Method FindClosestNPoints

Common/DataModel/vtkOctreePointLocator.cxx:794–949

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//------------------------------------------------------------------------------
void vtkOctreePointLocator::FindClosestNPoints(int N, const double x[3], vtkIdList* result)
{
  result->Reset();
  if (N <= 0)
  {
    return;
  }
  this->BuildLocator();

  int numTotalPoints = this->Top->GetNumberOfPoints();
  if (numTotalPoints < N)
  {
    vtkWarningMacro(
      "Number of requested points is greater than total number of points in OctreePointLocator");
    N = numTotalPoints;
  }
  result->SetNumberOfIds(N);

  // now we want to go about finding a region that contains at least N points
  // but not many more -- hopefully the region contains X as well but we
  // can't depend on that
  vtkOctreePointLocatorNode* node = this->Top;
  vtkOctreePointLocatorNode* startingNode = nullptr;
  if (!node->ContainsPoint(x[0], x[1], x[2], 0))
  {
    // point is not in the region
    int numPoints = node->GetNumberOfPoints();
    vtkOctreePointLocatorNode* prevNode = node;
    while (node->GetChild(0) && numPoints > N)
    {
      prevNode = node;
      vtkOctreePointLocatorNode* nextNode = node->GetChild(0);
      double minDist2 = nextNode->GetDistance2ToBoundary(x[0], x[1], x[2], this->Top, 1);
      for (int i = 1; i < 8; i++)
      {
        double dist2 = node->GetChild(i)->GetDistance2ToBoundary(x[0], x[1], x[2], this->Top, 1);
        if (dist2 < minDist2)
        {
          nextNode = node->GetChild(i);
          minDist2 = dist2;
        }
      }
      node = nextNode;
      numPoints = node->GetNumberOfPoints();
    }
    if (numPoints < N)
    {
      startingNode = prevNode;
    }
    else
    {
      startingNode = node;
    }
  }
  else
  {
    int numPoints = node->GetNumberOfPoints();
    vtkOctreePointLocatorNode* prevNode = node;