Implement BTInstance - runtime instance of BehaviorTree

blackboard/bb_variable.cpp

@@ -25,7 +25,7 @@ void BBVariable::set_value(const Variant &p_value) {
 	data->value_changed = true;
 
 	if (is_bound()) {
-		Object *obj = ObjectDB::get_instance(ObjectID(data->bound_object));
+		Object *obj = OBJECT_DB_GET_INSTANCE(data->bound_object);
 		ERR_FAIL_COND_MSG(!obj, "Blackboard: Failed to get bound object.");
 #ifdef LIMBOAI_MODULE
 		bool r_valid;
@@ -39,7 +39,7 @@ void BBVariable::set_value(const Variant &p_value) {
 
 Variant BBVariable::get_value() const {
 	if (is_bound()) {
-		Object *obj = ObjectDB::get_instance(ObjectID(data->bound_object));
+		Object *obj = OBJECT_DB_GET_INSTANCE(data->bound_object);
 		ERR_FAIL_COND_V_MSG(!obj, data->value, "Blackboard: Failed to get bound object.");
 #ifdef LIMBOAI_MODULE
 		bool r_valid;

bt/behavior_tree.cpp

@@ -77,13 +77,15 @@ void BehaviorTree::copy_other(const Ref<BehaviorTree> &p_other) {
 	root_task = p_other->get_root_task();
 }
 
-Ref<BTTask> BehaviorTree::instantiate(Node *p_agent, const Ref<Blackboard> &p_blackboard, Node *p_scene_root) const {
+Ref<BTInstance> BehaviorTree::instantiate(Node *p_agent, const Ref<Blackboard> &p_blackboard, Node *p_instance_owner) const {
-	ERR_FAIL_COND_V_MSG(root_task == nullptr, memnew(BTTask), "Trying to instance a behavior tree with no valid root task.");
+	ERR_FAIL_COND_V_MSG(root_task == nullptr, nullptr, "BehaviorTree: Instantiation failed - BT has no valid root task.");
-	ERR_FAIL_NULL_V_MSG(p_agent, memnew(BTTask), "Trying to instance a behavior tree with no valid agent.");
+	ERR_FAIL_NULL_V_MSG(p_agent, nullptr, "BehaviorTree: Instantiation failed - agent can't be null.");
-	ERR_FAIL_NULL_V_MSG(p_scene_root, memnew(BTTask), "Trying to instance a behavior tree with no valid scene root.");
+	ERR_FAIL_NULL_V_MSG(p_instance_owner, nullptr, "BehaviorTree: Instantiation failed -- instance owner can't be null.");
-	Ref<BTTask> inst = root_task->clone();
+	Node *scene_root = p_instance_owner->get_owner();
-	inst->initialize(p_agent, p_blackboard, p_scene_root);
+	ERR_FAIL_NULL_V_MSG(scene_root, nullptr, "BehaviorTree: Instantiation failed - can't get scene root, because instance_owner not owned by a scene node. Hint: Try my_player.set_owner(get_owner()).");
-	return inst;
+	Ref<BTTask> root_copy = root_task->clone();
+	root_copy->initialize(p_agent, p_blackboard, scene_root);
+	return BTInstance::create(root_copy, get_path(), p_instance_owner);
 }
 
 void BehaviorTree::_plan_changed() {

bt/behavior_tree.h

@@ -13,6 +13,7 @@
 #define BEHAVIOR_TREE_H
 
 #include "../blackboard/blackboard_plan.h"
+#include "bt_instance.h"
 #include "tasks/bt_task.h"
 
 #ifdef LIMBOAI_MODULE
@@ -58,7 +59,7 @@ public:
 
 	Ref<BehaviorTree> clone() const;
 	void copy_other(const Ref<BehaviorTree> &p_other);
-	Ref<BTTask> instantiate(Node *p_agent, const Ref<Blackboard> &p_blackboard, Node *p_scene_root) const;
+	Ref<BTInstance> instantiate(Node *p_agent, const Ref<Blackboard> &p_blackboard, Node *p_instance_owner) const;
 
 	BehaviorTree();
 	~BehaviorTree();

