Method BuildLocatorInternal

Common/DataModel/vtkCellLocator.cxx:710–814

------------------------------------------------------------------------------ Method to form subdivision of space based on the cells provided and subject to the constraints of levels and NumberOfCellsPerNode. The result is directly addressable and of uniform subdivision.

//  subject to the constraints of levels and NumberOfCellsPerNode.
//  The result is directly addressable and of uniform subdivision.
void vtkCellLocator::BuildLocatorInternal()
{
  double cellBounds[6], *cellBoundsPtr;
  cellBoundsPtr = cellBounds;
  vtkIdType numCells;
  int ndivs, product;
  int i, j, k, ijkMin[3], ijkMax[3];
  vtkIdType cellId, idx;
  int parentOffset;
  int numCellsPerBucket = this->NumberOfCellsPerNode;
  int prod, numOctants;
  double hTol[3];

  vtkDebugMacro(<< "Subdividing octree...");

  if (!this->DataSet || (numCells = this->DataSet->GetNumberOfCells()) < 1)
  {
    vtkErrorMacro(<< "No cells to subdivide");
    return;
  }
  this->DataSet->ComputeBounds();

  //  Make sure the appropriate data is available
  this->FreeSearchStructure();

  //  Size the root cell.  Initialize cell data structure, compute
  //  level and divisions.
  const double* bounds = this->DataSet->GetBounds();
  vtkBoundingBox bbox(bounds);
  bbox.Inflate();
  bbox.GetBounds(this->Bounds);

  if (this->Automatic)
  {
    this->Level = static_cast<int>(
      std::ceil(std::log(static_cast<double>(numCells) / numCellsPerBucket) / (std::log(8.0))));
  }
  this->Level = (this->Level > this->MaxLevel ? this->MaxLevel : this->Level);

  // compute number of octants and number of divisions
  for (ndivs = 1, prod = 1, numOctants = 1, i = 0; i < this->Level; i++)
  {
    ndivs *= 2;
    prod *= 8;
    numOctants += prod;
  }
  this->NumberOfDivisions = ndivs;
  this->NumberOfOctants = numOctants;

  this->TreeSharedPtr =
    std::make_shared<std::vector<vtkSmartPointer<vtkIdList>>>(numOctants, nullptr);
  this->Tree = TreeSharedPtr->data();

  this->ComputeCellBounds();

  //  Compute width of leaf octant in three directions
  for (i = 0; i < 3; i++)
  {