sPHENIX tracking discussion

[Christof E Roland <cer AT mit.edu>]

Hi Everybody, 

I just updated to the latest master version of coresoftware and the 
PHG4TrackKalmanFitter is broken. It exits with the following error:
PHG4TrackKalmanFitter.C:783: ERROR: Can't find node G4CELL_SVTX

I assume this is related to the recent retooling of the PHG4CylinderCell
classes. In the KalmanFitter and the Combinatorial Track finding
the CylinderCellMaps were used to access the sensor positions
and angles for a given hit. See code snippet below. 
Could someone remind me what the replacement code with the 
new PHG4Cell model is supposed to look like?

Thanks a lot

   Christof

code that needs to be replaced: 

        PHG4CylinderCell_MAPS* cell =
                                        (PHG4CylinderCell_MAPS*) 
cells_maps->findCylinderCell(
                                                        hit->get_cellid());
                        int stave_index = cell->get_stave_index();
                        int half_stave_index = cell->get_half_stave_index();
                        int module_index = cell->get_module_index();
                        int chip_index = cell->get_chip_index();

                        double ladder_location[3] = { 0.0, 0.0, 0.0 };
                        PHG4CylinderGeom_MAPS *geom =
                                        (PHG4CylinderGeom_MAPS*) 
geom_container_maps->GetLayerGeom(
                                                        layer);
                        // returns the center of the sensor in world 
coordinates - used to get the ladder phi location
                        geom->find_sensor_center(stave_index, 
half_stave_index,
                                        module_index, chip_index, 
ladder_location);
                        //n.Print();
                        n.SetXYZ(ladder_location[0], ladder_location[1], 0);
                        n.RotateZ(phi_tilt[layer]);