BGE bug: crash when an object being tracked-to is deleted (bad practice anyway). Fix by creating a generic cross reference between actuators (only TrackTo uses it at the moment) and objects so that the actuator is informed when the target object is deleted

3 files changed, 35 insertions, 0 deletions

diff --git a/source/gameengine/GameLogic/SCA_IActuator.h b/source/gameengine/GameLogic/SCA_IActuator.h
index bff32dcebaa..b802aa4b298 100644
--- a/source/gameengine/GameLogic/SCA_IActuator.h
+++ b/source/gameengine/GameLogic/SCA_IActuator.h
@@ -47,6 +47,15 @@ public:
 				  PyTypeObject* T =&Type); 
 
 	/**
+	 * UnlinkObject(...)
+	 * Certain actuator use gameobject pointers (like TractTo actuator)
+	 * This function can be called when an object is removed to make
+	 * sure that the actuator will not use it anymore.
+	 */
+
+	virtual bool UnlinkObject(SCA_IObject* clientobj) { return false; }
+
+	/**
 	 * Update(...)
 	 * Update the actuator based upon the events received since 
 	 * the last call to Update, the current time and deltatime the
diff --git a/source/gameengine/GameLogic/SCA_IObject.cpp b/source/gameengine/GameLogic/SCA_IObject.cpp
index 465dd981406..6df9e23f3fa 100644
--- a/source/gameengine/GameLogic/SCA_IObject.cpp
+++ b/source/gameengine/GameLogic/SCA_IObject.cpp
@@ -62,6 +62,10 @@ SCA_IObject::~SCA_IObject()
 		((CValue*)(*itc))->Release();
 	}
 	SCA_ActuatorList::iterator ita;
+	for (ita = m_registeredActuators.begin(); !(ita==m_registeredActuators.end()); ++ita)
+	{
+		(*ita)->UnlinkObject(this);
+	}
 	for (ita = m_actuators.begin(); !(ita==m_actuators.end()); ++ita)
 	{
 		((CValue*)(*ita))->Release();
@@ -118,7 +122,24 @@ void SCA_IObject::AddActuator(SCA_IActuator* act)
 	m_actuators.push_back(act);
 }
 
+void SCA_IObject::RegisterActuator(SCA_IActuator* act)
+{
+	// don't increase ref count, it would create dead lock
+	m_registeredActuators.push_back(act);
+}
 
+void SCA_IObject::UnregisterActuator(SCA_IActuator* act)
+{
+	SCA_ActuatorList::iterator ita;
+	for (ita = m_registeredActuators.begin(); ita != m_registeredActuators.end(); ita++)
+	{
+		if ((*ita) == act) {
+			(*ita) = m_registeredActuators.back();
+			m_registeredActuators.pop_back();
+			break;
+		}
+	}
+}
 
 void SCA_IObject::SetIgnoreActivityCulling(bool b)
 {
@@ -168,6 +189,8 @@ void SCA_IObject::ReParentLogic()
 		newactuator->SetActive(false);
 		oldactuators[act++] = newactuator;
 	}
+	// a new object cannot be client of any actuator
+	m_registeredActuators.clear();
 		
 }
 
diff --git a/source/gameengine/GameLogic/SCA_IObject.h b/source/gameengine/GameLogic/SCA_IObject.h
index 8f3e25afa03..4b0fc741b8f 100644
--- a/source/gameengine/GameLogic/SCA_IObject.h
+++ b/source/gameengine/GameLogic/SCA_IObject.h
@@ -55,6 +55,7 @@ protected:
 	SCA_SensorList         m_sensors;
 	SCA_ControllerList     m_controllers;
 	SCA_ActuatorList       m_actuators;
+	SCA_ActuatorList       m_registeredActuators;	// actuators that use a pointer to this object
 	static class MT_Point3 m_sDummy;
 
 	/**
@@ -79,6 +80,8 @@ public:
 	void AddSensor(SCA_ISensor* act);
 	void AddController(SCA_IController* act);
 	void AddActuator(SCA_IActuator* act);
+	void RegisterActuator(SCA_IActuator* act);
+	void UnregisterActuator(SCA_IActuator* act);
 	
 	SCA_ISensor* FindSensor(const STR_String& sensorname);
 	SCA_IActuator* FindActuator(const STR_String& actuatorname);