refactor: monogame camera transform caching

Engine.Core/Abstract/IBehaviourController.cs

@@ -62,7 +62,8 @@ public interface IBehaviourController : IEntity, IHasUniverseObject
     /// </summary>
     /// <typeparam name="T">The type of <see cref="IBehaviour"/>s to get.</typeparam>
     /// <param name="results">The list to store the <see cref="IBehaviour"/>s.</param>
-    void GetBehaviours<T>(IList<T> results);
+    /// <param name="collectionMethod">Whether to clear the <paramref name="results"/> before collection or append the results to the list.</param>
+    void GetBehaviours<T>(IList<T> results, CollectionMethod collectionMethod = CollectionMethod.Clear);
 
     /// <summary>
     /// Removes <see cref="IBehaviour"/>s of the specified type from the <see cref="IBehaviourController"/>.
@@ -78,6 +79,8 @@ public interface IBehaviourController : IEntity, IHasUniverseObject
     /// <param name="behaviour">The <see cref="IBehaviour"/> to remove.</param>
     void RemoveBehaviour<T>(T behaviour) where T : class, IBehaviour;
 
+    enum CollectionMethod { Clear, Append };
+
     readonly record struct BehaviourAddedArguments(IBehaviour BehaviourAdded);
     readonly record struct BehaviourRemovedArguments(IBehaviour BehaviourRemoved);
 }

Engine.Core/Abstract/ICamera3D.cs

@@ -6,7 +6,32 @@ namespace Engine.Core;
 public interface ICamera3D : IBehaviour3D
 {
     /// <summary>
-    /// Field of View (FOV) value of the camera
+    /// Event triggered when the near plane of the <see cref="ICamera3D"/> changes.
+    /// </summary>
+    Event<ICamera3D, NearPlaneChangedArguments> OnNearPlaneChanged { get; }
+
+    /// <summary>
+    /// Event triggered when the far plane of the <see cref="ICamera3D"/> changes.
+    /// </summary>
+    Event<ICamera3D, FarPlaneChangedArguments> OnFarPlaneChanged { get; }
+
+    /// <summary>
+    /// Event triggered when the field of view of the <see cref="ICamera3D"/> changes.
+    /// </summary>
+    Event<ICamera3D, FieldOfViewChangedArguments> OnFieldOfViewChanged { get; }
+
+    /// <summary>
+    /// Near plane distance of the camera.
+    /// </summary>
+    float NearPlane { get; set; }
+
+    /// <summary>
+    /// Far plane distance of the camera.
+    /// </summary>
+    float FarPlane { get; set; }
+
+    /// <summary>
+    /// Field of View (FOV) value of the camera in degrees.
     /// </summary>
     float FieldOfView { get; set; }
 
@@ -23,4 +48,8 @@ public interface ICamera3D : IBehaviour3D
     /// <param name="worldPosition">The position in world coordinates.</param>
     /// <returns>The position in screen coordinates.</returns>
     Vector2D WorldToScreenPosition(Vector3D worldPosition);
+
+    readonly record struct NearPlaneChangedArguments(float PreviousNearPlane);
+    readonly record struct FarPlaneChangedArguments(float PreviousFarPlane);
+    readonly record struct FieldOfViewChangedArguments(float PreviousFieldOfView);
 }

Engine.Core/Abstract/IEntity.cs

@@ -3,18 +3,4 @@ namespace Engine.Core;
 /// <summary>
 /// Represents a basic entity in the engine.
 /// </summary>
-public interface IEntity : IInitializable, IHasStateEnable
-{
-    /// <summary>
-    /// Event triggered when the <see cref="Id"/> of the <see cref="IEntity"/> changes.
-    /// The string action parameter is the previous <see cref="Id"/> of the <see cref="IEntity"/>. 
-    /// </summary>
-    Event<IEntity, IdChangedArguments> OnIdChanged { get; }
-
-    /// <summary>
-    /// The ID of the <see cref="IEntity"/>.
-    /// </summary>
-    string Id { get; set; }
-
-    readonly record struct IdChangedArguments(string PreviousId);
-}
+public interface IEntity : IInitializable, IIdentifiable, IHasStateEnable;

Engine.Core/Abstract/IHasId.cs

@@ -0,0 +1,20 @@
+namespace Engine.Core;
+
+/// <summary>
+/// Represents any instance in the engine with an id.
+/// </summary>
+public interface IIdentifiable
+{
+    /// <summary>
+    /// Event triggered when the <see cref="Id"/> of the <see cref="IIdentifiable"/> changes.
+    /// The string action parameter is the previous <see cref="Id"/> of the <see cref="IIdentifiable"/>. 
+    /// </summary>
+    Event<IIdentifiable, IdChangedArguments> OnIdChanged { get; }
+
+    /// <summary>
+    /// The ID of the <see cref="IIdentifiable"/>.
+    /// </summary>
+    string Id { get; set; }
+
+    readonly record struct IdChangedArguments(string PreviousId);
+}

Engine.Core/Abstract/IUniverse.cs

@@ -78,9 +78,9 @@ public interface IUniverse : IEntity, IEnumerable<IUniverseObject>
     UniverseTime UnscaledTime { get; }
 
     /// <summary>
-    /// Gets a read-only list of <see cref="IUniverseObject"/>s managed by the <see cref="IUniverse"/>.
+    /// Gets the root <see cref="IUniverseObject"/> of the <see cref="IUniverse"/>.
     /// </summary>
-    IReadOnlyList<IUniverseObject> UniverseObjects { get; }
+    IUniverseObject Root { get; }
 
     /// <summary>
     /// Registers an <see cref="IUniverseObject"/> to the <see cref="IUniverse"/>.

Engine.Core/BaseEntity.cs

@@ -4,7 +4,7 @@ namespace Engine.Core;
 
 public abstract class BaseEntity : IEntity
 {
-    public Event<IEntity, IEntity.IdChangedArguments> OnIdChanged { get; } = new();
+    public Event<IIdentifiable, IIdentifiable.IdChangedArguments> OnIdChanged { get; } = new();
     public Event<IInitializable> OnInitialized { get; } = new();
     public Event<IInitializable> OnFinalized { get; } = new();
     public Event<IHasStateEnable> OnStateEnableAssigned { get; } = new();

Engine.Core/BehaviourController.cs

@@ -58,9 +58,11 @@ public class BehaviourController : BaseEntity, IBehaviourController
         return behaviours;
     }
 
-    public void GetBehaviours<T>(IList<T> results)
+    public void GetBehaviours<T>(IList<T> results, IBehaviourController.CollectionMethod collectionMethod = IBehaviourController.CollectionMethod.Clear)
     {
-        results.Clear();
+        if (collectionMethod == IBehaviourController.CollectionMethod.Clear)
+            results.Clear();
+
         foreach (IBehaviour behaviourItem in behaviours)
         {
             if (behaviourItem is not T behaviour)

Engine.Core/Collectors/ActiveBehaviourCollectorBase.cs

@@ -29,7 +29,7 @@ public abstract class ActiveBehaviourCollectorBase<T> : IBehaviourCollector<T> w
         if (Universe is not null)
             return false;
 
-        foreach (IUniverseObject universeObject in universe.UniverseObjects)
+        foreach (IUniverseObject universeObject in universe)
             OnUniverseObjectRegistered(universe, new(universeObject));
 
         universe.OnUniverseObjectRegistered.AddListener(delegateOnUniverseObjectRegistered);
@@ -46,7 +46,7 @@ public abstract class ActiveBehaviourCollectorBase<T> : IBehaviourCollector<T> w
         if (Universe is null)
             return false;
 
-        foreach (IUniverseObject universeObject in Universe.UniverseObjects)
+        foreach (IUniverseObject universeObject in Universe)
             OnUniverseObjectUnregistered(Universe, new(universeObject));
 
         Universe.OnUniverseObjectRegistered.RemoveListener(delegateOnUniverseObjectRegistered);

