From 5e8d55c2caf8537dd0f90bb11e1406d38efbfb94 Mon Sep 17 00:00:00 2001
From: Alexis Pereda <alexis.pereda@clermont.in2p3.fr>
Date: Fri, 21 Mar 2025 16:15:52 +0100
Subject: [PATCH] Add InitializeG4PreInitState step in Actors

---
 core/opengate_core/opengate_lib/GateVActor.h     |  3 +++
 core/opengate_core/opengate_lib/pyGateVActor.cpp |  1 +
 opengate/engines.py                              | 15 +++++++++++++++
 3 files changed, 19 insertions(+)

diff --git a/core/opengate_core/opengate_lib/GateVActor.h b/core/opengate_core/opengate_lib/GateVActor.h
index 2f1282a56..7c84f589a 100644
--- a/core/opengate_core/opengate_lib/GateVActor.h
+++ b/core/opengate_core/opengate_lib/GateVActor.h
@@ -27,6 +27,9 @@ class GateVActor : public G4VPrimitiveScorer {
 
   virtual void AddActions(std::set<std::string> &actions);
 
+  // Called at initialisation in late G4 PreInit state
+  virtual void InitializeG4PreInitState() {}
+
   // Called at initialisation
   virtual void InitializeCpp();
 
diff --git a/core/opengate_core/opengate_lib/pyGateVActor.cpp b/core/opengate_core/opengate_lib/pyGateVActor.cpp
index 6a60c30f5..729cf9c2e 100644
--- a/core/opengate_core/opengate_lib/pyGateVActor.cpp
+++ b/core/opengate_core/opengate_lib/pyGateVActor.cpp
@@ -79,6 +79,7 @@ void init_GateVActor(py::module &m) {
       //      .def_readonly("fActions", &GateVActor::fActions) // avoid wrapping
       //      this -> problems with pickle
       .def_readwrite("fFilters", &GateVActor::fFilters)
+      .def("InitializeG4PreInitState", &GateVActor::InitializeG4PreInitState)
       .def("InitializeCpp", &GateVActor::InitializeCpp)
       .def("InitializeUserInfo", &GateVActor::InitializeUserInfo)
       .def("AddActions", &GateVActor::AddActions)
diff --git a/opengate/engines.py b/opengate/engines.py
index 034016e4d..23d6a4855 100644
--- a/opengate/engines.py
+++ b/opengate/engines.py
@@ -591,6 +591,13 @@ def close(self):
             actor.close()
         super().close()
 
+    def initialize_preinit(self):
+        for actor in self.actor_manager.sorted_actors:
+            global_log.debug(
+                f"Actor: initialize_preinit [{actor.type_name}] {actor.name}"
+            )
+            actor.InitializeG4PreInitState()
+
     def initialize(self):
         for actor in self.actor_manager.sorted_actors:
             global_log.debug(f"Actor: initialize [{actor.type_name}] {actor.name}")
@@ -1278,6 +1285,9 @@ def initialize(self):
         """
         Build the main geant4 objects and initialize them.
         """
+
+        # From this line, G4 is in G4State_PreInit state
+
         # get log
         log = global_log
 
@@ -1346,6 +1356,9 @@ def initialize(self):
             self.action_engine
         )  # G4 internally calls action_engine.Build()
 
+        # late-G4 PreInit state actor initialisation phase
+        self.actor_engine.initialize_preinit()
+
         # Important: The volumes are constructed
         # when the G4RunManager calls the Construct method of the VolumeEngine,
         # which happens in the InitializeGeometry() method of the
@@ -1360,6 +1373,8 @@ def initialize(self):
         else:
             self.g4_RunManager.Initialize()
 
+        # From this line, G4 is in G4State_Idle state
+
         log.info("Simulation: initialize PhysicsEngine after RunManager initialization")
         self.physics_engine.initialize_after_runmanager()
         self.g4_RunManager.PhysicsHasBeenModified()