Merge pull request #66 from limbonaut/prefetching

Prefetching rework

blackboard/blackboard.cpp

@@ -79,19 +79,6 @@ void Blackboard::add_var(const StringName &p_name, const BBVariable &p_var) {
 	data.insert(p_name, p_var);
 }
 
-void Blackboard::prefetch_nodepath_vars(Node *p_node) {
-	ERR_FAIL_COND(p_node == nullptr);
-	for (const KeyValue<StringName, BBVariable> &kv : data) {
-		BBVariable var = kv.value;
-		if (var.get_value().get_type() == Variant::NODE_PATH) {
-			Node *fetched_node = p_node->get_node_or_null(var.get_value());
-			if (fetched_node != nullptr) {
-				var.set_value(fetched_node);
-			}
-		}
-	}
-}
-
 void Blackboard::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_var", "var_name", "default", "complain"), &Blackboard::get_var, Variant(), true);
 	ClassDB::bind_method(D_METHOD("set_var", "var_name", "value"), &Blackboard::set_var);
@@ -99,7 +86,6 @@ void Blackboard::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_parent", "blackboard"), &Blackboard::set_parent);
 	ClassDB::bind_method(D_METHOD("get_parent"), &Blackboard::get_parent);
 	ClassDB::bind_method(D_METHOD("erase_var", "var_name"), &Blackboard::erase_var);
-	ClassDB::bind_method(D_METHOD("prefetch_nodepath_vars", "node"), &Blackboard::prefetch_nodepath_vars);
 	ClassDB::bind_method(D_METHOD("top"), &Blackboard::top);
 	ClassDB::bind_method(D_METHOD("bind_var_to_property", "var_name", "object", "property"), &Blackboard::bind_var_to_property);
 	ClassDB::bind_method(D_METHOD("unbind_var", "var_name"), &Blackboard::unbind_var);

blackboard/blackboard.h

@@ -56,8 +56,6 @@ public:
 
 	void add_var(const StringName &p_name, const BBVariable &p_var);
 
-	void prefetch_nodepath_vars(Node *p_node);
-
 	// TODO: Add serialization API.
 };
 

blackboard/blackboard_plan.cpp

@@ -119,6 +119,19 @@ void BlackboardPlan::set_base_plan(const Ref<BlackboardPlan> &p_base) {
 	notify_property_list_changed();
 }
 
+void BlackboardPlan::set_prefetch_nodepath_vars(bool p_enable) {
+	prefetch_nodepath_vars = p_enable;
+	emit_changed();
+}
+
+bool BlackboardPlan::is_prefetching_nodepath_vars() const {
+	if (is_derived()) {
+		return base->is_prefetching_nodepath_vars();
+	} else {
+		return prefetch_nodepath_vars;
+	}
+}
+
 void BlackboardPlan::add_var(const StringName &p_name, const BBVariable &p_var) {
 	ERR_FAIL_COND(var_map.has(p_name));
 	var_map.insert(p_name, p_var);
@@ -263,15 +276,33 @@ void BlackboardPlan::sync_with_base_plan() {
 	}
 }
 
-Ref<Blackboard> BlackboardPlan::create_blackboard() {
+// Add a variable duplicate to the blackboard, optionally with NodePath prefetch.
+inline void bb_add_var_dup_with_prefetch(const Ref<Blackboard> &p_blackboard, const StringName &p_name, const BBVariable &p_var, bool p_prefetch, Node *p_node) {
+	if (unlikely(p_prefetch && p_var.get_type() == Variant::NODE_PATH)) {
+		Node *n = p_node->get_node_or_null(p_var.get_value());
+		BBVariable var = p_var.duplicate();
+		if (n != nullptr) {
+			var.set_value(n);
+		} else {
+			ERR_PRINT(vformat("BlackboardPlan: Prefetch failed for variable $%s with value: %s", p_name, p_var.get_value()));
+		}
+		p_blackboard->add_var(p_name, var);
+	} else {
+		p_blackboard->add_var(p_name, p_var.duplicate());
+	}
+}
+
+Ref<Blackboard> BlackboardPlan::create_blackboard(Node *p_node) {
+	ERR_FAIL_COND_V(p_node == nullptr && prefetch_nodepath_vars, memnew(Blackboard));
 	Ref<Blackboard> bb = memnew(Blackboard);
 	for (const Pair<StringName, BBVariable> &p : var_list) {
-		bb->add_var(p.first, p.second.duplicate());
+		bb_add_var_dup_with_prefetch(bb, p.first, p.second, prefetch_nodepath_vars, p_node);
 	}
 	return bb;
 }
 