Engine.Core/Collectors/ActiveBehaviourCollectorOrdered.cs

@@ -5,9 +5,8 @@ namespace Engine.Core;
 
 public class ActiveBehaviourCollectorOrdered<TIndex, TItem> : ActiveBehaviourCollector<TItem> where TItem : class, IBehaviour where TIndex : IComparable
 {
-    private readonly Event<IBehaviour, IBehaviour.PriorityChangedArguments>.EventHandler delegateOnPriorityChanged = null!;
-
     private readonly SortedDictionary<TIndex, FastList<TItem>> behaviours = null!;
+    private readonly Dictionary<TItem, TIndex> indexCache = [];
 
     private readonly Func<TItem, TIndex> getIndexFunc = null!;
     private readonly IComparer<TIndex> sortBy = null!;
@@ -39,11 +38,10 @@ public class ActiveBehaviourCollectorOrdered<TIndex, TItem> : ActiveBehaviourCol
 
     protected override bool RemoveBehaviour(TItem tBehaviour)
     {
-        TIndex index = getIndexFunc(tBehaviour);
-        if (!behaviours.TryGetValue(index, out FastList<TItem>? list))
+        if (!indexCache.TryGetValue(tBehaviour, out TIndex? index) || !behaviours.TryGetValue(index, out FastList<TItem>? list))
             throw new Exceptions.NotFoundException($"Index of '{index}' is not found in the collector");
 
-        if (!list.Remove(tBehaviour))
+        if (!list.Remove(tBehaviour) || !indexCache.Remove(tBehaviour))
             return false;
 
         count--;
@@ -58,21 +56,11 @@ public class ActiveBehaviourCollectorOrdered<TIndex, TItem> : ActiveBehaviourCol
 
         count++;
         list.Add(behaviour);
-    }
-
-    protected override void OnBehaviourAdd(IBehaviour behaviour) => behaviour.OnPriorityChanged.AddListener(delegateOnPriorityChanged);
-    protected override void OnBehaviourRemove(IBehaviour behaviour) => behaviour.OnPriorityChanged.RemoveListener(delegateOnPriorityChanged);
-
-    private void OnPriorityChanged(IBehaviour sender, IBehaviour.PriorityChangedArguments args)
-    {
-        TItem behaviour = (TItem)sender;
-        RemoveBehaviour(behaviour);
-        AddBehaviour(behaviour);
+        indexCache.Add(behaviour, key);
     }
 
     public ActiveBehaviourCollectorOrdered(Func<TItem, TIndex> getIndexFunc, Comparison<TIndex> sortBy)
     {
-        delegateOnPriorityChanged = OnPriorityChanged;
         this.getIndexFunc = getIndexFunc;
         this.sortBy = Comparer<TIndex>.Create(sortBy);
         behaviours = new(this.sortBy);
@@ -80,7 +68,6 @@ public class ActiveBehaviourCollectorOrdered<TIndex, TItem> : ActiveBehaviourCol
 
     public ActiveBehaviourCollectorOrdered(IUniverse universe, Func<TItem, TIndex> getIndexFunc, Comparison<TIndex> sortBy) : base(universe)
     {
-        delegateOnPriorityChanged = OnPriorityChanged;
         this.getIndexFunc = getIndexFunc;
         this.sortBy = Comparer<TIndex>.Create(sortBy);
         behaviours = new(this.sortBy);
@@ -89,14 +76,12 @@ public class ActiveBehaviourCollectorOrdered<TIndex, TItem> : ActiveBehaviourCol
     public ActiveBehaviourCollectorOrdered(Func<TItem, TIndex> getIndexFunc, IComparer<TIndex> sortBy)
     {
         this.getIndexFunc = getIndexFunc;
-        delegateOnPriorityChanged = OnPriorityChanged;
         this.sortBy = sortBy;
         behaviours = new(sortBy);
     }
 
     public ActiveBehaviourCollectorOrdered(IUniverse universe, Func<TItem, TIndex> getIndexFunc, IComparer<TIndex> sortBy) : base(universe)
     {
-        delegateOnPriorityChanged = OnPriorityChanged;
         this.getIndexFunc = getIndexFunc;
         this.sortBy = sortBy;
         behaviours = new(sortBy);

Engine.Core/Collectors/BehaviourCollectorBase.cs

@@ -25,7 +25,7 @@ public abstract class BehaviourCollectorBase<T> : IBehaviourCollector<T> where T
         if (Universe is not null)
             return false;
 
-        foreach (IUniverseObject universeObject in universe.UniverseObjects)
+        foreach (IUniverseObject universeObject in universe)
             OnUniverseObjectRegistered(universe, new(universeObject));
 
         universe.OnUniverseObjectRegistered.AddListener(delegateOnUniverseObjectRegistered);
@@ -43,7 +43,7 @@ public abstract class BehaviourCollectorBase<T> : IBehaviourCollector<T> where T
         if (Universe is null)
             return false;
 
-        foreach (IUniverseObject universeObject in Universe.UniverseObjects)
+        foreach (IUniverseObject universeObject in Universe)
             OnUniverseObjectUnregistered(Universe, new(universeObject));
 
         Universe.OnUniverseObjectRegistered.RemoveListener(delegateOnUniverseObjectRegistered);

Engine.Core/Collectors/BehaviourCollectorOrdered.cs

@@ -5,9 +5,8 @@ namespace Engine.Core;
 
 public class BehaviourCollectorOrdered<TIndex, TItem> : BehaviourCollectorBase<TItem> where TItem : class where TIndex : IComparable
 {
-    private readonly Event<IBehaviour, IBehaviour.PriorityChangedArguments>.EventHandler delegateOnPriorityChanged = null!;
-
     private readonly SortedDictionary<TIndex, FastList<TItem>> behaviours = null!;
+    private readonly Dictionary<TItem, TIndex> indexCache = null!;
 
     private readonly Func<TItem, TIndex> getIndexFunc = null!;
     private readonly IComparer<TIndex> sortBy = null!;
@@ -39,11 +38,10 @@ public class BehaviourCollectorOrdered<TIndex, TItem> : BehaviourCollectorBase<T
 
     protected override bool RemoveBehaviour(TItem tBehaviour)
     {
-        TIndex index = getIndexFunc(tBehaviour);
-        if (!behaviours.TryGetValue(index, out FastList<TItem>? list))
+        if (!indexCache.TryGetValue(tBehaviour, out TIndex? index) || !behaviours.TryGetValue(index, out FastList<TItem>? list))
             throw new Exceptions.NotFoundException($"Index of '{index}' is not found in the collector");
 
-        if (!list.Remove(tBehaviour))
+        if (!list.Remove(tBehaviour) || !indexCache.Remove(tBehaviour))
             return false;
 
         count--;
@@ -58,21 +56,11 @@ public class BehaviourCollectorOrdered<TIndex, TItem> : BehaviourCollectorBase<T
 
         count++;
         list.Add(behaviour);
-    }
-
-    protected override void OnBehaviourAdd(IBehaviour behaviour) => behaviour.OnPriorityChanged.AddListener(delegateOnPriorityChanged);
-    protected override void OnBehaviourRemove(IBehaviour behaviour) => behaviour.OnPriorityChanged.RemoveListener(delegateOnPriorityChanged);
-
-    private void OnPriorityChanged(IBehaviour sender, IBehaviour.PriorityChangedArguments args)
-    {
-        TItem behaviour = (TItem)sender;
-        RemoveBehaviour(behaviour);
-        AddBehaviour(behaviour);
+        indexCache.Add(behaviour, key);
     }
 
     public BehaviourCollectorOrdered(Func<TItem, TIndex> getIndexFunc, Comparison<TIndex> sortBy)
     {
-        delegateOnPriorityChanged = OnPriorityChanged;
         this.getIndexFunc = getIndexFunc;
         this.sortBy = Comparer<TIndex>.Create(sortBy);
         behaviours = new(this.sortBy);
@@ -80,7 +68,6 @@ public class BehaviourCollectorOrdered<TIndex, TItem> : BehaviourCollectorBase<T
 
