RectangularSegmentation.cxx

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

// RectangularSegmentation.cxx, ATLAS Detector software
 
 
#include "TrkDigEvent/RectangularSegmentation.h"
#include "TrkSurfaces/PlaneSurface.h"
#include "TrkSurfaces/RectangleBounds.h"
// Amg includes
#include "GeoPrimitives/GeoPrimitivesHelpers.h"
 
Trk::RectangularSegmentation::RectangularSegmentation(std::shared_ptr<const Trk::RectangleBounds> mBounds,
                                                      size_t numCellsX, size_t numCellsY) :
   m_activeBounds(std::move(mBounds)),
   m_binUtility(nullptr),
   m_binsX(numCellsX),
   m_binsY(numCellsY)
{
    // first the x dimension if needed
    if (numCellsX > 1)
         m_binUtility = new Trk::BinUtility(numCellsX, -m_activeBounds->halflengthX(), m_activeBounds->halflengthX(), Trk::open, Trk::binX);
    // use y dimension if needed
    if (numCellsY > 1){
        Trk::BinUtility yBinUtility(numCellsY, -m_activeBounds->halflengthY(), m_activeBounds->halflengthY(), Trk::open, Trk::binY);
        if (m_binUtility)
            (*m_binUtility) += yBinUtility;
        else
            m_binUtility = new Trk::BinUtility(std::move(yBinUtility));
    }
}

Trk::RectangularSegmentation::RectangularSegmentation(std::shared_ptr<const Trk::RectangleBounds> mBounds, size_t numCellsX, double longY, size_t numCellsY, double numberOfChip):
   m_activeBounds(std::move(mBounds)),
   m_binUtility(nullptr),
   m_binsX(numCellsX),
   m_binsY(numCellsY)
{
    // first the x dimension if needed
    if (numCellsX > 1)
         m_binUtility = new Trk::BinUtility(numCellsX, -m_activeBounds->halflengthX(), m_activeBounds->halflengthX(), Trk::open, Trk::binX);
    // use y dimension if needed
    if (numCellsY > 1){
 
      int numCellsYinChip = numCellsY/numberOfChip;
      double begin = -m_activeBounds->halflengthY();
      double end = (2. * m_activeBounds->halflengthY() / numberOfChip) - m_activeBounds->halflengthY();
      std::vector<float> boundaries;
 
      boundaries.push_back(begin);
 
      for (int i = 0; i< numberOfChip; i++){
    Trk::BinUtility SmallBinUtility((size_t) numCellsYinChip-2, begin+longY, end-longY, Trk::open, Trk::binY);
 
 
    boundaries.insert(boundaries.end(), SmallBinUtility.binningData().at(0).boundaries.begin(), SmallBinUtility.binningData().at(0).boundaries.end());
    boundaries.push_back(end);
 
    begin=end;
    end+=(2 * m_activeBounds->halflengthY() / numberOfChip);
 
      }
 
 
      if (boundaries.size() != numCellsY+1) {
        throw std::runtime_error("RectangularSegmentation: invalid numCellsY");
      }
 
      Trk::BinUtility yBinUtility(boundaries, Trk::open, Trk::binY);
      if (m_binUtility)
    (*m_binUtility) += yBinUtility;
      else
    m_binUtility = new Trk::BinUtility(std::move(yBinUtility));
 
       boundaries.clear();
    }
}
 
 
Trk::RectangularSegmentation::~RectangularSegmentation()
{
    delete m_binUtility;
}
 
void Trk::RectangularSegmentation::createSegmenationSurfaces(std::vector< std::shared_ptr< const Trk::Surface> >& boundarySurfaces,
                                                             std::vector< std::shared_ptr< const Trk::Surface> >& segmentationSurfacesX,
                                                             std::vector< std::shared_ptr< const Trk::Surface> >& segmentationSurfacesY,
                                                             double halfThickness,
                                                             int readoutDirection,
                                                             double lorentzAngle) const
{
    // may be needed throughout
    double lorentzAngleTan    =  std::tan(lorentzAngle);
    double lorentzPlaneShiftX = halfThickness*lorentzAngleTan;
 
