Method UpdateTransferFunction

Rendering/RayTracing/vtkOSPRayVolumeMapperNode.cxx:403–464

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//------------------------------------------------------------------------------
void vtkOSPRayVolumeMapperNode::UpdateTransferFunction(
  RTW::Backend* backend, vtkVolume* vol, double* dataRange)
{
  if (backend == nullptr)
    return;
  vtkVolumeProperty* volProperty = vol->GetProperty();
  vtkColorTransferFunction* colorTF = volProperty->GetRGBTransferFunction(0);
  vtkPiecewiseFunction* scalarTF = volProperty->GetScalarOpacity(0);

  this->TFVals.resize(this->NumColors * 3);
  this->TFOVals.resize(this->NumColors);
  double tfRangeD[2];
  // prefer transfer function's range
  colorTF->GetRange(tfRangeD);
  // but use data's range if we can and we have to
  if (dataRange && (dataRange[1] > dataRange[0]) && (tfRangeD[1] <= tfRangeD[0]))
  {
    tfRangeD[0] = dataRange[0];
    tfRangeD[1] = dataRange[1];
  }
  osp::vec2f tfRange = { float(tfRangeD[0]), float(tfRangeD[1]) };
  scalarTF->GetTable(tfRangeD[0], tfRangeD[1], this->NumColors, &this->TFOVals[0]);
  colorTF->GetTable(tfRangeD[0], tfRangeD[1], this->NumColors, &this->TFVals[0]);

  ospRelease(this->TransferFunction);
  this->TransferFunction = ospNewTransferFunction("piecewiseLinear");

  OSPData colorData = ospNewCopyData1D(&this->TFVals[0], OSP_VEC3F, this->NumColors);
  ospCommit(colorData);
  ospSetObject(this->TransferFunction, "color", colorData);

#if OSPRAY_VERSION_MAJOR < 3
  ospSetVec2f(this->TransferFunction, "valueRange", tfRange.x, tfRange.y);
#else
  ospSetBox1f(this->TransferFunction, "value", tfRange.x, tfRange.y);
#endif

  OSPData tfAlphaData = ospNewCopyData1D(&this->TFOVals[0], OSP_FLOAT, this->NumColors);
  ospCommit(tfAlphaData);
  ospSetObject(this->TransferFunction, "opacity", tfAlphaData);

  ospCommit(this->TransferFunction);
  ospRelease(colorData);
  ospRelease(tfAlphaData);

  vtkContourValues* contours = volProperty->GetIsoSurfaceValues();
  this->IsoColors.clear();
  if (contours)
  {
    this->IsoColors.reserve(4 * contours->GetNumberOfContours());
    double* p = contours->GetValues();
    for (auto i = 0; i < contours->GetNumberOfContours(); ++i)
    {
      double* ncol = colorTF->GetColor(p[i]);
      this->IsoColors.push_back(ncol[0]);
      this->IsoColors.push_back(ncol[1]);
      this->IsoColors.push_back(ncol[2]);
      this->IsoColors.push_back(scalarTF->GetValue(p[i]));