New complex example, refactored BTNodeState with enum and several optimisations.

Author: kagenashi

addons/behavior_tree/src/behavior_tree.gd

@@ -19,7 +19,7 @@ onready var bt_root = get_child(0) as BTNode
 
 
 func _ready() -> void:
-	assert(get_child_count() == 1)
+	assert(get_child_count() == 1, "A Behavior Tree can only have one entry point.")
 	bt_root.propagate_call("connect", ["abort_tree", self, "abort"])
 	start()
 

addons/behavior_tree/src/blackboard.gd

@@ -15,15 +15,13 @@ export(Dictionary) var data: Dictionary
 
 
 
-
 func _enter_tree() -> void:
 	data = data.duplicate()
 
 
-
 func _ready() -> void :
 	for key in data.keys():
-		assert(key is String)
+		assert(key is String, "Blackboard keys must be stored as strings.")
 
 
 func set_data(key: String, value) -> void:

addons/behavior_tree/src/bt_node.gd

@@ -5,40 +5,11 @@ extends Node
 # You don't usually need to instance this node directly.
 # To define your behaviors, use and extend BTLeaf instead.
 
-class BTNodeState:
-	var success: bool = true  setget set_success
-	var failure: bool = false setget set_failure
-	var running: bool = false setget set_running
-	
-	
-	func set_success(value: bool = true):
-		if value == false:
-			print_debug("Ignoring manual change of BTNodeState. Use setters.")
-			return
-		success = true
-		failure = false
-		running = false
-	
-	
-	func set_failure(value: bool = true):
-		if value == false:
-			print_debug("Ignoring manual change of BTNodeState. Use setters.")
-			return
-		success = false
-		failure = true
-		running = false
-	
-	
-	func set_running(value: bool = true):
-		if value == false:
-			print_debug("Ignoring manual change of BTNodeState. Use setters.")
-			return
-		success = false
-		failure = false
-		running = true
-
-
-
+enum BTNodeState {
+	FAILURE,
+	SUCCESS,
+	RUNNING,
+}
 
 # (Optional) Emitted after a tick() call. True is success, false is failure. 
 signal tick(result)
@@ -55,7 +26,7 @@ export(bool) var debug: bool = false
 # Turn this on to abort the tree after completion.
 export(bool) var abort_tree: bool
 
-var state: BTNodeState = BTNodeState.new()
+var state: int setget set_state
 
 
 
@@ -89,49 +60,51 @@ func _post_tick(agent: Node, blackboard: Blackboard, result: bool) -> void:
 
 ### BEGIN: RETURN VALUES ###
 
-# Your _tick() must return on of the two following funcs.
+# Your _tick() must return one of the following functions.
 
 # Return this to set the state to success.
 func succeed() -> bool:
-	state.set_success()
+	state = BTNodeState.SUCCESS
 	return true
 
 
 # Return this to set the state to failure.
 func fail() -> bool:
-	state.set_failure()
+	state = BTNodeState.FAILURE
 	return false
 
 
 # Return this to match the state to another state.
-func set_state(rhs: BTNodeState) -> bool:
-	if rhs.success:
-		return succeed()
-	else:
-		return fail()
+func set_state(rhs: int) -> bool:
+	match rhs:
+		BTNodeState.SUCCESS:
+			return succeed()
+		BTNodeState.FAILURE:
+			return fail()
+	
+	assert(false, "Invalid BTNodeState assignment. Can only set to success or failure.")
+	return false
 
 ### END: RETURN VALUES ###
 
 
 
-# You are not supposed to use this. 
-# It's called automatically. 
-# It won't do what you think.
+# Don't call this.
 func run():
-	state.set_running()
+	state = BTNodeState.RUNNING
 
 
 # You can use the following to recover the state of the node
 func succeeded() -> bool:
-	return state.success
+	return state == BTNodeState.SUCCESS
 
 
 func failed() -> bool:
-	return state.failure
+	return state == BTNodeState.FAILURE
 
 
 func running() -> bool:
-	return state.running
+	return state == BTNodeState.RUNNING
 
 
 # Or this, as a string.
@@ -163,21 +136,18 @@ func tick(agent: Node, blackboard: Blackboard) -> bool:
 	var result = _tick(agent, blackboard)
 
 	if result is GDScriptFunctionState:
-		# If you yield, the node must be running.
-		# If you crash here it means you changed the state before yield.
-		assert(running())
+		assert(running(), "BTNode execution was suspended but it's not running. Did you succeed() or fail() before yield?")
 		result = yield(result, "completed")
 
-	# If you complete execution (or don't yield anymore), the node can't be running.
-	# If you crash here it means you forgot to return succeed() or fail().
-	assert(not running()) 
+	assert(not running(), "BTNode execution was completed but it's still running. Did you forget to return succeed() or fail()?") 
 