    // (A) --- top/bottom surfaces -----------------------------------------------------------
    // let's create the top/botten surfaces first - we call them readout / counter readout
    // there are some things to consider
    // - they share the RectangleBounds only if the lorentzAngle is 0, otherwise only the readout surface has full length bounds like the module
    std::shared_ptr<Trk::SurfaceBounds> moduleBounds = std::make_shared<Trk::RectangleBounds>(m_activeBounds->halflengthX(),m_activeBounds->halflengthY());
    // - they are separated by half a thickness in z
    Amg::Transform3D readoutPlaneTransform(Amg::Transform3D::Identity());
    Amg::Transform3D counterPlaneTransform(Amg::Transform3D::Identity());
    // readout and counter readout bounds, the bounds of the readout plane are like the active ones
    std::shared_ptr<Trk::SurfaceBounds> readoutPlaneBounds = moduleBounds;
    std::shared_ptr<Trk::SurfaceBounds> counterPlaneBounds(nullptr);
    // the transform of the readout plane is always centric
    readoutPlaneTransform.translation()     = Amg::Vector3D(0.,0.,readoutDirection*halfThickness);
    // no lorentz angle and everything is straight-forward
    if (lorentzAngle == 0.){
        counterPlaneBounds = std::move(moduleBounds);
        counterPlaneTransform.translation()     = Amg::Vector3D(0.,0.,-readoutDirection*halfThickness);
    } else {
        // lorentz reduced Bounds
        double lorentzReducedHalfX = m_activeBounds->halflengthX() - std::abs(lorentzPlaneShiftX);
        std::shared_ptr<Trk::SurfaceBounds> lorentzReducedBounds(std::make_shared<Trk::RectangleBounds>(lorentzReducedHalfX,m_activeBounds->halflengthY()));
        counterPlaneBounds  = std::move(lorentzReducedBounds);
        // now we shift the counter plane in position - this depends on lorentz angle
        double counterPlaneShift = -readoutDirection*lorentzPlaneShiftX;
        counterPlaneTransform.translation() = Amg::Vector3D(counterPlaneShift,0.,-readoutDirection*halfThickness);
    }
    // - build the readout & counter readout surfaces
    boundarySurfaces.push_back(std::make_shared<const Trk::PlaneSurface>(readoutPlaneTransform,readoutPlaneBounds));
    boundarySurfaces.push_back(std::make_shared<const Trk::PlaneSurface>(counterPlaneTransform,counterPlaneBounds));
 
    // (B) - bin X and lorentz surfaces -----------------------------------------------------------
    // easy stuff first, constant pitch size and
    double pitchX             =  2.*m_activeBounds->halflengthX()/m_binsX;
 
    // now, let's create the SharedBounds of all surfaces marking x bins - choice fixes orientation of the matrix
    std::shared_ptr<Trk::SurfaceBounds> xBinBounds(std::make_shared<Trk::RectangleBounds>(m_activeBounds->halflengthY(),halfThickness));
    // now, let's create the SharedBounds of all surfaces marking lorentz planes
    double lorentzPlaneHalfX  = std::abs(halfThickness/std::cos(lorentzAngle));
    // the bounds of the lorentz plane
    std::shared_ptr<Trk::SurfaceBounds> lorentzPlaneBounds = (lorentzAngle==0.) ? xBinBounds :
        std::shared_ptr<Trk::SurfaceBounds>(std::make_shared<Trk::RectangleBounds>(m_activeBounds->halflengthY(),lorentzPlaneHalfX));
 
    // now the rotation matrix for the xBins
    Amg::RotationMatrix3D xBinRotationMatrix;
    xBinRotationMatrix.col(0) = Amg::Vector3D::UnitY();
    xBinRotationMatrix.col(1) = Amg::Vector3D::UnitZ();
    xBinRotationMatrix.col(2) = Amg::Vector3D::UnitX();
    // now the lorentz plane rotation should be the xBin rotation, rotated by the lorentz angle around y
    Amg::RotationMatrix3D lorentzPlaneRotationMatrix =  (lorentzAngle !=0.) ?
        xBinRotationMatrix * Amg::AngleAxis3D(lorentzAngle, Amg::Vector3D::UnitX()) : xBinRotationMatrix;
 