bt/bt_instance.cpp

@@ -0,0 +1,138 @@
+/**
+ * bt_instance.cpp
+ * =============================================================================
+ * Copyright 2021-2024 Serhii Snitsaruk
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ * =============================================================================
+ */
+
+#include "bt_instance.h"
+
+#include "../editor/debugger/limbo_debugger.h"
+#include "behavior_tree.h"
+
+#ifdef LIMBOAI_MODULE
+#include "core/os/time.h"
+#include "main/performance.h"
+#endif
+
+#ifdef LIMBOAI_GDEXTENSION
+#include <godot_cpp/classes/performance.hpp>
+#include <godot_cpp/classes/time.hpp>
+#endif
+
+Ref<BTInstance> BTInstance::create(Ref<BTTask> p_root_task, String p_source_bt_path, Node *p_owner_node) {
+	ERR_FAIL_NULL_V(p_root_task, nullptr);
+	ERR_FAIL_NULL_V(p_owner_node, nullptr);
+	Ref<BTInstance> inst;
+	inst.instantiate();
+	inst->root_task = p_root_task;
+	inst->owner_node_id = p_owner_node->get_instance_id();
+	inst->source_bt_path = p_source_bt_path;
+	return inst;
+}
+
+void BTInstance::update(double p_delta) {
+	ERR_FAIL_COND(!root_task.is_valid());
+
+#ifdef DEBUG_ENABLED
+	double start = Time::get_singleton()->get_ticks_usec();
+#endif
+
+	last_status = root_task->execute(p_delta);
+	emit_signal(LimboStringNames::get_singleton()->updated, last_status);
+
+#ifdef DEBUG_ENABLED
+	double end = Time::get_singleton()->get_ticks_usec();
+	update_time_acc += (end - start);
+	update_time_n += 1.0;
+#endif
+}
+
+void BTInstance::set_monitor_performance(bool p_monitor) {
+#ifdef DEBUG_ENABLED
+	monitor_performance = p_monitor;
+	if (monitor_performance) {
+		_add_custom_monitor();
+	} else {
+		_remove_custom_monitor();
+	}
+#endif
+}
+
+bool BTInstance::get_monitor_performance() const {
+#ifdef DEBUG_ENABLED
+	return monitor_performance;
+#else
+	return false;
+#endif
+}
+
+void BTInstance::register_with_debugger() {
+#ifdef DEBUG_ENABLED
+	LimboDebugger::get_singleton()->register_bt_instance(get_instance_id());
+#endif
+}
+
+#ifdef DEBUG_ENABLED
+
+double BTInstance::_get_mean_update_time_msec_and_reset() {
+	if (update_time_n) {
+		double mean_time_msec = (update_time_acc * 0.001) / update_time_n;
+		update_time_acc = 0.0;
+		update_time_n = 0.0;
+		return mean_time_msec;
+	}
+	return 0.0;
+}
+
+void BTInstance::_add_custom_monitor() {
+	ERR_FAIL_NULL(get_owner_node());
+	ERR_FAIL_NULL(root_task);
+	ERR_FAIL_NULL(root_task->get_agent());
+
+	if (monitor_id == StringName()) {
+		monitor_id = vformat("LimboAI/update_ms|%s_%s_%s", root_task->get_agent()->get_name(), get_owner_node()->get_name(),
+				String(itos(get_instance_id())).md5_text().substr(0, 4));
+	}
+	if (!Performance::get_singleton()->has_custom_monitor(monitor_id)) {
+		PERFORMANCE_ADD_CUSTOM_MONITOR(monitor_id, callable_mp(this, &BTInstance::_get_mean_update_time_msec_and_reset));
+	}
+}
+
+void BTInstance::_remove_custom_monitor() {
+	if (monitor_id != StringName() && Performance::get_singleton()->has_custom_monitor(monitor_id)) {
+		Performance::get_singleton()->remove_custom_monitor(monitor_id);
+	}
+}
+
+#endif // * DEBUG_ENABLED
+
+void BTInstance::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("get_root_task"), &BTInstance::get_root_task);
+	ClassDB::bind_method(D_METHOD("get_owner_node"), &BTInstance::get_owner_node);
+	ClassDB::bind_method(D_METHOD("get_last_status"), &BTInstance::get_last_status);
+	ClassDB::bind_method(D_METHOD("get_source_bt_path"), &BTInstance::get_source_bt_path);
+
+	ClassDB::bind_method(D_METHOD("set_monitor_performance", "monitor"), &BTInstance::set_monitor_performance);
+	ClassDB::bind_method(D_METHOD("get_monitor_performance"), &BTInstance::get_monitor_performance);
+
+	ClassDB::bind_method(D_METHOD("update", "delta"), &BTInstance::update);
+
+	ClassDB::bind_method(D_METHOD("register_with_debugger"), &BTInstance::register_with_debugger);
+
+	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "monitor_performance"), "set_monitor_performance", "get_monitor_performance");
+
+	ADD_SIGNAL(MethodInfo("updated", PropertyInfo(Variant::INT, "status")));
+	ADD_SIGNAL(MethodInfo("freed"));
+}
+
+BTInstance::~BTInstance() {
+	emit_signal(LW_NAME(freed));
+#ifdef DEBUG_ENABLED
+	_remove_custom_monitor();
+#endif
+}

bt/bt_instance.h

@@ -0,0 +1,60 @@
+/**
+ * bt_instance.h
+ * =============================================================================
+ * Copyright 2021-2024 Serhii Snitsaruk
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ * =============================================================================
+ */
+#ifndef BT_INSTANCE_H
+#define BT_INSTANCE_H
+
+#include "tasks/bt_task.h"
+
+class BTInstance : public RefCounted {
+	GDCLASS(BTInstance, RefCounted);
+
+private:
+	Ref<BTTask> root_task;
+	uint64_t owner_node_id;
+	String source_bt_path;
+	BTTask::Status last_status = BTTask::FRESH;
+
+#ifdef DEBUG_ENABLED
+	bool monitor_performance = false;
+	StringName monitor_id;
+	double update_time_acc = 0.0;
+	double update_time_n = 0.0;
+
+	double _get_mean_update_time_msec_and_reset();
+	void _add_custom_monitor();
+	void _remove_custom_monitor();
+
+#endif // * DEBUG_ENABLED
+
+protected:
+	static void _bind_methods();
+
+public:
+	_FORCE_INLINE_ Ref<BTTask> get_root_task() const { return root_task; }
+	_FORCE_INLINE_ Node *get_owner_node() const { return Object::cast_to<Node>(OBJECT_DB_GET_INSTANCE(owner_node_id)); }
+	_FORCE_INLINE_ BTTask::Status get_last_status() const { return last_status; }
+	_FORCE_INLINE_ bool is_instance_valid() const { return root_task.is_valid(); }
+	_FORCE_INLINE_ String get_source_bt_path() const { return source_bt_path; }
+
+	void update(double p_delta);
+
+	void set_monitor_performance(bool p_monitor);
+	bool get_monitor_performance() const;
+
+	void register_with_debugger();
+
+	static Ref<BTInstance> create(Ref<BTTask> p_root_task, String p_source_bt_path, Node *p_owner_node);
+
+	BTInstance() = default;
+	~BTInstance();
+};
+
+#endif // BT_INSTANCE_H

bt/bt_player.cpp

@@ -11,7 +11,6 @@
 
 #include "bt_player.h"
 
-#include "../editor/debugger/limbo_debugger.h"
 #include "../util/limbo_compat.h"
 #include "../util/limbo_string_names.h"
 
@@ -44,24 +43,18 @@
 VARIANT_ENUM_CAST(BTPlayer::UpdateMode);
 
 void BTPlayer::_load_tree() {
-#ifdef DEBUG_ENABLED
+	bt_instance.unref();
-	if (tree_instance.is_valid() && IS_DEBUGGER_ACTIVE()) {
-		LimboDebugger::get_singleton()->unregister_bt_instance(tree_instance, get_path());
-	}
-#endif
-	tree_instance.unref();
 	ERR_FAIL_COND_MSG(!behavior_tree.is_valid(), "BTPlayer: Initialization failed - needs a valid behavior tree.");
 	ERR_FAIL_COND_MSG(!behavior_tree->get_root_task().is_valid(), "BTPlayer: Initialization failed - behavior tree has no valid root task.");
 	Node *agent = GET_NODE(this, agent_node);
 	ERR_FAIL_NULL_MSG(agent, vformat("BTPlayer: Initialization failed - can't get agent with path '%s'.", agent_node));
 	Node *scene_root = get_owner();
 	ERR_FAIL_NULL_MSG(scene_root, "BTPlayer: Initialization failed - can't get scene root (make sure the BTPlayer's owner property is set).");
-	tree_instance = behavior_tree->instantiate(agent, blackboard, scene_root);
+	bt_instance = behavior_tree->instantiate(agent, blackboard, this);
 #ifdef DEBUG_ENABLED
-	if (IS_DEBUGGER_ACTIVE()) {
+	bt_instance->set_monitor_performance(monitor_performance);
-		LimboDebugger::get_singleton()->register_bt_instance(tree_instance, get_path());
+	bt_instance->register_with_debugger();
-	}
+#endif // DEBUG_ENABLED
-#endif
 }
 
