feat: IUniverse.OnTimeChanged event added

Engine.Core/Abstract/IUniverse.cs

@@ -32,6 +32,11 @@ public interface IUniverse : IEntity, IEnumerable<IUniverseObject>
     /// </summary>
     event UniverseObjectUnRegisteredEventHandler? OnUniverseObjectUnRegistered;
 
+    /// <summary>
+    /// Event triggered when <see cref="TimeScale"/> is changed on the <see cref="IUniverse"/>.
+    /// </summary>
+    event TimeScaleChangedEventHandler? OnTimeScaleChanged;
+
     /// <summary>
     /// Current time scale the <see cref="IUniverse"/> operates on.
     /// </summary>
@@ -83,6 +88,8 @@ public interface IUniverse : IEntity, IEnumerable<IUniverseObject>
     /// </summary>
     void PreDraw();
 
+    delegate void TimeScaleChangedEventHandler(IUniverse sender, float previousTimeScale);
+
     delegate void UpdateEventHandler(IUniverse sender, UniverseTime engineTime);
     delegate void PreDrawEventHandler(IUniverse sender);
 

Engine.Core/Universe.cs

@@ -16,6 +16,8 @@ public class Universe : BaseEntity, IUniverse
     public event IUniverse.UniverseObjectRegisteredEventHandler? OnUniverseObjectRegistered = null;
     public event IUniverse.UniverseObjectUnRegisteredEventHandler? OnUniverseObjectUnRegistered = null;
 
+    public event IUniverse.TimeScaleChangedEventHandler? OnTimeScaleChanged = null;
+
     private readonly List<IUniverseObject> _universeObjects = new(Constants.UNIVERSE_OBJECTS_SIZE_INITIAL);
     private float _timeScale = 1f;
 
@@ -26,7 +28,16 @@ public class Universe : BaseEntity, IUniverse
     public float TimeScale
     {
         get => _timeScale;
-        set => _timeScale = value.Max(0f);
+        set
+        {
+            value = value.Max(0f);
+            if (value == _timeScale)
+                return;
+
+            float previousTimeScale = _timeScale;
+            _timeScale = value;
+            OnTimeScaleChanged?.InvokeSafe(this, previousTimeScale);
+        }
     }
 
     public void Register(IUniverseObject universeObject)