message: add ability to override TF type using env var in VolumeSceneParser
diff: @@ -158,7 +158,13 @@ void VolumeSceneParser::importTransferFunction(const std::string &filename)
  tfn::TransferFunction fcn(filename);
  auto colorsData = ospray::cpp::Data(fcn.rgbValues.size(), OSP_FLOAT3,
  fcn.rgbValues.data());
  + auto tfFromEnv = getEnvVar<std::string>("OSPRAY_USE_TF_TYPE");
  +
  + if (tfFromEnv.first) {
  + transferFunction = cpp::TransferFunction(tfFromEnv.second);
  + } else {
  transferFunction = cpp::TransferFunction("piecewise_linear");
  + }
  transferFunction.set("colors", colorsData);
  tf_scale = fcn.opacityScaling;
  @@ -210,7 +216,13 @@ void VolumeSceneParser::importTransferFunction(const std::string &filename)
  }
  void VolumeSceneParser::createDefaultTransferFunction()
  {
  + auto tfFromEnv = getEnvVar<std::string>("OSPRAY_USE_TF_TYPE");
  +
  + if (tfFromEnv.first) {
  + transferFunction = cpp::TransferFunction(tfFromEnv.second);
  + } else {
  transferFunction = cpp::TransferFunction("piecewise_linear");
  + }
  // Add colors
  std::vector<vec4f> colors;
  