Method BuildLocatorInternal

Common/DataModel/vtkPointLocator.cxx:832–915

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

//  subject to the constraints of levels and NumberOfPointsPerBucket.
//  The result is directly addressable and of uniform subdivision.
void vtkPointLocator::BuildLocatorInternal()
{
  int ndivs[3];
  vtkIdType idx;
  vtkIdList* bucket;
  vtkIdType numPts;
  double x[3];
  typedef vtkIdList* vtkIdListPtr;

  vtkDebugMacro(<< "Hashing points...");
  this->Level = 1; // only single lowest level

  // Delete the current hash table values and reset dataset metrics to their original values.
  this->FreeSearchStructure();

  if (!this->DataSet || (numPts = this->DataSet->GetNumberOfPoints()) < 1)
  {
    // Missing datasets and datasets with no points are valid inputs and should not log an error.
    // Searching for the closest point id is always -1 for this data.
    return;
  }

  //  Size the root bucket.  Initialize bucket data structure, compute
  //  level and divisions.
  const double* bounds = this->DataSet->GetBounds();
  vtkIdType numBuckets = static_cast<vtkIdType>(
    static_cast<double>(numPts) / static_cast<double>(this->NumberOfPointsPerBucket));

  vtkBoundingBox bbox(bounds);
  if (this->Automatic)
  {
    bbox.ComputeDivisions(numBuckets, this->Bounds, ndivs);
  }
  else
  {
    bbox.Inflate(); // make sure non-zero volume
    bbox.GetBounds(this->Bounds);
    for (int i = 0; i < 3; ++i)
    {
      ndivs[i] = (this->Divisions[i] < 1 ? 1 : this->Divisions[i]);
    }
  }

  this->Divisions[0] = ndivs[0];
  this->Divisions[1] = ndivs[1];
  this->Divisions[2] = ndivs[2];
  this->NumberOfBuckets = numBuckets = static_cast<vtkIdType>(ndivs[0]) *
    static_cast<vtkIdType>(ndivs[1]) * static_cast<vtkIdType>(ndivs[2]);

  //  Compute width of bucket in three directions
  //
  for (int i = 0; i < 3; ++i)
  {
    this->H[i] = (this->Bounds[2 * i + 1] - this->Bounds[2 * i]) / static_cast<double>(ndivs[i]);
  }

  // Allocate the bins/buckets and initialize
  this->HashTable = new vtkIdListPtr[numBuckets];