refactor: Rework detector handling in Examples (#3498)

- Concrete detector interface for examples
- Align interfaces of different detectors
- Remove `DD4hepGeometryService`
- Improve DDG4 construction
  - `unique_ptr` for DD4hep detector with dedicated name
  - Concrete `Geant4Mapping` instance for conversion
- Simplify CMake for optional Geant4 construction for different detectors
- Move Geant4 construction code to detector folder

CI/physmon/physmon_common.py

@@ -33,7 +33,9 @@ def makeSetup() -> PhysmonSetup:
         level=acts.logging.INFO,
     )
 
-    detector, trackingGeometry, decorators = getOpenDataDetector(matDeco)
+    detector = getOpenDataDetector(matDeco)
+    trackingGeometry = detector.trackingGeometry()
+    decorators = detector.contextDecorators()
     setup = PhysmonSetup(
         detector=detector,
         trackingGeometry=trackingGeometry,

Core/include/Acts/Utilities/Logger.hpp

@@ -7,11 +7,9 @@
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
 #pragma once
+
 // STL include(s)
-#include <cassert>
 #include <ctime>
-#include <exception>
-#include <functional>
 #include <iomanip>
 #include <iostream>
 #include <memory>

Examples/Algorithms/Geant4/CMakeLists.txt

@@ -1,8 +1,6 @@
 add_library(
     ActsExamplesGeant4
     SHARED
-    src/GdmlDetectorConstruction.cpp
-    src/TelescopeG4DetectorConstruction.cpp
     src/Geant4Simulation.cpp
     src/MagneticFieldWrapper.cpp
     src/MaterialPhysicsList.cpp
@@ -32,43 +30,9 @@ target_link_libraries(
     PUBLIC
         ActsCore
         ActsExamplesFramework
-        ActsExamplesDetectorTelescope
+        ActsExamplesDetectorsCommon
         Boost::headers
         ${Geant4_LIBRARIES}
 )
 
-if(ACTS_BUILD_EXAMPLES_DD4HEP)
-    if(${DD4hep_VERSION} VERSION_LESS 1.11)
-        target_include_directories(
-            ActsExamplesGeant4
-            PRIVATE ${DD4hep_INCLUDE_DIRS}
-        )
-        target_link_libraries(
-            ActsExamplesGeant4
-            PRIVATE ${DD4hep_DDCORE_LIBRARY} ${DD4hep_DDG4_LIBRARY}
-        )
-    else()
-        target_link_libraries(
-            ActsExamplesGeant4
-            PUBLIC ActsExamplesDetectorDD4hep DD4hep::DDCore DD4hep::DDG4
-        )
-    endif()
-
-    target_sources(ActsExamplesGeant4 PUBLIC src/DDG4DetectorConstruction.cpp)
-endif()
-
-if(ACTS_BUILD_PLUGIN_GEOMODEL)
-    target_sources(
-        ActsExamplesGeant4
-        PUBLIC src/GeoModelDetectorConstruction.cpp
-    )
-
-    find_library(GeoModel2G4_LIBRARY GeoModel2G4 REQUIRED)
-
-    target_link_libraries(
-        ActsExamplesGeant4
-        PUBLIC ActsPluginGeoModel ${GeoModel2G4_LIBRARY}
-    )
-endif()
-
 install(TARGETS ActsExamplesGeant4 LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR})

Examples/Algorithms/Geant4/include/ActsExamples/Geant4/DetectorConstructionFactory.hpp → Examples/Algorithms/Geant4/include/ActsExamples/Geant4/Geant4ConstructionOptions.hpp

@@ -9,18 +9,16 @@
 #pragma once
 
 #include <memory>
-
-#include <G4VUserDetectorConstruction.hh>
+#include <vector>
 
 namespace ActsExamples::Geant4 {
+class RegionCreator;
+}  // namespace ActsExamples::Geant4
 
-/// Silly Geant4 will destroy the detector construction after the run manager is
-/// destructed. This class works around it by factorizing a factory.
-class DetectorConstructionFactory {
- public:
-  virtual ~DetectorConstructionFactory() = default;
+namespace ActsExamples {
 
-  virtual std::unique_ptr<G4VUserDetectorConstruction> factorize() const = 0;
+struct Geant4ConstructionOptions {
+  std::vector<std::shared_ptr<Geant4::RegionCreator>> regionCreators;
 };
 
-}  // namespace ActsExamples::Geant4
+}  // namespace ActsExamples

Examples/Algorithms/Geant4/include/ActsExamples/Geant4/Geant4Simulation.hpp

@@ -10,13 +10,15 @@
 
 #include "Acts/Material/MaterialInteraction.hpp"
 #include "Acts/Utilities/Logger.hpp"
+#include "ActsExamples/DetectorCommons/Detector.hpp"
 #include "ActsExamples/EventData/PropagationSummary.hpp"
 #include "ActsExamples/EventData/SimHit.hpp"
 #include "ActsExamples/EventData/SimParticle.hpp"
 #include "ActsExamples/Framework/DataHandle.hpp"
 #include "ActsExamples/Framework/IAlgorithm.hpp"
 #include "ActsExamples/Framework/ProcessCode.hpp"
 #include "ActsExamples/Framework/RandomNumbers.hpp"
+#include "ActsExamples/Geant4/Geant4ConstructionOptions.hpp"
 #include "ActsExamples/Geant4/SensitiveSurfaceMapper.hpp"
 
 #include <cstddef>
@@ -44,10 +46,8 @@ namespace ActsExamples {
 struct Geant4Handle;
 
 namespace Geant4 {
-class DetectorConstructionFactory;
 class SensitiveSurfaceMapper;
 struct EventStore;
-class RegionCreator;
 }  // namespace Geant4
 
 /// Abstracts common Geant4 Acts algorithm behaviour.
@@ -61,10 +61,11 @@ class Geant4SimulationBase : public IAlgorithm {
     /// Random number service.
     std::shared_ptr<const RandomNumbers> randomNumbers;
 
-    /// Detector construction object.
-    /// G4RunManager will take care of deletion
-    std::shared_ptr<Geant4::DetectorConstructionFactory>
-        detectorConstructionFactory;
+    /// Geant4 construction options.
+    Geant4ConstructionOptions constructionOptions;
+
+    /// Detector instance to access Geant4 geometry construction.
+    std::shared_ptr<Detector> detector;
 
     /// Optional Geant4 instance overwrite.
     std::shared_ptr<Geant4Handle> geant4Handle;
@@ -81,8 +82,7 @@ class Geant4SimulationBase : public IAlgorithm {
   /// Algorithm execute method, called once per event with context
   ///
   /// @param ctx the AlgorithmContext for this event
-  ActsExamples::ProcessCode execute(
-      const ActsExamples::AlgorithmContext& ctx) const override;
+  ProcessCode execute(const ActsExamples::AlgorithmContext& ctx) const override;
 
   /// Readonly access to the configuration
   virtual const Config& config() const = 0;
@@ -166,8 +166,7 @@ class Geant4Simulation final : public Geant4SimulationBase {
   /// Algorithm execute method, called once per event with context
   ///
   /// @param ctx the AlgorithmContext for this event
-  ActsExamples::ProcessCode execute(
-      const ActsExamples::AlgorithmContext& ctx) const final;
+  ProcessCode execute(const ActsExamples::AlgorithmContext& ctx) const final;
 
   /// Readonly access to the configuration
   const Config& config() const final { return m_cfg; }
@@ -209,8 +208,7 @@ class Geant4MaterialRecording final : public Geant4SimulationBase {
   /// Algorithm execute method, called once per event with context
   ///
   /// @param ctx the AlgorithmContext for this event
-  ActsExamples::ProcessCode execute(
-      const ActsExamples::AlgorithmContext& ctx) const final;
+  ProcessCode execute(const ActsExamples::AlgorithmContext& ctx) const final;
 
   /// Readonly access to the configuration
   const Config& config() const final { return m_cfg; }

Examples/Algorithms/Geant4/include/ActsExamples/Geant4/RegionCreator.hpp

@@ -13,6 +13,8 @@
 #include <string>
 #include <vector>
 
+class G4Region;
+
 namespace ActsExamples::Geant4 {
 
 /// Geant4 Region Creator
@@ -24,6 +26,9 @@ class RegionCreator {
  public:
   /// Nested configuration struct for the Geant4 region creator
   struct Config {
+    /// Region name
+    std::string name;
+
     /// Process cut to be applied for gammas, in mm
     double gammaCut{};
 
@@ -37,35 +42,25 @@ class RegionCreator {
     double protonCut{};
 
     /// Volume list to be included in this region
-    std::vector<std::string> volumes{};
+    std::vector<std::string> volumes;
   };
 
   /// Region creator constructor
   ///
   /// @param cfg is the configuration struct
-  /// @param name is the region name
-  /// @param level is the logging level to be used
-  RegionCreator(const Config& cfg, std::string name,
-                Acts::Logging::Level level);
+  explicit RegionCreator(const Config& cfg);
 
   /// Construct the region
-  void construct();
+  /// @note The lifetime of the returned region is managed by Geant4
+  G4Region* buildRegion(
+      const Acts::Logger& logger = Acts::getDummyLogger()) const;
 
   /// Readonly access to the configuration
   const Config& config() const { return m_cfg; }
 
  private:
-  /// Region name
-  std::string m_name;
-
   /// Config instance
   Config m_cfg;
-
-  /// Private access method to the logging instance
-  const Acts::Logger& logger() const { return *m_logger; }
-
-  /// The looging instance
-  std::unique_ptr<const Acts::Logger> m_logger;
 };
 
 }  // namespace ActsExamples::Geant4