Expo easing function + welcome screen

game/Scenes/WelcomeScreen.tscn

@@ -1,6 +1,9 @@
-[gd_scene format=3 uid="uid://57px5totoewp"]
+[gd_scene load_steps=2 format=3 uid="uid://57px5totoewp"]
+
+[ext_resource type="Script" uid="uid://mgj6wd25jrsn" path="res://Scripts/WelcomeScreen/welcome_screen.gd" id="1_5gy0r"]
 
 [node name="WelcomeScreen" type="CanvasLayer"]
+script = ExtResource("1_5gy0r")
 
 [node name="ColorRect" type="ColorRect" parent="."]
 anchors_preset = 15

game/Scripts/WelcomeScreen/welcome_screen.gd

@@ -0,0 +1,43 @@
+extends CanvasLayer
+
+
+# Called when the node enters the scene tree for the first time.
+func _ready() -> void:
+	
+	update_progress_bar(80)
+	
+	
+	pass # Replace with function body.
+
+
+# Called every frame. 'delta' is the elapsed time since the previous frame.
+func _process(delta: float) -> void:
+	pass
+
+
+
+func update_progress_bar(value: float):
+	var start_value = $ProgressBar.value
+	var percent = 0
+	
+	while  percent < 100:
+		var ease = expo_ease_in_out(start_value, value, percent)
+		$ProgressBar.value = ease
+		percent += 1
+		await get_tree().create_timer(0.05).timeout
+
+
+
+func expo_ease_in_out(start: float, end: float, percent: int) -> float:
+	var t: float = clamp(float(percent) / 100.0, 0, 1.0)
+	var change: float = end - start
+	
+	if t == 0:
+		return start
+	if t == 1.0:
+		return end
+		
+	if t < 0.5:
+		return change / 2 * pow(2, 20 * t - 10) + start
+	else:
+		return change / 2 * (-pow(2, -20 * t + 10) + 2) + start

game/Scripts/WelcomeScreen/welcome_screen.gd.uid

@@ -0,0 +1 @@
+uid://mgj6wd25jrsn