Feat/loot-and-drop (#17)

* feat: adds drop system

* chore(docs): adds docs for loot and drop

* chore(tests): adds drop tests

.gut_editor_config.json

@@ -32,12 +32,12 @@
  "post_run_script": "",
  "pre_run_script": "",
  "prefix": "test_",
- "selected": null,
+ "selected": "test_drop.gd",
  "should_exit": true,
  "should_exit_on_success": false,
  "should_maximize": false,
  "show_help": false,
  "suffix": ".gd",
  "tests": [],
- "unit_test_name": null
+ "unit_test_name": "test_drop"
 }

addons/godot_gameplay_systems/inventory_system/assets/DropGroupIcon.png.import

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addons/godot_gameplay_systems/inventory_system/assets/DropIcon.png.import

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addons/godot_gameplay_systems/inventory_system/assets/DropNode2D.png.import

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addons/godot_gameplay_systems/inventory_system/assets/DropTableIcon.png.import

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addons/godot_gameplay_systems/inventory_system/nodes/drop.gd

@@ -0,0 +1,89 @@
+@tool
+class_name Drop extends Node
+
+## It is the node responsible for dropping an array of [Items].
+##
+
+## Emitted when some [Item]s have been dropped.
+signal items_dropped(items: Array[Item], drop_owner: Node)
+
+
+@export_category("Drop")
+## The table used to drop items
+@export var drop_table: DropTable = null
+## The path to the owning node. This will determine if the drop will be performed in a 2D or 3D world.
+## [br]Note that the drop will occur at the same position of the owning node.
+@export_node_path("Node2D", "Node3D") var owning_node_path := NodePath()
+
+
+## It could be either a [Node2D] or [Node3D]
+var owning_node: Variant:
+	get:
+		if owning_node_path != null and not owning_node_path.is_empty():
+			return get_node(owning_node_path)
+		return null
+
+
+## Called when some [Item]s have been dropped.
+func _drop(items: Array[Item]) -> void:
+	var instances: Array[Node] = []
+	var _owning_node = owning_node
+
+	if _owning_node == null:
+		return
+
+	for item in items:
+		if item.scene and item.scene.can_instantiate():
+			var instance = item.scene.instantiate()
+			var nearest_drop = find_nearest_drop()
+
+			instance.position = _owning_node.position
+
+			if nearest_drop:
+				nearest_drop.add_child(instance)
+				nearest_drop.item_dropped.emit(item, instance)
+
+
+## It gets the droppable [Item]s from the [DropTable].
+## [br]It accepts an optional argument [code]drop_modifier[/code] which increases (or decreases if negative) drop chances for each [DropGroup] pool.
+## [br]The greater the modifier, the higher the chances to drop an [Item] from the [member DropTable.pools].
+func drop_items(drop_modifier: float = 0.0) -> void:
+	var items = drop_table.drop(drop_modifier)
+
+	if items.size() > 0:
+		# Who knows what happens in this method. Let's await it.
+		await _drop(items)
+
+		items_dropped.emit(items)
+
+
+## Finds the nearest [Drop2D] or [Drop3D] node.
+## [br]This could be useful in a world-partitioned scenario (like open world rpgs).
+func find_nearest_drop() -> Node:
+	var owner_node = owning_node
+
+	if owner_node == null:
+		return null
+
+	# gets all dropzones
+	var dropzones = get_tree().get_nodes_in_group("ggs.drop-node").duplicate()
+	var position = owner_node.position
+	var is_2d = (owner_node as Node2D) != null
+	var is_3d = (owner_node as Node3D) != null
+
+	if dropzones.size() == 0:
+		return null
+
+
+	# the sorting function, we will take the nearest [Drop2D] or [Drop3D] node.
+	dropzones.sort_custom(func (a: Variant, b: Variant) -> bool:
+		if a is Node2D and b is Node2D and is_2d:
+			return b.position.distance_to(position) > a.position.distance_to(position)
+		elif a is Node3D and b is Node3D and is_3d:
+			return b.position.distance_to(position) > a.position.distance_to(position)
+
+		return false
+	)
+
+	return dropzones[0]
+

addons/godot_gameplay_systems/inventory_system/nodes/drop_2d.gd

@@ -0,0 +1,12 @@
+class_name Drop2D extends Node2D
+
+
+## Is a drop zone in a 2D world
+
+
+# Emitted when items are dropped in this node.
+signal item_dropped(item: Item, node: Node2D)
+
+
+func _ready() -> void:	
+	add_to_group("ggs.drop-node")

addons/godot_gameplay_systems/inventory_system/nodes/drop_3d.gd

@@ -0,0 +1,11 @@
+class_name Drop3D extends Node3D
+
+## Is a drop zone in a 3D world
+
+
+# Emitted when items are dropped in this node.
+signal item_dropped(item: Item, node: Node3D)
+
+
+func _ready() -> void:	
+	add_to_group("ggs.drop-node")

