Geant4MaterialInterface.cc

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
#include <framework/logging/Logger.h>
#include <tracking/modules/genfitUtilities/Geant4MaterialInterface.h>
#include <geometry/GeometryManager.h>
 
#include "genfit/Exception.h"
#include "genfit/RKTrackRep.h"
 
#include <assert.h>
#include <math.h>
 
#include "G4ThreeVector.hh"
#include "G4Navigator.hh"
#include "G4VPhysicalVolume.hh"
#include "G4LogicalVolume.hh"
#include "G4Material.hh"
#include "G4TouchableHistory.hh"
 
 
#include <G4VExceptionHandler.hh>
#include <G4StateManager.hh>
 
 
using namespace Belle2;
 
namespace Belle2 {
  class Geant4MaterialInterfaceExceptioHandler : public G4VExceptionHandler {
  public:
    virtual ~Geant4MaterialInterfaceExceptioHandler() = default;
 
    virtual bool Notify(const char* origin, const char* code, G4ExceptionSeverity serv, const char* description)
    {
      B2WARNING("Geant4 exception during material lookup -- origin: "
                << origin << "\n code:"
                << code << "\n description:"
                << description);
 
      if (serv == EventMustBeAborted || serv == RunMustBeAborted) {
        m_inFailureState = true;
      }
 
      if (serv == FatalException || serv == FatalErrorInArgument) {
        // on fatal exceptions, instruct Geant4 to create core dump
        // and crash
        return true;
      }
 
      // returning false will continue the program execution
      // G4ExceptionSeverity = JustWarning will be covered by this, too
      return false;
    }
 
    bool isInFailureState() const
    {
      return m_inFailureState;
    }
 
    void resetFailureState()
    {
      m_inFailureState = false;
    }
 
  private:
    bool m_inFailureState = false;
  };
 
  class G4SafeNavigator {
  public:
    G4SafeNavigator() = default;
    ~G4SafeNavigator() = default;
 
    G4VPhysicalVolume* GetWorldVolume() const { return nav_.GetWorldVolume(); }
 
    void SetWorldVolume(G4VPhysicalVolume* pWorld)
    {
      nav_.SetWorldVolume(pWorld);
      worldsolid_ = pWorld->GetLogicalVolume()->GetSolid();
    }
 
    G4VPhysicalVolume* LocateGlobalPointAndSetup(const G4ThreeVector& point,
                                                 const G4ThreeVector* direction = 0,
                                                 const G4bool pRelativeSearch = true,
                                                 const G4bool ignoreDirection = true);
 
    G4double CheckNextStep(const G4ThreeVector& pGlobalPoint,
                           const G4ThreeVector& pDirection,
                           const G4double pCurrentProposedStepLength,
                           G4double& pNewSafety);
 
    G4VPhysicalVolume* ResetHierarchyAndLocate(const G4ThreeVector& point,
                                               const G4ThreeVector& direction,
                                               const G4TouchableHistory& h);
 
    void SetGeometricallyLimitedStep();
 
    G4TouchableHistory* CreateTouchableHistory() const
    {
      return nav_.CreateTouchableHistory();
    }
 
  private:
 
    void installOurExceptionHandler()
    {
      otherHandler = G4StateManager::GetStateManager()->GetExceptionHandler();
      exceptionHandler.resetFailureState();
      G4StateManager::GetStateManager()->SetExceptionHandler(&exceptionHandler);
    }
 
    void uninstallAndCheckOurExceptionHandler()
    {
      G4StateManager::GetStateManager()->SetExceptionHandler(otherHandler);
 
      // was the a problem in the last usage ?
      if (exceptionHandler.isInFailureState()) {
        genfit::Exception exc("Geant4MaterialInterface::findNextBoundary ==> Geant4 exception during geometry navigation", __LINE__,
                              __FILE__);
        exc.setFatal();
        throw exc;
      }
    }
 
