void Import_GDML_Export_ROOT() { TString vmcDir = TString(gSystem->Getenv("VMCWORKDIR")); TGeoManager *gdml = new TGeoManager("gdml", "FAIRGeom"); TGDMLParse parser; // Define your input GDML file HERE TGeoVolume* gdmlTop = parser.GDMLReadFile (vmcDir + "/geometry/rich/rich_v13c_pipe_1_al_1.gdml"); TGeoVolume* rootTop = new TGeoVolumeAssembly("TOP"); gGeoManager->SetTopVolume(rootTop); // Define your position HERE TGeoRotation* rot = new TGeoRotation ("rot", 0., 0., 0.); TGeoCombiTrans* posrot = new TGeoCombiTrans (0., 0., 270., rot); rootTop->AddNode (gdmlTop, 1, posrot); gGeoManager->CloseGeometry(); // Define you output ROOT file HERE TFile* outfile = new TFile(vmcDir + "/geometry/rich/rich_v13c_pipe_1_al_1.root", "RECREATE"); rootTop->Write(); outfile->Close(); }