Find coin nodes by their group

Previously, game_logic.gd walked recursively over all nodes in the tree,
counting those which are an instance of the Coin script.

A more idiomatic way to do this is to place coins into a group, and then
count how many nodes are in that group. This will also make it easier to
have some coins that don't count towards the goal, by having those coins
not be in this group.

Author: wjt

components/coin/coin.tscn

@@ -6,7 +6,7 @@
 [sub_resource type="CircleShape2D" id="CircleShape2D_5w0o8"]
 radius = 46.72
 
-[node name="Coin" type="Area2D"]
+[node name="Coin" type="Area2D" groups=["coins"]]
 collision_layer = 2
 script = ExtResource("1_4bks0")
 

project.godot

@@ -32,6 +32,7 @@ window/stretch/mode="canvas_items"
 [global_group]
 
 players=""
+coins="Coins that must be collected to win the level"
 
 [input]
 

scripts/rules_goals/game_logic.gd

@@ -44,13 +44,6 @@ func _set_lives(new_lives):
 	Global.lives = lives
 
 
-func _get_all_coins(node, accumulator = []):
-	if node is Coin:
-		accumulator.append(node)
-	for child in node.get_children():
-		_get_all_coins(child, accumulator)
-
-
 # Called when the node enters the scene tree for the first time.
 func _ready():
 	if Engine.is_editor_hint():
@@ -65,9 +58,7 @@ func _ready():
 	if win_by_collecting_coins:
 		Global.coin_collected.connect(_on_coin_collected)
 		if coins_to_win == 0:
-			var coins = []
-			_get_all_coins(get_parent(), coins)
-			coins_to_win = coins.size()
+			coins_to_win = get_tree().get_node_count_in_group(&"coins")
 	if win_by_reaching_flag:
 		Global.flag_raised.connect(_on_flag_raised)