BGE patch: Relink actuators with target within group when duplicating group; generalize protection against object deletion for all actuators that point to objects.

Certain actuators hold a pointer to an objects: Property,
SceneCamera, AddObject, Camera, Parent, TractTo. When a
group is duplicated, the actuators that point to objects
within the group will be relinked to point to the
replicated objects and not to the original objects.
This helps to setup self-contained group with a camera
following a character for example.
This feature also works when adding a single object
(and all its children) with the AddObject actuator.

The second part of the patch extends the protection
against object deletion to all the actuators of the above
list (previously, only the TrackTo, AddObject and
Property actuators were protected). In case the target
object of these actuators is deleted, the BGE won't
crash.

source/gameengine/Converter/BL_DeformableGameObject.h

@@ -60,6 +60,7 @@ public:
 	{
 		if (m_pDeformer)
 			m_pDeformer->Relink (map);
+		KX_GameObject::Relink(map);
 	};
 	void ProcessReplica(KX_GameObject* replica);
 

source/gameengine/Converter/KX_ConvertActuators.cpp

@@ -503,7 +503,7 @@ void BL_ConvertActuators(char* maggiename,
 		case ACT_PROPERTY:
 			{
 				bPropertyActuator* propact = (bPropertyActuator*) bact->data;
-				CValue* destinationObj = NULL;
+				SCA_IObject* destinationObj = NULL;
 				
 				/*
 				here the destinationobject is searched. problem with multiple scenes: other scenes

source/gameengine/GameLogic/SCA_ILogicBrick.cpp

@@ -82,7 +82,10 @@ void SCA_ILogicBrick::ReParent(SCA_IObject* parent)
 	m_gameobj = parent;
 }
 
-
+void SCA_ILogicBrick::Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map)
+{
+	// nothing to do
+}
 
 CValue* SCA_ILogicBrick::Calc(VALUE_OPERATOR op, CValue *val)
 {

source/gameengine/GameLogic/SCA_ILogicBrick.h

@@ -32,6 +32,8 @@
 #include "Value.h"
 #include "SCA_IObject.h"
 #include "BoolValue.h"
+#include "GEN_Map.h"
+#include "GEN_HashedPtr.h"
 
 class SCA_ILogicBrick : public CValue
 {
@@ -59,6 +61,7 @@ public:
 
 	SCA_IObject*	GetParent();
 	virtual void	ReParent(SCA_IObject* parent);
+	virtual void	Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map);
 
 	// act as a BoolValue (with value IsPositiveTrigger)
 	virtual CValue*	Calc(VALUE_OPERATOR op, CValue *val);

source/gameengine/GameLogic/SCA_PropertyActuator.cpp

@@ -42,7 +42,7 @@
 /* Native functions                                                          */
 /* ------------------------------------------------------------------------- */
 
-SCA_PropertyActuator::SCA_PropertyActuator(SCA_IObject* gameobj,CValue* sourceObj,const STR_String& propname,const STR_String& expr,int acttype,PyTypeObject* T )
+SCA_PropertyActuator::SCA_PropertyActuator(SCA_IObject* gameobj,SCA_IObject* sourceObj,const STR_String& propname,const STR_String& expr,int acttype,PyTypeObject* T )
    :	SCA_IActuator(gameobj,T),
 	m_type(acttype),
 	m_propname(propname),
@@ -51,14 +51,14 @@ SCA_PropertyActuator::SCA_PropertyActuator(SCA_IObject* gameobj,CValue* sourceOb
 {
 	// protect ourselves against someone else deleting the source object
 	// don't protect against ourselves: it would create a dead lock
-	if (m_sourceObj && m_sourceObj != GetParent())
-		m_sourceObj->AddRef();
+	if (m_sourceObj)
+		m_sourceObj->RegisterActuator(this);
 }
 
 SCA_PropertyActuator::~SCA_PropertyActuator()
 {
-	if (m_sourceObj && m_sourceObj != GetParent())
-		m_sourceObj->Release();
+	if (m_sourceObj)
+		m_sourceObj->UnregisterActuator(this);
 }
 
 bool SCA_PropertyActuator::Update()
@@ -185,10 +185,31 @@ void SCA_PropertyActuator::ProcessReplica()
 	// no need to check for self reference like in the constructor:
 	// the replica will always have a different parent
 	if (m_sourceObj)
-		m_sourceObj->AddRef();
+		m_sourceObj->RegisterActuator(this);
 	SCA_IActuator::ProcessReplica();
 }
 