addons/godot_gameplay_systems/inventory_system/plugin.gd

@@ -8,10 +8,20 @@ const item_script = preload("res://addons/godot_gameplay_systems/inventory_syste
 const item_activation_event_script = preload("res://addons/godot_gameplay_systems/inventory_system/objects/item_activation_event.gd")
 const pickable_item_2d = preload("res://addons/godot_gameplay_systems/inventory_system/nodes/pickable_item_2d.gd")
 const pickable_item_3d = preload("res://addons/godot_gameplay_systems/inventory_system/nodes/pickable_item_3d.gd")
+const drop_group_script = preload("res://addons/godot_gameplay_systems/inventory_system/resources/drop_group.gd")
+const drop_table_script = preload("res://addons/godot_gameplay_systems/inventory_system/resources/drop_table.gd")
+const drop_script = preload("res://addons/godot_gameplay_systems/inventory_system/nodes/drop.gd")
+const drop_2d_script = preload("res://addons/godot_gameplay_systems/inventory_system/nodes/drop_2d.gd")
+const drop_3d_script = preload("res://addons/godot_gameplay_systems/inventory_system/nodes/drop_3d.gd")
 
 
 func _enter_tree() -> void:
 	add_custom_type("Item", "Resource", item_script, preload("res://addons/godot_gameplay_systems/inventory_system/assets/ItemIcon.png"))
+	add_custom_type("Drop", "Node", drop_script, preload("res://addons/godot_gameplay_systems/inventory_system/assets/DropIcon.png"))
+	add_custom_type("Drop2D", "Node2D", drop_2d_script, preload("res://addons/godot_gameplay_systems/inventory_system/assets/DropNode2D.png"))
+	add_custom_type("Drop3D", "Node3D", drop_3d_script, preload("res://addons/godot_gameplay_systems/inventory_system/assets/DropNode3D.png"))
+	add_custom_type("DropGroup", "Resource", drop_group_script, preload("res://addons/godot_gameplay_systems/inventory_system/assets/DropGroupIcon.png"))
+	add_custom_type("DropTable", "Resource", drop_table_script, preload("res://addons/godot_gameplay_systems/inventory_system/assets/DropTableIcon.png"))
 	add_custom_type("ItemActivationEvent", "RefCounted", item_activation_event_script, null)
 	add_custom_type("Inventory", "Node", inventory_script, preload("res://addons/godot_gameplay_systems/inventory_system/assets/InventoryIcon.png"))
 	add_custom_type("Equipment", "Node", equipment_script, preload("res://addons/godot_gameplay_systems/inventory_system/assets/EquipmentIcon.png"))
@@ -27,5 +37,10 @@ func _exit_tree() -> void:
 	remove_custom_type("Equipment")
 	remove_custom_type("Inventory")
 	remove_custom_type("ItemActivationEvent")
+	remove_custom_type("DropTable")
+	remove_custom_type("DropGroup")
+	remove_custom_type("Drop")
+	remove_custom_type("Drop3D")
+	remove_custom_type("Drop2D")
 	remove_custom_type("Item")
 

addons/godot_gameplay_systems/inventory_system/resources/drop_group.gd

@@ -0,0 +1,30 @@
+class_name DropGroup extends Resource
+
+## Represents a drop rule.
+##
+## 
+
+@export_category("Drop")
+## Represents the pool of droppable [Item]s.
+@export var items_pool: Array[Item] = []
+## Represents the chance of dropping one item from the [member DropGroup.items_pool] pool.
+## [br]The higher the value, the higher the chances.
+@export_range(0.0, 100.0, 0.01) var drop_chance: float = 50.0
+
+
+## Returns if the group can drop an item from the [member DropGroup.items_pool] pool.
+## [br]It accepts an optional argument [code]drop_modifier[/code] which increases (or decreases if negative) drop chances.
+## [br]The greater the modifier, the higher the chances to drop an [Item] from the pool.
+func can_be_dropped(modifier: float = 0.0) -> bool:
+	return drop_chance + modifier >= randf_range(0.0, 100.0)
+
+
+## Drops an [Item]. 
+## [br]If the drop is unsuccessfull, it returns [code]null[/code].
+## [br]It accepts an optional argument [code]drop_modifier[/code] which increases (or decreases if negative) drop chances.
+## [br]The greater the modifier, the higher the chances to drop an [Item] from the pool.
+func drop(drop_modifier: float = 0.0) -> Item:
+	if can_be_dropped(drop_modifier):
+		return items_pool.pick_random()
+
+	return null

addons/godot_gameplay_systems/inventory_system/resources/drop_table.gd

@@ -0,0 +1,25 @@
+class_name DropTable extends Resource
+
+## Represents a drop table.
+##
+## It has several [DropGroup] pools. Each pool has a chance of dropping one [Item] based on it's [member DropGroup.drop_chance].
+
+@export_category("Drop")
+## An array of [DropGroup]. Each pool can drop one item.
+@export var pools: Array[DropGroup] = []
+
+
+## Drops an array of [Item]s. 
+## [br]It accepts an optional argument [code]drop_modifier[/code] which increases (or decreases if negative) drop chances for each [DropGroup] pool.
+## [br]The greater the modifier, the higher the chances to drop [Item]s from the pools.
+func drop(drop_modifier: float = 0.0) -> Array[Item]:
+	var out: Array[Item] = []
+
+	for pool in pools:
+		var maybe_item = pool.drop(drop_modifier)
+
+		if maybe_item != null:
+			out.append(maybe_item)
+
+	return out
+