 	# Do stuff after core behavior depending on the result
 	_post_tick(agent, blackboard, result)
 
 	# Notify completion and new state (i.e. the result of the execution)
 	emit_signal("tick", result)
 
+	# Queue tree abortion at the end of current tick
 	if abort_tree:
 		emit_signal("abort_tree")
 

addons/behavior_tree/src/btnodes/bt_composite.gd

@@ -15,7 +15,7 @@ var bt_child: BTNode # Used to iterate over children
 
 
 func _ready():
-	assert(get_child_count() > 1)
+	assert(get_child_count() > 1, "A BTComposite must have more than one child.")
 
 
 

addons/behavior_tree/src/btnodes/bt_decorator.gd

@@ -9,7 +9,7 @@ onready var bt_child: BTNode = get_child(0) as BTNode
 
 
 func _ready():
-	assert(get_child_count() == 1)
+	assert(get_child_count() == 1, "A BTDecorator can only have one child.")
 
 
 func _tick(agent: Node, blackboard: Blackboard) -> bool:

addons/behavior_tree/src/btnodes/bt_leaf.gd

@@ -9,5 +9,5 @@ extends BTNode
 
 
 func _ready():
-	assert(get_child_count() == 0)
+	assert(get_child_count() == 0, "A BTLeaf cannot have children.")
 

addons/behavior_tree/src/btnodes/decorators/bt_guard.gd

@@ -8,6 +8,7 @@ extends BTDecorator
 # If you don't specify an unlocker, the unlock_if variable is useless and only the lock_time will 
 # be considered, and viceversa.
 # You can also choose to lock permanently or to lock on startup.
+#
 # A locked BTGuard will always return fail().
 
 export(bool) var start_locked = false
@@ -41,6 +42,9 @@ func _on_locker_tick(_result):
 func lock():
 	locked = true
 
+	if debug:
+		print(name + " locked for " + str(lock_time) + " seconds")
+	
 	if permanent:
 		return
 	elif unlocker:
@@ -51,10 +55,13 @@ func lock():
 	else:
 		yield(get_tree().create_timer(lock_time, false), "timeout")
 		locked = false
+	
+	if debug:
+		print(name + " unlocked")
 
 
 func check_lock(current_locker: BTNode):
-	if ((lock_if == 2  and not current_locker.running()) 
+	if ((lock_if == 2 and not current_locker.running()) 
 	or ( lock_if == 1 and current_locker.succeeded()) 
 	or ( lock_if == 0 and current_locker.failed())):
 		lock()

bt_example/agent.gd

@@ -1,9 +1,23 @@
 extends Node
 
+const max_ammo = 10
+
 var is_alive = true
-var ammo = 5
+var ammo = max_ammo
+
+
 
 func _ready():
+	$Blackboard.set_data("target_aquired", false)
 	yield(get_tree().create_timer(3, false), "timeout")
 	print("\n - Agent: 'Target aquired!'\n")
 	$Blackboard.set_data("target_aquired", true)
+
+
+func _process(delta: float) -> void:
+	set_process(false)
+	yield(get_tree().create_timer(6.66, false), "timeout")
+	$Blackboard.set_data("target_aquired", false)
+	yield(get_tree().create_timer(2, false), "timeout")
+	$Blackboard.set_data("target_aquired", true)
+	set_process(true)

bt_example/ex_behavior_tree.tscn

@@ -1,4 +1,4 @@
-[gd_scene load_steps=11 format=2]
+[gd_scene load_steps=15 format=2]
 
 [ext_resource path="res://addons/behavior_tree/src/btnodes/decorators/bt_always.gd" type="Script" id=1]
 [ext_resource path="res://addons/behavior_tree/src/behavior_tree.gd" type="Script" id=2]
@@ -10,6 +10,10 @@
 [ext_resource path="res://addons/behavior_tree/src/btnodes/composites/bt_random_selector.gd" type="Script" id=8]
 [ext_resource path="res://addons/behavior_tree/src/btnodes/leaves/bt_wait.gd" type="Script" id=9]
 [ext_resource path="res://addons/behavior_tree/src/btnodes/decorators/bt_repeat.gd" type="Script" id=10]
+[ext_resource path="res://addons/behavior_tree/src/btnodes/decorators/bt_guard.gd" type="Script" id=11]
+[ext_resource path="res://bt_example/leaves/take_cover.gd" type="Script" id=12]
+[ext_resource path="res://addons/behavior_tree/src/btnodes/composites/bt_selector.gd" type="Script" id=13]
+[ext_resource path="res://addons/behavior_tree/src/btnodes/decorators/bt_repeat_until.gd" type="Script" id=14]
 
 [node name="BehaviorTree" type="Node"]
 script = ExtResource( 2 )
@@ -19,39 +23,61 @@ debug = true
 [node name="BTSequence" type="Node" parent="."]
 script = ExtResource( 6 )
 