-void BlackboardPlan::populate_blackboard(const Ref<Blackboard> &p_blackboard, bool overwrite) {
+void BlackboardPlan::populate_blackboard(const Ref<Blackboard> &p_blackboard, bool overwrite, Node *p_node) {
+	ERR_FAIL_COND(p_node == nullptr && prefetch_nodepath_vars);
 	for (const Pair<StringName, BBVariable> &p : var_list) {
 		if (p_blackboard->has_var(p.first)) {
 			if (overwrite) {
@@ -280,13 +311,18 @@ void BlackboardPlan::populate_blackboard(const Ref<Blackboard> &p_blackboard, bo
 				continue;
 			}
 		}
-		p_blackboard->add_var(p.first, p.second.duplicate());
+		bb_add_var_dup_with_prefetch(p_blackboard, p.first, p.second, prefetch_nodepath_vars, p_node);
 	}
 }
 
 void BlackboardPlan::_bind_methods() {
-	ClassDB::bind_method(D_METHOD("create_blackboard"), &BlackboardPlan::create_blackboard);
+	ClassDB::bind_method(D_METHOD("set_prefetch_nodepath_vars", "enable"), &BlackboardPlan::set_prefetch_nodepath_vars);
-	ClassDB::bind_method(D_METHOD("populate_blackboard", "blackboard", "overwrite"), &BlackboardPlan::populate_blackboard);
+	ClassDB::bind_method(D_METHOD("is_prefetching_nodepath_vars"), &BlackboardPlan::is_prefetching_nodepath_vars);
+
+	ClassDB::bind_method(D_METHOD("create_blackboard", "node"), &BlackboardPlan::create_blackboard);
+	ClassDB::bind_method(D_METHOD("populate_blackboard", "blackboard", "overwrite", "node"), &BlackboardPlan::populate_blackboard);
+
+	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "prefetch_nodepath_vars", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_STORAGE), "set_prefetch_nodepath_vars", "is_prefetching_nodepath_vars");
 }
 
 BlackboardPlan::BlackboardPlan() {

blackboard/blackboard_plan.h

@@ -36,6 +36,9 @@ private:
 	// and only the values can be different in those variables.
 	Ref<BlackboardPlan> base;
 
+	// If true, NodePath variables will be prefetched, so that the vars will contain node pointers instead (upon BB creation/population).
+	bool prefetch_nodepath_vars = true;
+
 protected:
 	static void _bind_methods();
 
@@ -49,12 +52,15 @@ public:
 	void set_base_plan(const Ref<BlackboardPlan> &p_base);
 	Ref<BlackboardPlan> get_base_plan() const { return base; }
 
+	void set_prefetch_nodepath_vars(bool p_enable);
+	bool is_prefetching_nodepath_vars() const;
+
 	void add_var(const StringName &p_name, const BBVariable &p_var);
 	void remove_var(const StringName &p_name);
 	BBVariable get_var(const StringName &p_name);
 	Pair<StringName, BBVariable> get_var_by_index(int p_index);
-	bool has_var(const StringName &p_name) { return var_map.has(p_name); }
+	_FORCE_INLINE_ bool has_var(const StringName &p_name) { return var_map.has(p_name); }
-	bool is_empty() const { return var_map.is_empty(); }
+	_FORCE_INLINE_ bool is_empty() const { return var_map.is_empty(); }
 	int get_var_count() const { return var_map.size(); }
 
 	PackedStringArray list_vars() const;
@@ -66,8 +72,8 @@ public:
 	void sync_with_base_plan();
 	bool is_derived() const { return base.is_valid(); }
 
