implement marathon start screen

menus/marathon_select_lives.gd

@@ -0,0 +1,49 @@
+extends Button
+
+
+const INFINITY_SIGIL := "▬↨"
+
+
+onready var back_arrow: TextureRect = $"../BackArrow"
+onready var next_arrow: TextureRect = $"../NextArrow"
+
+
+func _ready() -> void:
+	_update_display()
+
+
+func _update_display() -> void:
+	if Game.use_lives:
+		text = "%03d" % Game.marathon_lives
+	else:
+		text = INFINITY_SIGIL
+
+
+func _gui_input(event: InputEvent) -> void:
+	if event.is_action_pressed("ui_left"):
+		if Game.use_lives:
+			Game.marathon_lives -= 1
+			if Game.marathon_lives < 0:
+				Game.use_lives = false
+		else:
+			Game.use_lives = true
+			Game.marathon_lives = 999
+	if event.is_action_pressed("ui_right"):
+		if Game.use_lives:
+			Game.marathon_lives += 1
+			if Game.marathon_lives > 999:
+				Game.use_lives = false
+		else:
+			Game.use_lives = true
+			Game.marathon_lives = 0
+	_update_display()
+
+
+func _on_focus_entered() -> void:
+	back_arrow.visible = true
+	next_arrow.visible = true
+
+
+func _on_focus_exited() -> void:
+	back_arrow.visible = false
+	next_arrow.visible = false