Delayed speed increase modifier

Scripts/Bullet.cs

@@ -59,9 +59,14 @@ public partial class Bullet : Area2D
                 {
                     modifier.Applied = true;
                     modifier.TimeModifier.Start(this);
+                    modifier.Elapsed = 0;
+                }
+                else
+                {
+                    modifier.Elapsed += delta;
                 }
 
-                modifier.TimeModifier.Update(this, delta);
+                modifier.TimeModifier.Update(this, delta, modifier.Elapsed);
 
                 // switch (modifier.ModifierType)
                 // {

Scripts/Resources/Modifiers/DelayedContinuousRotationModifier.cs

@@ -5,7 +5,7 @@ namespace Cirno.Scripts.Resources.Modifiers;
 [GlobalClass]
 public partial class DelayedContinuousRotationModifier : TimeModifier
 {
-    public override void Update(Bullet bullet, double delta)
+    public override void Update(Bullet bullet, double delta, double elapsed)
     {
         bullet.RotateSpriteDegrees((float)(Value * delta));
     }

Scripts/Resources/Modifiers/DelayedSpeedIncreaseModifier.cs

@@ -0,0 +1,26 @@
+using Cirno.Scripts.Actors;
+using Godot;
+
+namespace Cirno.Scripts.Resources.Modifiers;
+
+[GlobalClass] 
+public partial class DelayedSpeedIncreaseModifier : TimeModifier
+{
+    
+    [Export] public Tween.TransitionType TransitionType { get; set; } = Tween.TransitionType.Linear;
+    [Export] public Tween.EaseType EaseType { get; set; } = Tween.EaseType.InOut;
+    
+    [Export] public float Duration { get; set; } = 1.0f;
+    
+    public override void Update(Bullet bullet, double delta, double elapsed)
+    {
+        float easedValue = ApplyEasing(Value, elapsed);
+        bullet.Speed += easedValue;
+    } 
+    
+    private float ApplyEasing(float value, double time)
+    {
+        float t = Mathf.Clamp((float)time, 0f, 1f); // Ensure the value stays within range
+        return (float)Tween.InterpolateValue(0f, value, t, Duration, TransitionType, EaseType);
+    }
+}

Scripts/Resources/Modifiers/DelayedSpeedIncreaseModifier.cs.uid

@@ -0,0 +1 @@
+uid://ci2vjo54w7i18

Scripts/Resources/TimeModifier.cs

@@ -17,7 +17,8 @@ public partial class TimeModifier : Resource
         return new ModifierWrapper()
         {
             TimeModifier = this,
-            Applied = false
+            Applied = false,
+            Elapsed = 0.0,
         };
     }
 
@@ -31,7 +32,7 @@ public partial class TimeModifier : Resource
 
     }
 
-    public virtual void Update(Bullet bullet, double delta)
+    public virtual void Update(Bullet bullet, double delta, double elapsed)
     {
         
     }
@@ -41,6 +42,7 @@ public class ModifierWrapper
 {
     public TimeModifier TimeModifier { get; set; }
     public bool Applied { get; set; } = false;
+    public double Elapsed { get; set; } = 0f;
 
     public virtual void Start()
     {