GeometryManager.cxx

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// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
// All rights not expressly granted are reserved.
//
// This software is distributed under the terms of the GNU General Public
// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
//
// In applying this license CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
 
 
#include <fairlogger/Logger.h> // for LOG
#include <TCollection.h>       // for TIter
#include <TFile.h>
#include <TGeoMatrix.h>       // for TGeoHMatrix
#include <TGeoNavigator.h>    // for TGeoNavigator
#include <TGeoNode.h>         // for TGeoNode
#include <TGeoPhysicalNode.h> // for TGeoPhysicalNode, TGeoPNEntry
#include <string>
#include <cassert>
#include <cstddef> // for NULL
#include <numeric>
 
#include "DetectorsBase/GeometryManager.h"
#include "DetectorsBase/GeometryManagerParam.h"
#include "DetectorsCommonDataFormats/AlignParam.h"
#include "CommonUtils/NameConf.h"
#include "DetectorsBase/Aligner.h"
 
#ifdef O2_WITH_VECGEOM
#include "TGeo2VecGeom/RootGeoManager.h"
#include <VecGeom/base/Version.h>
#include <VecGeom/management/GeoManager.h>
#include <VecGeom/management/ABBoxManager.h>
#include <VecGeom/management/BVHManager.h>
#include <VecGeom/navigation/GlobalLocator.h>
#include <VecGeom/navigation/NavigationState.h>
#include <VecGeom/navigation/NewSimpleNavigator.h>
#include <VecGeom/navigation/BVHNavigator.h>
#include <VecGeom/navigation/SimpleLevelLocator.h>
#if VECGEOM_VERSION >= 0x020000
#include <VecGeom/navigation/SimpleABBoxLevelLocator.h>
#else
#include <VecGeom/navigation/BVHLevelLocator.h>
#endif
#include <VecGeom/navigation/VNavigator.h>
#include <VecGeom/volumes/LogicalVolume.h>
#include <mutex>
// The BVH navigator of the VNavigator family, which Geant4 navigation needs on every volume.
#if __has_include(<VecGeom/navigation/BVHNavigatorV.h>)
#define O2_VECGEOM_HAS_BVH_VNAVIGATOR
#include <VecGeom/navigation/BVHNavigatorV.h>
#include <VecGeom/navigation/BVHLevelLocator.h>
#include <VecGeom/navigation/BVHSafetyEstimator.h>
#include <VecGeom/navigation/SimpleSafetyEstimator.h>
#endif
#endif
 
using namespace o2::detectors;
using namespace o2::base;
 
std::mutex GeometryManager::sTGMutex;
 
//______________________________________________________________________
Bool_t GeometryManager::getOriginalMatrix(const char* symname, TGeoHMatrix& m)
{
  m.Clear();
  if (!gGeoManager || !gGeoManager->IsClosed()) {
    LOG(error) << "No active geometry or geometry not yet closed!";
    ;
    return kFALSE;
  }
  std::lock_guard<std::mutex> guard(sTGMutex);
  if (!gGeoManager->GetListOfPhysicalNodes()) {
    LOG(warning) << "gGeoManager doesn't contain any aligned nodes!";
 
    if (!gGeoManager->cd(symname)) {
      LOG(error) << "Volume path " << symname << " not valid!";
      return kFALSE;
    } else {
      m = *gGeoManager->GetCurrentMatrix();
      return kTRUE;
    }
  }
 
  TGeoPNEntry* pne = gGeoManager->GetAlignableEntry(symname);
  const char* path = nullptr;
 
  if (pne) {
    m = *pne->GetGlobalOrig();
    return kTRUE;
  } else {
    LOG(warning) << "The symbolic volume name " << symname
                 << "does not correspond to a physical entry. Using it as a volume path!";
    path = symname;
  }
 
  return getOriginalMatrixFromPath(path, m);
}
 
//______________________________________________________________________
Bool_t GeometryManager::getOriginalMatrixFromPath(const char* path, TGeoHMatrix& m)
{
  m.Clear();
 
  if (!gGeoManager || !gGeoManager->IsClosed()) {
    LOG(error) << "Can't get the original global matrix! gGeoManager doesn't exist or it is still opened!";
    return kFALSE;
  }
  std::lock_guard<std::mutex> guard(sTGMutex);
  if (!gGeoManager->CheckPath(path)) {
    LOG(error) << "Volume path " << path << " not valid!";
    return kFALSE;
  }
 
