#19 : add an example how to share a blackboard in multiple trees

examples/blackboard_sharing/README.MD

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+# 🗣️ Sharing blackboard : the talking game !
+
+This example demonstrates how to share a single blackboard in multiple behavior trees.
+
+Sharing a blackboard can be necessary if you want to easily share data between trees, for example, to synchronize multiple NPCs. 
+
+The blackboard can be instantiate in a Scene Tree via the editor, or in a script (as in this example).
+
+## Technical elements
+
+- `main.tscn` : scene to run. The main scene instantiates a unique blackboard and give it to all player trees,
+- `player.tscn` : a player in the talking game. They all share the same blackboard to known who is the next to talk.

examples/blackboard_sharing/main.gd

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+extends Node2D
+
+#------------------------------------------
+# Signaux
+#------------------------------------------
+
+#------------------------------------------
+# Exports
+#------------------------------------------
+
+#------------------------------------------
+# Variables publiques
+#------------------------------------------
+
+#------------------------------------------
+# Variables privées
+#------------------------------------------
+
+var _shared_blackboard:BTBlackboard
+
+#------------------------------------------
+# Fonctions Godot redéfinies
+#------------------------------------------
+
+func _ready() -> void:
+    _shared_blackboard = BTBlackboard.new()
+    _shared_blackboard.set_data("next_talking", "Alice")
+    _shared_blackboard.set_data("players", [])
+
+    $"PlayerAlice/BTRoot/".blackboard = _shared_blackboard
+    $"PlayerBob/BTRoot/".blackboard = _shared_blackboard
+    $"PlayerCharles/BTRoot/".blackboard = _shared_blackboard
+    $"PlayerEmily/BTRoot/".blackboard = _shared_blackboard
+
+#------------------------------------------
+# Fonctions publiques
+#------------------------------------------
+
+#------------------------------------------
+# Fonctions privées
+#------------------------------------------
+

examples/blackboard_sharing/main.tscn

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+[gd_scene load_steps=3 format=3 uid="uid://d1s5iyoblr4cm"]
+
+[ext_resource type="Script" path="res://examples/blackboard_sharing/main.gd" id="1_g7q7h"]
+[ext_resource type="PackedScene" uid="uid://7k8r0e84lcr3" path="res://examples/blackboard_sharing/player.tscn" id="2_y55mt"]
+
+[node name="World" type="Node2D"]
+script = ExtResource("1_g7q7h")
+
+[node name="PlayerAlice" parent="." instance=ExtResource("2_y55mt")]
+position = Vector2(509, 181)
+player_name = "Alice"
+
+[node name="PlayerBob" parent="." instance=ExtResource("2_y55mt")]
+position = Vector2(515, 477)
+player_name = "Bob"
+
+[node name="PlayerCharles" parent="." instance=ExtResource("2_y55mt")]
+position = Vector2(309, 324)
+player_name = "Charles"
+
+[node name="PlayerEmily" parent="." instance=ExtResource("2_y55mt")]
+position = Vector2(733, 322)
+player_name = "Emily"

examples/blackboard_sharing/player.gd

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+extends Node2D
+
+#------------------------------------------
+# Signaux
+#------------------------------------------
+
+#------------------------------------------
+# Exports
+#------------------------------------------
+
+@export var player_name:String = "":
+    set(value):
+        player_name = value
+        if _name_label:
+            _name_label.text = player_name
+
+#------------------------------------------
+# Variables publiques
+#------------------------------------------
+
+#------------------------------------------
+# Variables privées
+#------------------------------------------
+
+@onready var _text_label:Label = $GUI/Text
+@onready var _name_label:Label = $GUI/Name
+
+#------------------------------------------
+# Fonctions Godot redéfinies
+#------------------------------------------
+
+func _ready() -> void:
+    _name_label.text = player_name
+
+#------------------------------------------
+# Fonctions publiques
+#------------------------------------------
+
+func declare_presence(blackboard:BTBlackboard) -> int:
+    blackboard.get_data("players").append(player_name)
+    return BTTickResult.SUCCESS
+
+func is_my_turn_to_talk(next_talking:String) -> bool:
+    return player_name == next_talking
+
+func talk() -> int:
+    _text_label.visible = true
+    get_tree().create_timer(1).timeout.connect(func():_text_label.visible = false)
+    return BTTickResult.SUCCESS
+
+func choose_next_player_talking(blackboard:BTBlackboard) -> int:
+    blackboard.set_data("next_talking", _pick_next_player(blackboard.get_data("players")))
+    return BTTickResult.SUCCESS
+
+#------------------------------------------
+# Fonctions privées
+#------------------------------------------
+
+func _pick_next_player(players:Array) -> String:
+    var result:String = players.pick_random()
+    while result == player_name:
+        result = players.pick_random()
+    return result