-	Ref<Blackboard> create_blackboard();
+	Ref<Blackboard> create_blackboard(Node *p_agent);
-	void populate_blackboard(const Ref<Blackboard> &p_blackboard, bool overwrite);
+	void populate_blackboard(const Ref<Blackboard> &p_blackboard, bool overwrite, Node *p_node);
 
 	BlackboardPlan();
 };

bt/bt_player.cpp

@@ -52,9 +52,6 @@ void BTPlayer::_load_tree() {
 	tree_instance.unref();
 	ERR_FAIL_COND_MSG(!behavior_tree.is_valid(), "BTPlayer: Needs a valid behavior tree.");
 	ERR_FAIL_COND_MSG(!behavior_tree->get_root_task().is_valid(), "BTPlayer: Behavior tree has no valid root task.");
-	if (prefetch_nodepath_vars == true) {
-		blackboard->prefetch_nodepath_vars(this);
-	}
 	tree_instance = behavior_tree->instantiate(get_owner(), blackboard);
 #ifdef DEBUG_ENABLED
 	if (IS_DEBUGGER_ACTIVE()) {
@@ -187,7 +184,7 @@ void BTPlayer::_notification(int p_notification) {
 					blackboard = Ref<Blackboard>(memnew(Blackboard));
 				}
 				if (blackboard_plan.is_valid()) {
-					blackboard_plan->populate_blackboard(blackboard, false);
+					blackboard_plan->populate_blackboard(blackboard, false, this);
 				}
 				if (behavior_tree.is_valid()) {
 					_load_tree();
@@ -231,8 +228,6 @@ void BTPlayer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_active"), &BTPlayer::get_active);
 	ClassDB::bind_method(D_METHOD("set_blackboard", "blackboard"), &BTPlayer::set_blackboard);
 	ClassDB::bind_method(D_METHOD("get_blackboard"), &BTPlayer::get_blackboard);
-	ClassDB::bind_method(D_METHOD("set_prefetch_nodepath_vars", "enable"), &BTPlayer::set_prefetch_nodepath_vars);
-	ClassDB::bind_method(D_METHOD("get_prefetch_nodepath_vars"), &BTPlayer::get_prefetch_nodepath_vars);
 
 	ClassDB::bind_method(D_METHOD("set_blackboard_plan", "plan"), &BTPlayer::set_blackboard_plan);
 	ClassDB::bind_method(D_METHOD("get_blackboard_plan"), &BTPlayer::get_blackboard_plan);
@@ -248,7 +243,6 @@ void BTPlayer::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "active"), "set_active", "get_active");
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "blackboard", PROPERTY_HINT_NONE, "Blackboard", 0), "set_blackboard", "get_blackboard");
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "blackboard_plan", PROPERTY_HINT_RESOURCE_TYPE, "BlackboardPlan", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_EDITOR_INSTANTIATE_OBJECT), "set_blackboard_plan", "get_blackboard_plan");
-	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "prefetch_nodepath_vars"), "set_prefetch_nodepath_vars", "get_prefetch_nodepath_vars");
 
 	BIND_ENUM_CONSTANT(IDLE);
 	BIND_ENUM_CONSTANT(PHYSICS);

bt/bt_player.h

@@ -41,7 +41,6 @@ private:
 	UpdateMode update_mode = UpdateMode::PHYSICS;
 	bool active = true;
 	Ref<Blackboard> blackboard;
-	bool prefetch_nodepath_vars = true;
 	int last_status = -1;
 
 	Ref<BTTask> tree_instance;
@@ -70,9 +69,6 @@ public:
 	Ref<Blackboard> get_blackboard() const { return blackboard; }
 	void set_blackboard(const Ref<Blackboard> &p_blackboard) { blackboard = p_blackboard; }
 