+bool SCA_PropertyActuator::UnlinkObject(SCA_IObject* clientobj)
+{
+	if (clientobj == m_sourceObj)
+	{
+		// this object is being deleted, we cannot continue to track it.
+		m_sourceObj = NULL;
+		return true;
+	}
+	return false;
+}
+
+void SCA_PropertyActuator::Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map)
+{
+	void **h_obj = (*obj_map)[m_sourceObj];
+	if (h_obj) {
+		if (m_sourceObj)
+			m_sourceObj->UnregisterActuator(this);
+		m_sourceObj = (SCA_IObject*)(*h_obj);
+		m_sourceObj->RegisterActuator(this);
+	}
+}
 
 
 /* ------------------------------------------------------------------------- */

source/gameengine/GameLogic/SCA_PropertyActuator.h

@@ -52,7 +52,7 @@ class SCA_PropertyActuator : public SCA_IActuator
 	int			m_type;
 	STR_String	m_propname;
 	STR_String	m_exprtxt;
-	CValue*		m_sourceObj; // for copy property actuator
+	SCA_IObject* m_sourceObj; // for copy property actuator
 
 public:
 
@@ -60,7 +60,7 @@ public:
 
 	SCA_PropertyActuator(
 		SCA_IObject* gameobj,
-		CValue* sourceObj,
+		SCA_IObject* sourceObj,
 		const STR_String& propname,
 		const STR_String& expr,
 		int acttype,
@@ -74,7 +74,9 @@ public:
 	GetReplica(
 	);
 
-	void ProcessReplica();
+	virtual void ProcessReplica();
+	virtual bool UnlinkObject(SCA_IObject* clientobj);
+	virtual void Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map);
 
 	virtual bool 
 	Update();

source/gameengine/Ketsji/KX_CameraActuator.cpp

@@ -49,7 +49,7 @@ STR_String KX_CameraActuator::Y_AXIS_STRING = "y";
 
 KX_CameraActuator::KX_CameraActuator(
 	SCA_IObject* gameobj, 
-	CValue *obj,
+	SCA_IObject *obj,
 	MT_Scalar hght,
 	MT_Scalar minhght,
 	MT_Scalar maxhght,
@@ -63,11 +63,14 @@ KX_CameraActuator::KX_CameraActuator(
 	m_maxHeight (maxhght),
 	m_x (xytog)
 {
+	if (m_ob)
+		m_ob->RegisterActuator(this);
 }
 
 KX_CameraActuator::~KX_CameraActuator()
 {
-	//nothing to do
+	if (m_ob)
+		m_ob->UnregisterActuator(this);
 }
 
 	CValue* 
@@ -81,8 +84,35 @@ GetReplica(
 	return replica;
 };
 
+void KX_CameraActuator::ProcessReplica()
+{
+	if (m_ob)
+		m_ob->RegisterActuator(this);
+	SCA_IActuator::ProcessReplica();
+}
+
+bool KX_CameraActuator::UnlinkObject(SCA_IObject* clientobj)
+{
+	if (clientobj == m_ob)
+	{
+		// this object is being deleted, we cannot continue to track it.
+		m_ob = NULL;
+		return true;
+	}
+	return false;
+}
 
 
+void KX_CameraActuator::Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map)
+{
+	void **h_obj = (*obj_map)[m_ob];
+	if (h_obj) {
+		if (m_ob)
+			m_ob->UnregisterActuator(this);
+		m_ob = (SCA_IObject*)(*h_obj);
+		m_ob->RegisterActuator(this);
+	}
+}
 
 /* three functions copied from blender arith... don't know if there's an equivalent */
 
@@ -181,8 +211,14 @@ static void Kx_VecUpMat3(float *vec, float mat[][3], short axis)
 
 bool KX_CameraActuator::Update(double curtime, bool frame)
 {
-	bool result = true;
+	/* wondering... is it really neccesary/desirable to suppress negative    */
+	/* events here?                                                          */
+	bool bNegativeEvent = IsNegativeEvent();
+	RemoveAllEvents();
 
+	if (bNegativeEvent || !m_ob) 
+		return false;
+	
 	KX_GameObject *obj = (KX_GameObject*) GetParent();
 	MT_Point3 from = obj->NodeGetWorldPosition();
 	MT_Matrix3x3 frommat = obj->NodeGetWorldOrientation();
@@ -195,13 +231,6 @@ bool KX_CameraActuator::Update(double curtime, bool frame)
 	float mindistsq, maxdistsq, distsq;
 	float mat[3][3];
 	