 void BTPlayer::_update_blackboard_plan() {
@@ -95,7 +88,7 @@ void BTPlayer::set_behavior_tree(const Ref<BehaviorTree> &p_tree) {
 
 void BTPlayer::set_agent_node(const NodePath &p_agent_node) {
 	agent_node = p_agent_node;
-	if (tree_instance.is_valid()) {
+	if (bt_instance.is_valid()) {
 		ERR_PRINT("BTPlayer: Agent node cannot be set after the behavior tree is instantiated. This change will not affect the behavior tree instance.");
 	}
 }
@@ -119,33 +112,19 @@ void BTPlayer::set_active(bool p_active) {
 }
 
 void BTPlayer::update(double p_delta) {
-	if (!tree_instance.is_valid()) {
+	if (!bt_instance.is_valid()) {
 		ERR_PRINT_ONCE(vformat("BTPlayer doesn't have a behavior tree with a valid root task to execute (owner: %s)", get_owner()));
 		return;
 	}
 
-#ifdef DEBUG_ENABLED
-	double start = GET_TICKS_USEC();
-#endif
-
 	if (active) {
-		last_status = tree_instance->execute(p_delta);
+		bt_instance->update(p_delta);
-		emit_signal(LimboStringNames::get_singleton()->updated, last_status);
-		if (last_status == BTTask::SUCCESS || last_status == BTTask::FAILURE) {
-			emit_signal(LimboStringNames::get_singleton()->behavior_tree_finished, last_status);
 	}
 }
 
-#ifdef DEBUG_ENABLED
-	double end = GET_TICKS_USEC();
-	update_time_acc += (end - start);
-	update_time_n += 1.0;
-#endif
-}
-
 void BTPlayer::restart() {
-	ERR_FAIL_COND_MSG(tree_instance.is_null(), "BTPlayer: Restart failed - no valid tree instance. Make sure the BTPlayer has a valid behavior tree with a valid root task.");
+	ERR_FAIL_COND_MSG(bt_instance.is_null(), "BTPlayer: Restart failed - no valid tree instance. Make sure the BTPlayer has a valid behavior tree with a valid root task.");
-	tree_instance->abort();
+	bt_instance->get_root_task()->abort();
 	set_active(true);
 }
 
@@ -154,42 +133,9 @@ void BTPlayer::restart() {
 void BTPlayer::_set_monitor_performance(bool p_monitor_performance) {
 	monitor_performance = p_monitor_performance;
 
-	if (!get_owner() && monitor_performance) {
+	if (bt_instance.is_valid()) {
-		// Don't add custom monitor if not in scene.
+		bt_instance->set_monitor_performance(monitor_performance);
-		return;
 	}
-
-	if (monitor_performance) {
-		_add_custom_monitor();
-	} else {
-		_remove_custom_monitor();
-	}
-}
-
-void BTPlayer::_add_custom_monitor() {
-	if (monitor_id == StringName()) {
-		monitor_id = vformat("LimboAI/update_ms|%s_%s_%s", get_owner()->get_name(), get_name(),
-				String(itos(get_instance_id())).md5_text().substr(0, 4));
-	}
-	if (!Performance::get_singleton()->has_custom_monitor(monitor_id)) {
-		PERFORMANCE_ADD_CUSTOM_MONITOR(monitor_id, callable_mp(this, &BTPlayer::_get_mean_update_time_msec));
-	}
-}
-
-void BTPlayer::_remove_custom_monitor() {
-	if (monitor_id != StringName() && Performance::get_singleton()->has_custom_monitor(monitor_id)) {
-		Performance::get_singleton()->remove_custom_monitor(monitor_id);
-	}
-}
-
-double BTPlayer::_get_mean_update_time_msec() {
-	if (update_time_n) {
-		double mean_time_msec = (update_time_acc * 0.001) / update_time_n;
-		update_time_acc = 0.0;
-		update_time_n = 0.0;
-		return mean_time_msec;
-	}
-	return 0.0;
 }
 
 #endif // ! DEBUG_ENABLED
@@ -222,21 +168,15 @@ void BTPlayer::_notification(int p_notification) {
 		} break;
 		case NOTIFICATION_ENTER_TREE: {
 #ifdef DEBUG_ENABLED
-			if (tree_instance.is_valid() && IS_DEBUGGER_ACTIVE()) {
+			if (bt_instance.is_valid()) {
-				LimboDebugger::get_singleton()->register_bt_instance(tree_instance, get_path());
+				bt_instance->set_monitor_performance(monitor_performance);
-			}
-			if (monitor_performance) {
-				_add_custom_monitor();
 			}
 #endif // DEBUG_ENABLED
 		} break;
 		case NOTIFICATION_EXIT_TREE: {
 #ifdef DEBUG_ENABLED
-			if (tree_instance.is_valid() && IS_DEBUGGER_ACTIVE()) {
+			if (bt_instance.is_valid()) {
-				LimboDebugger::get_singleton()->unregister_bt_instance(tree_instance, get_path());
+				bt_instance->set_monitor_performance(false);
-			}
-			if (monitor_performance) {
-				_remove_custom_monitor();
 			}
 #endif // DEBUG_ENABLED
 
@@ -266,9 +206,8 @@ void BTPlayer::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("update", "delta"), &BTPlayer::update);
 	ClassDB::bind_method(D_METHOD("restart"), &BTPlayer::restart);
-	ClassDB::bind_method(D_METHOD("get_last_status"), &BTPlayer::get_last_status);
 