-	void set_prefetch_nodepath_vars(bool p_value) { prefetch_nodepath_vars = p_value; }
-	bool get_prefetch_nodepath_vars() const { return prefetch_nodepath_vars; }
-
 	void update(double p_delta);
 	void restart();
 	int get_last_status() const { return last_status; }

bt/bt_state.cpp

@@ -34,6 +34,7 @@ void BTState::set_behavior_tree(const Ref<BehaviorTree> &p_tree) {
 		if (p_tree.is_valid()) {
 			p_tree->connect(LW_NAME(changed), callable_mp(this, &BTState::_update_blackboard_plan));
 		}
+		_update_blackboard_plan();
 	}
 	behavior_tree = p_tree;
 }
@@ -48,6 +49,7 @@ void BTState::_update_blackboard_plan() {
 void BTState::_setup() {
 	LimboState::_setup();
 	ERR_FAIL_COND_MSG(behavior_tree.is_null(), "BTState: BehaviorTree is not assigned.");
+	// TODO: BBNode relies on agent to be scene owner, so if the user provides anything else, the behavior tree can break.
 	tree_instance = behavior_tree->instantiate(get_agent(), get_blackboard());
 
 #ifdef DEBUG_ENABLED

bt/bt_state.h

@@ -33,6 +33,8 @@ protected:
 
 	void _notification(int p_notification);
 
+	virtual bool _should_use_new_scope() const override { return true; }
+
 	virtual void _setup() override;
 	virtual void _exit() override;
 	virtual void _update(double p_delta) override;

bt/tasks/decorators/bt_new_scope.cpp

@@ -17,7 +17,7 @@ void BTNewScope::initialize(Node *p_agent, const Ref<Blackboard> &p_blackboard)
 
 	Ref<Blackboard> bb;
 	if (blackboard_plan.is_valid()) {
-		bb = blackboard_plan->create_blackboard();
+		bb = blackboard_plan->create_blackboard(p_agent);
 	} else {
 		bb = Ref<Blackboard>(memnew(Blackboard));
 	}

doc/source/classes/class_blackboard.rst

@@ -44,8 +44,6 @@ Methods
    +-------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------+
    | bool                                | :ref:`has_var<class_Blackboard_method_has_var>` **(** StringName var_name **)** |const|                                                       |
    +-------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------+
-   | void                                | :ref:`prefetch_nodepath_vars<class_Blackboard_method_prefetch_nodepath_vars>` **(** Node node **)**                                           |
-   +-------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------+
    | void                                | :ref:`set_parent<class_Blackboard_method_set_parent>` **(** :ref:`Blackboard<class_Blackboard>` blackboard **)**                              |
    +-------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------+
    | void                                | :ref:`set_var<class_Blackboard_method_set_var>` **(** StringName var_name, Variant value **)**                                                |
@@ -124,18 +122,6 @@ Returns ``true`` if the Blackboard contains the ``var_name`` variable, including
 
 ----
 
-.. _class_Blackboard_method_prefetch_nodepath_vars:
-
-.. rst-class:: classref-method
-
-void **prefetch_nodepath_vars** **(** Node node **)**
-
-If ``true``, any ``NodePath`` variables in the **Blackboard** are replaced with ``Node`` references when the tree is instantiated. References are retrieved by calling :ref:`Node.get_node<class_Node_method_get_node>` on the agent instance.
-
-.. rst-class:: classref-item-separator
-
-----
-
 .. _class_Blackboard_method_set_parent:
 
 .. rst-class:: classref-method

doc/source/classes/class_blackboardplan.rst

@@ -16,17 +16,51 @@ Stores and manages variables that will be used in constructing new :ref:`Blackbo
 
 .. rst-class:: classref-reftable-group
 
+Properties
+----------
+
+.. table::
+   :widths: auto
+
+   +------+-------------------------------------------------------------------------------------+----------+
+   | bool | :ref:`prefetch_nodepath_vars<class_BlackboardPlan_property_prefetch_nodepath_vars>` | ``true`` |
+   +------+-------------------------------------------------------------------------------------+----------+
+
+.. rst-class:: classref-reftable-group
+
 Methods
 -------
 
