Combinable Items

Charcoal.tscn

@@ -6,12 +6,17 @@
 [ext_resource type="Script" uid="uid://dvobm6vcfnqe8" path="res://addons/godot-xr-tools/hands/poses/hand_pose_settings.gd" id="4_mgacb"]
 [ext_resource type="PackedScene" uid="uid://ctw7nbntd5pcj" path="res://addons/godot-xr-tools/objects/grab_points/grab_point_hand_right.tscn" id="5_vw7i6"]
 [ext_resource type="Animation" uid="uid://d1xnpyc08njjx" path="res://addons/godot-xr-tools/hands/animations/right/Grip 4.res" id="6_cp3eg"]
+[ext_resource type="Script" path="res://combinable_item.gd" id="7_comb"]
+[ext_resource type="Script" path="res://combine_zone.gd" id="8_zone"]
 
 [sub_resource type="CylinderShape3D" id="CylinderShape3D_gkni8"]
 custom_solver_bias = 0.1
 height = 0.1
 radius = 0.1
 
+[sub_resource type="BoxShape3D" id="BoxShape3D_combine"]
+size = Vector3(0.16, 0.16, 0.16)
+
 [sub_resource type="StandardMaterial3D" id="StandardMaterial3D_e28iu"]
 albedo_color = Color(0.06879827, 0.06879828, 0.06879828, 1)
 
@@ -46,3 +51,13 @@ hand_pose = SubResource("Resource_lc22d")
 [node name="GrabPointHandRight" parent="." index="3" unique_id=514404634 instance=ExtResource("5_vw7i6")]
 transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0.06531982, 0.042291984, -0.08604182)
 hand_pose = SubResource("Resource_qyiot")
+
+[node name="CombinableItem" type="Node" parent="." index="4"]
+script = ExtResource("7_comb")
+id = &"charcoal"
+
+[node name="CombineZone" type="Area3D" parent="." index="5"]
+script = ExtResource("8_zone")
+
+[node name="CollisionShape3D" type="CollisionShape3D" parent="CombineZone"]
+shape = SubResource("BoxShape3D_combine")

PickupCube.tscn

@@ -8,6 +8,9 @@
 [ext_resource type="Animation" uid="uid://d1xnpyc08njjx" path="res://addons/godot-xr-tools/hands/animations/right/Grip 4.res" id="6_bdp75"]
 [ext_resource type="Script" uid="uid://bs7cxydoxk1cx" path="res://cookable_item.gd" id="7_hc3f7"]
 [ext_resource type="PackedScene" uid="uid://cucc3gaqu2nab" path="res://Charcoal.tscn" id="8_a0a5b"]
+[ext_resource type="Script" uid="uid://dounic663dn5q" path="res://combinable_item.gd" id="9_comb"]
+[ext_resource type="Script" uid="uid://e3im02nq5cye" path="res://combine_zone.gd" id="10_zone"]
+[ext_resource type="Script" uid="uid://coidnv8b2yvxr" path="res://combine_recipe.gd" id="11_recipe"]
 
 [sub_resource type="BoxShape3D" id="BoxShape3D_m1xbq"]
 size = Vector3(0.1, 0.1, 0.1)
@@ -29,6 +32,14 @@ script = ExtResource("4_hc3f7")
 closed_pose = ExtResource("6_bdp75")
 metadata/_custom_type_script = "uid://dvobm6vcfnqe8"
 
+[sub_resource type="Resource" id="Resource_recipe_cube"]
+script = ExtResource("11_recipe")
+ingredient_id = &"cube"
+result = ExtResource("8_a0a5b")
+
+[sub_resource type="BoxShape3D" id="BoxShape3D_combine"]
+size = Vector3(0.16, 0.16, 0.16)
+
 [node name="PickableObject" unique_id=1675596942 instance=ExtResource("1_dbtw8")]
 
 [node name="CollisionShape3D" parent="." index="0"]
@@ -49,3 +60,14 @@ hand_pose = SubResource("Resource_qyiot")
 script = ExtResource("7_hc3f7")
 cooking_time = 2.0
 turns_into = ExtResource("8_a0a5b")
+
+[node name="CombinableItem" type="Node" parent="." index="5" unique_id=1265358312]
+script = ExtResource("9_comb")
+id = &"cube"
+recipes = Array[ExtResource("11_recipe")]([SubResource("Resource_recipe_cube")])
+
+[node name="CombineZone" type="Area3D" parent="." index="6" unique_id=1412308162]
+script = ExtResource("10_zone")
+
+[node name="CollisionShape3D" type="CollisionShape3D" parent="CombineZone" index="0" unique_id=1926800015]
+shape = SubResource("BoxShape3D_combine")