-	/* wondering... is it really neccesary/desirable to suppress negative    */
-	/* events here?                                                          */
-	bool bNegativeEvent = IsNegativeEvent();
-	RemoveAllEvents();
-
-	if (bNegativeEvent) return false;
-	
 	/* The rules:                                                            */
 	/* CONSTRAINT 1: not implemented */
 	/* CONSTRAINT 2: can camera see actor?              */
@@ -315,7 +344,7 @@ bool KX_CameraActuator::Update(double curtime, bool frame)
 	actormat[2][0]= mat[0][2]; actormat[2][1]= mat[1][2]; actormat[2][2]= mat[2][2];
 	obj->NodeSetLocalOrientation(actormat);
 
-	return result;
+	return true;
 }
 
 CValue *KX_CameraActuator::findObject(char *obName) 
@@ -404,7 +433,11 @@ PyObject* KX_CameraActuator::PySetObject(PyObject* self,
 	PyObject* gameobj;
 	if (PyArg_ParseTuple(args, "O!", &KX_GameObject::Type, &gameobj))
 	{
-		m_ob = (CValue*)gameobj;
+		if (m_ob)
+			m_ob->UnregisterActuator(this);
+		m_ob = (SCA_IObject*)gameobj;
+		if (m_ob)
+			m_ob->RegisterActuator(this);
 		Py_Return;
 	}
 	PyErr_Clear();
@@ -412,10 +445,13 @@ PyObject* KX_CameraActuator::PySetObject(PyObject* self,
 	char* objectname;
 	if (PyArg_ParseTuple(args, "s", &objectname))
 	{
-		CValue *object = (CValue*)SCA_ILogicBrick::m_sCurrentLogicManager->GetGameObjectByName(STR_String(objectname));
+		SCA_IObject *object = (SCA_IObject*)SCA_ILogicBrick::m_sCurrentLogicManager->GetGameObjectByName(STR_String(objectname));
 		if(object)
 		{
+			if (m_ob != NULL)
+				m_ob->UnregisterActuator(this);
 			m_ob = object;
+			m_ob->RegisterActuator(this);
 			Py_Return;
 		}
 	}

source/gameengine/Ketsji/KX_CameraActuator.h

@@ -49,7 +49,7 @@ class KX_CameraActuator : public SCA_IActuator
 	Py_Header;
 private :
 	/** Object that will be tracked. */
-	CValue *m_ob;
+	SCA_IObject *m_ob;
 
 	/** height (float), */
 	//const MT_Scalar m_height;
@@ -87,7 +87,7 @@ private :
 
 		SCA_IObject *gameobj,
 		//const CValue *ob,
-		CValue *ob,
+		SCA_IObject *ob,
 		MT_Scalar hght,
 		MT_Scalar minhght,
 		MT_Scalar maxhght,
@@ -103,6 +103,7 @@ private :
 
 	/** Methods Inherited from  CValue */
 	CValue* GetReplica();
+	virtual void ProcessReplica();
 	
 
 	/** Methods inherited from SCA_IActuator */
@@ -110,7 +111,10 @@ private :
 		double curtime,
 		bool frame
 	);
+	virtual bool	UnlinkObject(SCA_IObject* clientobj);
 
+	/** Methods inherited from SCA_ILogicBrick */
+	virtual void	Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map);
 
 	/* --------------------------------------------------------------------- */
 	/* Python interface ---------------------------------------------------- */

source/gameengine/Ketsji/KX_GameObject.cpp

@@ -61,6 +61,8 @@ typedef unsigned long uint_ptr;
 #include "KX_RayCast.h"
 #include "KX_PythonInit.h"
 #include "KX_PyMath.h"
+#include "SCA_IActuator.h"
+#include "SCA_ISensor.h"
 
 // This file defines relationships between parents and children
 // in the game engine.
@@ -1668,6 +1670,20 @@ KX_PYMETHODDEF_DOC(KX_GameObject, rayCast,
  * --------------------------------------------------------------------- */
 void KX_GameObject::Relink(GEN_Map<GEN_HashedPtr, void*> *map_parameter)	
 {
-	/* intentionally empty ? */
+	// we will relink the sensors and actuators that use object references
+	// if the object is part of the replicated hierarchy, use the new
+	// object reference instead
+	SCA_SensorList& sensorlist = GetSensors();
+	SCA_SensorList::iterator sit;
+	for (sit=sensorlist.begin(); sit != sensorlist.end(); sit++)
+	{
+		(*sit)->Relink(map_parameter);
+	}
+	SCA_ActuatorList& actuatorlist = GetActuators();
+	SCA_ActuatorList::iterator ait;
+	for (ait=actuatorlist.begin(); ait != actuatorlist.end(); ait++)
+	{
+		(*ait)->Relink(map_parameter);
+	}
 }
 

source/gameengine/Ketsji/KX_ParentActuator.cpp

@@ -46,19 +46,22 @@
 
 KX_ParentActuator::KX_ParentActuator(SCA_IObject *gameobj, 
 									 int mode,
-									 CValue *ob,
+									 SCA_IObject *ob,
 									 PyTypeObject* T)
 	: SCA_IActuator(gameobj, T),
 	  m_mode(mode),
 	  m_ob(ob)
 {
+	if (m_ob)
+		m_ob->RegisterActuator(this);
 } 
 
 
 
 KX_ParentActuator::~KX_ParentActuator()
 {
-	/* intentionally empty */ 
+	if (m_ob)
+		m_ob->UnregisterActuator(this);
 } 
 
 
@@ -73,6 +76,36 @@ CValue* KX_ParentActuator::GetReplica()
 	return replica;
 }
 
+void KX_ParentActuator::ProcessReplica()
+{
+	if (m_ob)
+		m_ob->RegisterActuator(this);
+	SCA_IActuator::ProcessReplica();
+}
+
+
+bool KX_ParentActuator::UnlinkObject(SCA_IObject* clientobj)
+{
+	if (clientobj == m_ob)
+	{
+		// this object is being deleted, we cannot continue to track it.
+		m_ob = NULL;
+		return true;
+	}
+	return false;
+}
+
+void KX_ParentActuator::Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map)
+{
+	void **h_obj = (*obj_map)[m_ob];
+	if (h_obj) {
+		if (m_ob)
+			m_ob->UnregisterActuator(this);
+		m_ob = (SCA_IObject*)(*h_obj);
+		m_ob->RegisterActuator(this);
+	}
+}
+
 
 
 bool KX_ParentActuator::Update()
@@ -87,7 +120,8 @@ bool KX_ParentActuator::Update()
 	KX_Scene *scene = PHY_GetActiveScene();
 	switch (m_mode) {
 		case KX_PARENT_SET:
-			obj->SetParent(scene, (KX_GameObject*)m_ob);
+			if (m_ob)
+				obj->SetParent(scene, (KX_GameObject*)m_ob);
 			break;
 		case KX_PARENT_REMOVE:
 			obj->RemoveParent(scene);
@@ -148,7 +182,11 @@ PyObject* KX_ParentActuator::PySetObject(PyObject* self, PyObject* args, PyObjec
 	PyObject* gameobj;
 	if (PyArg_ParseTuple(args, "O!", &KX_GameObject::Type, &gameobj))
 	{
-		m_ob = (CValue*)gameobj;
+		if (m_ob != NULL)
+			m_ob->UnregisterActuator(this);
+		m_ob = (SCA_IObject*)gameobj;
+		if (m_ob)
+			m_ob->RegisterActuator(this);
 		Py_Return;
 	}
 	PyErr_Clear();
@@ -156,10 +194,13 @@ PyObject* KX_ParentActuator::PySetObject(PyObject* self, PyObject* args, PyObjec
 	char* objectname;
 	if (PyArg_ParseTuple(args, "s", &objectname))
 	{
-		CValue *object = (CValue*)SCA_ILogicBrick::m_sCurrentLogicManager->GetGameObjectByName(STR_String(objectname));
+		SCA_IObject *object = (SCA_IObject*)SCA_ILogicBrick::m_sCurrentLogicManager->GetGameObjectByName(STR_String(objectname));
 		if(object)
 		{
+			if (m_ob != NULL)
+				m_ob->UnregisterActuator(this);
 			m_ob = object;
+			m_ob->RegisterActuator(this);
 			Py_Return;
 		}
 	}

source/gameengine/Ketsji/KX_ParentActuator.h

@@ -47,7 +47,7 @@ class KX_ParentActuator : public SCA_IActuator
 	int m_mode;
 	
 	/** Object to set as parent */
-	CValue *m_ob;
+	SCA_IObject *m_ob;
 	
 	
 
