Method UpdateGradients

Rendering/Volume/vtkFixedPointVolumeRayCastMapper.cxx:2753–2798

}

int vtkFixedPointVolumeRayCastMapper::UpdateGradients(vtkVolume* vol)
{
  int needToUpdate = 0;

  this->GradientOpacityRequired = 0;
  this->ShadingRequired = 0;

  // Get the image data
  vtkImageData* input = vtkImageData::SafeDownCast(this->GetInput());

  if (vol->GetProperty()->GetShade())
  {
    needToUpdate = 1;
    this->ShadingRequired = 1;
  }

  for (int c = 0; c < this->CurrentScalars->GetNumberOfComponents(); c++)
  {
    vtkPiecewiseFunction* f = vol->GetProperty()->GetGradientOpacity(c);
    if (strcmp(f->GetType(), "Constant") != 0 || f->GetValue(0.0) != 1.0)
    {
      needToUpdate = 1;
      this->GradientOpacityRequired = 1;
    }
  }

  if (!needToUpdate)
  {
    return 0;
  }

  // Check if the input has changed
  if (input == this->SavedGradientsInput && this->CurrentScalars == this->PreviousScalars &&
    input->GetMTime() < this->SavedGradientsMTime.GetMTime())
  {
    return 0;
  }

  this->ComputeGradients(vol);

  // Time to save the input used to update the tables
  this->SavedGradientsInput = vtkImageData::SafeDownCast(this->GetInput());
  this->SavedGradientsMTime.Modified();

  return 1;
}

int vtkFixedPointVolumeRayCastMapper::UpdateColorTable(vtkVolume* vol)
{