-	ClassDB::bind_method(D_METHOD("get_tree_instance"), &BTPlayer::get_tree_instance);
+	ClassDB::bind_method(D_METHOD("get_bt_instance"), &BTPlayer::get_bt_instance);
 
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "behavior_tree", PROPERTY_HINT_RESOURCE_TYPE, "BehaviorTree"), "set_behavior_tree", "get_behavior_tree");
 	ADD_PROPERTY(PropertyInfo(Variant::NODE_PATH, "agent_node"), "set_agent_node", "get_agent_node");

bt/bt_player.h

@@ -15,6 +15,7 @@
 #include "../blackboard/blackboard.h"
 #include "../blackboard/blackboard_plan.h"
 #include "behavior_tree.h"
+#include "bt_instance.h"
 #include "tasks/bt_task.h"
 
 #ifdef LIMBOAI_MODULE
@@ -42,9 +43,8 @@ private:
 	UpdateMode update_mode = UpdateMode::PHYSICS;
 	bool active = true;
 	Ref<Blackboard> blackboard;
-	int last_status = -1;
 
-	Ref<BTTask> tree_instance;
+	Ref<BTInstance> bt_instance;
 
 	void _load_tree();
 	void _update_blackboard_plan();
@@ -75,9 +75,8 @@ public:
 
 	void update(double p_delta);
 	void restart();
-	int get_last_status() const { return last_status; }
 
-	Ref<BTTask> get_tree_instance() { return tree_instance; }
+	Ref<BTInstance> get_bt_instance() { return bt_instance; }
 
 	BTPlayer();
 	~BTPlayer();
@@ -86,19 +85,11 @@ public:
 
 private:
 	bool monitor_performance = false;
-	StringName monitor_id;
-	double update_time_acc = 0.0;
-	double update_time_n = 0.0;
 
 	void _set_monitor_performance(bool p_monitor_performance);
 	bool _get_monitor_performance() const { return monitor_performance; }
 
-	void _add_custom_monitor();
+#endif // * DEBUG_ENABLED
-	void _remove_custom_monitor();
-
-	double _get_mean_update_time_msec();
-
-#endif // DEBUG_ENABLED
 };
 
 #endif // BT_PLAYER_H

editor/debugger/behavior_tree_data.cpp

@@ -17,14 +17,15 @@
 
 //**** BehaviorTreeData
 
-Array BehaviorTreeData::serialize(const Ref<BTTask> &p_tree_instance, const NodePath &p_player_path, const String &p_bt_resource_path) {
+Array BehaviorTreeData::serialize(const Ref<BTInstance> &p_instance) {
 	Array arr;
-	arr.push_back(p_player_path);
+	arr.push_back(uint64_t(p_instance->get_instance_id()));
-	arr.push_back(p_bt_resource_path);
+	arr.push_back(p_instance->get_owner_node() ? p_instance->get_owner_node()->get_path() : NodePath());
+	arr.push_back(p_instance->get_source_bt_path());
 
 	// Flatten tree into list depth first
 	List<Ref<BTTask>> stack;
-	stack.push_back(p_tree_instance);
+	stack.push_back(p_instance->get_root_task());
 	while (stack.size()) {
 		Ref<BTTask> task = stack.front()->get();
 		stack.pop_front();
@@ -54,15 +55,17 @@ Array BehaviorTreeData::serialize(const Ref<BTTask> &p_tree_instance, const Node
 }
 
 Ref<BehaviorTreeData> BehaviorTreeData::deserialize(const Array &p_array) {
-	ERR_FAIL_COND_V(p_array.size() < 2, nullptr);
+	ERR_FAIL_COND_V(p_array.size() < 3, nullptr);
-	ERR_FAIL_COND_V(p_array[0].get_type() != Variant::NODE_PATH, nullptr);
+	ERR_FAIL_COND_V(p_array[0].get_type() != Variant::INT, nullptr);
-	ERR_FAIL_COND_V(p_array[1].get_type() != Variant::STRING, nullptr);
+	ERR_FAIL_COND_V(p_array[1].get_type() != Variant::NODE_PATH, nullptr);
+	ERR_FAIL_COND_V(p_array[2].get_type() != Variant::STRING, nullptr);
 
 	Ref<BehaviorTreeData> data = memnew(BehaviorTreeData);
-	data->bt_player_path = p_array[0];
+	data->bt_instance_id = uint64_t(p_array[0]);
-	data->bt_resource_path = p_array[1];
+	data->node_owner_path = p_array[1];
+	data->source_bt_path = p_array[2];
 
-	int idx = 2;
+	int idx = 3;
 	while (p_array.size() > idx + 1) {
 		ERR_FAIL_COND_V(p_array.size() < idx + 7, nullptr);
 		ERR_FAIL_COND_V(p_array[idx].get_type() != Variant::INT, nullptr);
@@ -80,12 +83,16 @@ Ref<BehaviorTreeData> BehaviorTreeData::deserialize(const Array &p_array) {
 	return data;
 }
 
-Ref<BehaviorTreeData> BehaviorTreeData::create_from_tree_instance(const Ref<BTTask> &p_tree_instance) {
+Ref<BehaviorTreeData> BehaviorTreeData::create_from_bt_instance(const Ref<BTInstance> &p_bt_instance) {
 	Ref<BehaviorTreeData> data = memnew(BehaviorTreeData);
 
+	data->bt_instance_id = p_bt_instance->get_instance_id();
+	data->node_owner_path = p_bt_instance->get_owner_node() ? p_bt_instance->get_owner_node()->get_path() : NodePath();
+	data->source_bt_path = p_bt_instance->get_source_bt_path();
+
 	// Flatten tree into list depth first
 	List<Ref<BTTask>> stack;
-	stack.push_back(p_tree_instance);
+	stack.push_back(p_bt_instance->get_root_task());
 	while (stack.size()) {
 		Ref<BTTask> task = stack.front()->get();
 		stack.pop_front();
@@ -115,9 +122,7 @@ Ref<BehaviorTreeData> BehaviorTreeData::create_from_tree_instance(const Ref<BTTa
 }
 
 void BehaviorTreeData::_bind_methods() {
-	// ClassDB::bind_static_method("BehaviorTreeData", D_METHOD("serialize", "p_tree_instance", "p_player_path", "p_bt_resource_path"), &BehaviorTreeData::serialize);
+	ClassDB::bind_static_method("BehaviorTreeData", D_METHOD("create_from_bt_instance", "bt_instance"), &BehaviorTreeData::create_from_bt_instance);
-	// ClassDB::bind_static_method("BehaviorTreeData", D_METHOD("deserialize", "p_array"), &BehaviorTreeData::deserialize);
-	ClassDB::bind_static_method("BehaviorTreeData", D_METHOD("create_from_tree_instance", "tree_instance"), &BehaviorTreeData::create_from_tree_instance);
 }
 
