Method Initialize

Rendering/Volume/vtkUnstructuredGridPreIntegration.cxx:330–367

//------------------------------------------------------------------------------

void vtkUnstructuredGridPreIntegration::Initialize(vtkVolume* volume, vtkDataArray* scalars)
{
  vtkVolumeProperty* property = volume->GetProperty();

  if ((property == this->Property) && (this->IntegrationTableBuilt > property->GetMTime()) &&
    (this->IntegrationTableBuilt > this->MTime))
  {
    // Nothing changed from the last time Initialize was run.
    return;
  }

  this->Property = property;
  this->Volume = volume;
  this->IntegrationTableBuilt.Modified();

  if (!property->GetIndependentComponents())
  {
    vtkErrorMacro("Cannot store dependent components in pre-integration table.");
    return;
  }

  // Determine the maximum possible length of a ray segment.
  vtkDataSet* input = volume->GetMapper()->GetDataSetInput();
  vtkIdType numcells = input->GetNumberOfCells();
  this->MaxLength = 0;
  for (vtkIdType i = 0; i < numcells; i++)
  {
    double cellbounds[6];
    input->GetCellBounds(i, cellbounds);
#define SQR(x) ((x) * (x))
    double diagonal_length = sqrt(SQR(cellbounds[1] - cellbounds[0]) +
      SQR(cellbounds[3] - cellbounds[2]) + SQR(cellbounds[5] - cellbounds[4]));
#undef SQR
    this->MaxLength = std::max(diagonal_length, this->MaxLength);
  }

  this->BuildPreIntegrationTables(scalars);
}

//------------------------------------------------------------------------------