  TIter next(gGeoManager->GetListOfPhysicalNodes());
  gGeoManager->cd(path);
 
  while (gGeoManager->GetLevel()) {
    TGeoPhysicalNode* physNode = nullptr;
    next.Reset();
    TGeoNode* node = gGeoManager->GetCurrentNode();
 
    while ((physNode = (TGeoPhysicalNode*)next())) {
      if (physNode->GetNode() == node) {
        break;
      }
    }
 
    TGeoMatrix* lm = nullptr;
    if (physNode) {
      lm = physNode->GetOriginalMatrix();
      if (!lm) {
        lm = node->GetMatrix();
      }
    } else {
      lm = node->GetMatrix();
    }
 
    m.MultiplyLeft(lm);
 
    gGeoManager->CdUp();
  }
  return kTRUE;
}
 
//______________________________________________________________________
TGeoHMatrix* GeometryManager::getMatrix(TGeoPNEntry* pne)
{
  // Get the global transformation matrix for a given PNEntry
  // by quering the TGeoManager
 
  if (!gGeoManager || !gGeoManager->IsClosed()) {
    LOG(error) << "Can't get the global matrix! gGeoManager doesn't exist or it is still opened!";
    return nullptr;
  }
 
  // if matrix already known --> return it
  TGeoPhysicalNode* pnode = pne->GetPhysicalNode();
  if (pnode) {
    return pnode->GetMatrix();
  }
 
  // otherwise calculate it from title and attach via TGeoPhysicalNode
  pne->SetPhysicalNode(new TGeoPhysicalNode(pne->GetTitle()));
  return pne->GetPhysicalNode()->GetMatrix();
}
 
//______________________________________________________________________
TGeoHMatrix* GeometryManager::getMatrix(const char* symname)
{
  // Get the global transformation matrix for a given alignable volume
  //  identified by its symbolic name 'symname' by quering the TGeoManager
 
  if (!gGeoManager || !gGeoManager->IsClosed()) {
    LOG(error) << "No active geometry or geometry not yet closed!";
    return nullptr;
  }
 
  TGeoPNEntry* pne = gGeoManager->GetAlignableEntry(symname);
  if (!pne) {
    return nullptr;
  }
 
  return getMatrix(pne);
}
 
//______________________________________________________________________
const char* GeometryManager::getSymbolicName(DetID detid, int sensid)
{
  int id = getSensID(detid, sensid);
  TGeoPNEntry* pne = gGeoManager->GetAlignableEntryByUID(id);
  if (!pne) {
    LOG(error) << "Failed to find alignable entry with index " << id << ": Det" << detid << " Sens.Vol:" << sensid << ") !";
    return nullptr;
  }
  return pne->GetName();
}
 
TGeoPNEntry* GeometryManager::getPNEntry(DetID detid, Int_t sensid)
{
  int id = getSensID(detid, sensid);
  TGeoPNEntry* pne = gGeoManager->GetAlignableEntryByUID(id);
  if (!pne) {
    LOG(error) << "The sens.vol " << sensid << " of det " << detid << " does not correspond to a physical entry!";
  }
  return pne;
}
 
//______________________________________________________________________
TGeoHMatrix* GeometryManager::getMatrix(DetID detid, Int_t sensid)
{
  static TGeoHMatrix matTmp;
  TGeoPNEntry* pne = getPNEntry(detid, sensid);
  if (!pne) {
    return nullptr;
  }
 
  TGeoPhysicalNode* pnode = pne->GetPhysicalNode();
  if (pnode) {
    return pnode->GetMatrix();
  }
 
  const char* path = pne->GetTitle();
  gGeoManager->PushPath(); // Preserve the modeler state.
  if (!gGeoManager->cd(path)) {
    gGeoManager->PopPath();
    LOG(error) << "Volume path " << path << " not valid!";
    return nullptr;
  }
  matTmp = *gGeoManager->GetCurrentMatrix();
  gGeoManager->PopPath();
  return &matTmp;
}
 