     public BehaviourCollectorOrdered(IUniverse universe, Func<TItem, TIndex> getIndexFunc, Comparison<TIndex> sortBy) : base(universe)
     {
-        delegateOnPriorityChanged = OnPriorityChanged;
         this.getIndexFunc = getIndexFunc;
         this.sortBy = Comparer<TIndex>.Create(sortBy);
         behaviours = new(this.sortBy);
@@ -89,14 +76,12 @@ public class BehaviourCollectorOrdered<TIndex, TItem> : BehaviourCollectorBase<T
     public BehaviourCollectorOrdered(Func<TItem, TIndex> getIndexFunc, IComparer<TIndex> sortBy)
     {
         this.getIndexFunc = getIndexFunc;
-        delegateOnPriorityChanged = OnPriorityChanged;
         this.sortBy = sortBy;
         behaviours = new(sortBy);
     }
 
     public BehaviourCollectorOrdered(IUniverse universe, Func<TItem, TIndex> getIndexFunc, IComparer<TIndex> sortBy) : base(universe)
     {
-        delegateOnPriorityChanged = OnPriorityChanged;
         this.getIndexFunc = getIndexFunc;
         this.sortBy = sortBy;
         behaviours = new(sortBy);

Engine.Core/Extensions/BehaviourControllerExtensions.cs

@@ -100,18 +100,16 @@ public static class BehaviourControllerExtensions
     /// </summary>
     /// <typeparam name="T">The type of <see cref="IBehaviour"/>s to get.</typeparam>
     /// <param name="behavioursInParent">The list to store the <see cref="IBehaviour"/>s.</param>
-    public static void GetBehavioursInParent<T>(this IBehaviourController behaviourController, IList<T> behavioursInParent) where T : class
+    /// <param name="collectionMethod">Whether to clear the <paramref name="behavioursInParent"/> before collection or append the results to the list.</param>
+    public static void GetBehavioursInParent<T>(this IBehaviourController behaviourController, IList<T> behavioursInParent, IBehaviourController.CollectionMethod collectionMethod = IBehaviourController.CollectionMethod.Clear) where T : class
     {
-        IBehaviourController? controller = behaviourController;
-        List<T> cache = [];
-        behavioursInParent.Clear();
+        if (collectionMethod == IBehaviourController.CollectionMethod.Clear)
+            behavioursInParent.Clear();
 
+        IBehaviourController? controller = behaviourController;
         while (controller is not null)
         {
-            controller.GetBehaviours(cache);
-            foreach (T behaviour in cache)
-                behavioursInParent.Add(behaviour);
-
+            controller.GetBehaviours(behavioursInParent, IBehaviourController.CollectionMethod.Append);
             controller = controller.UniverseObject.Parent?.BehaviourController;
         }
     }
@@ -161,22 +159,20 @@ public static class BehaviourControllerExtensions
     /// </summary>
     /// <typeparam name="T">The type of <see cref="IBehaviour"/>s to get.</typeparam>
     /// <param name="behavioursInChildren">The list to store the <see cref="IBehaviour"/>s.</param>
-    public static void GetBehavioursInChildren<T>(this IBehaviourController behaviourController, IList<T> behavioursInChildren) where T : class
+    /// <param name="collectionMethod">Whether to clear the <paramref name="behavioursInChildren"/> before collection or append the results to the list.</param>
+    public static void GetBehavioursInChildren<T>(this IBehaviourController behaviourController, IList<T> behavioursInChildren, IBehaviourController.CollectionMethod collectionMethod = IBehaviourController.CollectionMethod.Clear) where T : class
     {
-        List<T> cache = [];
-        behavioursInChildren.Clear();
+        if (collectionMethod == IBehaviourController.CollectionMethod.Clear)
+            behavioursInChildren.Clear();
 
-        TraverseChildrenForBehaviour(behaviourController.UniverseObject, behavioursInChildren, cache);
+        TraverseChildrenForBehaviour(behaviourController.UniverseObject, behavioursInChildren);
     }
 
-    private static void TraverseChildrenForBehaviour<T>(IUniverseObject universeObject, IList<T> behaviours, IList<T> cache) where T : class
+    private static void TraverseChildrenForBehaviour<T>(IUniverseObject universeObject, IList<T> behaviours) where T : class
     {
-        universeObject.BehaviourController.GetBehaviours(cache);
-
-        foreach (T behaviour in cache)
-            behaviours.Add(behaviour);
+        universeObject.BehaviourController.GetBehaviours(behaviours, IBehaviourController.CollectionMethod.Append);
 
         foreach (IUniverseObject child in universeObject.Children)
-            TraverseChildrenForBehaviour(child, behaviours, cache);
+            TraverseChildrenForBehaviour(child, behaviours);
     }
 }

Engine.Core/Extensions/UniverseExtensions.cs

@@ -32,5 +32,5 @@ public static class UniverseExtensions
     /// <typeparam name="T">Type to be searched through the <see cref="IUniverse"/>.</typeparam>
     /// <returns>The specified type if found; otherwise, throws <see cref="NotFoundException"/>.</returns>
     public static T FindRequired<T>(this IUniverse universe) where T : class
-        => universe.Find<T>() ?? throw new NotFoundException($"{universe.GetType().FullName}({universe.Id}) does not contain any {nameof(IUniverseObject)} or {nameof(IBehaviour)} of type {typeof(T).FullName}");
+        => universe.Root.BehaviourController.GetBehaviourInChildren<T>() ?? throw new NotFoundException($"{universe.GetType().FullName}({universe.Id}) does not contain any {nameof(IUniverseObject)} or {nameof(IBehaviour)} of type {typeof(T).FullName}");
 }

Engine.Core/Extensions/UniverseObjectExtensions.cs

@@ -16,6 +16,21 @@ public static class UniverseObjectExtensions
         return universeObject;
     }
 
+    public static IEnumerator<IUniverseObject> TraverseChildren(this IUniverseObject universeObject)
+    {
+        static IEnumerable<IUniverseObject> Traverse(IUniverseObject obj)
+        {
+            foreach (IUniverseObject child in obj.Children)
+            {
+                yield return child;
+                foreach (IUniverseObject descendant in Traverse(child))
+                    yield return descendant;
+            }
+        }
+
+        return Traverse(universeObject).GetEnumerator();
+    }
+
     #region Universe Object Search
     /// <summary>
     /// Gets a <see cref="IUniverseObject"/> of the specified type.

Engine.Core/Math.cs

@@ -110,6 +110,13 @@ public static class Math
     /// <returns>The sine of <paramref name="x"/>.</returns>
     public static float Sin(float x) => MathF.Sin(x);
 
+    /// <summary>
+    /// Returns the tangent of a number.
+    /// </summary>
+    /// <param name="x">The angle, in radians.</param>
+    /// <returns>The tangent of <paramref name="x"/>.</returns>
+    public static float Tan(float x) => MathF.Tan(x);
+
     /// <summary>
     /// Returns the arccosine of a number.
     /// </summary>
@@ -124,6 +131,13 @@ public static class Math
     /// <returns>The arcsine of <paramref name="x"/>.</returns>
     public static float Asin(float x) => MathF.Asin(x);
 
+    /// <summary>
+    /// Returns the angle whose tangent is the specified number.
+    /// </summary>
+    /// <param name="x">The tangent value.</param>
+    /// <returns>The angle, in radians.</returns>
+    public static float Atan(float x) => MathF.Atan(x);
+
     /// <summary>
     /// Returns the angle whose tangent is the quotient of two specified numbers.
     /// </summary>

Engine.Core/MathExtensions.cs

@@ -32,12 +32,18 @@ public static class MathExtensions
     /// <inheritdoc cref="Math.Sin(float)" />
     public static float Sin(this float x) => Math.Sin(x);
 
+    /// <inheritdoc cref="Math.Tan(float)" />
+    public static float Tan(this float x) => Math.Tan(x);
+
     /// <inheritdoc cref="Math.Acos(float)" />
     public static float Acos(this float x) => Math.Acos(x);
 
