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

Rene Brun (Rene.Brun@cern.ch)
Fri, 21 May 1999 06:52:54 +0000

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