Introduced new class TRestGeant4GeometryInfo

[lobis]

New class TRestGeant4GeometryInfo used to store geometry information. Code originally from https://github.com/lobis/radiation-transport, needed to correctly work with assembly gdml geometries.

[jgalan]

I think a usage example would be desirable, including a pipeline.

[nkx111]

I think a usage example would be desirable, including a pipeline.

Would this PR change anything for the user? I guess the pipeline is not changed. May be the example could be just loading an individual gdml file with this new class?

[lobis]

I think a usage example would be desirable, including a pipeline.

Would this PR change anything for the user? I guess the pipeline is not changed. May be the example could be just loading an individual gdml file with this new class?

@jgalan

Yes, this should not change anything for the user.

It just adds a new member to TRestGeant4Metadata, GetGeant4GeometryInfo which returns a reference to the geometry info where some important information is stored, such as the name of logical, physical volumes, materials.. also some important information such as geometry volumes positions, which can later be used on analysis.

The original motivation was that the usage of assembly geometries requires a new way to define a "volume name", since the one provided by Geant4 GDML parser and ROOT differs. This class takes care of this internally, keeping the usual volume names for geometries that are not using assembly.

I also added an example to restG4 (10.Geometries) to check the correct reading of assembly geometries, but its not working due to bugs in the Geant4 10.4.3 and older versions, so the validation script doesn't throw until we upgrade Geant4 version.