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Question problems with BREPS 

Forum: Geometry
Date: 12 Mar, 2012
From: Nika Valencic <Nika Valencic>

Dear Geanters,

I have a couple of questions concerning BREP Solids construction.

Browsing through the forum and User Manuals I saw several warnings that BREPS are not fully implemented. I managed to construct a solid using G4BREPSolidPolyhedra and it worked. However, when I tried to construct a G4BREPSolidCylinder and visualize it I got a cube(?!) (the code is attached bellow).

My first question: Am I doing something wrong? Is the problem only in visualization (I use Qt) or is just that this class is not implemented completely?

My second question: I want to construct a body that looks like a trapezoid, but with two circular edges and two straight but nonparallel edges, of thickness z (figure is attached bellow) . So far I successfully constructed (approximation) of this body, using G4ExtrudedSolid. Now I want to construct the body with actual circular edges. I see two options; BREPS or boolean solids. Which method needs more CPU time? I really want to try and build this body using BREPS. Can this be done? I tried defining all the surfaces that confine this body (planes + cylindrical surfaces) but failed. Can you give me some advice where can I look for examples of BREP construction and if this is possible?

My third question: When I visualize the body made by G4ExtrudedSolid I get some lines inside the body (figure attached bellow). I know this is just a consequence of visualization, but I was wondering if there is a way to get rid of them. I tried with /vis/viewer/set/edge and /vis/viewer/set/hiddenEdge commands but the lines are always present. Even if I draw this body as solid (/vis/viewer/set/style solid). Can you give me some advice how to make these lines invisible?

Thank you! :)

Nika

P.S: I'm using Geant4.9.5 on mac OS X (10.7.2).

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2012/03/12/13.09-72011-code.txt
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2012/03/12/13.07-45714-shape.jpg
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2012/03/12/13.09-15736-extruded.jpg

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1 None: Re: problems with BREPS   (John Allison - 13 Mar, 2012)
2 More: Re: problems with BREPS   (Gabriele Cosmo - 13 Mar, 2012)
3 None: Re: problems with BREPS   (Nika Valencic - 13 Mar, 2012)
1 None: Re: problems with BREPS   (John Allison - 13 Mar, 2012)
(_ More: Re: problems with BREPS   (Gabriele Cosmo - 13 Mar, 2012)
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