fix BGE bug #8309: After Parent Object added to the visual layer, Child Camera won't follow.

This bug fix is made of two parts:
1) It's now possible to dynamically add a camera.
2) Empty camera name on a SetCamera actuator now points to the actuator's parent object if this object is a camera. 
This trick is useful to make current a dynamically created camera: just add a SetCamera actuator on the camera itself and leave the name empty. Later, when the camera is added in the scene with an AddObject actuator, either directly or via a parent object, you just need to activate the actuator to make the newly created camera current. If you set a name on a SetCamera actuator, it will always point to the original camera, even after replication.

source/gameengine/Converter/KX_ConvertActuators.cpp

@@ -684,15 +684,11 @@ void BL_ConvertActuators(char* maggiename,
 						break;
 					}
 				case ACT_SCENE_CAMERA:
+					mode = KX_SceneActuator::KX_SCENE_SET_CAMERA;
 					if (sceneact->camera)
 					{
-						mode = KX_SceneActuator::KX_SCENE_SET_CAMERA;
 						cam = (KX_Camera*) converter->FindGameObject(sceneact->camera);
 					}
-					else
-					{
-						// TODO:warn user
-					}
 					break;
 				case ACT_SCENE_RESTART:
 					{

source/gameengine/Ketsji/KX_Camera.cpp

@@ -69,7 +69,22 @@ KX_Camera::~KX_Camera()
 }	
 
 
+CValue*	KX_Camera::GetReplica()
+{
+	KX_Camera* replica = new KX_Camera(*this);
 	
+	// this will copy properties and so on...
+	CValue::AddDataToReplica(replica);
+	ProcessReplica(replica);
+	
+	return replica;
+}
+	
+void KX_Camera::ProcessReplica(KX_Camera* replica)
+{
+	KX_GameObject::ProcessReplica(replica);
+}
+
 MT_Transform KX_Camera::GetWorldToCamera() const
 { 
 	MT_Transform camtrans;

source/gameengine/Ketsji/KX_Camera.h

@@ -134,6 +134,24 @@ public:
 	KX_Camera(void* sgReplicationInfo,SG_Callbacks callbacks,const RAS_CameraData& camdata, bool frustum_culling = true, PyTypeObject *T = &Type);
 	virtual ~KX_Camera();
 	
+	/** 
+	 * Inherited from CValue -- return a new copy of this
+	 * instance allocated on the heap. Ownership of the new 
+	 * object belongs with the caller.
+	 */
+	virtual	CValue*				
+	GetReplica(
+	);
+	
+	/**
+	 * Inherited from CValue -- Makes sure any internal 
+	 * data owned by this class is deep copied. Called internally
+	 */
+	virtual	void				
+	ProcessReplica(
+		KX_Camera* replica
+	);
+
 	MT_Transform		GetWorldToCamera() const;
 	MT_Transform		GetCameraToWorld() const;
 

source/gameengine/Ketsji/KX_SceneActuator.cpp

@@ -105,6 +105,15 @@ bool KX_SceneActuator::Update()
 		{
 			m_scene->SetActiveCamera(m_camera);
 		}
+		else
+		{
+			// if no camera is set and the parent object is a camera, use it as the camera
+			SCA_IObject* parent = GetParent();
+			if (parent->isA(&KX_Camera::Type))
+			{
+				m_scene->SetActiveCamera((KX_Camera*)parent);
+			}
+		}
 		break;
 	default:
 		break;