    G4ThreeVector lastpoint_;
    G4VPhysicalVolume* lastvolume_{0};
    G4Navigator nav_;
    const G4VSolid* worldsolid_ {0};
    G4VExceptionHandler* otherHandler = nullptr;
    Geant4MaterialInterfaceExceptioHandler exceptionHandler;
  };
}
 
void G4SafeNavigator::SetGeometricallyLimitedStep()
{
  nav_.SetGeometricallyLimitedStep();
}
 
G4VPhysicalVolume* G4SafeNavigator::LocateGlobalPointAndSetup(const G4ThreeVector& point,
    const G4ThreeVector* direction,
    const G4bool pRelativeSearch,
    const G4bool ignoreDirection)
{
  if (point == lastpoint_ && lastvolume_) {
    return lastvolume_;
  }
  //B2INFO("###  init: " << point);
 
  installOurExceptionHandler();
  G4VPhysicalVolume* volume = nav_.LocateGlobalPointAndSetup(point, direction, pRelativeSearch, ignoreDirection);
  uninstallAndCheckOurExceptionHandler();
 
  if (!volume) {
    volume = nav_.GetWorldVolume();
  }
  // remember last point to speed up setup if possible
  lastpoint_ = point;
  lastvolume_ = volume;
  return volume;
}
 
G4VPhysicalVolume* G4SafeNavigator::ResetHierarchyAndLocate(const G4ThreeVector& point,
                                                            const G4ThreeVector& direction,
                                                            const G4TouchableHistory& h)
{
  if (point == lastpoint_ && lastvolume_) {
    return lastvolume_;
  }
  //B2INFO("### reset: " << point);
  installOurExceptionHandler();
  G4VPhysicalVolume* volume = nav_.ResetHierarchyAndLocate(point, direction, h);
  uninstallAndCheckOurExceptionHandler();
 
  if (!volume) {
    volume = nav_.GetWorldVolume();
  }
  // remember last point to speed up setup if possible
  lastpoint_ = point;
  lastvolume_ = volume;
  return volume;
}
 
G4double G4SafeNavigator::CheckNextStep(const G4ThreeVector& point,
                                        const G4ThreeVector& direction,
                                        const G4double pCurrentProposedStepLength,
                                        G4double& pNewSafety)
{
  //make sure we're inside the world volume
  if (worldsolid_->Inside(point) == kOutside) {
    pNewSafety = worldsolid_->DistanceToIn(point);
    return worldsolid_->DistanceToIn(point, direction);
  }
 
  installOurExceptionHandler();
  const auto distance =  nav_.CheckNextStep(point, direction, pCurrentProposedStepLength, pNewSafety);
  uninstallAndCheckOurExceptionHandler();
 
  return distance;
}
 
 
Geant4MaterialInterface::Geant4MaterialInterface()
  : nav_(new G4SafeNavigator()), currentVolume_(0)
{
  G4VPhysicalVolume* world = geometry::GeometryManager::getInstance().getTopVolume();
  nav_->SetWorldVolume(world);
}
 
Geant4MaterialInterface::~Geant4MaterialInterface()
{
}
 
 
bool
Geant4MaterialInterface::initTrack(double posX, double posY, double posZ,
                                   double dirX, double dirY, double dirZ)
{
  G4ThreeVector pos(posX * CLHEP::cm, posY * CLHEP::cm, posZ * CLHEP::cm);
  G4ThreeVector dir(dirX, dirY, dirZ);
 
  if (m_takingFullStep) {
    m_takingFullStep = false;
    nav_->SetGeometricallyLimitedStep();
  }
 
  const G4VPhysicalVolume* newVolume = nav_->LocateGlobalPointAndSetup(pos, &dir);
  bool volChanged = newVolume != currentVolume_;
  currentVolume_ = newVolume;
 
  return volChanged;
}
 
 
genfit::Material
Geant4MaterialInterface::getMaterialParameters()
{
  assert(currentVolume_);
 
  const G4Material* mat = currentVolume_->GetLogicalVolume()->GetMaterial();
 