//______________________________________________________________________
Bool_t GeometryManager::getOriginalMatrix(DetID detid, int sensid, TGeoHMatrix& m)
{
  m.Clear();
 
  const char* symname = getSymbolicName(detid, sensid);
  if (!symname) {
    return kFALSE;
  }
 
  return getOriginalMatrix(symname, m);
}
 
//______________________________________________________________________
bool GeometryManager::applyAlignment(const std::vector<const std::vector<o2::detectors::AlignParam>*> algPars)
{
  for (auto dv : algPars) {
    if (dv && !applyAlignment(*dv)) {
      return false;
    }
  }
  return true;
}
 
//______________________________________________________________________
bool GeometryManager::applyAlignment(const std::vector<o2::detectors::AlignParam>& algPars)
{
  int nvols = algPars.size();
  std::vector<int> ord(nvols);
  std::iota(std::begin(ord), std::end(ord), 0); // sort to apply alignment in correct hierarchy
  std::sort(std::begin(ord), std::end(ord), [&algPars](int a, int b) { return algPars[a].getLevel() < algPars[b].getLevel(); });
 
  bool res = true;
  for (int i = 0; i < nvols; i++) {
    if (!algPars[ord[i]].applyToGeometry(GeometryManagerParam::Instance().printLevel)) {
      res = false;
      LOG(error) << "Error applying alignment object for volume" << algPars[ord[i]].getSymName();
    }
  }
  return res;
}
 
// ================= methods for nested MatBudgetExt class ================
 
//______________________________________________________________________
void GeometryManager::MatBudgetExt::normalize(double step)
{
  double nrm = 1. / step;
  meanRho *= nrm;
  meanA *= nrm;
  meanZ *= nrm;
  meanZ2A *= nrm;
  if (nrm > 0.) {
    length = step;
  }
}
 
//______________________________________________________________________
void GeometryManager::accountMaterial(const TGeoMaterial* material, GeometryManager::MatBudgetExt& bd)
{
  bd.meanRho = material->GetDensity();
  bd.meanX2X0 = material->GetRadLen();
  bd.meanA = material->GetA();
  bd.meanZ = material->GetZ();
  if (material->IsMixture()) {
    TGeoMixture* mixture = (TGeoMixture*)material;
    Double_t norm = 0.;
    bd.meanZ2A = 0.;
    for (Int_t iel = 0; iel < mixture->GetNelements(); iel++) {
      norm += mixture->GetWmixt()[iel];
      bd.meanZ2A += mixture->GetZmixt()[iel] * mixture->GetWmixt()[iel] / mixture->GetAmixt()[iel];
    }
    bd.meanZ2A /= norm;
  } else {
    bd.meanZ2A = bd.meanZ / bd.meanA;
  }
}
 
//_____________________________________________________________________________________
GeometryManager::MatBudgetExt GeometryManager::meanMaterialBudgetExt(float x0, float y0, float z0, float x1, float y1, float z1)
{
  //
  // TODO? It seems there is no real nead for extended material budget, consider eliminating it
  //
  // Calculate mean material budget and material properties (extended version) between
  //    the points "0" and "1".
  //
  // see MatBudgetExt data members for provided information
  //
  //  Origin:  Marian Ivanov, Marian.Ivanov@cern.ch
  //
  //  Corrections and improvements by
  //        Andrea Dainese, Andrea.Dainese@lnl.infn.it,
  //        Andrei Gheata,  Andrei.Gheata@cern.ch
  //
  //  Ported to O2: ruben.shahoyan@cern.ch
  //
  if (!gGeoManager) {
    throw std::runtime_error("meanMaterialBudgetExt requires geometry loaded");
  }
  double length, startD[3] = {x0, y0, z0};
  double dir[3] = {x1 - x0, y1 - y0, z1 - z0};
  if ((length = dir[0] * dir[0] + dir[1] * dir[1] + dir[2] * dir[2]) < TGeoShape::Tolerance() * TGeoShape::Tolerance()) {
    return MatBudgetExt(); // return empty struct
  }
  length = TMath::Sqrt(length);
  double invlen = 1. / length;
  for (int i = 3; i--;) {
    dir[i] *= invlen;
  }
  std::lock_guard<std::mutex> guard(sTGMutex);
  // Initialize start point and direction
  TGeoNode* currentnode = gGeoManager->InitTrack(startD, dir);
  if (!currentnode) {
    LOG(error) << "start point out of geometry: " << x0 << ':' << y0 << ':' << z0;
    return MatBudgetExt(); // return empty struct
  }
 