 .. table::
    :widths: auto
 
-   +-------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
+   +-------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------+
-   | :ref:`Blackboard<class_Blackboard>` | :ref:`create_blackboard<class_BlackboardPlan_method_create_blackboard>` **(** **)**                                                                    |
+   | :ref:`Blackboard<class_Blackboard>` | :ref:`create_blackboard<class_BlackboardPlan_method_create_blackboard>` **(** Node node **)**                                                                     |
-   +-------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
+   +-------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------+
-   | void                                | :ref:`populate_blackboard<class_BlackboardPlan_method_populate_blackboard>` **(** :ref:`Blackboard<class_Blackboard>` blackboard, bool overwrite **)** |
+   | void                                | :ref:`populate_blackboard<class_BlackboardPlan_method_populate_blackboard>` **(** :ref:`Blackboard<class_Blackboard>` blackboard, bool overwrite, Node node **)** |
-   +-------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
+   +-------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+
+.. rst-class:: classref-section-separator
+
+----
+
+.. rst-class:: classref-descriptions-group
+
+Property Descriptions
+---------------------
+
+.. _class_BlackboardPlan_property_prefetch_nodepath_vars:
+
+.. rst-class:: classref-property
+
+bool **prefetch_nodepath_vars** = ``true``
+
+.. rst-class:: classref-property-setget
+
+- void **set_prefetch_nodepath_vars** **(** bool value **)**
+- bool **is_prefetching_nodepath_vars** **(** **)**
+
+Enables or disables ``NodePath`` variable prefetching. If ``true``, ``NodePath`` values will be replaced with node instances when the :ref:`Blackboard<class_Blackboard>` is created.
 
 .. rst-class:: classref-section-separator
 
@@ -41,9 +75,9 @@ Method Descriptions
 
 .. rst-class:: classref-method
 
-:ref:`Blackboard<class_Blackboard>` **create_blackboard** **(** **)**
+:ref:`Blackboard<class_Blackboard>` **create_blackboard** **(** Node node **)**
 
-Constructs a new instance of a :ref:`Blackboard<class_Blackboard>` using this plan.
+Constructs a new instance of a :ref:`Blackboard<class_Blackboard>` using this plan. If ``NodePath`` prefetching is enabled, ``node`` will be used to retrieve node instances for ``NodePath`` variables and substitute their values.
 
 .. rst-class:: classref-item-separator
 
@@ -53,9 +87,9 @@ Constructs a new instance of a :ref:`Blackboard<class_Blackboard>` using this pl
 
 .. rst-class:: classref-method
 
-void **populate_blackboard** **(** :ref:`Blackboard<class_Blackboard>` blackboard, bool overwrite **)**
+void **populate_blackboard** **(** :ref:`Blackboard<class_Blackboard>` blackboard, bool overwrite, Node node **)**
 
-Populates ``blackboard`` with the variables from this plan. If ``overwrite`` is ``true``, existing variables with the same names will be overwritten.
+Populates ``blackboard`` with the variables from this plan. If ``overwrite`` is ``true``, existing variables with the same names will be overwritten. If ``NodePath`` prefetching is enabled, ``node`` will be used to retrieve node instances for ``NodePath`` variables and substitute their values.
 
 .. |virtual| replace:: :abbr:`virtual (This method should typically be overridden by the user to have any effect.)`
 .. |const| replace:: :abbr:`const (This method has no side effects. It doesn't modify any of the instance's member variables.)`

doc/source/classes/class_btplayer.rst

@@ -31,21 +31,19 @@ Properties
 .. table::
    :widths: auto
 
-   +---------------------------------------------+-------------------------------------------------------------------------------+-----------+
+   +---------------------------------------------+-------------------------------------------------------------------------+-----------+
    | bool                                        | :ref:`active<class_BTPlayer_property_active>`                           | ``true``  |
-   +---------------------------------------------+-------------------------------------------------------------------------------+-----------+
+   +---------------------------------------------+-------------------------------------------------------------------------+-----------+
    | :ref:`BehaviorTree<class_BehaviorTree>`     | :ref:`behavior_tree<class_BTPlayer_property_behavior_tree>`             |           |
-   +---------------------------------------------+-------------------------------------------------------------------------------+-----------+
+   +---------------------------------------------+-------------------------------------------------------------------------+-----------+
    | :ref:`Blackboard<class_Blackboard>`         | :ref:`blackboard<class_BTPlayer_property_blackboard>`                   |           |
-   +---------------------------------------------+-------------------------------------------------------------------------------+-----------+
+   +---------------------------------------------+-------------------------------------------------------------------------+-----------+
    | :ref:`BlackboardPlan<class_BlackboardPlan>` | :ref:`blackboard_plan<class_BTPlayer_property_blackboard_plan>`         |           |
-   +---------------------------------------------+-------------------------------------------------------------------------------+-----------+
+   +---------------------------------------------+-------------------------------------------------------------------------+-----------+
    | bool                                        | :ref:`monitor_performance<class_BTPlayer_property_monitor_performance>` | ``false`` |
-   +---------------------------------------------+-------------------------------------------------------------------------------+-----------+
+   +---------------------------------------------+-------------------------------------------------------------------------+-----------+
-   | bool                                        | :ref:`prefetch_nodepath_vars<class_BTPlayer_property_prefetch_nodepath_vars>` | ``true``  |
-   +---------------------------------------------+-------------------------------------------------------------------------------+-----------+
    | :ref:`UpdateMode<enum_BTPlayer_UpdateMode>` | :ref:`update_mode<class_BTPlayer_property_update_mode>`                 | ``1``     |
-   +---------------------------------------------+-------------------------------------------------------------------------------+-----------+
+   +---------------------------------------------+-------------------------------------------------------------------------+-----------+
 
