TruthTrackCreation.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/

// TruthTrackCreation.cxx, (c) ATLAS Detector software
 
#include "TruthTrackCreation.h"
// Trk includes
#include "TrkTruthTrackInterfaces/IPRD_TruthTrajectoryBuilder.h"
#include "TrkTruthTrackInterfaces/IPRD_TruthTrajectorySelector.h"
#include "TrkTruthTrackInterfaces/ITruthTrackBuilder.h"
#include "TrkTruthTrackInterfaces/PRD_TruthTrajectory.h"
#include "TrkToolInterfaces/ITrackSelectorTool.h"
// HepMC
#include "AtlasHepMC/GenParticle.h"
#include "AtlasHepMC/SimpleVector.h"
 
//================ Constructor =================================================
 
Trk::TruthTrackCreation::TruthTrackCreation(const std::string& name, ISvcLocator* pSvcLocator)
    :
    AthReentrantAlgorithm(name,pSvcLocator),
    m_prdTruthTrajectoryBuilder("Trk::PRD_TruthTrajectoryBuilder/InDetPRD_TruthTrajectoryBuilder"),
    m_truthTrackBuilder("Trk::TruthTrackBuilder/InDetTruthTrackBuilder"),
    m_trackSummaryTool("")
{
    // Trk Truth Tools
  declareProperty("PRD_TruthTrajectoryBuilder",   m_prdTruthTrajectoryBuilder, "Truth Trajectory Builder Tool");
  declareProperty("TruthTrackBuilder",            m_truthTrackBuilder, "Truth Track Builder Tool");
  declareProperty("PRD_TruthTrajectorySelectors", m_prdTruthTrajectorySelectors, "PRD truth trajectory selectors");
    // Trk Tools
  declareProperty("TrackSelectors",               m_trackSelectors, "Track selectors for a posteriori track selection");
  declareProperty("TrackSummaryTool",             m_trackSummaryTool, "Summary tool for completing the track with its summary info");
}
 
//================ Destructor =================================================
 
Trk::TruthTrackCreation::~TruthTrackCreation()
    = default;
 
 
//================ Initialisation =================================================
 
StatusCode Trk::TruthTrackCreation::initialize()
{
    // trajectory creator
    if (m_prdTruthTrajectoryBuilder.retrieve().isFailure()){
        ATH_MSG_ERROR("Could not retrieve " << m_prdTruthTrajectoryBuilder << ". Aborting ...");
        return StatusCode::FAILURE;
    }
    // truth track builder
    if (m_truthTrackBuilder.retrieve().isFailure()){
        ATH_MSG_ERROR("Could not retrieve " << m_truthTrackBuilder << ". Aborting ...");
        return StatusCode::FAILURE;
    }
    // PRD truth trajectory selectors
    if (!m_prdTruthTrajectorySelectors.empty() && m_prdTruthTrajectorySelectors.retrieve().isFailure()){
        ATH_MSG_ERROR("Could not retrieve " << m_prdTruthTrajectorySelectors << ". Aborting ...");
        return StatusCode::FAILURE;
    }
    ATH_CHECK( m_assoTool.retrieve( DisableTool {m_assoTool.empty()} ));
 
    // track summary tool if configured
    if (!m_trackSummaryTool.empty() && m_trackSummaryTool.retrieve().isFailure()){
        ATH_MSG_ERROR("Could not retrieve " << m_trackSummaryTool << ". Aborting ...");
        return StatusCode::FAILURE;
    }
    // track selector if configured
    if (!m_trackSelectors.empty() && m_trackSelectors.retrieve().isFailure()){
        ATH_MSG_ERROR("Could not retrieve " << m_trackSelectors << ". Aborting ...");
        return StatusCode::FAILURE;
    }
 
    ATH_CHECK( m_outputTrackCollectionName.initialize() );
    ATH_CHECK( m_skippedTrackCollectionName.initialize() );
 
    return StatusCode::SUCCESS;
}
 
//================ Finalisation =================================================
 
StatusCode Trk::TruthTrackCreation::finalize()
{
  // Code entered here will be executed once at the end of the program run.
    return StatusCode::SUCCESS;
}
 
//================ Execution ====================================================
 
StatusCode Trk::TruthTrackCreation::execute(const EventContext& ctx) const
{
    std::unique_ptr<Trk::PRDtoTrackMap> prd_to_track_map(!m_assoTool.empty()
                                                         ? m_assoTool->createPRDtoTrackMap() 
                                                         : std::unique_ptr<Trk::PRDtoTrackMap>());
    // create the track collection
    std::unique_ptr<TrackCollection> outputTrackCollection = std::make_unique<TrackCollection>();
    std::unique_ptr<TrackCollection> skippedTrackCollection = std::make_unique<TrackCollection>();
    SG::WriteHandle<TrackCollection> outputTrackCollectionHandle(m_outputTrackCollectionName, ctx);
    SG::WriteHandle<TrackCollection> skippedTrackCollectionHandle(m_skippedTrackCollectionName, ctx);
 
    std::vector<std::unique_ptr<Trk::Track> > tmp_track_collection;
 