     /// <inheritdoc cref="Math.Asin(float)" />
     public static float Asin(this float x) => Math.Asin(x);
 
+    /// <inheritdoc cref="Math.Atan(float)" />
+    public static float Atan(this float x) => Math.Atan(x);
+
     /// <inheritdoc cref="Math.Atan2(float, float)" />
     public static float Atan2(this float y, float x) => Math.Atan2(y, x);
 

Engine.Core/Primitives/Matrix4x4.cs

@@ -0,0 +1,294 @@
+using System;
+using System.Numerics;
+
+namespace Engine.Core;
+
+// TODO Comments
+
+/// <summary>
+/// Represents a 4D left handed space matrix.
+/// </summary>
+/// <remarks>
+/// Initializes a new instance of the <see cref="Matrix4x4"/> struct with the specified values.
+/// </remarks>
+[System.Diagnostics.DebuggerDisplay("{ToString(),nq}")]
+public readonly struct Matrix4x4(
+    float m11, float m12, float m13, float m14,
+    float m21, float m22, float m23, float m24,
+    float m31, float m32, float m33, float m34,
+    float m41, float m42, float m43, float m44
+) : IEquatable<Matrix4x4>
+{
+    public readonly float M11 = m11, M12 = m12, M13 = m13, M14 = m14;
+    public readonly float M21 = m21, M22 = m22, M23 = m23, M24 = m24;
+    public readonly float M31 = m31, M32 = m32, M33 = m33, M34 = m34;
+    public readonly float M41 = m41, M42 = m42, M43 = m43, M44 = m44;
+
+    /// <summary>
+    /// Extracts the position (translation) from the <see cref="Matrix4x4"/>.
+    /// </summary>
+    public readonly Vector3D Position => new(M41, M42, M43);
+
+    /// <summary>
+    /// Extracts the scale from the <see cref="Matrix4x4"/>.
+    /// </summary>
+    public readonly Vector3D Scale
+    {
+        get
+        {
+            float scaleX = new Vector3D(M11, M12, M13).Length();
+            float scaleY = new Vector3D(M21, M22, M23).Length();
+            float scaleZ = new Vector3D(M31, M32, M33).Length();
+
+            if (Determinant(this) < 0)
+                scaleX *= -1;
+
+            return new(scaleX, scaleY, scaleZ);
+        }
+    }
+
+    /// <summary>
+    /// Extracts the rotation from the <see cref="Matrix4x4"/>.
+    /// </summary>
+    public readonly Quaternion Rotation => Quaternion.FromRotationMatrix4x4(this).Normalized;
+
+    /// <summary>
+    /// Represents the identity <see cref="Matrix4x4"/>.
+    /// </summary>
+    public static Matrix4x4 Identity => new(
+        1f, 0f, 0f, 0f,
+        0f, 1f, 0f, 0f,
+        0f, 0f, 1f, 0f,
+        0f, 0f, 0f, 1f
+    );
+
+    public static Matrix4x4 operator *(Matrix4x4 a, Matrix4x4 b) => new(
+        a.M11 * b.M11 + a.M12 * b.M21 + a.M13 * b.M31 + a.M14 * b.M41,
+        a.M11 * b.M12 + a.M12 * b.M22 + a.M13 * b.M32 + a.M14 * b.M42,
+        a.M11 * b.M13 + a.M12 * b.M23 + a.M13 * b.M33 + a.M14 * b.M43,
+        a.M11 * b.M14 + a.M12 * b.M24 + a.M13 * b.M34 + a.M14 * b.M44,
+
+        a.M21 * b.M11 + a.M22 * b.M21 + a.M23 * b.M31 + a.M24 * b.M41,
+        a.M21 * b.M12 + a.M22 * b.M22 + a.M23 * b.M32 + a.M24 * b.M42,
+        a.M21 * b.M13 + a.M22 * b.M23 + a.M23 * b.M33 + a.M24 * b.M43,
+        a.M21 * b.M14 + a.M22 * b.M24 + a.M23 * b.M34 + a.M24 * b.M44,
+
+        a.M31 * b.M11 + a.M32 * b.M21 + a.M33 * b.M31 + a.M34 * b.M41,
+        a.M31 * b.M12 + a.M32 * b.M22 + a.M33 * b.M32 + a.M34 * b.M42,
+        a.M31 * b.M13 + a.M32 * b.M23 + a.M33 * b.M33 + a.M34 * b.M43,
+        a.M31 * b.M14 + a.M32 * b.M24 + a.M33 * b.M34 + a.M34 * b.M44,
+
+        a.M41 * b.M11 + a.M42 * b.M21 + a.M43 * b.M31 + a.M44 * b.M41,
+        a.M41 * b.M12 + a.M42 * b.M22 + a.M43 * b.M32 + a.M44 * b.M42,
+        a.M41 * b.M13 + a.M42 * b.M23 + a.M43 * b.M33 + a.M44 * b.M43,
+        a.M41 * b.M14 + a.M42 * b.M24 + a.M43 * b.M34 + a.M44 * b.M44
+    );
+
+    public static bool operator ==(Matrix4x4 left, Matrix4x4 right) =>
+        left.M11 == right.M11 && left.M12 == right.M12 && left.M13 == right.M13 && left.M14 == right.M14 &&
+        left.M21 == right.M21 && left.M22 == right.M22 && left.M23 == right.M23 && left.M24 == right.M24 &&
+        left.M31 == right.M31 && left.M32 == right.M32 && left.M33 == right.M33 && left.M34 == right.M34 &&
+        left.M41 == right.M41 && left.M42 == right.M42 && left.M43 == right.M43 && left.M44 == right.M44;
+
+    public static bool operator !=(Matrix4x4 left, Matrix4x4 right) =>
+        left.M11 != right.M11 || left.M12 != right.M12 || left.M13 != right.M13 || left.M14 != right.M14 ||
+        left.M21 != right.M21 || left.M22 != right.M22 || left.M23 != right.M23 || left.M24 != right.M24 ||
+        left.M31 != right.M31 || left.M32 != right.M32 || left.M33 != right.M33 || left.M34 != right.M34 ||
+        left.M41 != right.M41 || left.M42 != right.M42 || left.M43 != right.M43 || left.M44 != right.M44;
+
+    public static implicit operator System.Numerics.Matrix4x4(Matrix4x4 m) => new(
+        m.M11, m.M12, m.M13, m.M14,
+        m.M21, m.M22, m.M23, m.M24,
+        m.M31, m.M32, m.M33, m.M34,
+        m.M41, m.M42, m.M43, m.M44
+    );
+
+    public static implicit operator Matrix4x4(System.Numerics.Matrix4x4 m) => new(
+        m.M11, m.M12, m.M13, m.M14,
+        m.M21, m.M22, m.M23, m.M24,
+        m.M31, m.M32, m.M33, m.M34,
+        m.M41, m.M42, m.M43, m.M44
+    );
+
+    /// <summary>
+    /// Calculates the determinant of the <see cref="Matrix4x4"/>.
+    /// </summary>
+    /// <param name="m">The <see cref="Matrix4x4"/>.</param>
+    /// <returns>The determinant of the <see cref="Matrix4x4"/>.</returns>
+    public static float Determinant(Matrix4x4 m) => // https://www.euclideanspace.com/maths/algebra/matrix/functions/determinant/fourD/index.htm
+         m.M14 * m.M23 * m.M32 * m.M41 - m.M13 * m.M24 * m.M32 * m.M41 -
+         m.M14 * m.M22 * m.M33 * m.M41 + m.M12 * m.M24 * m.M33 * m.M41 +
+         m.M13 * m.M22 * m.M34 * m.M41 - m.M12 * m.M23 * m.M34 * m.M41 -
+         m.M14 * m.M23 * m.M31 * m.M42 + m.M13 * m.M24 * m.M31 * m.M42 +
+         m.M14 * m.M21 * m.M33 * m.M42 - m.M11 * m.M24 * m.M33 * m.M42 -
+         m.M13 * m.M21 * m.M34 * m.M42 + m.M11 * m.M23 * m.M34 * m.M42 +
+         m.M14 * m.M22 * m.M31 * m.M43 - m.M12 * m.M24 * m.M31 * m.M43 -
+         m.M14 * m.M21 * m.M32 * m.M43 + m.M11 * m.M24 * m.M32 * m.M43 +
+         m.M12 * m.M21 * m.M34 * m.M43 - m.M11 * m.M22 * m.M34 * m.M43 -
+         m.M13 * m.M22 * m.M31 * m.M44 + m.M12 * m.M23 * m.M31 * m.M44 +
+         m.M13 * m.M21 * m.M32 * m.M44 - m.M11 * m.M23 * m.M32 * m.M44 -
+         m.M12 * m.M21 * m.M33 * m.M44 + m.M11 * m.M22 * m.M33 * m.M44;
+
