Re: [ROOTTALK] Overlaping nodes + a geometry package in Root

From: Rene Brun (Rene.Brun@cern.ch)
Date: Fri May 21 1999 - 08:52:54 MEST


Gerco Onderwater wrote:
> 
> Hi All,
> 
> Is it possible to use one node to "cut" a piece out of another one? In
> Geant it was possible to overwrite one region of space occupied by an
> object consisting of a certain material by another one consisting of
> another material (the "only" option). In that way it was possible to
> create complicated shapes by trimming the edges of simple shapes with
> pieces of air, which are then invisible.
> 
> What I am trying to do is to make a drawing of a light guide that is
> triangular on one side and circular on the other. The circular end is the
> narrow end of a cone; the other end of this cone just circumscribes the
> triangle. A TPGON unfortuately doesn't let you set the inner and outer
> radii for each point independently, otherwise it would be easy.
> 

Hi Gerco,
Yes, with Geant3 it is possible to define overlapping volumes and draw
"cut" views of this setup.
You can translate your Geant3 geometry into a Root geometry using the
tool g2root provided in the distribution kit for most systems.
You can visualize this setup in Root with either X3D or OpenGL.
Unfortunately getting a high quality print with Postscript is not yet
possible. You will have to take a low quality screen dump.

> Anybody who knows how to solve this problem? Or is it simply not possible
> in Root since it is not an AutoCad clone?
> 

I would be interested to know how many people would be interested to
have
a real geometry package in the Root framework. I mean a package able to:
  - model complex objects
  - with visualisation including
     - 2-d projections (a la CAD)
     - 3-d views with cut boxes, etc
     - real-time graphics
     - Postscript output
  - answer the questions
     - where am I ?
     - surface intersect 

Yes, I know that this problem is (may be) solved by detector simulation
tools.

Rene Brun



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