Introduce the abstract screen

Main.gd

@@ -1,5 +1,35 @@
 extends Node
 
+# The main scene manages the displayed screens
+const BattleScreen = preload("res://screens/battle_screen.tscn")
+
+# Variables
+# The stack of screens. All are displayed one above the others.
+var screens: Array = []
+var current_screen: String
+
 # Called when the node enters the scene tree for the first time.
 func _ready():
+    go_to_battle_screen()
+
+# Function to change screen
+func on_next_screen(screen: String):
+    match screen:
+        'battle':
+            go_to_battle_screen()
+# Function to leave current screen
+func on_leave_screen():
     pass
+
+# Common screen management
+func go_to_screen(type, name):
+    current_screen = name
+    var scr = type.instance()
+    scr.connect("next_screen", self, "on_next_screen")
+    scr.connect("leave_screen", self, "on_leave_screen")
+    screens.push_back(scr)
+    $Screens.add_child(scr)
+
+# Screen transitions
+func go_to_battle_screen():
+    go_to_screen(BattleScreen, 'battle')

Main.tscn

@@ -1,9 +1,10 @@
-[gd_scene load_steps=3 format=2]
+[gd_scene load_steps=2 format=2]
 
-[ext_resource path="res://screens/battle_screen.tscn" type="PackedScene" id=1]
 [ext_resource path="res://Main.gd" type="Script" id=3]
 
 [node name="Main" type="Node"]
 script = ExtResource( 3 )
 
-[node name="BattleScreen" parent="." instance=ExtResource( 1 )]
+[node name="Screens" type="Control" parent="."]
+anchor_right = 1.0
+anchor_bottom = 1.0

project.godot

@@ -10,6 +10,11 @@ config_version=4
 
 _global_script_classes=[ {
 "base": "Control",
+"class": "AbstractScreen",
+"language": "GDScript",
+"path": "res://screens/abstract_screen.gd"
+}, {
+"base": "Control",
 "class": "Gem",
 "language": "GDScript",
 "path": "res://entities/gem.gd"
@@ -25,6 +30,7 @@ _global_script_classes=[ {
 "path": "res://tools/random.gd"
 } ]
 _global_script_class_icons={
+"AbstractScreen": "",
 "Gem": "",
 "LogicalGrid": "",
 "Random": ""

screens/abstract_screen.gd

@@ -0,0 +1,8 @@
+class_name AbstractScreen
+extends Control
+
+# Abstract screen, only for definition of signals
+# Go to a given screen
+signal next_screen(screen_name)
+# Exit current screen
+signal leave_screen()

screens/battle_screen.gd

@@ -1,4 +1,4 @@
-extends Control
+extends AbstractScreen
 
 # Called when the node enters the scene tree for the first time.
 func _ready():

screens/battle_screen.tscn

@@ -4,10 +4,8 @@
 [ext_resource path="res://screens/battle_screen.gd" type="Script" id=2]
 
 [node name="BattleScreen" type="Control"]
-anchor_left = 0.5
-anchor_top = 0.5
-anchor_right = 0.5
-anchor_bottom = 0.5
+anchor_right = 1.0
+anchor_bottom = 1.0
 script = ExtResource( 2 )
 
 [node name="GemGrid" parent="." instance=ExtResource( 1 )]