+    public static Matrix4x4 CreateTranslation(Vector3D position) => new(
+        1f, 0f, 0f, 0f,
+        0f, 1f, 0f, 0f,
+        0f, 0f, 1f, 0f,
+        position.X, position.Y, position.Z, 1
+    );
+
+    public static Matrix4x4 CreateScale(Vector3D scale) => new(
+        scale.X, 0f, 0f, 0f,
+        0f, scale.Y, 0f, 0f,
+        0f, 0f, scale.Z, 0f,
+        0f, 0f, 0f, 1f
+    );
+
+    public static Matrix4x4 CreateRotationX(float radians)
+    {
+        float c = Math.Cos(radians);
+        float s = Math.Sin(radians);
+
+        return new Matrix4x4(
+            1f, 0f, 0f, 0f,
+            0f, c, s, 0f,
+            0f, -s, c, 0f,
+            0f, 0f, 0f, 1f
+        );
+    }
+
+    public static Matrix4x4 CreateRotationY(float radians)
+    {
+        float c = Math.Cos(radians);
+        float s = Math.Sin(radians);
+
+        return new Matrix4x4(
+            c, 0f, -s, 0f,
+            0f, 1f, 0f, 0f,
+            s, 0f, c, 0f,
+            0f, 0f, 0f, 1f
+        );
+    }
+
+    public static Matrix4x4 CreateRotationZ(float radians)
+    {
+        float c = Math.Cos(radians);
+        float s = Math.Sin(radians);
+
+        return new Matrix4x4(
+            c, s, 0f, 0f,
+            -s, c, 0f, 0f,
+            0f, 0f, 1f, 0f,
+            0f, 0f, 0f, 1f
+        );
+    }
+
+    // TODO Find a better calculation for this 
+    public static Matrix4x4 CreateRotation(Quaternion quaternion)
+    {
+        Vector3D angles = quaternion.ToAngles();
+        return Identity * CreateRotationX(angles.X) * CreateRotationY(angles.Y) * CreateRotationZ(angles.Z);
+    }
+
+    public static Matrix4x4 CreateLookMatrix(Vector3D forward, Vector3D up)
+    {
+        Vector3D z = forward.Normalized;
+        Vector3D x = up.Cross(z).Normalized;
+        Vector3D y = z.Cross(x);
+
+        return new Matrix4x4(
+            x.X, y.X, z.X, 0f,
+            x.Y, y.Y, z.Y, 0f,
+            x.Z, y.Z, z.Z, 0f,
+            0f, 0f, 0f, 1f
+        );
+    }
+
+    public static Matrix4x4 CreateLookMatrix(Vector3D position, Vector3D target, Vector3D up)
+    {
+        Vector3D z = position.FromTo(target).Normalized;
+        Vector3D x = up.Cross(z).Normalized;
+        Vector3D y = z.Cross(x);
+
+        return new Matrix4x4(
+            x.X, y.X, z.X, 0f,
+            x.Y, y.Y, z.Y, 0f,
+            x.Z, y.Z, z.Z, 0f,
+            -x.Dot(position), -y.Dot(position), -z.Dot(position), 1f
+        );
+    }
+
+    public static Matrix4x4 CreatePerspectiveFieldOfView(float fieldOfViewInRadians, float aspectRatio, float nearPlane, float farPlane)
+    {
+        float yScale = 1f / Math.Tan(fieldOfViewInRadians / 2f);
+        float xScale = yScale / aspectRatio;
+
+        return new Matrix4x4(
+            xScale, 0f, 0f, 0f,
+            0f, yScale, 0f, 0f,
+            0f, 0f, farPlane / (farPlane - nearPlane), 1f,
+            0f, 0f, -nearPlane * farPlane / (farPlane - nearPlane), 0f
+        );
+    }
+
+    public static Matrix4x4 ToRightHanded(Matrix4x4 m) => new(
+        m.M11, m.M12, m.M13, m.M14,
+        m.M31, m.M32, m.M33, m.M34,
+        m.M21, m.M22, m.M23, m.M24,
+        m.M41, m.M42, m.M43, m.M44
+    );
+
+    public override bool Equals(object? obj) => obj is Matrix4x4 matrix && this == matrix;
+    public bool Equals(Matrix4x4 other) => this == other;
+
+    public override int GetHashCode()
+    {
+        HashCode hashCode = new();
+        hashCode.Add(M11); hashCode.Add(M12); hashCode.Add(M13); hashCode.Add(M14);
+        hashCode.Add(M21); hashCode.Add(M22); hashCode.Add(M23); hashCode.Add(M24);
+        hashCode.Add(M31); hashCode.Add(M32); hashCode.Add(M33); hashCode.Add(M34);
+        hashCode.Add(M41); hashCode.Add(M42); hashCode.Add(M43); hashCode.Add(M44);
+        return hashCode.ToHashCode();
+    }
+
+    public override string ToString() => $"Matrix4x4({M11}, {M12}, {M13}, {M14},{M21}, {M22}, {M23}, {M24},{M31}, {M32}, {M33}, {M34},{M41}, {M42}, {M43}, {M44})";
+}
+
+/// <summary>
+/// Provides extension methods for <see cref="Matrix4x4"/> type.
+/// </summary>
+public static class Matrix4x4Extensions
+{
+    /// <inheritdoc cref="Matrix4x4.Determinant(Matrix4x4)" />
+    public static float Determinant(this Matrix4x4 matrix) => Matrix4x4.Determinant(matrix);
+
+    /// <inheritdoc cref="Matrix4x4.CreateTranslation(Vector3D)" />
+    public static Matrix4x4 ApplyTranslation(this Matrix4x4 matrix, Vector3D translation) => matrix * Matrix4x4.CreateTranslation(translation);
+
+    /// <inheritdoc cref="Matrix4x4.CreateScale(Vector3D)" />
+    public static Matrix4x4 ApplyScale(this Matrix4x4 matrix, Vector3 scale) => matrix * Matrix4x4.CreateScale(scale);
+
+    /// <inheritdoc cref="Matrix4x4.CreateRotationZ(float)" />
+    public static Matrix4x4 ApplyRotationX(this Matrix4x4 matrix, float radians) => matrix * Matrix4x4.CreateRotationX(radians);
+
+    /// <inheritdoc cref="Matrix4x4.CreateRotationY(float)" />
+    public static Matrix4x4 ApplyRotationY(this Matrix4x4 matrix, float radians) => matrix * Matrix4x4.CreateRotationY(radians);
+
+    /// <inheritdoc cref="Matrix4x4.CreateRotationZ(float)" />
+    public static Matrix4x4 ApplyRotationZ(this Matrix4x4 matrix, float radians) => matrix * Matrix4x4.CreateRotationZ(radians);
+
+    /// <inheritdoc cref="Matrix4x4.CreateRotation(Quater)" />
+    public static Matrix4x4 ApplyRotation(this Matrix4x4 matrix, Quaternion quaternion) => matrix * Matrix4x4.CreateRotation(quaternion);
+
+    /// <inheritdoc cref="Matrix4x4.CreateLookMatrix( Vector3D, Vector3D)" />
+    public static Matrix4x4 ApplyLookRotationTo(this Matrix4x4 matrix, Vector3D forward, Vector3 up) => matrix * Matrix4x4.CreateLookMatrix(forward, up);
+
+    /// <inheritdoc cref="Matrix4x4.CreateLookMatrix(Vector3D, Vector3D, Vector3D)" />
+    public static Matrix4x4 CreateLookMatrixTo(this Vector3D from, Vector3D to, Vector3 up) => Matrix4x4.CreateLookMatrix(from, to, up);
+
+    /// <inheritdoc cref="Matrix4x4.CreatePerspectiveFieldOfView(float, float, float, float)" />
+    public static Matrix4x4 ApplyPerspectiveFieldOfView(this Matrix4x4 matrix, float fieldOfViewInRadians, float aspectRatio, float nearPlane, float farPlane)
+        => matrix * Matrix4x4.CreatePerspectiveFieldOfView(fieldOfViewInRadians, aspectRatio, nearPlane, farPlane);
+
+    /// <inheritdoc cref="Matrix4x4.ToRightHanded(Matrix4x4) />
+    public static Matrix4x4 ToRightHanded(this Matrix4x4 matrix) => Matrix4x4.ToRightHanded(matrix);
+}

