Method PerImageInitialization

Rendering/Volume/vtkFixedPointVolumeRayCastMapper.cxx:1037–1085

This is the initialization that should be done once per image The render has been broken into several parts to support AMR volume rendering. Basically, this is done by having the AMR mapper call the PerImageInitialization once, then the PerVolumeInitialization once for each volume in the hierarchical structure. Finally, the AMR mapper divides all the volumes into subvolumes in order to render ever

// volume so the multiRender flag indicates whether to do this
// computation here or skip it for later.
int vtkFixedPointVolumeRayCastMapper::PerImageInitialization(vtkRenderer* ren, vtkVolume* vol,
  int multiRender, double inputOrigin[3], double inputSpacing[3], int inputExtent[6])
{
  // Save this so that we can restore it if the image is cancelled
  this->OldImageSampleDistance = this->ImageSampleDistance;
  this->OldSampleDistance = this->SampleDistance;

  // If we are automatically adjusting the size to achieve a desired frame
  // rate, then do that adjustment here. Base the new image sample distance
  // on the previous one and the previous render time. Don't let
  // the adjusted image sample distance be less than the minimum image sample
  // distance or more than the maximum image sample distance.
  if (this->AutoAdjustSampleDistances)
  {
    this->ImageSampleDistance =
      this->ComputeRequiredImageSampleDistance(vol->GetAllocatedRenderTime(), ren, vol);

    // If this is an interactive render (faster than 1 frame per second) then we'll
    // increase the sample distance along the ray to improve performance
    if (vol->GetAllocatedRenderTime() < 1.0)
    {
      this->SampleDistance = this->InteractiveSampleDistance;
    }
  }

  // Pass the ImageSampleDistance on the RayCastImage
  this->RayCastImage->SetImageSampleDistance(this->ImageSampleDistance);

  // The full image fills the viewport. First, compute the actual viewport
  // size, then divide by the ImageSampleDistance to find the full image
  // size in pixels
  int width, height;
  ren->GetTiledSize(&width, &height);
  this->RayCastImage->SetImageViewportSize(static_cast<int>(width / this->ImageSampleDistance),
    static_cast<int>(height / this->ImageSampleDistance));

  if (multiRender)
  {
    this->UpdateCroppingRegions();
    this->ComputeMatrices(inputOrigin, inputSpacing, inputExtent, ren, vol);

    if (!this->ComputeRowBounds(ren, 1, 0, inputExtent))
    {
      return 0;
    }
  }

  return 1;
}

// This is the initialization that should be done once per volume
void vtkFixedPointVolumeRayCastMapper::PerVolumeInitialization(vtkRenderer* ren, vtkVolume* vol)