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Keywords: Boolean Processor error unknown faces G4SubtractionSolid
Forum: Geometry
Re: Sad For John Allison: how come I get "unknown faces!!" when hollowing out a box? (Blair Smith)
Re: None Re: For John Allison: how come I get "unknown faces!!" when hollowing out a box? (Blair Smith)
Re: Question Re: For John Allison: how come I get "unknown faces!!" when hollowing out a box? (Blair Smith)
Date: 13 May, 2005
From: John Allison <John Allison>

> Does using a parent-child pair in this way ever give funny results.
> e.g., if I was to ask for the mass of the mother (say filled with lead),
> would geant's G4VSolid class methods "know" to subtract the mass of the
> inner daughter volume (say filled with air or vaccum)?

Yes, this accounted for in the calculation of mass, and in tracking, etc.

Incidentally, a daughter may not protrude outside the mother, or tracking will be incorrect. There are tools for testing this -- DAVID (see Application Developer's Guid and thread 362).

> ...how do I request JUST the mass
> of the "virtual boolean" solid that I've just defined using the
> mother-daughter trick without recourse to G4SubtractionSolid?

With the flexibility gained by using elemental commands, rather than the compound /vis/drawTree, you can specify the depth of search. For example:

  /vis/open ATree
  /vis/scene/create
  /vis/scene/add/volume parent-name ! 1
  /vis/sceneHandler/attach
  /vis/ASCIITree/verbose 14
  /vis/viewer/flush

and it should say something like

  Overall volume of "thePit":0, is 8000 m3 
  Mass of tree, ignoring daughters at depth 1 and below, is 800 kg

You are my first known customer for this feauture. Glad it is useful.

> Oh, and why do you Europeans use the sexist "mother/daughter" jargon
> when "parent/child" is just as good and more pleasant? ;-)

Fewer hang-ups?!! :)

> I have a different question about how to compute bounding boxes for
> general solid regions,

Each solid has a CalculateExtent and GetExtent method. But I wait to hear exactly what it is you are trying to do.

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