integer ColStart[4] = {aPoles.LowerCol(), aPoles.LowerCol(), aPoles.LowerCol(), aPoles.UpperCol()};
	227	Standard_Integer RowStep[4] = {0, 1, 0, 1};
	228	Standard_Integer ColStep[4] = {1, 0, 1, 0};
	229	Standard_Integer NbSteps[4] = {aPoles.RowLength(), aPoles.ColLength(), aPoles.RowLength(), aPoles.ColLength()};
	230	for (Standard_Integer iSide = 0; iSide < 4; iSide++)
	231	{
	232	// compute center of gravity of side poles
	233	gp_XYZ aSum;
	234	for (int iPole = 0; iPole < NbSteps[iSide]; iPole++)
	235	{
	236	aSum += aPoles (RowStart[iSide] + iPole * RowStep[iSide], ColStart[iSide] + iPole * ColStep[iSide]).XYZ();
	237	}
	238	gp_Pnt aCenter (aSum / NbSteps[iSide]);
7fd59977	239
8574e329	240	// determine if all poles of the side fit into:
	241	Standard_Boolean isCollapsed = Standard_True; // aCenter precisely (with gp::Resolution())
	242	Standard_Boolean isSingular = Standard_True; // aCenter with thePrecision
	243	NCollection_LocalArray<Standard_Boolean,4> isDegenerated (aDegenPnt.Extent()); // degenerated vertex
	244	for (size_t iDegen = 0; iDegen < isDegenerated.Size(); ++iDegen) isDegenerated[iDegen] = Standard_True;
	245	for (int iPole = 0; iPole < NbSteps[iSide]; iPole++)
	246	{
	247	const gp_Pnt& aPole = aPoles (RowStart[iSide] + iPole * RowStep[iSide], ColStart[iSide] + iPole * ColStep[iSide]);
	248
	249	// distance from CG
	250	Standard_Real aDistCG = aCenter.Distance (aPole);
	251	if (aDistCG > gp::Resolution())
	252	isCollapsed = Standard_False;
	253	if (aDistCG > thePrecision)
	254	isSingular = Standard_False;
	255
	256	// distances from degenerated points
	257	NCollection_List<gp_Pnt>::Iterator aDegPntIt (aDegenPnt);
	258	NCollection_List<Standard_Real>::Iterator aDegTolIt(aDegenTol);
	259	for (size_t iDegen = 0; iDegen < isDegenerated.Size(); aDegPntIt.Next(), aDegTolIt.Next(), ++iDegen)
	260	{
	261	if (isDegenerated[iDegen] && aDegPntIt.Value().Distance (aPole) >= aDegTolIt.Value())
	262	{
	263	isDegenerated[iDegen] = Standard_False;
	264	}
	265	}
	266	}
	267	if (isCollapsed)
	268	{
	269	continue; // already Ok, nothing to be done
	270	}
	271
	272	// decide to collapse the side: either if it is singular with thePrecision,
	273	// or if it fits into one (and only one) degenerated point
	274	if (! isSingular)
	275	{
	276	Standard_Integer aNbFit = 0;
	277	NCollection_List<gp_Pnt>::Iterator aDegPntIt (aDegenPnt);
	278	NCollection_List<Standard_Real>::Iterator aDegTolIt(aDegenTol);
	279	for (size_t iDegen = 0; iDegen < isDegenerated.Size(); ++iDegen)
	280	{
	281	if (isDegenerated[iDegen])
	282	{
	283	// remove degenerated point as soon as it fits at least one side, to prevent total collapse
	284	aDegenPnt.Remove (aDegPntIt);
	285	aDegenTol.Remove (aDegTolIt);
	286	aNbFit++;
	287	}
	288	else
	289	{
	290	aDegPntIt.Next();
	291	aDegTolIt.Next();
	292	}
	293	}
	294
	295	// if side fits more than one degenerated vertex, do not collapse it
	296	// to be on the safe side
	297	isSingular = (aNbFit == 1);
	298	}
	299
	300	// do collapse
	301	if (isSingular)
	302	{
	303	if (aCopy.IsNull())
304	{
305	aCopy = Handle(Geom_BSplineSurface)::DownCast (theSurface->Copy());
306	}
307	for (int iPole = 0; iPole < NbSteps[iSide]; iPole++)
308	{
309	aCopy->SetPole (RowStart[iSide] + iPole * RowStep[iSide], ColStart[iSide] + iPole * ColStep[iSide], aCenter);
310	}
311	}
312	}
313
314	if (! aCopy.IsNull())
315	return aCopy;
316	}
317
318	return theSurface;
319	}