  double density, Z, A, radiationLength, mEE;
  if (mat->GetNumberOfElements() == 1) {
    Z = mat->GetZ();
    A = mat->GetA();
  } else {
    // Calculate weight-averaged A, Z
    A = Z = 0;
    for (unsigned i = 0; i < mat->GetNumberOfElements(); ++i) {
      const G4Element* element = (*mat->GetElementVector())[i];
      Z += element->GetZ() * mat->GetFractionVector()[i];
      A += element->GetA() * mat->GetFractionVector()[i];
    }
  }
 
  density = mat->GetDensity() / CLHEP::g * CLHEP::cm3;
  // Z has correct units
  A *= CLHEP::mole / CLHEP::g;
  radiationLength = mat->GetRadlen() / CLHEP::cm;
  mEE = mat->GetIonisation()->GetMeanExcitationEnergy() / CLHEP::eV;
  return genfit::Material(density, Z, A, radiationLength, mEE);
}
 
 
double
Geant4MaterialInterface::findNextBoundary(const genfit::RKTrackRep* rep,
                                          const genfit::M1x7& stateOrig,
                                          double sMax, // signed
                                          bool varField)
{
  // This assumes that sMax is small enough to take only a single RK
  // step.  This restriction comes about because RKPropagate only
  // takes one step.
  const double delta(1.E-2); // cm, distance limit beneath which straight-line steps are taken.
  const double epsilon(1.E-1); // cm, allowed upper bound on arch deviation from straight line
 
  genfit::M1x3 SA;
  genfit::M1x7 state7, oldState7;
  oldState7 = stateOrig;
 
  int stepSign(sMax < 0 ? -1 : 1);
 
  G4ThreeVector pointOld(stateOrig[0] * CLHEP::cm,
                         stateOrig[1] * CLHEP::cm,
                         stateOrig[2] * CLHEP::cm);
  G4ThreeVector dirOld(stepSign * stateOrig[3],
                       stepSign * stateOrig[4],
                       stepSign * stateOrig[5]);
 
  double s = 0;  // trajectory length to boundary
 
  const unsigned maxIt = 300;
  unsigned it = 0;
 
  // Initialize the geometry to the current location (set by caller).
  double safety;
 
  m_takingFullStep = false;
  double slDist = nav_->CheckNextStep(pointOld, dirOld, fabs(sMax) * CLHEP::cm, safety);
  if (slDist == kInfinity) {
    slDist = fabs(sMax);
    m_takingFullStep = true;
  } else {
    slDist /= CLHEP::cm;
  }
  safety /= CLHEP::cm;
 
  // No boundary in sight?
  if (safety > fabs(sMax)) {
    B2DEBUG(20, "   next boundary is farther away than sMax ");
    return stepSign * safety; // sMax
  }
 
  // Are we at the boundary?
  if (slDist < delta) {
    B2DEBUG(20, "   very close to the boundary -> return @ it " << it
            << " stepSign*slDist = "
            << stepSign << "*" << slDist);
    return stepSign * slDist;
  }
  double step = slDist;
 
  while (1) {
    if (++it > maxIt) {
      genfit::Exception exc("Geant4MaterialInterface::findNextBoundary ==> maximum number of iterations exceeded", __LINE__, __FILE__);
      exc.setFatal();
      throw exc;
    }
 
    if (step < delta)
      return stepSign * (s + step);
 
    // We have to find whether there's any boundary on our path.
 
    // Follow curved arch, then see if we may have missed a boundary.
    // Always propagate complete way from original start to avoid
    // inconsistent extrapolations.  This is always a single RK step.
    state7 = stateOrig;
    rep->RKPropagate(state7, nullptr, SA, stepSign * (s + step), varField);
 
    G4ThreeVector pos(state7[0] * CLHEP::cm, state7[1] * CLHEP::cm, state7[2] * CLHEP::cm);
    G4ThreeVector dir(stepSign * state7[3], stepSign * state7[4], stepSign * state7[5]);
 
    // Straight line distance between extrapolation finish and
    // the end of the previously determined safe segment.
    double dist2 = (pow(state7[0] - oldState7[0], 2)
                    + pow(state7[1] - oldState7[1], 2)
                    + pow(state7[2] - oldState7[2], 2));
 
    // If we moved less than safety, the volume cannot possibly have
    // changed, so we skip further checks.
    if (dist2 > safety * safety) {
 
      // Do we need to try again with a shorter step?  There are two
      // possible reasons:
      //
      // 1. Too much curvature?
 