  MatBudgetExt budTotal, budStep;
  accountMaterial(currentnode->GetVolume()->GetMedium()->GetMaterial(), budStep);
  budStep.length = length;
 
  // Locate next boundary within length without computing safety.
  // Propagate either with length (if no boundary found) or just cross boundary
  gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
  Double_t stepTot = 0.0; // Step made
  Double_t step = gGeoManager->GetStep();
  // If no boundary within proposed length, return current step data
  if (!gGeoManager->IsOnBoundary()) {
    budStep.meanX2X0 = budStep.length / budStep.meanX2X0;
    return MatBudgetExt(budStep);
  }
  // Try to cross the boundary and see what is next
  Int_t nzero = 0;
  while (length > TGeoShape::Tolerance()) {
    if (step < 2. * TGeoShape::Tolerance()) {
      nzero++;
    } else {
      nzero = 0;
    }
    if (nzero > 3) {
      // This means navigation has problems on one boundary
      // Try to cross by making a small step
      const double* curPos = gGeoManager->GetCurrentPoint();
      LOG(warning) << "Cannot cross boundary at (" << curPos[0] << ',' << curPos[1] << ',' << curPos[2] << ')';
      budTotal.normalize(stepTot);
      budTotal.nCross = -1; // flag failed navigation
      return MatBudgetExt(budTotal);
    }
    stepTot += step;
 
    budTotal.meanRho += step * budStep.meanRho;
    budTotal.meanX2X0 += step / budStep.meanX2X0;
    budTotal.meanA += step * budStep.meanA;
    budTotal.meanZ += step * budStep.meanZ;
    budTotal.meanZ2A += step * budStep.meanZ2A;
    budTotal.nCross++;
 
    if (step >= length) {
      break;
    }
    currentnode = gGeoManager->GetCurrentNode();
    if (!currentnode) {
      break;
    }
    length -= step;
    accountMaterial(currentnode->GetVolume()->GetMedium()->GetMaterial(), budStep);
    gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
    step = gGeoManager->GetStep();
  }
  budTotal.normalize(stepTot);
  return MatBudgetExt(budTotal);
}
 
//_____________________________________________________________________________________
o2::base::MatBudget GeometryManager::meanMaterialBudget(float x0, float y0, float z0, float x1, float y1, float z1,
                                                        TGeoNavigator* nav)
{
  //
  // Calculate mean material budget and material properties between
  //    the points "0" and "1".
  //
  //  see MatBudget data members for provided information
  //
  //  Origin:  Marian Ivanov, Marian.Ivanov@cern.ch
  //
  //  Corrections and improvements by
  //        Andrea Dainese, Andrea.Dainese@lnl.infn.it,
  //        Andrei Gheata,  Andrei.Gheata@cern.ch
  //
  //  Ported to O2: ruben.shahoyan@cern.ch
  //
  //  Multi-threaded execution: pass a navigator owned by the calling thread.
  //
 
  double length, startD[3] = {x0, y0, z0};
  double dir[3] = {x1 - x0, y1 - y0, z1 - z0};
  if ((length = dir[0] * dir[0] + dir[1] * dir[1] + dir[2] * dir[2]) < TGeoShape::Tolerance() * TGeoShape::Tolerance()) {
    return o2::base::MatBudget(); // return empty struct
  }
  length = TMath::Sqrt(length);
  double invlen = 1. / length;
  for (int i = 3; i--;) {
    dir[i] *= invlen;
  }
  // A caller that passes its own navigator owns it exclusively, so no locking is needed. A caller
  // that passes none shares gGeoManager's current navigator and must still serialize. Deciding
  // this from the argument keeps the choice local: it does not depend on -- and cannot be broken
  // by -- process-global state such as TGeoManager::GetMaxThreads().
  std::unique_lock<std::mutex> guard(sTGMutex, std::defer_lock);
  if (!nav) {
    guard.lock();
    nav = gGeoManager->GetCurrentNavigator();
  }
  // Initialize start point and direction
  TGeoNode* currentnode = nav->InitTrack(startD, dir);
  if (!currentnode) {
    LOG(error) << "start point out of geometry: " << x0 << ':' << y0 << ':' << z0;
    return o2::base::MatBudget(); // return empty struct
  }
 
  o2::base::MatBudget budTotal, budStep;
  accountMaterial(currentnode->GetVolume()->GetMedium()->GetMaterial(), budStep);
  budStep.length = length;
 