 .. rst-class:: classref-reftable-group
 
@@ -226,23 +224,6 @@ If ``true``, adds a performance monitor to "Debugger->Monitors" for each instanc
 
 ----
 
-.. _class_BTPlayer_property_prefetch_nodepath_vars:
-
-.. rst-class:: classref-property
-
-bool **prefetch_nodepath_vars** = ``true``
-
-.. rst-class:: classref-property-setget
-
-- void **set_prefetch_nodepath_vars** **(** bool value **)**
-- bool **get_prefetch_nodepath_vars** **(** **)**
-
-If ``true``, any ``NodePath`` variables in the :ref:`Blackboard<class_Blackboard>` are replaced with ``Node`` references when the tree is instantiated. References are retrieved by calling :ref:`Node.get_node<class_Node_method_get_node>` on the agent instance (agent is the owner of the BTPlayer node).
-
-.. rst-class:: classref-item-separator
-
-----
-
 .. _class_BTPlayer_property_update_mode:
 
 .. rst-class:: classref-property

doc_classes/BTPlayer.xml

@@ -52,9 +52,6 @@
 		<member name="monitor_performance" type="bool" setter="_set_monitor_performance" getter="_get_monitor_performance" default="false">
 			If [code]true[/code], adds a performance monitor to "Debugger-&gt;Monitors" for each instance of this [BTPlayer] node.
 		</member>
-		<member name="prefetch_nodepath_vars" type="bool" setter="set_prefetch_nodepath_vars" getter="get_prefetch_nodepath_vars" default="true">
-			If [code]true[/code], any [NodePath] variables in the [Blackboard] are replaced with [Node] references when the tree is instantiated. References are retrieved by calling [method Node.get_node] on the agent instance (agent is the owner of the BTPlayer node).
-		</member>
 		<member name="update_mode" type="int" setter="set_update_mode" getter="get_update_mode" enum="BTPlayer.UpdateMode" default="1">
 			Determines when the behavior tree is executed. See [enum UpdateMode].
 		</member>

doc_classes/Blackboard.xml

@@ -49,13 +49,6 @@
 				Returns [code]true[/code] if the Blackboard contains the [param var_name] variable, including the parent scopes.
 			</description>
 		</method>
-		<method name="prefetch_nodepath_vars">
-			<return type="void" />
-			<param index="0" name="node" type="Node" />
-			<description>
-				If [code]true[/code], any [NodePath] variables in the [Blackboard] are replaced with [Node] references when the tree is instantiated. References are retrieved by calling [method Node.get_node] on the agent instance.
-			</description>
-		</method>
 		<method name="set_parent">
 			<return type="void" />
 			<param index="0" name="blackboard" type="Blackboard" />

