gGeoManager->GetCurrentNodeId()

Hi All,

I'm working with a geometry and need to assign unique read out channel numbers to the lowest level nodes in my geometry. I thought I could use the "gGeoManager->GetCurrentNodeId()" to map each detector cell uniquely to an integer, but when I do that, I discover that my geometry has duplicate ID numbers (that is, TGeoNodes located along different paths that return the same ID number). Perhaps I am misinterpreting what is meant my the NodeId's?

Looking at the code that assigns NodeId's it seems to me that duplicate ID's are expected:

Int_t TGeoNodeCache::GetNodeId() const
{
// Get unique node id.

    Long_t id=0;
    for (Int_t level=0;level<fLevel+1; level++)

       id += (Long_t)fNodeBranch[level];     return (Int_t)id;
}

This sum which defines id's has an obvious degeneracy when fNodeBranch [0,1] = 1,2 and fNodeBranch[0,1] = 2,1. That's oversimplified, of course, since the fNodeBranch[]'s are pointers, but other such degeneracies must exist.

Any tips on how to efficiently map a geometry path to a single ID number?

Thanks,
Mark

Mark Messier                                         messier_at_indiana.edu
Department of Physics            http://www.physics.indiana.edu/~messier
Indiana University                                 Phone: (812) 855-0236
Bloomington, IN 47405                                Fax: (812) 855-0440