 BehaviorTreeData::BehaviorTreeData() {

editor/debugger/behavior_tree_data.h

@@ -12,6 +12,7 @@
 #ifndef BEHAVIOR_TREE_DATA_H
 #define BEHAVIOR_TREE_DATA_H
 
+#include "../../bt/bt_instance.h"
 #include "../../bt/tasks/bt_task.h"
 
 class BehaviorTreeData : public RefCounted {
@@ -46,13 +47,14 @@ public:
 	};
 
 	List<TaskData> tasks;
-	NodePath bt_player_path;
+	uint64_t bt_instance_id;
-	String bt_resource_path;
+	NodePath node_owner_path;
+	String source_bt_path;
 
 public:
-	static Array serialize(const Ref<BTTask> &p_tree_instance, const NodePath &p_player_path, const String &p_bt_resource_path);
+	static Array serialize(const Ref<BTInstance> &p_instance);
 	static Ref<BehaviorTreeData> deserialize(const Array &p_array);
-	static Ref<BehaviorTreeData> create_from_tree_instance(const Ref<BTTask> &p_tree_instance);
+	static Ref<BehaviorTreeData> create_from_bt_instance(const Ref<BTInstance> &p_bt_instance);
 
 	BehaviorTreeData();
 };

editor/debugger/limbo_debugger.cpp

@@ -11,13 +11,13 @@
 
 #include "limbo_debugger.h"
 
+#include "../../bt/bt_instance.h"
 #include "../../bt/tasks/bt_task.h"
 #include "../../util/limbo_compat.h"
 #include "behavior_tree_data.h"
 
 #ifdef LIMBOAI_MODULE
 #include "core/debugger/engine_debugger.h"
-#include "core/error/error_macros.h"
 #include "core/io/resource.h"
 #include "core/string/node_path.h"
 #include "scene/main/scene_tree.h"
@@ -63,14 +63,6 @@ void LimboDebugger::deinitialize() {
 }
 
 void LimboDebugger::_bind_methods() {
-#ifdef DEBUG_ENABLED
-
-#ifdef LIMBOAI_GDEXTENSION
-	ClassDB::bind_method(D_METHOD("parse_message_gdext"), &LimboDebugger::parse_message_gdext);
-#endif
-	ClassDB::bind_method(D_METHOD("_on_bt_updated", "status", "path"), &LimboDebugger::_on_bt_updated);
-	ClassDB::bind_method(D_METHOD("_on_state_updated", "delta", "path"), &LimboDebugger::_on_state_updated);
-#endif // ! DEBUG_ENABLED
 }
 
 #ifdef DEBUG_ENABLED
@@ -99,100 +91,87 @@ bool LimboDebugger::parse_message_gdext(const String &p_msg, const Array &p_args
 }
 #endif // LIMBOAI_GDEXTENSION
 
-void LimboDebugger::register_bt_instance(Ref<BTTask> p_instance, NodePath p_player_path) {
+void LimboDebugger::register_bt_instance(uint64_t p_instance_id) {
-	ERR_FAIL_COND(p_instance.is_null());
+	ERR_FAIL_COND(p_instance_id == 0);
-	ERR_FAIL_COND(p_player_path.is_empty());
+	BTInstance *inst = Object::cast_to<BTInstance>(OBJECT_DB_GET_INSTANCE(p_instance_id));
-	if (active_trees.has(p_player_path)) {
+	ERR_FAIL_NULL(inst);
+	ERR_FAIL_COND(!inst->is_instance_valid());
+
+	if (active_bt_instances.has(p_instance_id)) {
 		return;
 	}
 
-	active_trees.insert(p_player_path, p_instance);
+	if (!inst->is_connected(LW_NAME(freed), callable_mp(this, &LimboDebugger::unregister_bt_instance).bind(p_instance_id))) {
+		inst->connect(LW_NAME(freed), callable_mp(this, &LimboDebugger::unregister_bt_instance).bind(p_instance_id));
+	}
+
+	active_bt_instances.insert(p_instance_id);
 	if (session_active) {
 		_send_active_bt_players();
 	}
 }
 
-void LimboDebugger::unregister_bt_instance(Ref<BTTask> p_instance, NodePath p_player_path) {
+void LimboDebugger::unregister_bt_instance(uint64_t p_instance_id) {
-	ERR_FAIL_COND(p_instance.is_null());
+	if (!active_bt_instances.has(p_instance_id)) {
-	ERR_FAIL_COND(p_player_path.is_empty());
+		return;
-	ERR_FAIL_COND(!active_trees.has(p_player_path));
+	}
 
-	if (tracked_player == p_player_path) {
+	if (tracked_instance_id == p_instance_id) {
 		_untrack_tree();
 	}
-	active_trees.erase(p_player_path);
+	active_bt_instances.erase(p_instance_id);
 
 	if (session_active) {
 		_send_active_bt_players();
 	}
 }
 
-void LimboDebugger::_track_tree(NodePath p_path) {
+void LimboDebugger::_track_tree(uint64_t p_instance_id) {
-	ERR_FAIL_COND(!active_trees.has(p_path));
+	ERR_FAIL_COND(!active_bt_instances.has(p_instance_id));
 
-	if (!tracked_player.is_empty()) {
 	_untrack_tree();
-	}
 
-	Node *node = SCENE_TREE()->get_root()->get_node_or_null(p_path);
+	tracked_instance_id = p_instance_id;
-	ERR_FAIL_COND(node == nullptr);
 