      // Maximal lateral deviation² of the curved path from the
      // straight line connecting beginning and end.
      double maxDeviation2 = 0.25 * (step * step - dist2);
      if (maxDeviation2 > epsilon * epsilon) {
        // Need to take a shorter step to reliably estimate material,
        // but only if we didn't move by safety.
 
        // Take a shorter step, but never shorter than safety.
        step = safety + 0.5 * (step - safety);
 
        continue;
      }
 
      // 2. Volume changed?
      //
      // Where are we after the step?
 
      if (m_takingFullStep) {
        m_takingFullStep = false;
        nav_->SetGeometricallyLimitedStep();
      }
 
      std::unique_ptr<G4TouchableHistory> hist(nav_->CreateTouchableHistory());
      G4VPhysicalVolume* newVolume = nav_->LocateGlobalPointAndSetup(pos, &dir);
 
      if (newVolume != currentVolume_) {
 
        // Volume changed during the extrapolation.
 
        // Extrapolation may not take the exact step length we asked
        // for, so it can happen that a requested step < safety takes
        // us across the boundary.  This is then the best estimate we
        // can get of the distance to the boundary with the stepper.
        if (step <= safety)
          return stepSign * (s + step);
 
        // Move back to last good point, but looking in the actual
        // direction of the step.
        G4ThreeVector dirCloser(pos - pointOld);
        dirCloser.setMag(1.);
        nav_->ResetHierarchyAndLocate(pointOld, dirCloser, *hist);
 
        // Look along the secant of the actual trajectory instead of
        // the original direction. There should be a crossing within
        // distance step.
        double secantDist = nav_->CheckNextStep(pointOld, dirCloser,
                                                step * CLHEP::cm, safety) / CLHEP::cm;
        safety /= CLHEP::cm;
        if (secantDist >= step) {
          // Cannot be.  Just take a shorter step, and hope that this
          // works.
          slDist = secantDist;
          step = std::max(0.9 * step, safety);
        } else {
          slDist = step = std::max(secantDist, safety);
        }
 
        // Are we at the boundary?
        if (slDist < delta) {
          B2DEBUG(20, "   very close to the boundary -> return @ it " << it
                  << " stepSign*(s + slDist) = "
                  << stepSign << "*(" << s + slDist << ")");
          return stepSign * (s + slDist);
        }
 
        continue;
      }
    }
 
    // We're in the new place, the step was safe, advance.
    s += step;
 
    oldState7 = state7;
    pointOld = pos;
    if (m_takingFullStep) {
      m_takingFullStep = false;
      // inform the navigator that the full geometrical step was taken. This is required for
      // some Geant4 volume enter/exit optimizations to work.
      nav_->SetGeometricallyLimitedStep();
    }
    nav_->LocateGlobalPointAndSetup(pos, &dir);
    slDist = nav_->CheckNextStep(pos, dir,
                                 (fabs(sMax) - s) * CLHEP::cm, safety);
    if (slDist == kInfinity) {
      m_takingFullStep = true;
      slDist = fabs(sMax) - s;
    } else {
      slDist /= CLHEP::cm;
    }
    safety /= CLHEP::cm;
    step = slDist;
 
    // No boundary in sight?
    if (s + safety > fabs(sMax)) {
      B2DEBUG(20, "   next boundary is farther away than sMax");
      return stepSign * (s + safety); // sMax
    }
 
    // Are we at the boundary?
    if (slDist < delta) {
      B2DEBUG(20, "   very close to the boundary -> return @ it " << it
              << " stepSign*(s + slDist) = "
              << stepSign << "*(" << s + slDist << ")");
      return stepSign * (s + slDist);
    }
  }
}