doc_classes/BlackboardPlan.xml

@@ -10,17 +10,24 @@
 	<methods>
 		<method name="create_blackboard">
 			<return type="Blackboard" />
+			<param index="0" name="node" type="Node" />
 			<description>
-				Constructs a new instance of a [Blackboard] using this plan.
+				Constructs a new instance of a [Blackboard] using this plan. If [NodePath] prefetching is enabled, [param node] will be used to retrieve node instances for [NodePath] variables and substitute their values.
 			</description>
 		</method>
 		<method name="populate_blackboard">
 			<return type="void" />
 			<param index="0" name="blackboard" type="Blackboard" />
 			<param index="1" name="overwrite" type="bool" />
+			<param index="2" name="node" type="Node" />
 			<description>
-				Populates [param blackboard] with the variables from this plan. If [param overwrite] is [code]true[/code], existing variables with the same names will be overwritten.
+				Populates [param blackboard] with the variables from this plan. If [param overwrite] is [code]true[/code], existing variables with the same names will be overwritten. If [NodePath] prefetching is enabled, [param node] will be used to retrieve node instances for [NodePath] variables and substitute their values.
 			</description>
 		</method>
 	</methods>
+	<members>
+		<member name="prefetch_nodepath_vars" type="bool" setter="set_prefetch_nodepath_vars" getter="is_prefetching_nodepath_vars" default="true">
+			Enables or disables [NodePath] variable prefetching. If [code]true[/code], [NodePath] values will be replaced with node instances when the [Blackboard] is created.
+		</member>
+	</members>
 </class>

editor/blackboard_plan_editor.cpp

@@ -176,6 +176,11 @@ void BlackboardPlanEditor::_add_var_pressed() {
 	scroll_container->call_deferred(LW_NAME(call_deferred), LW_NAME(set_v_scroll), 888888888);
 }
 
+void BlackboardPlanEditor::_prefetching_toggled(bool p_toggle_on) {
+	ERR_FAIL_COND(plan.is_null());
+	plan->set_prefetch_nodepath_vars(p_toggle_on);
+}
+
 void BlackboardPlanEditor::_drag_button_down(Control *p_row) {
 	drag_index = p_row->get_index();
 	drag_start = drag_index;
@@ -240,7 +245,7 @@ void BlackboardPlanEditor::_refresh() {
 		child->queue_free();
 	}
 
-	// TODO: Name validation
+	nodepath_prefetching->set_pressed(plan->is_prefetching_nodepath_vars());
 
 	PackedStringArray names = plan->list_vars();
 	int idx = 0;
@@ -345,6 +350,7 @@ void BlackboardPlanEditor::_notification(int p_what) {
 			connect(LW_NAME(visibility_changed), callable_mp(this, &BlackboardPlanEditor::_visibility_changed));
 			type_menu->connect(LW_NAME(id_pressed), callable_mp(this, &BlackboardPlanEditor::_type_chosen));
 			hint_menu->connect(LW_NAME(id_pressed), callable_mp(this, &BlackboardPlanEditor::_hint_chosen));
+			nodepath_prefetching->connect(LW_NAME(toggled), callable_mp(this, &BlackboardPlanEditor::_prefetching_toggled));
 
 			for (int i = 0; i < PropertyHint::PROPERTY_HINT_MAX; i++) {
 				hint_menu->add_item(LimboUtility::get_singleton()->get_property_hint_text(PropertyHint(i)), i);
@@ -377,6 +383,13 @@ BlackboardPlanEditor::BlackboardPlanEditor() {
 	add_var_tool->set_focus_mode(Control::FOCUS_NONE);
 	add_var_tool->set_text(TTR("Add variable"));
 
+	nodepath_prefetching = memnew(CheckBox);
+	toolbar->add_child(nodepath_prefetching);
+	nodepath_prefetching->set_text(TTR("NodePath Prefetching"));
+	nodepath_prefetching->set_tooltip_text(TTR("If checked, NodePath variables will be prefetched on Blackboard initialization."));
+	nodepath_prefetching->set_h_size_flags(Control::SIZE_EXPAND | Control::SIZE_SHRINK_END);
+	nodepath_prefetching->set_focus_mode(Control::FOCUS_NONE);
+
 	{
 		// * Header
 		header_row = memnew(PanelContainer);

editor/blackboard_plan_editor.h

@@ -18,11 +18,13 @@
 
 #ifdef LIMBOAI_MODULE
 #include "editor/editor_inspector.h"
+#include "scene/gui/check_box.h"
 #include "scene/gui/dialogs.h"
 #endif // LIMBOAI_MODULE
 