-	tracked_player = p_path;
+	BTInstance *inst = Object::cast_to<BTInstance>(OBJECT_DB_GET_INSTANCE(p_instance_id));
-
+	ERR_FAIL_NULL(inst);
-	Ref<Resource> bt = node->get(LW_NAME(behavior_tree));
+	inst->connect(LW_NAME(updated), callable_mp(this, &LimboDebugger::_on_bt_instance_updated).bind(p_instance_id));
-
-	if (bt.is_valid()) {
-		bt_resource_path = bt->get_path();
-	} else {
-		bt_resource_path = "";
-	}
-
-	if (node->is_class("BTPlayer")) {
-		node->connect(LW_NAME(updated), callable_mp(this, &LimboDebugger::_on_bt_updated).bind(p_path));
-	} else if (node->is_class("BTState")) {
-		node->connect(LW_NAME(updated), callable_mp(this, &LimboDebugger::_on_state_updated).bind(p_path));
-	}
 }
 
 void LimboDebugger::_untrack_tree() {
-	if (tracked_player.is_empty()) {
+	if (tracked_instance_id == 0) {
 		return;
 	}
 
-	NodePath was_tracking = tracked_player;
+	BTInstance *inst = Object::cast_to<BTInstance>(OBJECT_DB_GET_INSTANCE(tracked_instance_id));
-	tracked_player = NodePath();
+	if (inst) {
-
+		inst->disconnect(LW_NAME(updated), callable_mp(this, &LimboDebugger::_on_bt_instance_updated));
-	Node *node = SCENE_TREE()->get_root()->get_node_or_null(was_tracking);
-	ERR_FAIL_COND(node == nullptr);
-
-	if (node->is_class("BTPlayer")) {
-		node->disconnect(LW_NAME(updated), callable_mp(this, &LimboDebugger::_on_bt_updated));
-	} else if (node->is_class("BTState")) {
-		node->disconnect(LW_NAME(updated), callable_mp(this, &LimboDebugger::_on_state_updated));
 	}
+	tracked_instance_id = 0;
 }
 
 void LimboDebugger::_send_active_bt_players() {
 	Array arr;
-	for (KeyValue<NodePath, Ref<BTTask>> kv : active_trees) {
+	for (uint64_t instance_id : active_bt_instances) {
-		arr.append(kv.key);
+		arr.append(instance_id);
+		BTInstance *inst = Object::cast_to<BTInstance>(OBJECT_DB_GET_INSTANCE(instance_id));
+		if (inst == nullptr) {
+			ERR_PRINT("LimboDebugger::_send_active_bt_players: Registered BTInstance not found (no longer exists?).");
+			continue;
+		}
+		Node *owner_node = inst->get_owner_node();
+		arr.append(owner_node ? owner_node->get_path() : NodePath());
 	}
 	EngineDebugger::get_singleton()->send_message("limboai:active_bt_players", arr);
 }
 
-void LimboDebugger::_on_bt_updated(int _status, NodePath p_path) {
+void LimboDebugger::_on_bt_instance_updated(int _status, uint64_t p_instance_id) {
-	if (p_path != tracked_player) {
+	if (p_instance_id != tracked_instance_id) {
 		return;
 	}
-	Array arr = BehaviorTreeData::serialize(active_trees.get(tracked_player), tracked_player, bt_resource_path);
+	BTInstance *inst = Object::cast_to<BTInstance>(OBJECT_DB_GET_INSTANCE(p_instance_id));
-	EngineDebugger::get_singleton()->send_message("limboai:bt_update", arr);
+	ERR_FAIL_NULL(inst);
-}
+	Array arr = BehaviorTreeData::serialize(inst);
-
-void LimboDebugger::_on_state_updated(float _delta, NodePath p_path) {
-	if (p_path != tracked_player) {
-		return;
-	}
-	Array arr = BehaviorTreeData::serialize(active_trees.get(tracked_player), tracked_player, bt_resource_path);
 	EngineDebugger::get_singleton()->send_message("limboai:bt_update", arr);
 }
 

editor/debugger/limbo_debugger.h

@@ -12,6 +12,7 @@
 #ifndef LIMBO_DEBUGGER_H
 #define LIMBO_DEBUGGER_H
 
+#include "../../bt/bt_instance.h"
 #include "../../bt/tasks/bt_task.h"
 
 #ifdef LIMBOAI_MODULE
@@ -23,6 +24,7 @@
 #ifdef LIMBOAI_GDEXTENSION
 #include <godot_cpp/classes/object.hpp>
 #include <godot_cpp/core/class_db.hpp>
+#include <godot_cpp/templates/hash_set.hpp>
 #include <godot_cpp/variant/node_path.hpp>
 #endif // LIMBOAI_GDEXTENSION
 
@@ -46,17 +48,15 @@ protected:
 
 #ifdef DEBUG_ENABLED
 private:
-	HashMap<NodePath, Ref<BTTask>> active_trees;
+	HashSet<uint64_t> active_bt_instances;
-	NodePath tracked_player;
+	uint64_t tracked_instance_id;
-	String bt_resource_path;
 	bool session_active = false;
 
-	void _track_tree(NodePath p_path);
+	void _track_tree(uint64_t p_instance_id);
 	void _untrack_tree();
 	void _send_active_bt_players();
 
-	void _on_bt_updated(int status, NodePath p_path);
+	void _on_bt_instance_updated(int status, uint64_t p_instance_id);
-	void _on_state_updated(float _delta, NodePath p_path);
 
 public:
 	static Error parse_message(void *p_user, const String &p_msg, const Array &p_args, bool &r_captured);
@@ -64,8 +64,8 @@ public:
 	bool parse_message_gdext(const String &p_msg, const Array &p_args);
 #endif
 
-	void register_bt_instance(Ref<BTTask> p_instance, NodePath p_player_path);
+	void register_bt_instance(uint64_t p_instance_id);
-	void unregister_bt_instance(Ref<BTTask> p_instance, NodePath p_player_path);
+	void unregister_bt_instance(uint64_t p_instance_id);
 
 #endif // ! DEBUG_ENABLED
 };

editor/debugger/limbo_debugger_plugin.cpp

@@ -58,7 +58,7 @@
 //**** LimboDebuggerTab
 
 void LimboDebuggerTab::_reset_controls() {
-	bt_player_list->clear();
+	bt_instance_list->clear();
 	bt_view->clear();
 	alert_box->hide();
 	info_message->set_text(TTR("Run project to start debugging."));
@@ -68,7 +68,7 @@ void LimboDebuggerTab::_reset_controls() {
 }
 
 void LimboDebuggerTab::start_session() {
-	bt_player_list->clear();
+	bt_instance_list->clear();
 	bt_view->clear();
 	alert_box->hide();
 	info_message->set_text(TTR("Pick a player from the list to display behavior tree."));
@@ -81,23 +81,25 @@ void LimboDebuggerTab::stop_session() {
 	session->send_message("limboai:stop_session", Array());
 }
 