Engine.Core/Primitives/Quaternion.cs

@@ -156,6 +156,27 @@ public readonly struct Quaternion(float x, float y, float z, float w) : IEquatab
     /// <returns>The normalized <see cref="Quaternion"/>.</returns>
     public static Quaternion Normalize(Quaternion quaternion) => quaternion / Length(quaternion);
 
+    public static Quaternion LookAt(Vector3D origin, Vector3D target, Vector3D up) => LookAt(target - origin, up);
+    public static Quaternion LookAt(Vector3D target, Vector3D up)
+    {
+        Vector3D forward = target.Normalized;
+
+        if (forward.LengthSquared() < 1e-6f)
+            return Identity;
+
+        Vector3D right = up.Cross(forward).Normalized;
+        Vector3D newUp = forward.Cross(right);
+
+        Matrix4x4 rot = new(
+            right.X, right.Y, right.Z, 0f,
+            newUp.X, newUp.Y, newUp.Z, 0f,
+            forward.X, forward.Y, forward.Z, 0f,
+            0f, 0f, 0f, 1f
+        );
+
+        return FromRotationMatrix4x4(rot);
+    }
+
     /// <summary>
     /// Rotates a <see cref="Quaternion"/> around a axis by the specified angle (in radians).
     /// </summary>
@@ -212,8 +233,8 @@ public readonly struct Quaternion(float x, float y, float z, float w) : IEquatab
             dot = -dot;
         }
 
-        if (dot > 0.9995f)
-            return Lerp(from, to, t);
+        if (dot > 0.999999f)
+            return to;
 
         float angle = Math.Acos(dot);
         float sinAngle = Math.Sin(angle);
@@ -276,12 +297,11 @@ public readonly struct Quaternion(float x, float y, float z, float w) : IEquatab
     }
 
     /// <summary>
-    /// Calculates the <see cref="System.Numerics.Matrix4x4"/> from given <see cref="Quaternion"/>.
+    /// Calculates the <see cref="Matrix4x4"/> from given <see cref="Quaternion"/>.
     /// </summary>
-    /// <param name="axis">The axis of the rotation in <see cref="Vector3D"/>.</param>
-    /// <param name="angle">The angle in radians.</param>
-    /// <returns>The rotation <see cref="System.Numerics.Matrix4x4"/> calculated by the given <see cref="Quaternion"/>.</returns>
-    public static System.Numerics.Matrix4x4 ToRotationMatrix4x4(Quaternion quaternion)
+    /// <param name="quaternion">The rotation <see cref="Quaternion"/>.</param>
+    /// <returns>The rotation <see cref="Matrix4x4"/> calculated by the given <see cref="Quaternion"/>.</returns>
+    public static Matrix4x4 ToRotationMatrix4x4(Quaternion quaternion)
     {
         float m00 = 1 - 2 * (quaternion.Y * quaternion.Y + quaternion.Z * quaternion.Z);
         float m01 = 2 * (quaternion.X * quaternion.Y - quaternion.W * quaternion.Z);
@@ -311,6 +331,52 @@ public readonly struct Quaternion(float x, float y, float z, float w) : IEquatab
         );
     }
 
+    /// <summary>
+    /// Calculates the <see cref="Quaternion"/> from given <see cref="Matrix4x4"/>.
+    /// </summary>
+    /// <param name="martix">The rotation <see cref="Matrix4x4"/>.</param>
+    /// <returns>The rotation <see cref="Quaternion"/> calculated by the given <see cref="Matrix4x4"/>.</returns>
+    public static Quaternion FromRotationMatrix4x4(Matrix4x4 martix)
+    {
+        float trace = martix.M11 + martix.M22 + martix.M33;
+        float w, x, y, z;
+
+        if (trace > 0)
+        {
+            float s = Math.Sqrt(trace + 1.0f) * 2f;
+            w = .25f * s;
+            x = (martix.M23 - martix.M32) / s;
+            y = (martix.M31 - martix.M13) / s;
+            z = (martix.M12 - martix.M21) / s;
+        }
+        else if ((martix.M11 > martix.M22) && (martix.M11 > martix.M33))
+        {
+            float s = Math.Sqrt(1.0f + martix.M11 - martix.M22 - martix.M33) * 2f;
+            w = (martix.M23 - martix.M32) / s;
+            x = .25f * s;
+            y = (martix.M12 + martix.M21) / s;
+            z = (martix.M31 + martix.M13) / s;
+        }
+        else if (martix.M22 > martix.M33)
+        {
+            float s = Math.Sqrt(1.0f + martix.M22 - martix.M11 - martix.M33) * 2f;
+            w = (martix.M31 - martix.M13) / s;
+            x = (martix.M12 + martix.M21) / s;
+            y = .25f * s;
+            z = (martix.M23 + martix.M32) / s;
+        }
+        else
+        {
+            float s = Math.Sqrt(1.0f + martix.M33 - martix.M11 - martix.M22) * 2f;
+            w = (martix.M12 - martix.M21) / s;
+            x = (martix.M31 + martix.M13) / s;
+            y = (martix.M23 + martix.M32) / s;
+            z = .25f * s;
+        }
+
+        return new(x, y, z, w);
+    }
+
     /// <summary>
     /// Checks if two <see cref="Quaternion"/>s are approximately equal within a specified epsilon range.
     /// </summary>
@@ -393,7 +459,7 @@ public static class QuaternionExtensions
     public static float Dot(this Quaternion left, Quaternion right) => Quaternion.Dot(left, right);
 
     /// <inheritdoc cref="Quaternion.ToRotationMatrix4x4(Quaternion, Quaternion)" />
-    public static System.Numerics.Matrix4x4 ToRotationMatrix4x4(this Quaternion quaternion) => Quaternion.ToRotationMatrix4x4(quaternion);
+    public static Matrix4x4 ToRotationMatrix4x4(this Quaternion quaternion) => Quaternion.ToRotationMatrix4x4(quaternion);
 
     /// <inheritdoc cref="Quaternion.FromAxisAngle(Vector3D, float)" />
     public static Quaternion CreateRotation(this Vector3D axis, float angle) => Quaternion.FromAxisAngle(axis, angle);

