PathLengthUtils.h

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/*
  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
*/
 
/***************************************************************************
 PathLengthUtils.h  -  Description
 -------------------
 begin   : Summer 2014
 authors : Marius Cornelis van Woerden
 email   : mvanwoer@cern.ch
 changes :
 
 ***************************************************************************/
 
#ifndef PATHLENGTUTILS_H
#define PATHLENGTUTILS_H
 
#include <cmath>
 
#include "CaloEvent/CaloCell.h"
#include "CaloEvent/CaloCellContainer.h"
#include "CaloGeoHelpers/CaloPhiRange.h"
#include "CaloGeoHelpers/CaloSampling.h"
#include "TrkCaloExtension/CaloExtensionHelpers.h"
#include "xAODTracking/TrackParticle.h"
#include "xAODTracking/TrackParticleContainer.h"
 
class PathLengthUtils {
public:
    PathLengthUtils();
    ~PathLengthUtils() = default;
 
    double pathInsideCell(const CaloCell& cell, const CaloExtensionHelpers::EntryExitLayerMap& entryExitLayerMap) const;
    static double get3DPathLength(const CaloCell& cell, const Amg::Vector3D& entry, const Amg::Vector3D& exit, double drFix, double dzFix) ;
 
    static double getPathLengthInTile(const CaloCell& cell, const Amg::Vector3D& entry, const Amg::Vector3D& exit) ;
    // double path(xAOD::TrackParticle& trackParticle, const CaloCell* cell);
    // double path(xAOD::TrackParticle& trackParticle, const CaloCell_ID::CaloSample sample);
 
private:
    static CaloSampling::CaloSample tileEntrance(CaloSampling::CaloSample sample) ;
    static CaloSampling::CaloSample tileExit(CaloSampling::CaloSample sample) ;
 
    double phiMean(double a, double b) const;
    bool crossedPhi(const CaloCell& cell, double phi_entrance, double phi_exit) const;
    double getPathLengthInEta(const CaloCell& cell, double eta_entrance, double eta_exit) const;
    double getPathLengthInZ(double zMin, double zMax, double z_entrance, double z_exit) const;
    double getPathLengthInZ(const CaloCell& cell, double z_entrance, double z_exit) const;
    static bool crossingMatrix(const AmgMatrix(3,3)& Matrix, const Amg::Vector3D& entry, Amg::Vector3D& path) ;
};
 
inline double PathLengthUtils::phiMean(double a, double b) const { return 0.5 * (a + b) + (a * b < 0) * M_PI; }
 
inline bool PathLengthUtils::crossedPhi(const CaloCell& cell, double phi_entrance, double phi_exit) const {
    double mean_phi = phiMean(phi_entrance, phi_exit);
    double dphi = fabs(CaloPhiRange::diff(phi_entrance, phi_exit));
    double phi_min = mean_phi - dphi, phi_max = mean_phi + dphi;
 
    return (CaloPhiRange::diff(cell.phi() + cell.caloDDE()->dphi() / 2., phi_min) > 0 &&
            CaloPhiRange::diff(phi_max, cell.phi() - cell.caloDDE()->dphi() / 2.) > 0);
}
 
inline double PathLengthUtils::getPathLengthInEta(const CaloCell& cell, double eta_entrance, double eta_exit) const {
    double etaMin = cell.eta() - 0.5 * cell.caloDDE()->deta();
    double etaMax = cell.eta() + 0.5 * cell.caloDDE()->deta();
    if (fabs(eta_entrance - eta_exit) < 1e-6)  // to avoid FPE
        return eta_entrance > etaMin && eta_entrance < etaMax;
 
    double etaMinTrack = std::min(eta_entrance, eta_exit);
    double etaMaxTrack = std::max(eta_entrance, eta_exit);
    return (std::min(etaMax, etaMaxTrack) - std::max(etaMin, etaMinTrack)) / (etaMaxTrack - etaMinTrack);
}
 
inline double PathLengthUtils::getPathLengthInZ(double zMin, double zMax, double z_entrance, double z_exit) const {
    if (fabs(z_entrance - z_exit) < 1e-6)  // to avoid FPE
        return z_entrance > zMin && z_entrance < zMax;
 
    double zMinTrack = std::min(z_entrance, z_exit);
    double zMaxTrack = std::max(z_entrance, z_exit);
    return (std::min(zMax, zMaxTrack) - std::max(zMin, zMinTrack)) / (zMaxTrack - zMinTrack);
}
 
inline double PathLengthUtils::getPathLengthInZ(const CaloCell& cell, double z_entrance, double z_exit) const {
    return getPathLengthInZ(cell.z() - 0.5 * cell.caloDDE()->dz(), cell.z() + 0.5 * cell.caloDDE()->dz(), z_entrance, z_exit);
}
 
#endif  //> !PATHLENGTUTILS_H