DeltaRRoIComboHypoTool.cxx

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
#include "DeltaRRoIComboHypoTool.h"
#include "TrigSteeringEvent/TrigRoiDescriptorCollection.h"
#include <algorithm>
#include <cmath>
 
using namespace TrigCompositeUtils;
 
DeltaRRoIComboHypoTool::DeltaRRoIComboHypoTool(const std::string& type,
                           const std::string& name,
                           const IInterface* parent)
  : ComboHypoToolBase(type, name, parent)
{ }
 
 
StatusCode DeltaRRoIComboHypoTool::initialize() {
  ATH_MSG_DEBUG("DR threshold set to " << m_DRcut );
  return StatusCode::SUCCESS;
}
 
 
 
bool DeltaRRoIComboHypoTool::executeAlg(const std::vector<Combo::LegDecision>& combination,
                                        const EventContext& ctx) const
{
  //retrieve the rois 
  std::vector<ElementLink<TrigRoiDescriptorCollection>> selected_rois;
 
  // Expecting to only run over chains with two legs and one Decision Object required on each leg
  // So should always have two objects from which to check DeltaR
  if(combination.size() != 2){
    ATH_MSG_ERROR(
      "Expecting to combine exactly two Decision Objects, but instead found "
      << combination.size() << ". Will throw a runtime error");
    throw std::runtime_error(
      "Expecting to combine exactly two Decision Objects, but instead found " +
      std::to_string(combination.size()));
  }
 
  for (const auto& el: combination){
    const auto EL= el.second;    
    const auto dec= (*EL);
    const auto roiLink = TrigCompositeUtils::findLink<TrigRoiDescriptorCollection>( ctx, dec, initialRoIString() ).link;
    selected_rois.push_back(roiLink);
  }
 
  auto roiLink1=selected_rois[0];
  auto roiLink2=selected_rois[1];
  // calucalte DeltaR
  float Dr = deltaR((*roiLink1)->eta(), (*roiLink2)->eta(), (*roiLink1)->phi(), (*roiLink2)->phi());
  ATH_MSG_DEBUG("Found two RoIs with eta/phi " << (*roiLink1)->eta() <<"/"<<(*roiLink1)->phi() <<" and "<< (*roiLink2)->eta()<<"/"<<(*roiLink2)->phi() <<" with Dr="<<Dr);
 
  // apply the cut
  bool pass=true;
  if (Dr > m_DRcut) pass=false;
 
  if (pass)
    ATH_MSG_DEBUG( "  RoIs within DR<"<<m_DRcut<<". This seleciton passed! ");
  
  return pass;
}
 
 
double DeltaRRoIComboHypoTool::deltaR(double eta1, double eta2, double phi1, double phi2) const {
  double dPhi=std::remainder( phi1 - phi2, 2*M_PI );
  double dEta=std::fabs(eta1-eta2);
  return std::sqrt(dEta*dEta + dPhi*dPhi);
}