Method GetScalarFieldCriticalIndex

Common/DataModel/vtkPolyData.cxx:1810–2025

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//------------------------------------------------------------------------------
int vtkPolyData::GetScalarFieldCriticalIndex(vtkIdType pointId, vtkDataArray* scalarField)
{
  /*
   * implements scalar field critical point classification for manifold
   * 2D meshes.
   */

  /*
   * returned value:
   *   -4: no such field
   *   -3: attribute check failed
   *   -2: non 2-manifold star
   *   -1: regular point
   *   0: minimum
   *   1: saddle
   *   2: maximum
   */

  bool is_min = true, is_max = true;
  vtkIdList *starTriangleList = vtkIdList::New(), *lowerLinkPointList = vtkIdList::New(),
            *upperLinkPointList = vtkIdList::New(), *pointList = nullptr;
  double pointFieldValue = scalarField->GetComponent(pointId, 0);

  if (this->GetNumberOfPoints() != scalarField->GetNumberOfTuples())
  {
    return vtkPolyData::ERR_INCORRECT_FIELD;
  }

  /* make sure the connectivity is built */
  if (!this->Links)
  {
    this->BuildLinks();
  }

  /* build the lower and upper links */
  this->GetPointCells(pointId, starTriangleList);
  int starNb = starTriangleList->GetNumberOfIds();
  for (int i = 0; i < starNb; i++)
  {
    vtkCell* c = this->GetCell(starTriangleList->GetId(i));
    pointList = c->GetPointIds();
    int pointNb = pointList->GetNumberOfIds();
    if (pointNb != 3)
    {
      starTriangleList->Delete();
      lowerLinkPointList->Delete();
      upperLinkPointList->Delete();
      return vtkPolyData::ERR_NON_MANIFOLD_STAR;
    }

    for (int j = 0; j < pointNb; j++)
    {
      vtkIdType currentPointId = pointList->GetId(j);

      /* quick check for extrema */
      double neighborFieldValue = scalarField->GetComponent(currentPointId, 0);
      if ((currentPointId != pointId) && (neighborFieldValue == pointFieldValue))
      {