    // reserve, it's always (number of bins-1) as the boundaries are within the boundarySurfaces
    segmentationSurfacesX.reserve(m_binsX);
    for (size_t ibinx = 0; ibinx <= m_binsX; ++ibinx){
           // the current step x position
           double cPosX = -m_activeBounds->halflengthX()+ibinx*pitchX;
           // (i) this is the low/high boundary --- ( ibin == 0/m_binsX )
           if (!ibinx || ibinx == m_binsX){
               // check if it a straight boundary or not: always straight for no lorentz angle, and either the first boundary or the last dependening on lorentz & readout
               bool boundaryStraight = (lorentzAngle == 0. || (!ibinx && readoutDirection*lorentzAngle > 0.) || (ibinx==m_binsX && readoutDirection*lorentzAngle < 0));
               // set the low boundary parameters : position & rotation
               Amg::Vector3D boundaryXPosition = boundaryStraight  ? Amg::Vector3D(cPosX, 0.,0.) : Amg::Vector3D(cPosX-readoutDirection*lorentzPlaneShiftX, 0., 0.);
               const Amg::RotationMatrix3D& boundaryXRotation = boundaryStraight ? xBinRotationMatrix : lorentzPlaneRotationMatrix;
               // build the rotation from it
               Amg::Transform3D boundaryXTransform(Amg::getTransformFromRotTransl(boundaryXRotation, boundaryXPosition));
               // the correct bounds for this
               std::shared_ptr<Trk::SurfaceBounds> boundaryXBounds = boundaryStraight ? xBinBounds : lorentzPlaneBounds;
               // boundary surfaces
               boundarySurfaces.push_back(std::make_shared<const Trk::PlaneSurface>(boundaryXTransform,boundaryXBounds));
           // (ii) this is the in between bins  --- ( 1 <= ibin < m_mbnsX )
           } else {
               // shift by the lorentz angle
               Amg::Vector3D lorentzPlanePosition(cPosX-readoutDirection*lorentzPlaneShiftX, 0., 0.);
               Amg::Transform3D lorentzPlaneTransform(Amg::getTransformFromRotTransl(lorentzPlaneRotationMatrix,lorentzPlanePosition));
               // lorentz plane surfaces
               segmentationSurfacesX.push_back(std::make_shared<Trk::PlaneSurface>(lorentzPlaneTransform,lorentzPlaneBounds));
           }
    }
 
    // (C) - bin Y surfaces - everything is defined -----------------------------------------------------------
    // now the rotation matrix for the yBins - anticyclic
    Amg::RotationMatrix3D yBinRotationMatrix;
    yBinRotationMatrix.col(0) = Amg::Vector3D::UnitX();
    yBinRotationMatrix.col(1) = Amg::Vector3D::UnitZ();
    yBinRotationMatrix.col(2) = Amg::Vector3D(0.,-1.,0.);
    // easy stuff first, constant pitch in Y
    // let's create the SharedBounds of all surfaces marking y bins
    std::shared_ptr<Trk::SurfaceBounds> yBinBounds(std::make_shared<Trk::RectangleBounds>(m_activeBounds->halflengthX(),halfThickness));
    // reserve, it's always (number of bins-1) as the boundaries are within the boundarySurfaces
    segmentationSurfacesY.reserve(m_binsY);
    for (size_t ibiny = 0; ibiny <= m_binsY; ++ibiny){
        // the position of the bin surface
        //Use the bin utility to find center of different surfaces
        double binPosY = m_binUtility->binningData().at(1).boundaries[ibiny];
        Amg::Vector3D binSurfaceCenter(0.,binPosY,0.);
        Amg::Transform3D binTransform(Amg::getTransformFromRotTransl(yBinRotationMatrix,binSurfaceCenter));
        // these are the boundaries
        if (ibiny == 0 || ibiny == m_binsY)
            boundarySurfaces.push_back(std::make_shared<const Trk::PlaneSurface>(binTransform,yBinBounds));
        else // these are the bin boundaries
            segmentationSurfacesY.push_back(std::make_shared<const Trk::PlaneSurface>(binTransform,yBinBounds));
    }
}
 
 
const Amg::Vector2D Trk::RectangularSegmentation::cellPosition(const DigitizationCell& dCell) const
{
 
    // use the bin utility for this job
    double bX = m_binsX ? m_binUtility->binPosition(dCell.first,0.,0) : 0.;
    double bY = m_binsY ? m_binUtility->binPosition(dCell.second,0.,1) : 0.;
    return Amg::Vector2D(bX,bY);
}
 

const Trk::DigitizationStep Trk::RectangularSegmentation::digitizationStep(const Amg::Vector3D& startStep,
                                                                           const Amg::Vector3D& endStep,
                                                                           double halfThickness,
                                                                           int readoutDirection,
                                                                           double lorentzAngle) const
{
    Amg::Vector3D stepCenter = 0.5*(startStep+endStep);
    // take the full drift length
    // this is the absolute drift in z
    double driftInZ     = halfThickness-readoutDirection*stepCenter.z();
    // this is the absolute drift length
    double driftLength  = driftInZ/cos(lorentzAngle);
    // project to parameter the readout surface
    double lorentzDeltaX = readoutDirection*driftInZ*tan(lorentzAngle);
    // the projected center, it has the lorentz shift applied
    Amg::Vector2D stepCenterProjected(stepCenter.x()+lorentzDeltaX,stepCenter.y());
    // the cell & its center
    Trk::DigitizationCell dCell = cell(stepCenterProjected);
    Amg::Vector2D cellCenter    = cellPosition(dCell);
    // we are ready to return what we have
    return Trk::DigitizationStep((endStep-startStep).mag(),driftLength,dCell,startStep,endStep,stepCenterProjected,cellCenter);
}