TRT_EndcapElement.cxx

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
#include "TRT_ReadoutGeometry/TRT_EndcapElement.h"
#include "InDetReadoutGeometry/SurfaceCache.h"
#include "TRT_ReadoutGeometry/TRT_Conditions.h"
 
#include "Identifier/Identifier.h"
#include "InDetIdentifier/TRT_ID.h"
 
#include "GeoPrimitives/CLHEPtoEigenConverter.h"
#include "GeoPrimitives/GeoPrimitives.h"
 
#include "CLHEP/Geometry/Transform3D.h"
#include "GeoModelKernel/GeoDefinitions.h"
#include "GeoModelUtilities/GeoAlignmentStore.h"
 
#include "TrkSurfaces/DiscBounds.h"
#include "TrkSurfaces/DiscSurface.h"
 
#include "TRT_ConditionsData/ExpandedIdentifier.h"
#include "TRT_ConditionsData/StrawDxContainer.h"
 
namespace InDetDD {
 
TRT_EndcapElement::TRT_EndcapElement(const GeoVFullPhysVol* volume,
                                     const TRT_EndcapDescriptor* descriptor,
                                     bool isPositive,
                                     unsigned int wheelIndex,
                                     unsigned int strawLayIndex,
                                     unsigned int phiIndex,
                                     const TRT_ID* idHelper,
                                     const TRT_Conditions* conditions)
  :
 
  TRT_BaseElement(volume,
                  idHelper->layer_id((isPositive ? 2 : -2),
                                     phiIndex,
                                     wheelIndex,
                                     strawLayIndex),
                  idHelper,
                  conditions)
  , m_code(isPositive, wheelIndex, strawLayIndex, phiIndex)
  , m_descriptor(descriptor)
  , m_nextInZ(nullptr)
  , m_previousInZ(nullptr)
{
  m_nstraws = m_descriptor->nStraws();
  m_strawSurfaces.resize(m_nstraws);
  m_strawSurfacesCache.resize(m_nstraws);
}
 
TRT_EndcapElement::TRT_EndcapElement(const TRT_EndcapElement& right)
  : TRT_BaseElement(right)
  , m_code(right.m_code)
  , m_descriptor(right.m_descriptor)
  , m_nextInZ(right.m_nextInZ)
  , m_previousInZ(right.m_previousInZ)
{
  m_nstraws = right.m_nstraws;
  m_strawSurfaces.resize(m_nstraws);
  m_strawSurfacesCache.resize(m_nstraws);
}
 
TRT_EndcapElement::~TRT_EndcapElement() = default;
 
 
const double&
TRT_EndcapElement::strawLength() const
{
  return m_descriptor->strawLength();
}
 
const TRT_EndcapConditions*
TRT_EndcapElement::getConditionsData() 
{
  return nullptr;
}
 
const TRT_EndcapDescriptor*
TRT_EndcapElement::getDescriptor() const
{
  return m_descriptor;
}
 
void
TRT_EndcapElement::setNextInZ(const TRT_EndcapElement* element)
{
  m_nextInZ = element;
}
 
void
TRT_EndcapElement::setPreviousInZ(const TRT_EndcapElement* element)
{
  m_previousInZ = element;
}
 
HepGeom::Transform3D
TRT_EndcapElement::calculateStrawTransform(int straw, GeoAlignmentStore* alignStore) const
{
  // NB The tranformation to a straw is reconstructed here precisely as
  // it was ... hopefully... in the factory.  One could eliminate this
  // requirement and make the code a little more robust in this regard but
  // at the cost of doubling the descriptors.  (One descriptor now suffices
  // for both positive and negative endcaps).
  const GeoXF::Function* f = m_descriptor->getStrawTransform();
 
  if (f) {
    int istraw = m_code.isPosZ() ? straw : m_descriptor->nStraws() - 1 - straw;
 
    size_t offsetInto = m_descriptor->getStrawTransformOffset();
 
    return Amg::EigenTransformToCLHEP(
             getMaterialGeom()->getAbsoluteTransform(alignStore) *
             ((*f)(istraw + offsetInto))) *
           calculateLocalStrawTransform(straw);
 
  } else {
 
    // Will not work properly with alignments.
    std::cout << "ALTERNATIVE METHOD" << std::endl;
 
    double phi = m_descriptor->startPhi() + m_descriptor->strawPitch() * straw;
    double r = m_descriptor->innerRadius() + 0.5 * m_descriptor->strawLength();
    CLHEP::Hep3Vector pos(
      r * cos(phi),
      r * sin(phi),
      (Amg::EigenTransformToCLHEP(getMaterialGeom()->getAbsoluteTransform(alignStore)) *
       HepGeom::Point3D<double>())
        .z());
    CLHEP::HepRotation rot;
    // Axis (in local (0,0,1)) points towards beam axis.
    rot.rotateY(-0.5 * M_PI); // Make it point along -ve X.
    rot.rotateZ(phi);
    return HepGeom::Transform3D(rot, pos);
  }
}
 