-void LimboDebuggerTab::update_active_bt_players(const Array &p_node_paths) {
+void LimboDebuggerTab::update_active_bt_instances(const Array &p_data) {
-	active_bt_players.clear();
+	active_bt_instances.clear();
-	for (int i = 0; i < p_node_paths.size(); i++) {
+	for (int i = 0; i < p_data.size(); i += 2) {
-		active_bt_players.push_back(p_node_paths[i]);
+		BTInstanceInfo info{ p_data[i], p_data[i + 1] };
+
+		active_bt_instances.push_back(info);
 	}
-	_update_bt_player_list(active_bt_players, filter_players->get_text());
+	_update_bt_instance_list(active_bt_instances, filter_players->get_text());
 }
 
-String LimboDebuggerTab::get_selected_bt_player() {
+uint64_t LimboDebuggerTab::get_selected_bt_instance_id() {
-	if (!bt_player_list->is_anything_selected()) {
+	if (!bt_instance_list->is_anything_selected()) {
-		return "";
+		return 0;
 	}
-	return bt_player_list->get_item_text(bt_player_list->get_selected_items()[0]);
+	return bt_instance_list->get_item_metadata(bt_instance_list->get_selected_items()[0]);
 }
 
 void LimboDebuggerTab::update_behavior_tree(const Ref<BehaviorTreeData> &p_data) {
-	resource_header->set_text(p_data->bt_resource_path);
+	resource_header->set_text(p_data->source_bt_path);
 	resource_header->set_disabled(false);
 	bt_view->update_tree(p_data);
 	info_message->hide();
@@ -108,58 +110,58 @@ void LimboDebuggerTab::_show_alert(const String &p_message) {
 	alert_box->set_visible(!p_message.is_empty());
 }
 
-void LimboDebuggerTab::_update_bt_player_list(const List<String> &p_node_paths, const String &p_filter) {
+void LimboDebuggerTab::_update_bt_instance_list(const Vector<BTInstanceInfo> &p_instances, const String &p_filter) {
 	// Remember selected item.
-	String selected_player = "";
+	uint64_t selected_instance_id = 0;
-	if (bt_player_list->is_anything_selected()) {
+	if (bt_instance_list->is_anything_selected()) {
-		selected_player = bt_player_list->get_item_text(bt_player_list->get_selected_items()[0]);
+		selected_instance_id = uint64_t(bt_instance_list->get_item_metadata(bt_instance_list->get_selected_items()[0]));
 	}
 
-	bt_player_list->clear();
+	bt_instance_list->clear();
 	int select_idx = -1;
 	bool selection_filtered_out = false;
-	for (const String &p : p_node_paths) {
+	for (const BTInstanceInfo &info : p_instances) {
-		if (p_filter.is_empty() || p.contains(p_filter)) {
+		if (p_filter.is_empty() || info.owner_node_path.contains(p_filter)) {
-			int idx = bt_player_list->add_item(p);
+			int idx = bt_instance_list->add_item(info.owner_node_path);
+			bt_instance_list->set_item_metadata(idx, info.instance_id);
 			// Make item text shortened from the left, e.g ".../Agent/BTPlayer".
-			bt_player_list->set_item_text_direction(idx, TEXT_DIRECTION_RTL);
+			bt_instance_list->set_item_text_direction(idx, TEXT_DIRECTION_RTL);
-			if (p == selected_player) {
+			if (info.instance_id == selected_instance_id) {
 				select_idx = idx;
 			}
-		} else if (p == selected_player) {
+		} else if (info.instance_id == selected_instance_id) {
 			selection_filtered_out = true;
 		}
 	}
 
 	// Restore selected item.
 	if (select_idx > -1) {
-		bt_player_list->select(select_idx);
+		bt_instance_list->select(select_idx);
-	} else if (!selected_player.is_empty()) {
+	} else if (selected_instance_id != 0) {
 		if (selection_filtered_out) {
 			session->send_message("limboai:untrack_bt_player", Array());
 			bt_view->clear();
 			_show_alert("");
 		} else {
-			_show_alert("BehaviorTree player is no longer present.");
+			_show_alert(TTR("Behavior tree instance is no longer present."));
 		}
 	}
 }
 
-void LimboDebuggerTab::_bt_selected(int p_idx) {
+void LimboDebuggerTab::_bt_instance_selected(int p_idx) {
 	alert_box->hide();
 	bt_view->clear();
 	info_message->set_text(TTR("Waiting for behavior tree update."));
 	info_message->show();
 	resource_header->set_text(TTR("Waiting for data"));
 	resource_header->set_disabled(true);
-	NodePath path = bt_player_list->get_item_text(p_idx);
 	Array msg_data;
-	msg_data.push_back(path);
+	msg_data.push_back(bt_instance_list->get_item_metadata(p_idx));
 	session->send_message("limboai:track_bt_player", msg_data);
 }
 
 void LimboDebuggerTab::_filter_changed(String p_text) {
-	_update_bt_player_list(active_bt_players, p_text);
+	_update_bt_instance_list(active_bt_instances, p_text);
 }
 
 void LimboDebuggerTab::_window_visibility_changed(bool p_visible) {
@@ -185,7 +187,7 @@ void LimboDebuggerTab::_notification(int p_what) {
 		case NOTIFICATION_READY: {
 			resource_header->connect(LW_NAME(pressed), callable_mp(this, &LimboDebuggerTab::_resource_header_pressed));
 			filter_players->connect(LW_NAME(text_changed), callable_mp(this, &LimboDebuggerTab::_filter_changed));
-			bt_player_list->connect(LW_NAME(item_selected), callable_mp(this, &LimboDebuggerTab::_bt_selected));
+			bt_instance_list->connect(LW_NAME(item_selected), callable_mp(this, &LimboDebuggerTab::_bt_instance_selected));
 			update_interval->connect("value_changed", callable_mp(bt_view, &BehaviorTreeView::set_update_interval_msec));
 
 			Ref<ConfigFile> cf;
@@ -271,11 +273,11 @@ LimboDebuggerTab::LimboDebuggerTab() {
 	filter_players->set_placeholder(TTR("Filter Players"));
 	list_box->add_child(filter_players);
 