@@ -62,12 +62,15 @@ class KX_ParentActuator : public SCA_IActuator
  
 	KX_ParentActuator(class SCA_IObject* gameobj,
 						int mode,
-						CValue *ob,
+						SCA_IObject *ob,
 						PyTypeObject* T=&Type);
 	virtual ~KX_ParentActuator();
 	virtual bool Update();
 	
 	virtual CValue* GetReplica();
+	virtual void ProcessReplica();
+	virtual void KX_ParentActuator::Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map);
+	virtual bool KX_ParentActuator::UnlinkObject(SCA_IObject* clientobj);
 	
 	/* --------------------------------------------------------------------- */
 	/* Python interface ---------------------------------------------------- */

source/gameengine/Ketsji/KX_SCA_AddObjectActuator.cpp

@@ -137,6 +137,17 @@ bool KX_SCA_AddObjectActuator::UnlinkObject(SCA_IObject* clientobj)
 	return false;
 }
 
+void KX_SCA_AddObjectActuator::Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map)
+{
+	void **h_obj = (*obj_map)[m_OriginalObject];
+	if (h_obj) {
+		if (m_OriginalObject)
+			m_OriginalObject->UnregisterActuator(this);
+		m_OriginalObject = (SCA_IObject*)(*h_obj);
+		m_OriginalObject->RegisterActuator(this);
+	}
+}
+
 
 /* ------------------------------------------------------------------------- */
 /* Python functions                                                          */

source/gameengine/Ketsji/KX_SCA_AddObjectActuator.h

@@ -95,6 +95,9 @@ public:
 	virtual bool 
 	UnlinkObject(SCA_IObject* clientobj);
 
+	virtual void 
+	Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map);
+
 	virtual bool 
 	Update();
 

source/gameengine/Ketsji/KX_Scene.cpp

@@ -724,21 +724,23 @@ void KX_Scene::DupliGroupRecurse(CValue* obj, int level)
 		replica->Release();
 	}
 
-	//	relink any pointers as necessary, sort of a temporary solution
+	// the logic must be replicated first because we need
+	// the new logic bricks before relinking
 	vector<KX_GameObject*>::iterator git;
 	for (git = m_logicHierarchicalGameObjects.begin();!(git==m_logicHierarchicalGameObjects.end());++git)
-	{
-		(*git)->Relink(&m_map_gameobject_to_replica);
-		// add the object in the layer of the parent
-		(*git)->SetLayer(groupobj->GetLayer());
-	}
-
-	// now replicate logic
-	for (git = m_logicHierarchicalGameObjects.begin();!(git==m_logicHierarchicalGameObjects.end());++git)
 	{
 		(*git)->ReParentLogic();
 	}
 	
+	//	relink any pointers as necessary, sort of a temporary solution
+	for (git = m_logicHierarchicalGameObjects.begin();!(git==m_logicHierarchicalGameObjects.end());++git)
+	{
+		// this will also relink the actuator to objects within the hierarchy
+		(*git)->Relink(&m_map_gameobject_to_replica);
+		// add the object in the layer of the parent
+		(*git)->SetLayer(groupobj->GetLayer());
+	}
+
 	// replicate crosslinks etc. between logic bricks
 	for (git = m_logicHierarchicalGameObjects.begin();!(git==m_logicHierarchicalGameObjects.end());++git)
 	{
@@ -805,21 +807,22 @@ SCA_IObject* KX_Scene::AddReplicaObject(class CValue* originalobject,
 			replica->GetSGNode()->AddChild(childreplicanode);
 	}
 
-	//	relink any pointers as necessary, sort of a temporary solution
-	vector<KX_GameObject*>::iterator git;
-	for (git = m_logicHierarchicalGameObjects.begin();!(git==m_logicHierarchicalGameObjects.end());++git)
-	{
-		(*git)->Relink(&m_map_gameobject_to_replica);
-		// add the object in the layer of the parent
-		(*git)->SetLayer(parentobj->GetLayer());
-	}
-
 	// now replicate logic
+	vector<KX_GameObject*>::iterator git;
 	for (git = m_logicHierarchicalGameObjects.begin();!(git==m_logicHierarchicalGameObjects.end());++git)
 	{
 		(*git)->ReParentLogic();
 	}
 	
