Getting started

What's needed

Using GDML

• Using GDML with Geant4
  In order to use the GDML file as geometry source for a Geant4 application one needs to instanciate and call the GDML parser. This can, for instance, be done within a special G4VUserDetectorConstruction class implementation. The examples located inside the Geant4 distribution (see inside examples/extended/persistency/gdml directory) provide implementations of such a detector construction class.
  In order to export the Geant4 geometry in the form of the GDML file, one needs to call the writer through the G4GDMLParser instance for dumping the geometry tree identified by the pointer to the top volume provided as argument. This can be done anywhere in the user code provided only that the Geant4 geometry tree is already instanciated in the memory. The example code can be found in Geant4 example G02 in the same directory as specified above.
• Using GDML with Root
  GDML reader and writer is fully integrated within the TGeoManager::Import and TGeoManager::Export methods which will call the appropriate GDML processing code whenever the file extension is .gdml.