-	bt_player_list = memnew(ItemList);
+	bt_instance_list = memnew(ItemList);
-	bt_player_list->set_custom_minimum_size(Size2(240.0 * EDSCALE, 0.0));
+	bt_instance_list->set_custom_minimum_size(Size2(240.0 * EDSCALE, 0.0));
-	bt_player_list->set_h_size_flags(SIZE_FILL);
+	bt_instance_list->set_h_size_flags(SIZE_FILL);
-	bt_player_list->set_v_size_flags(SIZE_EXPAND_FILL);
+	bt_instance_list->set_v_size_flags(SIZE_EXPAND_FILL);
-	list_box->add_child(bt_player_list);
+	list_box->add_child(bt_instance_list);
 
 	view_box = memnew(VBoxContainer);
 	hsc->add_child(view_box);
@@ -352,10 +354,10 @@ bool LimboDebuggerPlugin::_capture(const String &p_message, const Array &p_data,
 	ERR_FAIL_NULL_V(tab, false);
 	bool captured = true;
 	if (p_message == "limboai:active_bt_players") {
-		tab->update_active_bt_players(p_data);
+		tab->update_active_bt_instances(p_data);
 	} else if (p_message == "limboai:bt_update") {
 		Ref<BehaviorTreeData> data = BehaviorTreeData::deserialize(p_data);
-		if (data->bt_player_path == NodePath(tab->get_selected_bt_player())) {
+		if (data->bt_instance_id == tab->get_selected_bt_instance_id()) {
 			tab->update_behavior_tree(data);
 		}
 	} else {

editor/debugger/limbo_debugger_plugin.h

@@ -51,13 +51,18 @@ class LimboDebuggerTab : public PanelContainer {
 	GDCLASS(LimboDebuggerTab, PanelContainer);
 
 private:
-	List<String> active_bt_players;
+	struct BTInstanceInfo {
+		uint64_t instance_id;
+		String owner_node_path;
+	};
+
+	Vector<BTInstanceInfo> active_bt_instances;
 	Ref<EditorDebuggerSession> session;
 	VBoxContainer *root_vb = nullptr;
 	HBoxContainer *toolbar = nullptr;
 	HSplitContainer *hsc = nullptr;
 	Label *info_message = nullptr;
-	ItemList *bt_player_list = nullptr;
+	ItemList *bt_instance_list = nullptr;
 	BehaviorTreeView *bt_view = nullptr;
 	VBoxContainer *view_box = nullptr;
 	HBoxContainer *alert_box = nullptr;
@@ -71,8 +76,8 @@ private:
 
 	void _reset_controls();
 	void _show_alert(const String &p_message);
-	void _update_bt_player_list(const List<String> &p_node_paths, const String &p_filter);
+	void _update_bt_instance_list(const Vector<BTInstanceInfo> &p_instances, const String &p_filter);
-	void _bt_selected(int p_idx);
+	void _bt_instance_selected(int p_idx);
 	void _filter_changed(String p_text);
 	void _window_visibility_changed(bool p_visible);
 	void _resource_header_pressed();
@@ -84,9 +89,9 @@ protected:
 public:
 	void start_session();
 	void stop_session();
-	void update_active_bt_players(const Array &p_node_paths);
+	void update_active_bt_instances(const Array &p_data);
 	BehaviorTreeView *get_behavior_tree_view() const { return bt_view; }
-	String get_selected_bt_player();
+	uint64_t get_selected_bt_instance_id();
 	void update_behavior_tree(const Ref<BehaviorTreeData> &p_data);
 
 	void setup(Ref<EditorDebuggerSession> p_session, CompatWindowWrapper *p_wrapper);

register_types.cpp

@@ -148,6 +148,7 @@ void initialize_limboai_module(ModuleInitializationLevel p_level) {
 		GDREGISTER_ABSTRACT_CLASS(BT);
 		GDREGISTER_ABSTRACT_CLASS(BTTask);
 		GDREGISTER_CLASS(BehaviorTree);
+		GDREGISTER_CLASS(BTInstance);
 		GDREGISTER_CLASS(BTPlayer);
 		GDREGISTER_CLASS(BTState);
 

util/limbo_compat.h

@@ -54,6 +54,7 @@
 #define GET_SCRIPT(m_obj) (m_obj->get_script_instance() ? m_obj->get_script_instance()->get_script() : nullptr)
 #define ADD_STYLEBOX_OVERRIDE(m_control, m_name, m_stylebox) (m_control->add_theme_style_override(m_name, m_stylebox))
 #define GET_NODE(m_parent, m_path) m_parent->get_node(m_path)
+#define OBJECT_DB_GET_INSTANCE(m_id) ObjectDB::get_instance(ObjectID(m_id))
 
 _FORCE_INLINE_ bool OBJECT_HAS_PROPERTY(Object *p_obj, const StringName &p_prop) {
 	bool r_valid;
@@ -112,6 +113,7 @@ using namespace godot;
 #define GET_SCRIPT(m_obj) (m_obj->get_script())
 #define ADD_STYLEBOX_OVERRIDE(m_control, m_name, m_stylebox) (m_control->add_theme_stylebox_override(m_name, m_stylebox))
 #define GET_NODE(m_parent, m_path) m_parent->get_node_internal(m_path)
+#define OBJECT_DB_GET_INSTANCE(m_id) ObjectDB::get_instance(m_id)
 
 _FORCE_INLINE_ bool OBJECT_HAS_PROPERTY(Object *p_obj, const StringName &p_prop) {
 	return Variant(p_obj).has_key(p_prop);

util/limbo_string_names.cpp

@@ -85,6 +85,7 @@ LimboStringNames::LimboStringNames() {
 	font_color = SN("font_color");
 	font_size = SN("font_size");
 	Forward = SN("Forward");
+	freed = SN("freed");
 	gui_input = SN("gui_input");
 	GuiOptionArrow = SN("GuiOptionArrow");
 	GuiTreeArrowDown = SN("GuiTreeArrowDown");

util/limbo_string_names.h

@@ -101,6 +101,7 @@ public:
 	StringName font_size;
 	StringName font;
 	StringName Forward;
+	StringName freed;
 	StringName gui_input;
 	StringName GuiOptionArrow;
 	StringName GuiTreeArrowDown;