// The L3 Alignment
HepGeom::Transform3D
TRT_EndcapElement::calculateLocalStrawTransform(int straw) const
{
  const TRTCond::StrawDxContainer* container = conditions()->dxContainer();
  HepGeom::Transform3D rc;
  if (container) {
 
    // important note: dx1 moves the 'negative' wire endpoint end dx2
    // the 'positive' wire endpoint in the local straw frame.
    // In the global frame, 'dx1' corresponds to the readout side and 'dx2'
    // to the side closest the beampipe.
 
    int bec = getCode().isPosZ() ? +2 : -2;
    int wheel = getCode().getWheelIndex();
    int phimodule = getCode().getPhiIndex();
    int strawlayer = getCode().getStrawLayerIndex();
    TRTCond::ExpandedIdentifier id =
      TRTCond::ExpandedIdentifier(bec,
                                  wheel,
                                  phimodule,
                                  strawlayer,
                                  straw,
                                  TRTCond::ExpandedIdentifier::STRAW);
 
    double dx1 = container->getDx1(id);
    double dx2 = container->getDx2(id);
    double ang = (dx2 - dx1) / strawLength();
    double dy = -1 * (dx2 + dx1) / 2.;
 
    // In the local straw frame:
    //   - the z-axis is along the straw and points toward the beampipe
    //   - the x-axis is along global-z and away from the interaction point
    //          (locX = globZ A-side / locX = -1 *gobZ C-side)
    //   - the y-axis is along global phi_hat direction determined by the
    //   other 2.
    //          (clockwise C-side, counter clockwise A-Side)
    rc = HepGeom::TranslateY3D(dy) * HepGeom::RotateX3D(ang);
  }
  return rc;
}
 
const Trk::SurfaceBounds&
TRT_EndcapElement::strawBounds() const
{
  return m_descriptor->strawBounds();
}
 
const Trk::Surface&
TRT_EndcapElement::elementSurface() const
{
  if (not m_surface)
    m_surface.set(std::make_unique<Trk::DiscSurface>(*this));
  return *m_surface;
}
 
void
TRT_EndcapElement::createSurfaceCache(GeoAlignmentStore* alignStore) const
{
 if (!m_surfaceCache.isValid()) {
    m_surfaceCache.set(createSurfaceCacheHelper(alignStore));
  }
  // create the surface if needed
  if (!m_surface) {
    elementSurface();
  }
}
 
SurfaceCache
TRT_EndcapElement::createSurfaceCacheHelper(GeoAlignmentStore* alignStore) const
{
  // Calculate the surface
  double phiCenter = m_descriptor->startPhi() +
                     m_descriptor->strawPitch() * 0.5 * (nStraws() - 1);
  double phiHalfWidth = 0.5 * m_descriptor->strawPitch() * nStraws();
  double rMin = m_descriptor->innerRadius();
  double rMax = rMin + m_descriptor->strawLength();
 
  // The transform of the endcap is a translation in z for no
  // misalignement. For the -ve endcap there is also a 180deg rotation
  // around the y axis. getAbsoluteTransform() will also include the
  // misalignment.
  //
  // To get the transform of the element we have to first rotate
  // around z to the phi center of the element.  We want the local z
  // to point in the same direction for both endcaps (approximately
  // global z axis). For the negative endcap we therefore have to
  // rotate 180 CLHEP::deg around the Y axis.
 
  // We need to rotate to phi center before we apply the
  // misalignment. However, in the negative endcap the the phi
  // location is inverted (due to 180 rotation around y axis). This is
  // taken care of by the extra 180 CLHEP::deg rotation around Y that we do
  // to get the z axis pointing in the correct direction.
  auto transform =
    m_code.isPosZ()
      ? Amg::Transform3D((getMaterialGeom()->getAbsoluteTransform(alignStore) *
                          GeoTrf::RotateZ3D(phiCenter)))
      : Amg::Transform3D((getMaterialGeom()->getAbsoluteTransform(alignStore) *
                          GeoTrf::RotateY3D(180 * CLHEP::deg) *
                          GeoTrf::RotateZ3D(phiCenter)));
 
  // create the igredients and the cache
  auto center = Amg::Vector3D(transform.translation());
  auto bounds = std::make_unique<Trk::DiscBounds>(rMin, rMax, phiHalfWidth);
  auto normal = Amg::Vector3D(transform.rotation().col(2));
 
  return {transform, center, normal, std::move(bounds)};
}
 
int
TRT_EndcapElement::strawDirection() const
{
  // Return +1 if the straw local axis is in the same direction as increasing
  // eta direction,
  //  -1 otherwise.
  // The straw axis by convention goes in the direction away from the readout.
  // This is towards the beam pipe. For +ve endcap it is what we want. For -ve
  // endcap it is oppposite.
  //
  //
  return (m_code.isPosZ()) ? +1 : -1;
}
 
} // end namespace