  // Locate next boundary within length without computing safety.
  // Propagate either with length (if no boundary found) or just cross boundary
  nav->FindNextBoundaryAndStep(length, kFALSE);
  Double_t stepTot = 0.0; // Step made
  Double_t step = nav->GetStep();
  // If no boundary within proposed length, return current step data
  if (!nav->IsOnBoundary()) {
    budStep.meanX2X0 = budStep.length / budStep.meanX2X0;
    return o2::base::MatBudget(budStep);
  }
  // Try to cross the boundary and see what is next
  Int_t nzero = 0;
  while (length > TGeoShape::Tolerance()) {
    if (step < 2. * TGeoShape::Tolerance()) {
      nzero++;
    } else {
      nzero = 0;
    }
    if (nzero > 3) {
      // This means navigation has problems on one boundary
      // Try to cross by making a small step
      const double* curPos = nav->GetCurrentPoint();
      LOG(warning) << "Cannot cross boundary at (" << curPos[0] << ',' << curPos[1] << ',' << curPos[2] << ')';
      budTotal.meanRho /= stepTot;
      budTotal.length = stepTot;
      return o2::base::MatBudget(budTotal);
    }
    stepTot += step;
 
    budTotal.meanRho += step * budStep.meanRho;
    budTotal.meanX2X0 += step / budStep.meanX2X0;
 
    if (step >= length) {
      break;
    }
    currentnode = nav->GetCurrentNode();
    if (!currentnode) {
      break;
    }
    length -= step;
    accountMaterial(currentnode->GetVolume()->GetMedium()->GetMaterial(), budStep);
    nav->FindNextBoundaryAndStep(length, kFALSE);
    step = nav->GetStep();
  }
  budTotal.meanRho /= stepTot;
  budTotal.length = stepTot;
  return o2::base::MatBudget(budTotal);
}
 
//_________________________________
void GeometryManager::applyMisalignent(bool applyMisalignment)
{
  if (!isGeometryLoaded()) {
    LOG(fatal) << "geometry is not loaded";
  }
  if (applyMisalignment) {
    auto& aligner = Aligner::Instance();
    aligner.applyAlignment();
  }
}
 
//_________________________________
void GeometryManager::loadGeometry(std::string_view simPrefix, bool applyMisalignment, bool preferAlignedFile)
{
  auto loadGeom = [](const std::string_view fname) {
    LOG(info) << "Loading geometry from " << fname;
    TFile flGeom(fname.data());
    if (flGeom.IsZombie()) {
      LOG(fatal) << "Failed to open file " << fname;
    }
    // try under the standard CCDB name
    if (!flGeom.Get(std::string(o2::base::NameConf::CCDBOBJECT).c_str()) &&
        !flGeom.Get(std::string(o2::base::NameConf::GEOMOBJECTNAME_FAIR).c_str())) {
      LOG(fatal) << "Did not find geometry named " << o2::base::NameConf::CCDBOBJECT << " or " << o2::base::NameConf::GEOMOBJECTNAME_FAIR;
    }
  };
 
  if (preferAlignedFile) {
    loadGeom(o2::base::NameConf::getAlignedGeomFileName(simPrefix));
  } else {
    loadGeom(o2::base::NameConf::getGeomFileName(simPrefix));
    applyMisalignent(applyMisalignment);
  }
}
 