combinable_item.gd

@@ -0,0 +1,24 @@
+class_name CombinableItem
+extends Node
+
+## Identity of this item, referenced by other items' recipes.
+@export var id: StringName
+
+## Recipes describing what the item holding this component turns into when
+## another item is combined into it while snapped. Recipes are directional:
+## only the snapped (base) item's recipes are consulted.
+@export var recipes: Array[CombineRecipe] = []
+
+
+func _ready() -> void:
+	if id.is_empty():
+		push_error("CombinableItem on ", get_parent().name, " has no 'id' set.")
+
+
+## Returns the scene this item becomes when combined with [param other_id],
+## or null if there is no matching recipe.
+func get_result_for(other_id: StringName) -> PackedScene:
+	for recipe in recipes:
+		if recipe and recipe.ingredient_id == other_id:
+			return recipe.result
+	return null

combinable_item.gd.uid

@@ -0,0 +1 @@
+uid://dounic663dn5q

combine_recipe.gd

@@ -0,0 +1,8 @@
+class_name CombineRecipe
+extends Resource
+
+## The [CombinableItem.id] of the item that must be combined into the base item.
+@export var ingredient_id: StringName
+
+## The scene the base item turns into when [member ingredient_id] is combined in.
+@export var result: PackedScene

combine_recipe.gd.uid

@@ -0,0 +1 @@
+uid://coidnv8b2yvxr

combine_zone.gd

@@ -0,0 +1,103 @@
+class_name CombineZone
+extends Area3D
+
+## Trigger area that lets a snapped item combine with another item pushed into
+## it. The zone only monitors while its owning item is held by an
+## [XRToolsSnapZone]; when an item carrying a matching [CombinableItem.id]
+## enters, the snapped (base) item transforms into the recipe result and the
+## incoming item is consumed.
+
+# The pickable this zone belongs to (its parent).
+@onready var _item: XRToolsPickable = get_parent() as XRToolsPickable
+
+# The base item's recipe data.
+@onready var _combinable: CombinableItem = _find_combinable(_item)
+
+# Guard so a combine only fires once.
+var _combining: bool = false
+
+
+func _ready() -> void:
+	# Detect items whether held (layer 17 "Held Objects") or loose
+	# (layer 3 "Pickable Objects"). Don't advertise a layer of our own.
+	collision_mask = 0b0000_0000_0000_0001_0000_0000_0000_0100
+	collision_layer = 0
+	# Deferred: _ready can run during a physics signal flush (when a combine
+	# spawns the result), where toggling monitoring directly is forbidden.
+	set_deferred("monitoring", false)
+	set_deferred("monitorable", false)
+
+	if not _item:
+		push_error("CombineZone must be a child of an XRToolsPickable.")
+		return
+	if not _combinable:
+		push_error("CombineZone requires a CombinableItem sibling on ", _item.name, ".")
+		return
+
+	_item.picked_up.connect(_on_item_picked_up)
+	_item.dropped.connect(_on_item_dropped)
+	body_entered.connect(_on_body_entered)
+
+
+# Enable the trigger only while snapped into a snap zone (not hand-held).
+func _on_item_picked_up(_pickable: Node3D) -> void:
+	var by := _item.get_picked_up_by()
+	var snapped: bool = by != null and by.has_method("is_xr_class") and by.is_xr_class("XRToolsSnapZone")
+	set_deferred("monitoring", snapped)
+
+
+func _on_item_dropped(_pickable: Node3D) -> void:
+	set_deferred("monitoring", false)
+
+
+func _on_body_entered(body: Node3D) -> void:
+	if _combining or body == _item:
+		return
+
+	var other := _find_combinable(body)
+	if not other:
+		return
+
+	var result: PackedScene = _combinable.get_result_for(other.id)
+	if not result:
+		return
+
+	_combine(body, result)
+
+
+# Transform the base item into [param result], consuming the incoming item.
+func _combine(other_body: Node3D, result: PackedScene) -> void:
+	_combining = true
+
+	var snap_zone := _item.get_picked_up_by()
+	if not snap_zone or not snap_zone.has_method("pick_up_object"):
+		push_warning("CombineZone: base item is not held by a snap zone; cannot combine.")
+		_combining = false
+		return
+
+	# Spawn the result at the base item's location, in world space.
+	var base_transform := _item.global_transform
+	var result_instance: Node3D = result.instantiate()
+	_item.get_tree().current_scene.add_child(result_instance)
+	result_instance.global_transform = base_transform
+
+	# Free the base item and consume the incoming item.
+	snap_zone.drop_object()
+	_item.queue_free()
+	if other_body.has_method("drop_and_free"):
+		other_body.drop_and_free()
+	else:
+		other_body.queue_free()
+
+	# Snap the result into the now-empty zone.
+	snap_zone.pick_up_object(result_instance)
+
+
+# Find a CombinableItem among the direct children of [param node].
+func _find_combinable(node: Node) -> CombinableItem:
+	if not node:
+		return null
+	for child in node.get_children():
+		if child is CombinableItem:
+			return child
+	return null

combine_zone.gd.uid

@@ -0,0 +1 @@
+uid://e3im02nq5cye