    // ----------------------------------- main loop ------------------------------------------------------------------
    // get the PRD truth trajectories
    const std::map< HepMC::ConstGenParticlePtr, PRD_TruthTrajectory >& truthTraj =
        m_prdTruthTrajectoryBuilder->truthTrajectories(ctx);
    // some screen output
    ATH_MSG_VERBOSE("PRD_TruthTrajectoryBuilder delivered " << truthTraj.size() << " PRD truth trajectories, starting track creation.");
    // loop over truth trajectories and create track
    auto ttIter  = truthTraj.begin();
    auto ttIterE = truthTraj.end();
    for ( ; ttIter != ttIterE; ++ttIter){
        // run through the selector chain
        if (!m_prdTruthTrajectorySelectors.empty()){
            ToolHandleArray<Trk::IPRD_TruthTrajectorySelector>::const_iterator prdTTSelIter  = m_prdTruthTrajectorySelectors.begin();
            ToolHandleArray<Trk::IPRD_TruthTrajectorySelector>::const_iterator prdTTSelIterE = m_prdTruthTrajectorySelectors.end();
            bool passed = true;
            for ( ; prdTTSelIter != prdTTSelIterE && passed; ++prdTTSelIter ){
                if (!(*prdTTSelIter)->pass((*ttIter).second)){
                    ATH_MSG_VERBOSE("PRD truth trajectory did not pass the selection cuts. Skipping ... ");
                    passed = false;
                }
            }
            // the consequence of the selection loop
            if (!passed) continue;
        }
        // create the truth track
        std::unique_ptr<Trk::Track> truthTrack( m_truthTrackBuilder->createTrack(ttIter->second));
        if (!truthTrack){
            ATH_MSG_VERBOSE("Track creation for PRD truth trajectory with size " << (*ttIter).second.prds.size() << " failed. Skipping ...");
            continue;
        } 
        ATH_MSG_VERBOSE("Track creation for PRD truth trajectory with size " << (*ttIter).second.prds.size() << " successful.");
        // If configured : update the track summary
        if (m_trackSummaryTool.isEnabled()){
            ATH_MSG_VERBOSE("Updating the TrackSummary.");
            m_trackSummaryTool->computeAndReplaceTrackSummary(ctx, *truthTrack,
                                                              false /* DO NOT suppress hole search*/);
 
        }
        // If configured : check with the TrackSelectors
        bool passed = m_trackSelectors.empty();
        if ( !m_trackSelectors.empty() ) {
            for (const auto& ts : m_trackSelectors) {
                passed = ts->decision(*truthTrack);
                if (passed) break;
            }
        } 
        // now check the result
        if (passed){
            // everything good
            ATH_MSG_VERBOSE("Track created and pushed into the output track collection.");
            if (prd_to_track_map  && m_assoTool->addPRDs(*prd_to_track_map, *truthTrack).isFailure())  {
              ATH_MSG_WARNING("Failed to add PRDs to map");
            }
            tmp_track_collection.push_back(std::move(truthTrack));
        } else {
            ATH_MSG_VERBOSE("Track did not pass the track selection. Putting it into skipped track collection.");
            skippedTrackCollection->push_back(truthTrack.release());
        }
    }
 
    // If configured : update the track summary
    if (m_trackSummaryTool.isEnabled()) {
        outputTrackCollection->reserve(tmp_track_collection.size());
        for (std::unique_ptr<Trk::Track> &track : tmp_track_collection) {
            ATH_MSG_VERBOSE("Updating the TrackSummary with shared hits.");
            m_trackSummaryTool->computeAndReplaceTrackSummary(ctx, *track, false /* DO NOT suppress hole search*/);
            outputTrackCollection->push_back(std::move(track));
        }
    }
    else {
       outputTrackCollection->reserve(tmp_track_collection.size());
       for (std::unique_ptr<Trk::Track> &track : tmp_track_collection) {
          outputTrackCollection->push_back(std::move(track));
       }
    }
 
    // ----------------------------------- record & cleanup ---------------------------------------------------------------    
 
    ATH_CHECK(outputTrackCollectionHandle.record(std::move(outputTrackCollection)));
 
    ATH_MSG_VERBOSE("Truth TrackCollection with name " << m_outputTrackCollectionName << " and size " <<  outputTrackCollectionHandle->size() << " recorded.");
 
    ATH_CHECK(skippedTrackCollectionHandle.record(std::move(skippedTrackCollection)));
 
    ATH_MSG_VERBOSE("Truth TrackCollection with name " << m_skippedTrackCollectionName << " and size " <<  skippedTrackCollectionHandle->size() << " recorded.");
 
    // job done
    return StatusCode::SUCCESS;
}
 
//============================================================================================