#ifdef O2_WITH_VECGEOM
 
namespace
{
bool usesBvhAcceleration(vecgeom::LogicalVolume const* vol)
{
  return vol->GetDaughtersp()->size() > 2;
}
 
void ensureVecGeomWorldBuilt()
{
  GeometryManager::buildVecGeomGeometry(true);
}
} // namespace
 
void GeometryManager::buildVecGeomGeometry(bool flattenAssemblies, int booleanThreshold)
{
  static std::once_flag onceFlag;
  std::call_once(onceFlag, [flattenAssemblies, booleanThreshold]() {
    if (!gGeoManager) {
      LOG(fatal) << "Cannot build VecGeom geometry: no TGeo geometry loaded (call GeometryManager::loadGeometry() first)";
    }
    // Translate geometry and material pointers, then build acceleration structures.
    tgeo2vecgeom::RootGeoManager::Instance().SetMaterialConversionHook([](TGeoMaterial const* m) { return (void*)m; });
    LOG(info) << "VecGeom conversion: flattenAssemblies=" << flattenAssemblies;
    tgeo2vecgeom::RootGeoManager::Instance().SetFlattenAssemblies(flattenAssemblies);
#if __has_include(<VecGeom/management/BooleanFactory.h>)
    // Applied when the conversion closes the geometry.
    LOG(info) << "VecGeom conversion: booleanThreshold=" << booleanThreshold;
    vecgeom::GeoManager::Instance().SetBooleanOptimizationThreshold(booleanThreshold > 0 ? booleanThreshold : 0);
#else
    if (booleanThreshold > 0) {
      LOG(warning) << "VecGeom without BooleanFactory: Boolean solids are kept as converted";
    }
#endif
    tgeo2vecgeom::RootGeoManager::Instance().LoadRootGeometry();
 
    // Acceleration structures must be built before the navigators/locators reference them.
#if VECGEOM_VERSION < 0x020000
    // VecGeom 2 has no ABBoxManager: the BVH below is built directly.
    vecgeom::ABBoxManager::Instance().InitABBoxesForCompleteGeometry();
#endif
    // Builds a BVH per logical volume.
    vecgeom::BVHManager::Init();
 
    // For each logical volume, set a navigator (used for ComputeStep), a matched level locator
    // (used for point relocation after a boundary crossing via GlobalLocator) and, where the
    // VNavigator family is complete, the safety estimator LogicalVolume::GetSafetyEstimator()
    // hands out, which is separate from the one a navigator uses internally.
    for (auto& lvol : vecgeom::GeoManager::Instance().GetLogicalVolumesMap()) {
      auto* vol = lvol.second;
      if (!usesBvhAcceleration(vol)) {
        vol->SetNavigator(vecgeom::NewSimpleNavigator<>::Instance());
#ifdef O2_VECGEOM_HAS_BVH_VNAVIGATOR
        vol->SetLevelLocator(vol->ContainsAssembly() ? vecgeom::SimpleAssemblyLevelLocator::GetInstance()
                                                     : vecgeom::SimpleLevelLocator::GetInstance());
        vol->SetSafetyEstimator(vecgeom::SimpleSafetyEstimator::Instance());
#else
        vol->SetLevelLocator(vecgeom::SimpleLevelLocator::GetInstance());
#endif
      } else {
#if defined(O2_VECGEOM_HAS_BVH_VNAVIGATOR)
        vol->SetNavigator(vecgeom::BVHNavigatorV<>::Instance());
        vol->SetLevelLocator(vol->ContainsAssembly() ? vecgeom::BVHAssemblyAwareLevelLocator::GetInstance()
                                                     : vecgeom::BVHLevelLocator::GetInstance());
        vol->SetSafetyEstimator(vecgeom::BVHSafetyEstimator::Instance());
#elif VECGEOM_VERSION >= 0x020000
        // VecGeom 2 turned BVHNavigator into a plain class with static entry points instead of a
        // VNavigator singleton, so there is nothing to attach: vecGeomMaterialBudget() calls it
        // directly.
        //
        // The locator changes too, and not by choice. BVHLevelLocator does not compile in 2.1.0 or
        // 2.1.1 -- the header is byte-identical in both -- because its four LevelLocate() calls
        // have no match among the single templated BVH::LevelLocate(int exclude_item_id, ...) that
        // v2 ships. It survived two releases because nothing in VecGeom includes that header
        // except itself, so upstream CI never compiles it; O2 appears to be its only consumer.
        //
        // SimpleABBoxLevelLocator is the accelerated stand-in, using the ABBoxes built just above.
        // Three of the four methods could be rebuilt on the templated API (the idiom is in
        // BVHNavigator itself: bvh->LevelInside<BVHNavigator>(exclude_id, point, id, dlp)), but
        // the direction-aware LevelLocateExclVol has no v2 counterpart at all, so this stays a
        // fallback rather than a reimplementation. Revert to BVHLevelLocator once upstream fixes
        // or removes it, and measure: whether ABBox location costs anything real here is unknown.
        vol->SetLevelLocator(vecgeom::SimpleABBoxLevelLocator::GetInstance());
#else
        vol->SetNavigator(vecgeom::BVHNavigator<>::Instance());
        vol->SetLevelLocator(vecgeom::BVHLevelLocator::GetInstance());
#endif
      }
    }
  });
}
 
