I am trying to understand the GDML xtru definition.
Page 24 - http://lcgapp.cern.ch/project/simu/framework/GDML/doc/GDMLmanual.pdf
specifically xOffset, yOffset, scalingFactor
Does the xOffsets mean I should add the xOffset to the corresponding x coordinate of the blueprint polygon when specifying its z coordinate,
similarly with yOffset.
How do I apply the scalingFactor? To the zPosition value ? if yes seems strange, why not just use the zPosition.
I note that the definitions of G4ExtrudedSolid at http://geant4-userdoc.web.cern.ch/geant4-userdoc/UsersGuides/ForApplicationDeveloper/html/Detector/Geometry/geomSolids.html seems to be different from the GDML xtru parameters.