+	//	relink any pointers as necessary, sort of a temporary solution
+	for (git = m_logicHierarchicalGameObjects.begin();!(git==m_logicHierarchicalGameObjects.end());++git)
+	{
+		// this will also relink the actuators in the hierarchy
+		(*git)->Relink(&m_map_gameobject_to_replica);
+		// add the object in the layer of the parent
+		(*git)->SetLayer(parentobj->GetLayer());
+	}
+
 	// replicate crosslinks etc. between logic bricks
 	for (git = m_logicHierarchicalGameObjects.begin();!(git==m_logicHierarchicalGameObjects.end());++git)
 	{

source/gameengine/Ketsji/KX_SceneActuator.cpp

@@ -58,13 +58,16 @@ KX_SceneActuator::KX_SceneActuator(SCA_IObject *gameobj,
 	m_KetsjiEngine=ketsjiEngine;
 	m_camera = camera;
 	m_nextSceneName = nextSceneName;
+	if (m_camera)
+		m_camera->RegisterActuator(this);
 } /* End of constructor */
 
 
 
 KX_SceneActuator::~KX_SceneActuator()
 { 
-	// there's nothing to be done here, really....
+	if (m_camera)
+		m_camera->UnregisterActuator(this);
 } /* end of destructor */
 
 
@@ -79,6 +82,34 @@ CValue* KX_SceneActuator::GetReplica()
 	return replica;
 }
 
+void KX_SceneActuator::ProcessReplica()
+{
+	if (m_camera)
+		m_camera->RegisterActuator(this);
+	SCA_IActuator::ProcessReplica();
+}
+
+bool KX_SceneActuator::UnlinkObject(SCA_IObject* clientobj)
+{
+	if (clientobj == (SCA_IObject*)m_camera)
+	{
+		// this object is being deleted, we cannot continue to track it.
+		m_camera = NULL;
+		return true;
+	}
+	return false;
+}
+
+void KX_SceneActuator::Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map)
+{
+	void **h_obj = (*obj_map)[m_camera];
+	if (h_obj) {
+		if (m_camera)
+			m_camera->UnregisterActuator(this);
+		m_camera = (KX_Camera*)(*h_obj);
+		m_camera->RegisterActuator(this);
+	}
+}
 
 
 bool KX_SceneActuator::Update()
@@ -332,7 +363,11 @@ PyObject* KX_SceneActuator::PySetCamera(PyObject* self,
 	PyObject *cam;
 	if (PyArg_ParseTuple(args, "O!", &KX_Camera::Type, &cam))
 	{
+		if (m_camera)
+			m_camera->UnregisterActuator(this);
 		m_camera = (KX_Camera*) cam;
+		if (m_camera)
+			m_camera->RegisterActuator(this);
 		Py_Return;
 	}
 	PyErr_Clear();
@@ -345,7 +380,13 @@ PyObject* KX_SceneActuator::PySetCamera(PyObject* self,
 	}
 
 	KX_Camera *camOb = FindCamera(camName);
-	if (camOb) m_camera = camOb;
+	if (camOb) 
+	{
+		if (m_camera)
+			m_camera->UnregisterActuator(this);
+		m_camera = camOb;
+		m_camera->RegisterActuator(this);
+	}
 
 	Py_Return;
 }

source/gameengine/Ketsji/KX_SceneActuator.h

@@ -82,6 +82,9 @@ class KX_SceneActuator : public SCA_IActuator
 	virtual ~KX_SceneActuator();
 
 	virtual CValue* GetReplica();
+	virtual void ProcessReplica();
+	virtual bool UnlinkObject(SCA_IObject* clientobj);
+	virtual void Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map);
 
 	virtual bool Update();
 	

source/gameengine/Ketsji/KX_TrackToActuator.cpp

@@ -210,6 +210,18 @@ bool KX_TrackToActuator::UnlinkObject(SCA_IObject* clientobj)
 	return false;
 }
 
+void KX_TrackToActuator::Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map)
+{
+	void **h_obj = (*obj_map)[m_object];
+	if (h_obj) {
+		if (m_object)
+			m_object->UnregisterActuator(this);
+		m_object = (SCA_IObject*)(*h_obj);
+		m_object->RegisterActuator(this);
+	}
+}
+
+
 bool KX_TrackToActuator::Update(double curtime, bool frame)
 {
 	bool result = false;	

source/gameengine/Ketsji/KX_TrackToActuator.h

@@ -68,6 +68,7 @@ class KX_TrackToActuator : public SCA_IActuator
 
 	virtual void ProcessReplica();
 	virtual bool UnlinkObject(SCA_IObject* clientobj);
+	virtual void Relink(GEN_Map<GEN_HashedPtr, void*> *obj_map);
 	virtual bool Update(double curtime, bool frame);
 
 	/* Python part */