//_____________________________________________________________________________________
o2::base::MatBudget GeometryManager::vecGeomMaterialBudget(float x0, float y0, float z0, float x1, float y1, float z1)
{
  // Mean material budget between "0" and "1" via VecGeom's BVH-accelerated ray/boundary
  // intersection, instead of TGeo.
  ensureVecGeomWorldBuilt();
 
  using Vector3D = vecgeom::Vector3D<vecgeom::Precision>;
 
  double length, start[3] = {x0, y0, z0};
  double dir[3] = {x1 - x0, y1 - y0, z1 - z0};
  if ((length = dir[0] * dir[0] + dir[1] * dir[1] + dir[2] * dir[2]) < TGeoShape::Tolerance() * TGeoShape::Tolerance()) {
    return o2::base::MatBudget(); // return empty struct
  }
  length = std::sqrt(length);
  double invlen = 1. / length;
  for (int i = 3; i--;) {
    dir[i] *= invlen;
  }
 
  // Only the allocation differs between VecGeom versions; everything below works on pointers in
  // both, which also keeps the std::swap() at the end of the loop a pointer swap rather than a
  // copy of the state itself.
  //
  // VecGeom 1 builds NavigationState as NavStatePath, a variable-size object that must be told the
  // maximum depth at construction and can only be made through MakeInstance(). VecGeom 2 dropped
  // NavStatePath and MakeInstance with it: NavigationState is NavStateIndex or NavStateTuple, both
  // fixed-size value types, so a thread_local object is the direct equivalent.
#if VECGEOM_VERSION >= 0x020000
  thread_local static vecgeom::NavigationState newnavstateStorage, currnavstateStorage, startCacheStorage;
  thread_local static vecgeom::NavigationState* newnavstate = &newnavstateStorage;
  thread_local static vecgeom::NavigationState* currnavstate = &currnavstateStorage;
  thread_local static vecgeom::NavigationState* startCache = &startCacheStorage;
#else
  thread_local static vecgeom::NavigationState* newnavstate = vecgeom::NavigationState::MakeInstance(vecgeom::GeoManager::Instance().getMaxDepth());
  thread_local static vecgeom::NavigationState* currnavstate = vecgeom::NavigationState::MakeInstance(vecgeom::GeoManager::Instance().getMaxDepth());
  thread_local static vecgeom::NavigationState* startCache = vecgeom::NavigationState::MakeInstance(vecgeom::GeoManager::Instance().getMaxDepth());
#endif
  thread_local static bool startCacheValid = false;
 
  Vector3D currPoint(x0, y0, z0);
  Vector3D dirr(dir[0], dir[1], dir[2]);
  constexpr double kPush = 1.E-6; // mimick the nudging of TGeo's FindNextBoundaryAndStep
  auto world = vecgeom::GeoManager::Instance().GetWorld();
  o2::base::MatBudget budTot, budStep;
  budStep.length = length;
 
  // Locate the starting volume, reusing the path from the previous call when still valid.
  if (startCacheValid && !startCache->IsOutside()) {
    startCache->CopyTo(currnavstate);
    vecgeom::Transformation3D m;
    currnavstate->TopMatrix(m);
    vecgeom::GlobalLocator::RelocatePointFromPath(m.Transform(currPoint), *currnavstate);
  } else {
    currnavstate->Clear();
    vecgeom::GlobalLocator::LocateGlobalPoint(world, currPoint, *currnavstate, true);
  }
  if (currnavstate->IsOutside() || currnavstate->Top() == nullptr) {
    LOG(error) << "start point out of geometry: " << x0 << ':' << y0 << ':' << z0;
    startCacheValid = false;
    return o2::base::MatBudget();
  }
  currnavstate->CopyTo(startCache);
  startCacheValid = true;
 
