Add a savegame system using slots and a main menu, allow player to move RigidBody2Ds using apply_impulse(), increased physics tick, enabled FXAA, and more.

core/globals/gamestate.gd

@@ -0,0 +1,87 @@
+extends Node
+
+# gamestate
+
+var last_entrypoint: String
+
+func reset_gamestate():
+	# defaults
+	last_entrypoint = "intro_start"
+
+# save/load slot
+
+const slot_min: int = 0
+const slot_max: int = 3
+
+var current_slot: int = -1
+var current_slot_locked: bool = false
+
+func _check_slot_idx(idx: int) -> bool:
+	# returns if slot index is valid (in bounds)
+	if idx < slot_min or idx > slot_max:
+		push_error("Slot index %s is invalid." % current_slot)
+		return false
+	return true
+
+func save_slot():
+	# flush game state to slot
+	if _check_slot_idx(current_slot):
+		var slot_path: String = "user://slot%s.save" % current_slot
+		var f = FileAccess.open(slot_path, FileAccess.WRITE)
+		if f == null:
+			push_error("Couldn't open %s" % slot_path)
+			quit(1)
+			return
+		# create serializable data structure
+		var data: Dictionary = {
+			"last_entrypoint": last_entrypoint
+		}
+		var data_serialized = JSON.stringify(data)
+		if data_serialized == null:
+			push_error("Couldn't serialize save data for slot %s" % current_slot)
+			quit(1)
+			return
+		f.store_string(data_serialized)
+
+func load_slot():
+	# load gamestate from slot
+	if _check_slot_idx(current_slot):
+		reset_gamestate() # init gamestate with defaults
+		var slot_path: String = "user://slot%s.save" % current_slot
+		if FileAccess.file_exists(slot_path):
+			var f = FileAccess.open(slot_path, FileAccess.READ)
+			if f == null:
+				push_error("Couldn't open %s" % slot_path)
+				quit(1)
+				return
+			var data_serialized = f.get_as_text()
+			var data = JSON.parse_string(data_serialized)
+			if data == null:
+				push_error("Couldn't deserialize slot %s" % slot_path)
+				quit(1)
+				return
+			# read values
+			last_entrypoint = data["last_entrypoint"]
+		else:
+			save_slot() # new game; save defaults
+
+func reset_slot(idx: int):
+	# reset a save slot
+	if _check_slot_idx(idx):
+		if current_slot == idx:
+			reset_gamestate()
+		# delete slot file
+		var slot_path: String = "user://slot%s.save" % idx
+		if FileAccess.file_exists(slot_path):
+			DirAccess.remove_absolute(slot_path)
+
+#
+
+func quit(code: int):
+	# defer get_tree().quit() to not lose the last error/stdout
+	# see https://github.com/godotengine/godot/issues/90667
+	await get_tree().create_timer(0.1).timeout
+	get_tree().quit(code)
+
+func _ready() -> void:
+	reset_gamestate()

core/globals/levels.gd

@@ -1,59 +1,79 @@
 extends Node
 
+const mainmenu_player_pos: Vector2 = Vector2(0, 128 + 32)
+
 class Entrypoint extends Object:
 	var scene_name: String
 	var player_position: Vector2
-	var reset_physics: bool
+	var initial_velocity: Vector2
 	func _init(
 		scene_name_: String,
 		player_position_: Vector2,
-		reset_physics_: bool
+		initial_velocity_: Vector2 = Vector2.ZERO
 	) -> void:
 		self.scene_name = scene_name_
 		self.player_position = player_position_
-		self.reset_physics = reset_physics_
+		self.initial_velocity = initial_velocity_
 
 const SCENES = {
-	"intro": "uid://c6w7lrydi43ts"
+	"intro": "uid://c6w7lrydi43ts",
+	"test": "uid://dqf665b540tfg",
 }
 
 var ENTRYPOINTS = {
-	"intro_start": Entrypoint.new("intro", Vector2(0, 0), true)
+	"intro_start": Entrypoint.new("intro", Vector2.ZERO),
+	"test": Entrypoint.new("test", Vector2.ZERO),
 }
 
+var MENU_SCENE: PackedScene = preload("res://menu/menu.tscn")
+
 # load that stuff
 
-var level_root: Node
-var player: Node2D
+func _pre_load_checks() -> bool:
+	if NodeRegistry.level_root_container == null:
+		push_error("Can't load level, level_root is not registered yet.")
+		return false
+	if NodeRegistry.player == null:
+		push_error("Can't load entrypoint, player is not registered yet.")
+		return false
+	return true
 
 func load_scene(scn_name: String) -> bool:  # returns true on success
-	if level_root == null:
-		push_error("Can't load level, level_root is not registered yet.")
+	if not _pre_load_checks():
 		return false
 	if not scn_name in SCENES:
 		push_error("Level " + scn_name + " doesn't exist.")
 		return false
 	unload_scene()
 	var scn = load(SCENES[scn_name])
-	level_root.add_child(scn.instantiate())
+	NodeRegistry.level_root_container.add_child(scn.instantiate())
 	return true
 
 func unload_scene():
-	for c in level_root.get_children():
-		c.queue_free()
+	if NodeRegistry.level_root_container != null:
+		for c in NodeRegistry.level_root_container.get_children():
+			c.queue_free()
 
 func load_entrypoint(ep_name: String) -> bool: # returns true on success
 	if not ep_name in ENTRYPOINTS:
 		push_error("Entrypoint " + ep_name + " doesn't exist.")
 		return false
-	if player == null:
-		push_error("Can't load entrypoint, player is not registered yet.")
+	if not _pre_load_checks():
 		return false
 	var e: Entrypoint = ENTRYPOINTS[ep_name]
 	if load_scene(e.scene_name):
-		player.position = e.player_position
-		if e.reset_physics:
-			player.reset_physics()
+		NodeRegistry.player.position = e.player_position
+		NodeRegistry.player.velocity = e.initial_velocity
+		Gamestate.last_entrypoint = ep_name
+		Gamestate.save_slot() # save game
 		return true
 	else:
 		return false
+
+func load_menu():
+	if not _pre_load_checks():
+		return false
+	unload_scene()
+	NodeRegistry.level_root_container.add_child(MENU_SCENE.instantiate())
+	NodeRegistry.player.position = mainmenu_player_pos
+	return true

core/globals/node_registry.gd

@@ -0,0 +1,4 @@
+extends Node
+
+var player: CharacterBody2D
+var level_root_container: Node