-[node name="BTRandomSelector" type="Node" parent="BTSequence"]
+[node name="Always succeed" type="Node" parent="BTSequence"]
+script = ExtResource( 1 )
+always_what = 1
+
+[node name="Lock while taking cover" type="Node" parent="BTSequence/Always succeed"]
+script = ExtResource( 11 )
+_locker = NodePath("../../BTSelector/Out of ammo\?/BTSequence/Repeat Until Success/Take Cover")
+_unlocker = NodePath("../../BTSelector/Out of ammo\?/BTSequence/Reload")
+unlock_if = 1
+
+[node name="BTRandomSelector" type="Node" parent="BTSequence/Always succeed/Lock while taking cover"]
 script = ExtResource( 8 )
 
-[node name="Wait 1 sec" type="Node" parent="BTSequence/BTRandomSelector"]
+[node name="Wait 1 sec" type="Node" parent="BTSequence/Always succeed/Lock while taking cover/BTRandomSelector"]
 script = ExtResource( 9 )
 debug = true
 wait_time = 1.0
 
-[node name="Wait 2 sec" type="Node" parent="BTSequence/BTRandomSelector"]
+[node name="Wait 2 sec" type="Node" parent="BTSequence/Always succeed/Lock while taking cover/BTRandomSelector"]
 script = ExtResource( 9 )
 debug = true
 wait_time = 2.0
 
-[node name="Always succeed" type="Node" parent="BTSequence"]
-script = ExtResource( 1 )
-always_what = 1
+[node name="BTSelector" type="Node" parent="BTSequence"]
+script = ExtResource( 13 )
 
-[node name="Out of ammo\?" type="Node" parent="BTSequence/Always succeed"]
+[node name="Out of ammo\?" type="Node" parent="BTSequence/BTSelector"]
 script = ExtResource( 5 )
 debug = true
 
-[node name="Reload" type="Node" parent="BTSequence/Always succeed/Out of ammo\?"]
+[node name="BTSequence" type="Node" parent="BTSequence/BTSelector/Out of ammo\?"]
+script = ExtResource( 6 )
+
+[node name="Repeat Until Success" type="Node" parent="BTSequence/BTSelector/Out of ammo\?/BTSequence"]
+script = ExtResource( 14 )
+until_what = 1
+
+[node name="Take Cover" type="Node" parent="BTSequence/BTSelector/Out of ammo\?/BTSequence/Repeat Until Success"]
+script = ExtResource( 12 )
+
+[node name="Reload" type="Node" parent="BTSequence/BTSelector/Out of ammo\?/BTSequence"]
 script = ExtResource( 4 )
 debug = true
 
-[node name="TargetAquired\?" type="Node" parent="BTSequence"]
+[node name="Repeat until fail" type="Node" parent="BTSequence/BTSelector"]
+script = ExtResource( 14 )
+
+[node name="Target Aquired\?" type="Node" parent="BTSequence/BTSelector/Repeat until fail"]
 script = ExtResource( 3 )
 debug = true
 
-[node name="BTRepeat" type="Node" parent="BTSequence/TargetAquired\?"]
+[node name="Repeat twice" type="Node" parent="BTSequence/BTSelector/Repeat until fail/Target Aquired\?"]
 script = ExtResource( 10 )
 times_to_repeat = 2
 
-[node name="Shoot" type="Node" parent="BTSequence/TargetAquired\?/BTRepeat"]
+[node name="Shoot" type="Node" parent="BTSequence/BTSelector/Repeat until fail/Target Aquired\?/Repeat twice"]
 script = ExtResource( 7 )
 debug = true

bt_example/leaves/reload.gd

@@ -4,5 +4,5 @@ func _tick(agent: Node, blackboard: Blackboard) -> bool:
 	assert("ammo" in agent)
 
 	yield(get_tree().create_timer(2, false), "timeout")
-	agent.ammo = 5
+	agent.ammo = agent.max_ammo
 	return succeed()

bt_example/leaves/shoot.gd

@@ -4,6 +4,7 @@ func _tick(agent: Node, blackboard: Blackboard) -> bool:
 	assert("ammo" in agent)
 
 	if agent.ammo <= 0:
+		print("No ammo!")
 		return fail()
 
 	yield(get_tree().create_timer(.4, false), "timeout")

bt_example/leaves/take_cover.gd

@@ -0,0 +1,18 @@
+extends BTLeaf
+
+
+var distance_to_cover = 4
+
+
+func _tick(agent: Node, blackboard: Blackboard) -> bool:
+	distance_to_cover -= 1
+	print("Walking towards cover..")
+	yield(get_tree().create_timer(1, false), "timeout")
+	
+	if distance_to_cover == 0:
+		print("Cover reached")
+		distance_to_cover = 4
+		return succeed()
+	
+	return fail()
+