TruthResetAlg.cxx

Go to the documentation of this file.

/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
#include "TruthResetAlg.h"
//
#include "AtlasHepMC/GenEvent.h"
#include "AtlasHepMC/GenVertex.h"
#include "TruthUtils/MagicNumbers.h"
#include "TruthUtils/HepMCHelpers.h"
#include "GeneratorObjects/McEventCollection.h"
 
#include "StoreGate/ReadHandle.h"
#include "StoreGate/WriteHandle.h"
 
#include "CLHEP/Vector/LorentzVector.h"
#include "CLHEP/Units/SystemOfUnits.h"
//
#include "CLHEP/Geometry/Point3D.h"
#include "GeoPrimitives/GeoPrimitives.h"
#include <climits>
 
//----------------------------------------------------
StatusCode TruthResetAlg::initialize() {
//----------------------------------------------------
 
  ATH_CHECK(m_inputMcEventCollection.initialize());
  ATH_CHECK(m_outputMcEventCollection.initialize());
  return StatusCode::SUCCESS;
 
}
 
//-------------------------------------------------
StatusCode TruthResetAlg::execute(const EventContext& ctx) const {
//-------------------------------------------------
 
  ATH_MSG_DEBUG( " execute..... " );
  SG::ReadHandle<McEventCollection> inputMcEventCollection(m_inputMcEventCollection, ctx);
  if (!inputMcEventCollection.isValid()) {
    ATH_MSG_ERROR("Could not find input McEventCollection called " << inputMcEventCollection.name() << " in store " << inputMcEventCollection.store() << ".");
    return StatusCode::FAILURE;
  }
  const HepMC::GenEvent& inputEvent(**(inputMcEventCollection->begin()));
 
  //Sanity check
  bool inputProblem(false);
  for (const auto& particle: inputEvent) {
    if (MC::isStable(particle)) {
      if (!particle->production_vertex()) {
        ATH_MSG_ERROR("Stable particle without a production vertex!! " << particle);
        inputProblem = true;
      }
    }
    else if (MC::isDecayed(particle)) {
      if (!particle->production_vertex()) {
        ATH_MSG_ERROR("Decyed particle without a production vertex!! " << particle);
        inputProblem = true;
      }
      if (!particle->end_vertex()) {
        ATH_MSG_ERROR("Decyed particle without an end vertex!! " << particle);
        inputProblem = true;
      }
    }
  }
  if (inputProblem) {
    ATH_MSG_FATAL("Problems in input GenEvent - bailing out.");
    return StatusCode::FAILURE;
  }
#ifdef HEPMC3
   std::unique_ptr<HepMC::GenEvent>  outputEvent = std::make_unique<HepMC::GenEvent>(inputEvent);
   if (inputEvent.run_info()) outputEvent->set_run_info(std::make_shared<HepMC3::GenRunInfo>(*(inputEvent.run_info().get())));
   for (;;) {
     std::vector<HepMC::GenParticlePtr> p_to_remove;
     std::vector<HepMC::GenVertexPtr> v_to_remove;
     for (auto& particle: outputEvent->particles()) {
       if (HepMC::is_simulation_particle(particle)) {
         p_to_remove.push_back(particle);
       }
     }
     for (auto& particle: p_to_remove) outputEvent->remove_particle(particle);
     for (auto& vertex: outputEvent->vertices()) {
       if (HepMC::is_simulation_vertex(vertex) || vertex->particles_out().empty() ) {
         v_to_remove.push_back(vertex);
       }
     }
     for (auto& vertex: v_to_remove) outputEvent->remove_vertex(vertex);
     if (p_to_remove.empty() && v_to_remove.empty()) break;
   }
#else
 
  std::unique_ptr<HepMC::GenEvent> outputEvent = std::make_unique<HepMC::GenEvent>(inputEvent.signal_process_id(),
                                                                                   inputEvent.event_number());
 
  outputEvent->set_mpi                  ( inputEvent.mpi() );
  outputEvent->set_event_scale          ( inputEvent.event_scale() );
  outputEvent->set_alphaQCD             ( inputEvent.alphaQCD() );
  outputEvent->set_alphaQED             ( inputEvent.alphaQED() );
  if ( inputEvent.cross_section() ) {
    outputEvent->set_cross_section        ( *inputEvent.cross_section());
  }
  if (inputEvent.heavy_ion()) {
    outputEvent->set_heavy_ion(*(inputEvent.heavy_ion()));
  }
  if (inputEvent.pdf_info()) {
    outputEvent->set_pdf_info(*(inputEvent.pdf_info()));
  }
  outputEvent->define_units( inputEvent.momentum_unit(), inputEvent.length_unit() );
 