Engine.Core/Serialization/EntityRegistry.cs

@@ -1,39 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-namespace Engine.Core.Serialization;
-
-public class EntityRegistry
-{
-    public Event<EntityRegistry, EntityRegisteredArguments> OnEntityRegistered = null!;
-
-    private readonly Dictionary<string, Action<IEntity>?> assignCallbacks = [];
-    private readonly Dictionary<string, IEntity> registeredEntities = [];
-    public IReadOnlyDictionary<string, IEntity> RegisteredEntities => registeredEntities;
-
-    public void Add(IEntity entity)
-    {
-        if (registeredEntities.TryAdd(entity.Id, entity))
-            OnEntityRegistered?.Invoke(this, new(entity));
-    }
-
-    public void QueueAssign(string id, Action<IEntity> setMethod)
-    {
-        assignCallbacks.TryAdd(id, null);
-        assignCallbacks[id] = assignCallbacks[id] + setMethod;
-    }
-
-    public void AssignAll()
-    {
-        foreach ((string id, Action<IEntity>? action) in assignCallbacks)
-            action?.Invoke(registeredEntities[id]);
-    }
-
-    public void Reset()
-    {
-        assignCallbacks.Clear();
-        registeredEntities.Clear();
-    }
-
-    public readonly record struct EntityRegisteredArguments(IEntity Entity);
-}

Engine.Core/Serialization/IdentifiableRegistry.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+
+namespace Engine.Core.Serialization;
+
+public class IdentifiableRegistry
+{
+    public Event<IdentifiableRegistry, EntityRegisteredArguments> OnEntityRegistered = null!;
+
+    private readonly Dictionary<string, Action<IIdentifiable>?> assignCallbacks = [];
+    private readonly Dictionary<string, IIdentifiable> registeredEntities = [];
+    public IReadOnlyDictionary<string, IIdentifiable> RegisteredEntities => registeredEntities;
+
+    public void Add(IIdentifiable identifiable)
+    {
+        if (registeredEntities.TryAdd(identifiable.Id, identifiable))
+            OnEntityRegistered?.Invoke(this, new(identifiable));
+    }
+
+    public void QueueAssign(string id, Action<IIdentifiable> setMethod)
+    {
+        assignCallbacks.TryAdd(id, null);
+        assignCallbacks[id] = assignCallbacks[id] + setMethod;
+    }
+
+    public void AssignAll()
+    {
+        foreach ((string id, Action<IIdentifiable>? action) in assignCallbacks)
+            action?.Invoke(registeredEntities[id]);
+    }
+
+    public void Reset()
+    {
+        assignCallbacks.Clear();
+        registeredEntities.Clear();
+    }
+
+    public readonly record struct EntityRegisteredArguments(IIdentifiable Entity);
+}

Engine.Core/Serialization/SerializedClass.cs

@@ -43,8 +43,8 @@ public class SerializedClass
                 continue;
 
             object? value = privatePropertyInfo.GetValue(@class);
-            if (value is IEntity entity)
-                Private.Add(privatePropertyInfo.Name, entity.Id);
+            if (value is IIdentifiable identifiable)
+                Private.Add(privatePropertyInfo.Name, identifiable.Id);
             else
                 Private.Add(privatePropertyInfo.Name, value);
         }
@@ -61,8 +61,8 @@ public class SerializedClass
                 continue;
 
             object? value = publicPropertyInfo.GetValue(@class);
-            if (value is IEntity entity)
-                Public.Add(publicPropertyInfo.Name, entity.Id);
+            if (value is IIdentifiable identifiable)
+                Public.Add(publicPropertyInfo.Name, identifiable.Id);
             else
                 Public.Add(publicPropertyInfo.Name, value);
         }
@@ -76,8 +76,8 @@ public class SerializedClass
                 continue;
 
             object? value = privateFieldInfo.GetValue(@class);
-            if (value is IEntity entity)
-                Private.Add(privateFieldInfo.Name, entity.Id);
+            if (value is IIdentifiable identifiable)
+                Private.Add(privateFieldInfo.Name, identifiable.Id);
             else
                 Private.Add(privateFieldInfo.Name, value);
         }
@@ -91,8 +91,8 @@ public class SerializedClass
                 continue;
 
             object? value = publicFieldInfo.GetValue(@class);
-            if (value is IEntity entity)
-                Public.Add(publicFieldInfo.Name, entity.Id);
+            if (value is IIdentifiable identifiable)
+                Public.Add(publicFieldInfo.Name, identifiable.Id);
             else
                 Public.Add(publicFieldInfo.Name, value);
         }
@@ -112,36 +112,36 @@ public class SerializedClass
         return instance;
     }
 
-    public object CreateInstance(EntityRegistry? entityRegistry)
+    public object CreateInstance(IdentifiableRegistry? identifiableRegistry)
     {
-        if (entityRegistry is null)
+        if (identifiableRegistry is null)
             return CreateInstance();
 
         Type type = TypeFactory.GetType(Type);
         object instance = TypeFactory.Get(type);
 
         foreach ((string key, object? value) in Private)
-            AssignVariable(key, type, instance, value, PRIVATE_BINDING_FLAGS, entityRegistry);
+            AssignVariable(key, type, instance, value, PRIVATE_BINDING_FLAGS, identifiableRegistry);
 
         foreach ((string key, object? value) in Public)
-            AssignVariable(key, type, instance, value, PUBLIC_BINDING_FLAGS, entityRegistry);
+            AssignVariable(key, type, instance, value, PUBLIC_BINDING_FLAGS, identifiableRegistry);
 
         return instance;
     }
 
-    private static void AssignVariable(string key, Type type, object instance, object? value, BindingFlags bindingFlags, EntityRegistry entityRegistry)
+    private static void AssignVariable(string key, Type type, object instance, object? value, BindingFlags bindingFlags, IdentifiableRegistry identifiableRegistry)
     {
         if (type.GetField(key, bindingFlags) is FieldInfo fieldInfo)
         {
-            if (typeof(IEntity).IsAssignableFrom(fieldInfo.FieldType))
-                entityRegistry.QueueAssign(value?.ToString() ?? "", (entity) => fieldInfo.SetValue(instance, entity));
+            if (typeof(IIdentifiable).IsAssignableFrom(fieldInfo.FieldType))
+                identifiableRegistry.QueueAssign(value?.ToString() ?? "", (entity) => fieldInfo.SetValue(instance, entity));
             else
                 fieldInfo.SetValue(instance, value);
         }
         else if (type.GetProperty(key, bindingFlags) is PropertyInfo propertyInfo)
         {
-            if (typeof(IEntity).IsAssignableFrom(propertyInfo.PropertyType))
-                entityRegistry.QueueAssign(value?.ToString() ?? "", (entity) => propertyInfo.SetValue(instance, entity));
+            if (typeof(IIdentifiable).IsAssignableFrom(propertyInfo.PropertyType))
+                identifiableRegistry.QueueAssign(value?.ToString() ?? "", (entity) => propertyInfo.SetValue(instance, entity));
             else
                 propertyInfo.SetValue(instance, value);
         }

Engine.Core/Systems/UniverseEntranceManager.cs

@@ -9,7 +9,6 @@ public class UniverseEntranceManager : Internal.BehaviourIndependent
     private static System.Func<IBehaviour, int> GetPriority() => (b) => b.Priority;
 
     private readonly ActiveBehaviourCollectorOrdered<int, IEnterUniverse> enterUniverses = new(GetPriority(), SortByAscendingPriority());
-    private readonly ActiveBehaviourCollectorOrdered<int, IExitUniverse> exitUniverses = new(GetPriority(), SortByAscendingPriority());
 
     private readonly List<IEnterUniverse> toCallEnterUniverses = new(32);
     private readonly List<IExitUniverse> toCallExitUniverses = new(32);
@@ -21,9 +20,8 @@ public class UniverseEntranceManager : Internal.BehaviourIndependent
         // event it tries to call OnUniverseObjectRegistered again on the same object, causing a duplicate entry error.
         Debug.Assert.AssertTrue(BehaviourController.Count == 1, $"{nameof(UniverseEntranceManager)} must be in it's own {nameof(IUniverseObject)} with no other {nameof(IBehaviour)}s attached at the moment. Failing to do so might cause instantiation or serialization issues.");
         enterUniverses.Assign(universe);
-        exitUniverses.Assign(universe);
 
-        foreach (IUniverseObject universeObject in universe.UniverseObjects)
+        foreach (IUniverseObject universeObject in universe)
             OnUniverseObjectRegistered(universe, new(universeObject));
 
         universe.OnUniverseObjectRegistered.AddListener(OnUniverseObjectRegistered);
@@ -33,9 +31,8 @@ public class UniverseEntranceManager : Internal.BehaviourIndependent
     protected override void OnExitedUniverse(IUniverse universe)
     {
         enterUniverses.Unassign();
-        exitUniverses.Unassign();
 
