From 1b9cf1733948a31149846c3e3749d1fc8ae03ba8 Mon Sep 17 00:00:00 2001
From: Serhii Snitsaruk <limbonaut@pm.me>
Date: Tue, 21 Jan 2025 23:35:28 +0100
Subject: [PATCH] Fix BTPlayer.set_behavior_tree() not populating Blackboard
 (#274)

---
 bt/bt_instance.cpp |  3 ++-
 bt/bt_player.cpp   | 29 +++++++++++++++++------------
 bt/bt_player.h     |  3 ++-
 3 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/bt/bt_instance.cpp b/bt/bt_instance.cpp
index 05db482..1abcc8b 100644
--- a/bt/bt_instance.cpp
+++ b/bt/bt_instance.cpp
@@ -83,7 +83,7 @@ void BTInstance::register_with_debugger() {
 
 void BTInstance::unregister_with_debugger() {
 #ifdef DEBUG_ENABLED
-	if (LimboDebugger::get_singleton()->is_active()) {
+	if (LimboDebugger::get_singleton() && LimboDebugger::get_singleton()->is_active()) {
 		LimboDebugger::get_singleton()->unregister_bt_instance(get_instance_id());
 	}
 #endif
@@ -151,5 +151,6 @@ BTInstance::~BTInstance() {
 	emit_signal(LW_NAME(freed));
 #ifdef DEBUG_ENABLED
 	_remove_custom_monitor();
+	unregister_with_debugger();
 #endif
 }
diff --git a/bt/bt_player.cpp b/bt/bt_player.cpp
index 8d36eab..4a1790d 100644
--- a/bt/bt_player.cpp
+++ b/bt/bt_player.cpp
@@ -42,7 +42,7 @@
 
 VARIANT_ENUM_CAST(BTPlayer::UpdateMode);
 
-void BTPlayer::_load_tree() {
+void BTPlayer::_instantiate_bt() {
 	bt_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.");
@@ -70,6 +70,19 @@ void BTPlayer::_update_blackboard_plan() {
 	blackboard_plan->set_base_plan(behavior_tree.is_valid() ? behavior_tree->get_blackboard_plan() : nullptr);
 }
 
+void BTPlayer::_initialize() {
+	if (blackboard.is_null()) {
+		blackboard = Ref<Blackboard>(memnew(Blackboard));
+	}
+	if (blackboard_plan.is_valid()) {
+		// Don't overwrite existing blackboard values as they may be initialized from code.
+		blackboard_plan->populate_blackboard(blackboard, false, this, _get_scene_root());
+	}
+	if (behavior_tree.is_valid()) {
+		_instantiate_bt();
+	}
+}
+
 void BTPlayer::set_bt_instance(const Ref<BTInstance> &p_bt_instance) {
 	ERR_FAIL_COND_MSG(p_bt_instance.is_null(), "BTPlayer: Failed to set behavior tree instance - instance is null.");
 	ERR_FAIL_COND_MSG(!p_bt_instance->is_instance_valid(), "BTPlayer: Failed to set behavior tree instance - instance is not valid.");
@@ -104,7 +117,8 @@ void BTPlayer::set_behavior_tree(const Ref<BehaviorTree> &p_tree) {
 	} else {
 		behavior_tree = p_tree;
 		if (get_owner() && is_inside_tree()) {
-			_load_tree();
+			_update_blackboard_plan();
+			_initialize();
 		}
 	}
 }
@@ -179,16 +193,7 @@ void BTPlayer::_notification(int p_notification) {
 		} break;
 		case NOTIFICATION_READY: {
 			if (!Engine::get_singleton()->is_editor_hint()) {
-				if (blackboard.is_null()) {
-					blackboard = Ref<Blackboard>(memnew(Blackboard));
-				}
-				if (blackboard_plan.is_valid()) {
-					// Don't overwrite existing blackboard values as they may be initialized from code.
-					blackboard_plan->populate_blackboard(blackboard, false, this, _get_scene_root());
-				}
-				if (behavior_tree.is_valid()) {
-					_load_tree();
-				}
+				_initialize();
 			} else {
 				_update_blackboard_plan();
 			}
diff --git a/bt/bt_player.h b/bt/bt_player.h
index 7d2ad6e..1644231 100644
--- a/bt/bt_player.h
+++ b/bt/bt_player.h
@@ -48,8 +48,9 @@ private:
 
 	Ref<BTInstance> bt_instance;
 
-	void _load_tree();
+	void _instantiate_bt();
 	void _update_blackboard_plan();
+	void _initialize();
 	_FORCE_INLINE_ Node *_get_scene_root() const { return scene_root_hint ? scene_root_hint : get_owner(); }
 
 protected: