factor out geometry part of AdePTGeant4Integration

Author: SeverinDiederichs

CMakeLists.txt

@@ -445,6 +445,7 @@ endif()
 #----------------------------------------------------------------------------#
 set(ADEPT_G4_INTEGRATION_SRCS
   src/AdePTHepEmHostData.cpp
+  src/AdePTGeometryBridge.cpp
   src/G4HepEmTrackingManagerSpecialized.cc
   src/AdePTTrackingManager.cc
   src/G4EmStandardPhysics_AdePT.cc

include/AdePT/integration/AdePTGeant4Integration.hh

@@ -17,11 +17,8 @@
 #include <G4EventManager.hh>
 #include <G4Event.hh>
 
-#include <unordered_map>
 #include <span>
 
-struct G4HepEmData;
-
 namespace AdePTGeant4Integration_detail {
 struct ScoringObjects;
 struct Deleter {
@@ -40,31 +37,6 @@ public:
   AdePTGeant4Integration(AdePTGeant4Integration &&)            = default;
   AdePTGeant4Integration &operator=(AdePTGeant4Integration &&) = default;
 
-#ifdef VECGEOM_GDML_SUPPORT
-  /// @brief Initializes VecGeom geometry
-  /// @details Currently VecGeom geometry is initialized by loading it from a GDML file,
-  /// however ideally this function will call the G4 to VecGeom geometry converter
-  static void CreateVecGeomWorld(/*Temporary parameter*/ std::string filename);
-#endif
-
-  /// @brief Construct VecGeom geometry from Geant4 physical volume
-  /// @details This calls the G4VG converter
-  /// @throws std::runtime_error if input or output volumes are nullptr
-  static void CreateVecGeomWorld(G4VPhysicalVolume const *physvol);
-
-  /// @brief This function compares G4 and VecGeom geometries and reports any differences
-  static void CheckGeometry(G4HepEmData const *hepEmData);
-
-  /// @brief Fills the auxiliary data needed for AdePT
-  static void InitVolAuxData(adeptint::VolAuxData *volAuxData, G4HepEmData const *hepEmData,
-                             G4HepEmTrackingManagerSpecialized *hepEmTM, bool trackInAllRegions,
-                             std::vector<std::string> const *gpuRegionNames, adeptint::WDTHostRaw &wdtRaw);
-
-  /// @brief Returns a mapping of VecGeom placed volume IDs to Geant4 physical volumes and a mapping of VecGeom logical
-  /// volume IDs to Geant4 logical volumes
-  static void MapVecGeomToG4(std::vector<G4VPhysicalVolume const *> &vecgeomPvToG4Map,
-                             std::vector<G4LogicalVolume const *> &vecgeomLvToG4Map);
-
   /// @brief Reconstructs GPU hits on host and calls the user-defined sensitive detector code
   void ProcessGPUStep(std::span<const GPUHit> gpuSteps, bool const callUserSteppingAction = false,
                       bool const callUserTrackingaction = false);
@@ -127,8 +99,6 @@ private:
   // helper class to provide the CPU-only data for the returning GPU tracks
   std::unique_ptr<HostTrackDataMapper> fHostTrackDataMapper;
 
-  static std::vector<G4VPhysicalVolume const *> fglobal_vecgeom_pv_to_g4_map;
-  static std::vector<G4LogicalVolume const *> fglobal_vecgeom_lv_to_g4_map;
   std::unique_ptr<AdePTGeant4Integration_detail::ScoringObjects, AdePTGeant4Integration_detail::Deleter>
       fScoringObjects{nullptr};
 };

include/AdePT/integration/AdePTGeometryBridge.hh

@@ -0,0 +1,59 @@
+// SPDX-FileCopyrightText: 2026 CERN
+// SPDX-License-Identifier: Apache-2.0
+
+#ifndef ADEPT_GEOMETRY_BRIDGE_HH
+#define ADEPT_GEOMETRY_BRIDGE_HH
+
+#include <AdePT/core/CommonStruct.h>
+#include <AdePT/integration/G4HepEmTrackingManagerSpecialized.hh>
+
+#include <VecGeom/base/Config.h>
+
+#include <string>
+#include <vector>
+
+class G4LogicalVolume;
+class G4VPhysicalVolume;
+struct G4HepEmData;
+
+/// @brief Global bridge between Geant4 host geometry and the VecGeom world used by AdePT.
+/// @details
+/// The geometry world and the VecGeom-to-Geant4 lookup tables are process-global,
+/// so this bridge provides the corresponding global services needed during setup and
+/// touchable reconstruction.
+class AdePTGeometryBridge {
+public:
+#ifdef VECGEOM_GDML_SUPPORT
+  /// @brief Initializes the VecGeom world from a GDML file.
+  /// @details
+  /// This is the temporary path used when a standalone VecGeom GDML description is
+  /// provided instead of converting the Geant4 world through G4VG.
+  static void CreateVecGeomWorld(std::string filename);
+#endif
+
+  /// @brief Converts the Geant4 world volume into the process-global VecGeom world.
+  /// @throws std::runtime_error if the input Geant4 world or resulting VecGeom world is null.
+  static void CreateVecGeomWorld(G4VPhysicalVolume const *physvol);
+
+  /// @brief Verifies that the Geant4 and VecGeom geometries match.
+  static void CheckGeometry(G4HepEmData const *hepEmData);
+
+  /// @brief Fills the auxiliary per-volume data needed by AdePT.
+  static void InitVolAuxData(adeptint::VolAuxData *volAuxData, G4HepEmData const *hepEmData,
+                             G4HepEmTrackingManagerSpecialized *hepEmTM, bool trackInAllRegions,
+                             std::vector<std::string> const *gpuRegionNames, adeptint::WDTHostRaw &wdtRaw);
+
+  /// @brief Returns the Geant4 placed volume matching a VecGeom placed volume.
+  /// @throws std::runtime_error if the VecGeom placed volume is not present in the global lookup table.
+  static G4VPhysicalVolume const *GetG4PhysicalVolume(vecgeom::VPlacedVolume const *placedVolume);
+
+private:
+  /// @brief Builds the lookup tables from VecGeom placed/logical volume ids to Geant4 volumes.
+  static void MapVecGeomToG4(std::vector<G4VPhysicalVolume const *> &vecgeomPvToG4Map,
+                             std::vector<G4LogicalVolume const *> &vecgeomLvToG4Map);
+
+  static std::vector<G4VPhysicalVolume const *> fGlobalVecGeomPvToG4Map;
+  static std::vector<G4LogicalVolume const *> fGlobalVecGeomLvToG4Map;
+};
+
+#endif