Pong demo: Add area for spawning balls

In Pong the balls spawn at a random position from the center vertical
line. To avoid the maths, one option is to pick a random point from an
Area2D with a thin vertical rectangle as collision shape. The area has
group "ball_spawn_area" so it can be referenced.

Author: manuq

pong_game/ball_spawn_area.tscn

@@ -0,0 +1,9 @@
+[gd_scene load_steps=2 format=3 uid="uid://1ownc3rikn2k"]
+
+[sub_resource type="RectangleShape2D" id="RectangleShape2D_tpd4f"]
+size = Vector2(128, 896)
+
+[node name="BallSpawnArea" type="Area2D"]
+
+[node name="CollisionShape2D" type="CollisionShape2D" parent="."]
+shape = SubResource("RectangleShape2D_tpd4f")

pong_game/pong_game.tscn

@@ -1,4 +1,4 @@
-[gd_scene load_steps=31 format=3 uid="uid://tf7b8c64ecc0"]
+[gd_scene load_steps=32 format=3 uid="uid://tf7b8c64ecc0"]
 
 [ext_resource type="PackedScene" uid="uid://s7enbp56f256" path="res://pong_game/paddle.tscn" id="1_1k5k2"]
 [ext_resource type="Script" path="res://pong_game/pong_game.gd" id="1_bjkc8"]
@@ -10,6 +10,7 @@
 [ext_resource type="Script" path="res://addons/block_code/block_script_data/block_script_data.gd" id="7_uuuue"]
 [ext_resource type="PackedScene" uid="uid://bis7afjjuwypq" path="res://pong_game/hud.tscn" id="8_yg457"]
 [ext_resource type="PackedScene" uid="uid://c7l70grmkauij" path="res://pong_game/ball.tscn" id="9_xrqll"]
+[ext_resource type="PackedScene" uid="uid://1ownc3rikn2k" path="res://pong_game/ball_spawn_area.tscn" id="10_5vs1t"]
 
 [sub_resource type="Resource" id="Resource_535fl"]
 script = ExtResource("5_wr38c")
@@ -152,25 +153,28 @@ script = ExtResource("1_bjkc8")
 
 [node name="PaddleLeft" parent="." instance=ExtResource("1_1k5k2")]
 modulate = Color(0.511, 0.362, 0.972, 1)
-position = Vector2(64, 576)
+position = Vector2(64, 544)
 
 [node name="BlockCode" type="Node" parent="PaddleLeft"]
 script = ExtResource("3_6jaq8")
 bsd = SubResource("Resource_t7nl4")
 
 [node name="PaddleRight" parent="." instance=ExtResource("1_1k5k2")]
 modulate = Color(0.511, 0.362, 0.972, 1)
-position = Vector2(1856, 576)
+position = Vector2(1856, 544)
 
 [node name="BlockCode" type="Node" parent="PaddleRight"]
 script = ExtResource("3_6jaq8")
 bsd = SubResource("Resource_52r02")
 
 [node name="Ball" parent="." instance=ExtResource("9_xrqll")]
 modulate = Color(0.511, 0.362, 0.972, 1)
-position = Vector2(960, 576)
+position = Vector2(960, 544)
 linear_velocity = Vector2(353.553, 353.553)
 
+[node name="BallSpawnArea" parent="." groups=["ball_spawn_area"] instance=ExtResource("10_5vs1t")]
+position = Vector2(960, 544)
+
 [node name="HUD" parent="." instance=ExtResource("8_yg457")]
 
 [node name="BlockCode" type="Node" parent="."]