Method GetReductionRatio

Rendering/VolumeOpenGL2/vtkOpenGLGPUVolumeRayCastMapper.cxx:4010–4043

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//------------------------------------------------------------------------------
void vtkOpenGLGPUVolumeRayCastMapper::GetReductionRatio(double* ratio)
{
  ratio[0] = ratio[1] = ratio[2] = 1.0; // default

  vtkImageData* input = vtkImageData::SafeDownCast(this->GetInput());
  if (!input)
  {
    return;
  }

  const int* dims = input->GetDimensions();
  const int dimCount = input->GetDataDimension();
  const size_t scalarSize = static_cast<size_t>(input->GetScalarSize());
  const size_t currentSize = static_cast<size_t>(dims[0]) * dims[1] * dims[2] * scalarSize;
  const size_t maxSize = static_cast<size_t>(
    this->GetMaxMemoryInBytes() * static_cast<double>(this->GetMaxMemoryFraction()));

  if (currentSize > maxSize)
  {
    const double totalRatio = static_cast<double>(maxSize) / currentSize;

    ratio[0] = 1.0 - ((1.0 - totalRatio) / dimCount);

    if (dims[1] != 1)
    {
      ratio[1] = ratio[0];
    }

    if (dims[2] != 1)
    {
      ratio[2] = ratio[0];
    }
  }
}

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vtkMTimeType vtkOpenGLGPUVolumeRayCastMapper::GetRenderPassStageMTime(vtkVolume* vol)