examples/blackboard_sharing/player.tscn

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+[gd_scene load_steps=11 format=3 uid="uid://7k8r0e84lcr3"]
+
+[ext_resource type="Script" path="res://examples/blackboard_sharing/player.gd" id="1_1ti0g"]
+[ext_resource type="Script" path="res://addons/yet_another_behavior_tree/src/Nodes/BTRoot.gd" id="2_sdd0w"]
+[ext_resource type="Script" path="res://addons/yet_another_behavior_tree/src/Nodes/Composite/BTSelector.gd" id="3_2v3m1"]
+[ext_resource type="Script" path="res://addons/yet_another_behavior_tree/src/Nodes/Composite/BTSequence.gd" id="4_fjw5l"]
+[ext_resource type="Script" path="res://addons/yet_another_behavior_tree/src/Nodes/Decorators/BTSuccess.gd" id="4_qnbqx"]
+[ext_resource type="Script" path="res://addons/yet_another_behavior_tree/src/Nodes/Leaves/BTConditionCallable.gd" id="5_8tfvp"]
+[ext_resource type="Script" path="res://addons/yet_another_behavior_tree/src/Nodes/Decorators/BTLimiter.gd" id="5_d3jao"]
+[ext_resource type="Script" path="res://addons/yet_another_behavior_tree/src/Nodes/Leaves/BTActionCallable.gd" id="6_i6lan"]
+[ext_resource type="Script" path="res://addons/yet_another_behavior_tree/src/Nodes/Leaves/BTActionWait.gd" id="10_1e6f0"]
+[ext_resource type="Script" path="res://addons/yet_another_behavior_tree/src/Nodes/Decorators/BTInverter.gd" id="11_fvy66"]
+
+[node name="Player" type="Node2D"]
+script = ExtResource("1_1ti0g")
+
+[node name="Shape" type="Node2D" parent="."]
+
+[node name="Ahahahah" type="Polygon2D" parent="Shape"]
+color = Color(0.188235, 0.490196, 0.505882, 1)
+polygon = PackedVector2Array(-27, -55, 22, -55, 22, -25, 10, -18, 24, 17, -30, 17, -30, 17, -30, 17, -13, -18, -13, -18, -13, -18, -27, -26, -27, -26, -27, -26)
+
+[node name="GUI" type="Control" parent="."]
+layout_mode = 3
+anchors_preset = 0
+offset_left = -61.0
+offset_top = -84.0
+offset_right = 61.0
+offset_bottom = -58.0
+
+[node name="Text" type="Label" parent="GUI"]
+visible = false
+layout_mode = 1
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+text = "My turn !"
+horizontal_alignment = 1
+vertical_alignment = 1
+
+[node name="Name" type="Label" parent="GUI"]
+layout_mode = 0
+offset_left = 24.0
+offset_top = 104.0
+offset_right = 98.0
+offset_bottom = 127.0
+horizontal_alignment = 1
+vertical_alignment = 1
+
+[node name="BTRoot" type="Node" parent="."]
+script = ExtResource("2_sdd0w")
+actor_path = NodePath("..")
+
+[node name="Do" type="Node" parent="BTRoot"]
+script = ExtResource("4_fjw5l")
+
+[node name="Init" type="Node" parent="BTRoot/Do"]
+script = ExtResource("4_fjw5l")
+save_progression = true
+
+[node name="Declare I am playing" type="Node" parent="BTRoot/Do/Init"]
+script = ExtResource("4_qnbqx")
+
+[node name="Do once" type="Node" parent="BTRoot/Do/Init/Declare I am playing"]
+script = ExtResource("5_d3jao")
+
+[node name="I\'m here !" type="Node" parent="BTRoot/Do/Init/Declare I am playing/Do once"]
+script = ExtResource("6_i6lan")
+method_owner_path = NodePath("../../../../../..")
+method_name = "declare_presence"
+method_arguments = ["blackboard"]
+
+[node name="Invert" type="Node" parent="BTRoot/Do/Init"]
+script = ExtResource("11_fvy66")
+
+[node name="Do once" type="Node" parent="BTRoot/Do/Init/Invert"]
+script = ExtResource("5_d3jao")
+
+[node name="Wait 1s" type="Node" parent="BTRoot/Do/Init/Invert/Do once"]
+script = ExtResource("10_1e6f0")
+
+[node name="One Between" type="Node" parent="BTRoot/Do"]
+script = ExtResource("3_2v3m1")
+save_progression = true
+
+[node name="I must talk" type="Node" parent="BTRoot/Do/One Between"]
+script = ExtResource("4_fjw5l")
+save_progression = true
+
+[node name="Is my Turn ?" type="Node" parent="BTRoot/Do/One Between/I must talk"]
+script = ExtResource("5_8tfvp")
+method_owner_path = NodePath("../../../../..")
+method_name = "is_my_turn_to_talk"
+method_arguments = ["blackboard.get_data(\"next_talking\")"]
+
+[node name="Talk" type="Node" parent="BTRoot/Do/One Between/I must talk"]
+script = ExtResource("6_i6lan")
+method_owner_path = NodePath("../../../../..")
+method_name = "talk"
+method_arguments = []
+
+[node name="Wait a little bit" type="Node" parent="BTRoot/Do/One Between/I must talk"]
+script = ExtResource("10_1e6f0")
+random_deviation_ms = 300
+
+[node name="Set Next Player To Talk" type="Node" parent="BTRoot/Do/One Between/I must talk"]
+script = ExtResource("6_i6lan")
+method_owner_path = NodePath("../../../../..")
+method_name = "choose_next_player_talking"
+method_arguments = ["blackboard"]
+
+[node name="I must listen" type="Node" parent="BTRoot/Do/One Between"]
+script = ExtResource("4_fjw5l")
+
+[node name="Not my turn" type="Node" parent="BTRoot/Do/One Between/I must listen"]
+script = ExtResource("11_fvy66")
+
+[node name="Is my Turn ?" type="Node" parent="BTRoot/Do/One Between/I must listen/Not my turn"]
+script = ExtResource("5_8tfvp")
+method_owner_path = NodePath("../../../../../..")
+method_name = "is_my_turn_to_talk"
+method_arguments = ["blackboard.get_data(\"next_talking\")"]