refactor: update & draw calls have been refactored into systems

Engine.Core/Systems/UpdateManager.cs

@@ -0,0 +1,69 @@
+
+using System.Collections.Generic;
+
+namespace Syntriax.Engine.Core;
+
+public class UpdateManager : UniverseObject
+{
+    private readonly BehaviourCollector<IFirstFrameUpdate> firstFrameUpdates = new();
+    private readonly BehaviourCollector<IPreUpdate> preUpdateEntities = new();
+    private readonly BehaviourCollector<IUpdate> updateEntities = new();
+    private readonly BehaviourCollector<IPostUpdate> postUpdateEntities = new();
+
+    private readonly List<IFirstFrameUpdate> toCallFirstFrameUpdates = [];
+
+    protected override void OnEnteringUniverse(IUniverse universe)
+    {
+        firstFrameUpdates.Assign(universe);
+        preUpdateEntities.Assign(universe);
+        updateEntities.Assign(universe);
+        postUpdateEntities.Assign(universe);
+
+        universe.OnPreUpdate += OnPreUpdate;
+        universe.OnUpdate += OnUpdate;
+        universe.OnPostUpdate += OnPostUpdate;
+    }
+
+    protected override void OnExitingUniverse(IUniverse universe)
+    {
+        firstFrameUpdates.Unassign();
+        preUpdateEntities.Unassign();
+        updateEntities.Unassign();
+        postUpdateEntities.Unassign();
+
+        universe.OnPreUpdate -= OnPreUpdate;
+        universe.OnUpdate -= OnUpdate;
+        universe.OnPostUpdate -= OnPostUpdate;
+    }
+
+    private void OnPreUpdate(IUniverse sender, UniverseTime engineTime)
+    {
+        for (int i = toCallFirstFrameUpdates.Count - 1; i >= 0; i--)
+            toCallFirstFrameUpdates[i].FirstActiveFrame();
+
+        for (int i = preUpdateEntities.Behaviours.Count - 1; i >= 0; i--)
+            preUpdateEntities.Behaviours[i].PreUpdate();
+    }
+
+    private void OnUpdate(IUniverse sender, UniverseTime engineTime)
+    {
+        for (int i = updateEntities.Behaviours.Count - 1; i >= 0; i--)
+            updateEntities.Behaviours[i].Update();
+    }
+
+    private void OnPostUpdate(IUniverse sender, UniverseTime engineTime)
+    {
+        for (int i = postUpdateEntities.Behaviours.Count - 1; i >= 0; i--)
+            postUpdateEntities.Behaviours[i].PostUpdate();
+    }
+
+    private void OnFirstFrameCollected(IBehaviourCollector<IFirstFrameUpdate> sender, IFirstFrameUpdate behaviourCollected)
+    {
+        toCallFirstFrameUpdates.Add(behaviourCollected);
+    }
+
+    public UpdateManager()
+    {
+        firstFrameUpdates.OnCollected += OnFirstFrameCollected;
+    }
+}