  // 1. create a NEW copy of all vertices from inputEvent
  //    taking care to map new vertices onto the vertices being copied
  //    and add these new vertices to this event.
  //    We do not use GenVertex::operator= because that would copy
  //    the attached particles as well.
  std::map<const HepMC::GenVertex*,HepMC::GenVertex*> inputEvtVtxToOutputEvtVtx;
  HepMC::GenEvent::vertex_const_iterator currentVertexIter(inputEvent.vertices_begin());
  const HepMC::GenEvent::vertex_const_iterator endOfCurrentListOfVertices(inputEvent.vertices_end());
  ATH_MSG_VERBOSE( "Starting a vertex loop ... " );
  for (; currentVertexIter != endOfCurrentListOfVertices; ++currentVertexIter) {
    const HepMC::GenVertex *pCurrentVertex(*currentVertexIter);
    if (HepMC::is_simulation_vertex(pCurrentVertex)) {
      continue; // skip vertices created by the simulation
    }
    std::unique_ptr<HepMC::GenVertex> copyOfGenVertex =std::make_unique<HepMC::GenVertex>(pCurrentVertex->position(), pCurrentVertex->id(), pCurrentVertex->weights() );
    copyOfGenVertex->suggest_barcode( HepMC::barcode(pCurrentVertex) );
    inputEvtVtxToOutputEvtVtx[pCurrentVertex] = copyOfGenVertex.get();
    outputEvent->add_vertex( copyOfGenVertex.release() );
  } //vertex loop
 
  // 2. copy the signal process vertex info.
  if ( inputEvent.signal_process_vertex() ) {
    outputEvent->set_signal_process_vertex( inputEvtVtxToOutputEvtVtx[inputEvent.signal_process_vertex()] );
  }
  else {
    outputEvent->set_signal_process_vertex( nullptr );
  }
  //
  // 3. create a NEW copy of all particles from inputEvent
  //    taking care to attach them to the appropriate vertex
  HepMC::GenParticle* beam1{};
  HepMC::GenParticle* beam2{};
  for ( HepMC::GenEvent::particle_const_iterator particleIter = inputEvent.particles_begin();
        particleIter != inputEvent.particles_end(); ++particleIter ) {
    const HepMC::GenParticle* currentParticle = *particleIter;
    if (HepMC::is_simulation_particle(currentParticle)) {
      continue; // skip particles created by simulation
    }
    std::unique_ptr<HepMC::GenParticle> copyOfGenParticle = std::make_unique<HepMC::GenParticle>(*currentParticle);
    const bool isBeamParticle1(currentParticle == inputEvent.beam_particles().first);
    const bool isBeamParticle2(currentParticle == inputEvent.beam_particles().second);
    // There may (will) be particles which had end vertices added by
    // the simulation (inputEvent). Those vertices will not be copied
    // to the outputEvent, so we should not try to use them here.
    const bool shouldAddProdVertex(currentParticle->production_vertex() && inputEvtVtxToOutputEvtVtx[ currentParticle->production_vertex() ]);
    const bool shouldAddEndVertex(currentParticle->end_vertex() && inputEvtVtxToOutputEvtVtx[ currentParticle->end_vertex() ]);
    if ( isBeamParticle1 || isBeamParticle2 || shouldAddProdVertex || shouldAddEndVertex ) {
      HepMC::GenParticle* particleCopy = copyOfGenParticle.release();
      if ( isBeamParticle1 ) {
        beam1 = particleCopy;
      }
      if ( isBeamParticle2 ) {
        beam2 = particleCopy;
      }
      if ( shouldAddProdVertex || shouldAddEndVertex ) {
        if ( shouldAddEndVertex  ) {
          inputEvtVtxToOutputEvtVtx[ currentParticle->end_vertex() ]->
            add_particle_in(particleCopy);
        }
        if ( shouldAddProdVertex ) {
          inputEvtVtxToOutputEvtVtx[ currentParticle->production_vertex() ]->
            add_particle_out(particleCopy);
        }
      }
      else {
        ATH_MSG_WARNING ( "Found GenParticle with no production or end vertex! \n" << *currentParticle);
      }
    }
  }
  outputEvent->set_beam_particles( beam1, beam2 );
  //
  // 4. now that vtx/particles are copied, copy weights and random states
  outputEvent->set_random_states( inputEvent.random_states() );
  outputEvent->weights() = inputEvent.weights();
#endif
 
  //Sanity check
  bool outputProblem(false);
  for (const auto& particle: *(outputEvent.get())) {
    if (MC::isStable(particle)) {
      if (!particle->production_vertex()) {
        ATH_MSG_ERROR("Stable particle without a production vertex!! " << particle);
        outputProblem = true;
      }
      if (particle->end_vertex()) {
        ATH_MSG_ERROR("Stable particle with an end vertex!! " << particle);
        outputProblem = true;
      }
    }
    else if (MC::isDecayed(particle)) {
      if (!particle->production_vertex()) {
        ATH_MSG_ERROR("Decayed particle without a production vertex!! " << particle);
        outputProblem = true;
      }
      if (!particle->end_vertex()) {
        ATH_MSG_ERROR("Decayed  particle without an end vertex!! " << particle);
        outputProblem = true;
      }
    }
  }
  if (outputProblem) {
    ATH_MSG_FATAL("Problems in output GenEvent - bailing out.");
    return StatusCode::FAILURE;
  }
 
  SG::WriteHandle<McEventCollection> outputMcEventCollection(m_outputMcEventCollection, ctx);
  ATH_CHECK(outputMcEventCollection.record(std::make_unique<McEventCollection>()));
  outputMcEventCollection->push_back(outputEvent.release());
  if (!outputMcEventCollection.isValid()) {
    ATH_MSG_ERROR("Could not record output McEventCollection called " << outputMcEventCollection.name() << " in store " << outputMcEventCollection.store() << ".");
    return StatusCode::FAILURE;
  }
 
  ATH_MSG_DEBUG( "succeded TruthResetAlg ..... " );
 
  return StatusCode::SUCCESS;
 
}