ParticleFilters.h

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#ifndef LARSIM_LARG4_PARTICLEFILTERS_H
#define LARSIM_LARG4_PARTICLEFILTERS_H

// LArSoft libraries

// ROOT libraries
#include "TGeoVolume.h"
#include "TGeoMatrix.h" // TGeoCombiTrans
#include "TLorentzVector.h"
#include "TVector3.h"

// C/C++ standard libraries
#include <array>
#include <vector>
#include <utility> // std::move()


namespace larg4 {

  struct KeepByPositionFilterTag {};


  class PositionInVolumeFilter: public KeepByPositionFilterTag {
      public:
    
    using Point_t = std::array<double, 3>;
    
    struct VolumeInfo_t {
      VolumeInfo_t(TGeoVolume const* new_vol, TGeoCombiTrans const* new_trans)
        : vol(new_vol), trans(new_trans) {}
      
      TGeoVolume const*     vol;   
      TGeoCombiTrans const* trans; 
    }; // VolumeInfo_t
    
    using AllVolumeInfo_t = std::vector<VolumeInfo_t>;
    
    PositionInVolumeFilter(std::vector<VolumeInfo_t> const& volumes)
      : volumeInfo(volumes)
      {}
    PositionInVolumeFilter(std::vector<VolumeInfo_t>&& volumes)
      : volumeInfo(std::move(volumes))
      {}
    
    bool mustKeep(Point_t const& pos) const
      {
        // if no volume is specified, it means we don't filter
        if (volumeInfo.empty()) return true;
        double local[3];
        for(auto const& info: volumeInfo) {
          // transform the point to relative to the volume
          info.trans->MasterToLocal(pos.data(), local);
          // containment check
          if (info.vol->Contains(local)) return true;
        } // for volumes
        return false;
      } // mustKeep()
    
    bool mustKeep(TVector3 const& pos) const
      { return mustKeep(Point_t{{ pos.X(), pos.Y(), pos.Z() }}); }

    bool mustKeep(TLorentzVector const& pos) const
      { return mustKeep(Point_t{{ pos.X(), pos.Y(), pos.Z() }}); }

    
      protected:
    std::vector<VolumeInfo_t> volumeInfo; 
    
  }; // PositionInVolumeFilter
  
} // namespace larg4

#endif // LARSIM_LARG4_PARTICLEFILTERS_H