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Forum: Geometry
Re: None Overlap of parameterized volumes (Niklas)
Re: None Re: Overlap of parameterized volumes (Joseph Perl)
Date: 23 Feb, 2009
From: Joseph Perl <Joseph Perl>

(cleaning up an old incorrect comment here while I tidy up some very old mail)

My statement that "you can't use rectangular parameterized volumes inside a G4Tub" was incorrect. You can't use REPLICAS in this situation, but you CAN use parameterized volumes.

Gabriele Cosmo explained it as follows:

 as far as one manages to define a -unique- parameterization
 algorithm that allows to:

 a] Position the different boxes within the cylinder, avoiding
    overlaps with it;
 b] Position and reduce the dimensions of the boxes as close to
    the border of the cylinder and avoiding overlaps with it;

 then, it is possible!  No problem if nested-parameterizations are
 applied... actually, the application of nested-parameterisation is
 the easiest part here, since the idea would be to:
 - first, slice the cylinder along Z with slices all of the
   same size (this could be a replica in principle... but a
   parameterization is just fine and simple here...);
 - second, parametrize the single slice with parallelepipeds with base
   of varied dimensions (either X or Y) according to the positioning
   in the cylinder (the most difficult part... one can start from the
   center row by row and column by column and try to fill as much as
   possible the area of the cylinder).

 Saying that it is not possible to place parameterized boxes inside a
 tube is certainly not correct... A tube is like any other solid.

 What is NOT possible is to apply REPLICAS, since replicas are real
 slices that must fill -completely- the mother volume (the cylinder),
 and only radial, phi or Z slices are allowed for replicas in the
 cylindrical case.

John Apostolakis also privately discussed with me that it would in principal be possible to develop a new specialized parameterization for this purpose. "Create a new parameterization, where all boxes have the same basic size - except that boxes which protrude from the envelope volume are clipped."

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