G4Hype CSG Volume
Ernesto Lamanna and Francesco Safai Tehrani
Universita' di Roma "La Sapienza" and INFN
We have decided to switch to the implementation of a CSG-style volume due to the problems we encountered with BREPs, and on recommendation of other people working on Bogus as well on Geant4 (G. Cosmo and B. Lockman).
Technicalia
The CSG implementation is quite different from the viewpoint of OOP since it is more Fortran-like, so it required quite a bit of reprogramming and reimplementation of functions.
As usual, since there exists little or no documentations about Geant4 internals, most things were discovered (and then learned) from direct code inspection of the already existing CSG solids.
The full CSG solid is implemented as a single class inheriting from G4VSOLID, and the implementation requires the following member functions:
- The constructor
- The destructor
- CalculateExtent
- Inside
- SurfaceNormal
- DistanceToIn(point)
- DistanceToIn(point, direction)
- DistanceToOut(point)
- DistanceToOut(point, direction, other params)
- Various service functions to check and change data member
- Some protected functions for internal use
User interface
Six parameters are requested from the G4Hype interface:
| The solid name |
G4String |
| The inner surface radius |
G4double |
| The outer surface radius |
G4double |
| The inner surface stereo angle [in radians] |
G4double |
| The outer surface stereo angle [in radians] |
G4double |
| The volume half length along the Z axis |
G4double |
Since an hyperbolical surface with stereo angle equal to zero is a cylindrical surface, the solids which can be represented via the G4Hype class are the following:
A tube with inner and outer hyperbolical surface
A full tube with external hyperbolical surface (no inner surface)
A full tube with external cylindrical surface
A tube with inner hyperbolical and outer cylindrical surface
A tube with inner cylindrical and outer hyperbolical surface
A tube with inner and outer cylindrical surfaces (same as G4Tubs)
Current status
The code is fully implemented, and undergoing extended debugging and optimization, to make this volume implementation as fast and reliable as possible.
The Geant4 examples, found under the /run/example?? are used as testbed for the implementation as well for performance benchmark.
For questions/comments please contact: Ernesto Lamanna or Francesco Safai Tehrani
Last modified: Wed Apr 29 15:23:49 METDST |