  double stepTot = 0.;
  double remainingDist = length;
  Int_t nzero = 0;
  while (remainingDist > 1.E-10) {
    auto* lvol = currnavstate->Top()->GetLogicalVolume();
    // Not LogicalVolume::GetMaterialPtr(): VecGeom 2 dropped the material slot from the logical
    // volume. TGeo2VecGeom keeps what its conversion hook returned, indexed by logical volume id,
    // and serves it for both VecGeom versions.
    accountMaterial(static_cast<TGeoMaterial*>(tgeo2vecgeom::RootGeoManager::Instance().GetMaterialPtr(lvol)), budStep);
#if VECGEOM_VERSION >= 0x020000
    const double step =
      usesBvhAcceleration(lvol)
        ? static_cast<double>(vecgeom::BVHNavigator::ComputeStepAndPropagatedState(currPoint, dirr, remainingDist, *currnavstate, *newnavstate))
        : static_cast<double>(lvol->GetNavigator()->ComputeStepAndPropagatedState(currPoint, dirr, remainingDist, *currnavstate, *newnavstate));
#else
    const double step = static_cast<double>(lvol->GetNavigator()->ComputeStepAndPropagatedState(currPoint, dirr, remainingDist, *currnavstate, *newnavstate));
#endif
    if (step < 2.E-10) {
      nzero++;
    } else {
      nzero = 0;
    }
    if (nzero > 3) {
      // This means navigation has problems on one boundary
      LOG(warning) << "Cannot cross boundary at (" << currPoint[0] << ',' << currPoint[1] << ',' << currPoint[2] << ')';
      budTot.meanRho /= stepTot;
      budTot.length = stepTot;
      return o2::base::MatBudget(budTot);
    }
 
    remainingDist -= step;
    stepTot += step;
    budTot.meanRho += step * budStep.meanRho;
    budTot.meanX2X0 += step / budStep.meanX2X0;
    currPoint = currPoint + (step + kPush) * dirr;
    std::swap(currnavstate, newnavstate);
  }
  budTot.meanRho /= stepTot;
  budTot.length = stepTot;
  return o2::base::MatBudget(budTot);
}
 
#endif // O2_WITH_VECGEOM
 
//_____________________________________________________________________________________
bool GeometryManager::ensureVecGeomWorld()
{
#ifdef O2_WITH_VECGEOM
  ensureVecGeomWorldBuilt();
  return true;
#else
  return false;
#endif
}
 
//_____________________________________________________________________________________
bool GeometryManager::vecGeomLocate(double x, double y, double z, std::vector<TGeoNode*>& chain)
{
  chain.clear();
#ifdef O2_WITH_VECGEOM
  ensureVecGeomWorldBuilt();
  // One state per thread, as for the material budget above, and allocated the
  // same way: see the comment there on NavStatePath vs NavStateIndex.
#if VECGEOM_VERSION >= 0x020000
  thread_local vecgeom::NavigationState stateStorage;
  thread_local vecgeom::NavigationState* state = &stateStorage;
#else
  thread_local vecgeom::NavigationState* state =
    vecgeom::NavigationState::MakeInstance(vecgeom::GeoManager::Instance().getMaxDepth());
#endif
  state->Clear();
  const vecgeom::Vector3D<vecgeom::Precision> point(x, y, z);
  if (vecgeom::GlobalLocator::LocateGlobalPoint(vecgeom::GeoManager::Instance().GetWorld(), point, *state, true) ==
      nullptr) {
    return false;
  }
  auto const& converter = tgeo2vecgeom::RootGeoManager::Instance();
  for (int level = 0; level < (int)state->GetCurrentLevel(); ++level) {
    auto const* placed = state->At(level);
    auto const* node = placed != nullptr ? converter.tgeonode(placed) : nullptr;
    if (node == nullptr) {
      chain.clear();
      return false;
    }
    chain.push_back(const_cast<TGeoNode*>(node));
  }
  return !chain.empty();
#else
  (void)x;
  (void)y;
  (void)z;
  return false;
#endif
}