message: fix compilation without openvdb
diff: @@ -146,6 +146,7 @@ namespace ospray::sg {
  VDBData VdbVolume::generateVDBData(const FileName &fileNameAbs)
  {
  VDBData vdbData;
  +#if USE_OPENVDB
  if (!fileLoaded) {
  openvdb::initialize(); // Must initialize first! It's ok to do this
  // multiple times.
  @@ -208,6 +209,8 @@ namespace ospray::sg {
  static_cast<float>(i2o[13]),
  static_cast<float>(i2o[14])};
  }
  +#endif //USE_OPENVDB
  +
  return vdbData;
  }
  