Method ComputeRenderMode

Rendering/VolumeOpenGL2/vtkSmartVolumeMapper.cxx:324–546

------------------------------------------------------------------------------ Compute the render mode based on what hardware is available, what the user requested as a render mode, and the desired update rate of the render window ------------------------------------------------------------------------------

// requested as a render mode, and the desired update rate of the render window
//------------------------------------------------------------------------------
void vtkSmartVolumeMapper::ComputeRenderMode(vtkRenderer* ren, vtkVolume* vol)
{
  // If we are already initialized, and the volume,
  // volume's input, and volume's property have not
  // changed since last time we computed the render mode,
  // then we don't need to initialize again
  if (!(this->Initialized && this->SupportStatusCheckTime.GetMTime() > this->GetMTime() &&
        this->SupportStatusCheckTime.GetMTime() > vol->GetProperty()->GetMTime() &&
        this->SupportStatusCheckTime.GetMTime() > this->GetInput()->GetMTime() &&
        this->InitializedBlendMode == this->GetBlendMode()))
  {
    this->Initialize(ren, vol);
  }

  // Use this as the initial state to simplify the code below
  this->CurrentRenderMode = vtkSmartVolumeMapper::InvalidRenderMode;

  if (!this->GetInput())
  {
    return;
  }

  double scale[3];
  double spacing[3];
  if (auto imData = vtkImageData::SafeDownCast(this->GetInput()))
  {
    imData->GetSpacing(spacing);
  }
  else if (auto rectGrid = vtkRectilinearGrid::SafeDownCast(this->GetInput()))
  {
    // compute average spacing along each dimension
    double bounds[6];
    rectGrid->GetBounds(bounds);
    int dims[3];
    rectGrid->GetDimensions(dims);
    for (int i = 0; i < 3; ++i)
    {
      spacing[i] = (bounds[2 * i + 1] - bounds[2 * i]) / dims[i];
    }
  }

  // Compute the sample distance based on dataset spacing.
  // It is assumed that a negative SampleDistance means the user would like to
  // compute volume mapper sample distance based on data spacing.
  if (this->SampleDistance < 0)
  {
    this->SampleDistance = static_cast<float>((spacing[0] + spacing[1] + spacing[2]) / 6.0);
  }

  vtkRenderWindow* win = ren->GetRenderWindow();

  switch (this->RequestedRenderMode)
  {
    // Requested ray casting - OK as long as it is supported
    // This ray caster is a software mapper so it is supported as
    // we aren't attempting to render cell scalars
    case vtkSmartVolumeMapper::RayCastRenderMode:
      if (this->RayCastSupported)