 #ifdef LIMBOAI_GDEXTENSION
 #include <godot_cpp/classes/accept_dialog.hpp>
+#include <godot_cpp/classes/check_box.hpp>
 #include <godot_cpp/classes/editor_inspector_plugin.hpp>
 #include <godot_cpp/classes/line_edit.hpp>
 #include <godot_cpp/classes/panel_container.hpp>
@@ -60,6 +62,7 @@ private:
 
 	VBoxContainer *rows_vbox;
 	Button *add_var_tool;
+	CheckBox *nodepath_prefetching;
 	PanelContainer *header_row;
 	ScrollContainer *scroll_container;
 	PopupMenu *type_menu;
@@ -78,6 +81,7 @@ private:
 	void _type_chosen(int id);
 	void _hint_chosen(int id);
 	void _add_var_pressed();
+	void _prefetching_toggled(bool p_toggle_on);
 
 	void _drag_button_down(Control *p_row);
 	void _drag_button_up();

hsm/limbo_hsm.cpp

@@ -195,9 +195,12 @@ bool LimboHSM::_dispatch(const StringName &p_event, const Variant &p_cargo) {
 
 void LimboHSM::initialize(Node *p_agent, const Ref<Blackboard> &p_parent_scope) {
 	ERR_FAIL_COND(p_agent == nullptr);
+	ERR_FAIL_COND_MSG(!is_root(), "LimboHSM: initialize() must be called on the root HSM.");
+
 	if (!p_parent_scope.is_null()) {
 		blackboard->set_parent(p_parent_scope);
 	}
+
 	_initialize(p_agent, nullptr);
 
 	if (initial_state == nullptr) {

hsm/limbo_state.cpp

@@ -28,7 +28,7 @@
 
 LimboState *LimboState::get_root() const {
 	const LimboState *state = this;
-	while (state->get_parent() && state->get_parent()->is_class("LimboState")) {
+	while (state->get_parent() && IS_CLASS(state->get_parent(), LimboState)) {
 		state = Object::cast_to<LimboState>(get_parent());
 	}
 	return const_cast<LimboState *>(state);
@@ -68,13 +68,13 @@ void LimboState::_initialize(Node *p_agent, const Ref<Blackboard> &p_blackboard)
 	ERR_FAIL_COND(p_agent == nullptr);
 	agent = p_agent;
 
-	if (!p_blackboard.is_null()) {
+	if (_should_use_new_scope()) {
-		if (blackboard_plan.is_valid() && !blackboard_plan->is_empty()) {
-			blackboard = blackboard_plan->create_blackboard();
 		blackboard->set_parent(p_blackboard);
 	} else {
 		blackboard = p_blackboard;
 	}
+	if (blackboard_plan.is_valid() && !blackboard_plan->is_empty()) {
+		blackboard_plan->populate_blackboard(blackboard, true, this);
 	}
 
 	_setup();

hsm/limbo_state.h

@@ -15,6 +15,7 @@
 #include "../blackboard/blackboard.h"
 #include "../blackboard/blackboard_plan.h"
 
+#include "../util/limbo_compat.h"
 #include "../util/limbo_string_names.h"
 
 #ifdef LIMBOAI_MODULE
@@ -56,6 +57,8 @@ protected:
 	virtual void _initialize(Node *p_agent, const Ref<Blackboard> &p_blackboard);
 	virtual bool _dispatch(const StringName &p_event, const Variant &p_cargo = Variant());
 
+	virtual bool _should_use_new_scope() const { return blackboard_plan.is_valid() || is_root(); }
+
 	virtual void _setup();
 	virtual void _enter();
 	virtual void _exit();
@@ -87,6 +90,7 @@ public:
 
 	_FORCE_INLINE_ StringName event_finished() const { return LW_NAME(EVENT_FINISHED); }
 	LimboState *get_root() const;
+	_FORCE_INLINE_ bool is_root() const { return !(get_parent() && IS_CLASS(get_parent(), LimboState)); }
 	bool is_active() const { return active; }
 
 	void set_guard(const Callable &p_guard_callable);