libGeom, Navigation in tesselated volumes imported from GDML

Dear ROOT team
Since ~ 2011 I have been using ROOT libGeom to simulate radiation transport by means of the MARS15 Monte Carlo code system. One of the common tasks is importing geometry from a GDML file. When imported, tessellated volumes from a GDML file are represented in the ROOT as TGeoVolume objects with a surface of the TGeoTessellated class. However, in the current version this class does not provide navigation functionality, making it impossible to use imported geometry in simulation.

Questions: Do you plan to implement navigation functions for the TGeoTesslated class, if so, when can we expect a ROOT version with implementation?
Thank you,
Igor Tropin
_ROOT Version: 6.23
_Platform: Linux, Fedora 32
_Compiler: gcc version 10.2

I guess that’s a question for @agheata.

Hi, TGeoTessellated was added to allow more complete geometry conversions using TGeo classes, and there is no plan for adding navigation functionality at this point. The intent is to be able to use navigation functionality via VecGeom conversion, so we will soon add support in TGeoVGShape::Convert. To use that, ROOT needs to be compiled with vecgeom support and the (closed) geometry has to be converted via: TGeoVGConverter::ConvertGeometry()

Is it worth expecting that it will be necessary to replace the calls to TGeoManager functions such as FindNextBoundaryAndStep, FindNode, etc., with calls specific to VecGeom ?

Hi Andrei,
What are your expectations (timescale) for implementation mentioned support in TGeoVGShape::Convert.