-        foreach (IUniverseObject universeObject in universe.UniverseObjects)
+        foreach (IUniverseObject universeObject in universe)
             OnUniverseObjectUnRegistered(universe, new(universeObject));
 
         universe.OnUniverseObjectRegistered.RemoveListener(OnUniverseObjectRegistered);
@@ -44,6 +41,8 @@ public class UniverseEntranceManager : Internal.BehaviourIndependent
 
     private void OnUniverseObjectUnRegistered(IUniverse sender, IUniverse.UniverseObjectUnRegisteredArguments args)
     {
+        args.UniverseObjectUnregistered.BehaviourController.GetBehavioursInChildren(toCallExitUniverses);
+
         for (int i = toCallExitUniverses.Count - 1; i >= 0; i--)
         {
             IExitUniverse exitUniverse = toCallExitUniverses[i];
@@ -67,14 +66,8 @@ public class UniverseEntranceManager : Internal.BehaviourIndependent
         toCallEnterUniverses.Add(args.BehaviourCollected);
     }
 
-    private void OnExitUniverseCollected(IBehaviourCollector<IExitUniverse> sender, IBehaviourCollector<IExitUniverse>.BehaviourCollectedArguments args)
-    {
-        toCallExitUniverses.Add(args.BehaviourCollected);
-    }
-
     public UniverseEntranceManager()
     {
         enterUniverses.OnCollected.AddListener(OnEnterUniverseCollected);
-        exitUniverses.OnCollected.AddListener(OnExitUniverseCollected);
     }
 }

Engine.Core/Universe.cs

@@ -31,7 +31,7 @@ public class Universe : BaseEntity, IUniverse
         delegateOnUniverseObjectExitedUniverse = OnUniverseObjectExitedUniverse;
     }
 
-    public IReadOnlyList<IUniverseObject> UniverseObjects => _universeObjects;
+    public IUniverseObject Root { get; private set; } = Factory.UniverseObjectFactory.Instantiate().SetUniverseObject("Root");
 
     public UniverseTime Time { get; private set; } = new();
     public UniverseTime UnscaledTime { get; private set; } = new();
@@ -63,14 +63,17 @@ public class Universe : BaseEntity, IUniverse
         if (!universeObject.Initialize())
             throw new Exception($"{universeObject.Name} can't be initialized");
 
-        for (int i = 0; i < universeObject.Children.Count; i++)
-            Register(universeObject.Children[i]);
+        if (universeObject.Parent == null)
+            universeObject.Parent = Root;
 
         _universeObjects.Add(universeObject);
 
         if (!universeObject.EnterUniverse(this))
             throw new Exception($"{universeObject.Name} can't enter the universe");
 
+        for (int i = 0; i < universeObject.Children.Count; i++)
+            Register(universeObject.Children[i]);
+
         OnUniverseObjectRegistered?.Invoke(this, new(universeObject));
     }
 
@@ -113,15 +116,15 @@ public class Universe : BaseEntity, IUniverse
 
     protected override void InitializeInternal()
     {
-        foreach (IUniverseObject universeObject in UniverseObjects)
+        foreach (IUniverseObject universeObject in _universeObjects)
             universeObject.Initialize();
     }
 
     protected override void FinalizeInternal()
     {
         base.FinalizeInternal();
-        for (int i = UniverseObjects.Count - 1; i >= 0; i--)
-            Remove(UniverseObjects[i]);
+        for (int i = _universeObjects.Count - 1; i >= 0; i--)
+            Remove(_universeObjects[i]);
     }
 
     public void Update(UniverseTime engineTime)
@@ -158,6 +161,6 @@ public class Universe : BaseEntity, IUniverse
             Remove(universeObject);
     }
 
-    public IEnumerator<IUniverseObject> GetEnumerator() => _universeObjects.GetEnumerator();
-    IEnumerator IEnumerable.GetEnumerator() => _universeObjects.GetEnumerator();
+    public IEnumerator<IUniverseObject> GetEnumerator() => Root.TraverseChildren();
+    IEnumerator IEnumerable.GetEnumerator() => Root.TraverseChildren();
 }

Engine.Integration/Engine.Integration.LiteNetLib/LiteNetLibClient.cs

@@ -11,6 +11,7 @@ namespace Engine.Systems.Network;
 public class LiteNetLibClient : LiteNetLibCommunicatorBase, INetworkCommunicatorClient
 {
     private readonly NetDataWriter netDataWriter = new();
+    private readonly NetDataWriter netDataWriterEncrypted = new();
 
     private CancellationTokenSource? cancellationTokenSource = null;
 
@@ -42,7 +43,20 @@ public class LiteNetLibClient : LiteNetLibCommunicatorBase, INetworkCommunicator
     public INetworkCommunicatorClient SendToServer<T>(T packet, PacketDelivery packetDelivery) where T : class, new()
     {
         netDataWriter.Reset();
-        netPacketProcessor.Write(netDataWriter, packet);
+        netDataWriterEncrypted.Reset();
+
+        if (packet is INetworkPacketEncrypted)
+        {
+            netPacketProcessor.Write(netDataWriterEncrypted, packet);
+            byte[] encryptedData = cryptor.Encrypt(netDataWriterEncrypted.CopyData());
+            netDataWriter.Put(true);
+            netDataWriter.PutBytesWithLength(encryptedData);
+        }
+        else
+        {
+            netDataWriter.Put(false);
+            netPacketProcessor.Write(netDataWriter, packet);
+        }
 
         switch (packetDelivery)
         {

Engine.Integration/Engine.Integration.LiteNetLib/LiteNetLibCommunicatorBase.cs

@@ -12,6 +12,7 @@ namespace Engine.Systems.Network;
 public abstract class LiteNetLibCommunicatorBase : Behaviour, IEnterUniverse, IExitUniverse, INetworkCommunicator
 {
     protected readonly NetPacketProcessor netPacketProcessor = new();
+    protected readonly PacketCryptor cryptor = new("At4ywW9PGoWH3g==", "NmpMFTvd3pvUbA=="); // TODO implement public key exchange
 
     private readonly Dictionary<Type, Event<IConnection, object>> listeners = [];
     private readonly Dictionary<string, IConnection> _connections = [];
@@ -54,7 +55,20 @@ public abstract class LiteNetLibCommunicatorBase : Behaviour, IEnterUniverse, IE
 
     private void NetworkReceiveEvent(NetPeer peer, NetPacketReader reader, byte channel, DeliveryMethod deliveryMethod)
     {
-        try { netPacketProcessor.ReadAllPackets(reader, peer); }
+        try
+        {
+            bool isEncrypted = reader.GetBool();
+            if (isEncrypted) // TODO performance improvements 
+            {
+                byte[] encryptedData = reader.GetBytesWithLength();
+                byte[] decryptedData = cryptor.Decrypt(encryptedData);
+                NetDataReader innerReader = new(decryptedData);
+                netPacketProcessor.ReadAllPackets(innerReader, peer);
+                return;
+            }
+
+            netPacketProcessor.ReadAllPackets(reader, peer);
+        }
         catch (Exception exception) { logger?.LogException(this, exception, force: true); }
     }
 

Engine.Integration/Engine.Integration.LiteNetLib/LiteNetLibServer.cs

@@ -13,6 +13,7 @@ public class LiteNetLibServer : LiteNetLibCommunicatorBase, INetworkCommunicator
     public int Port { get; private set; } = 8888;
 
     private readonly NetDataWriter netDataWriter = new();
+    private readonly NetDataWriter netDataWriterEncrypted = new();
 
     public LiteNetLibServer() : this(8888, 2) { }
     public LiteNetLibServer(int port, int maxConnectionCount) : base()
@@ -53,11 +54,25 @@ public class LiteNetLibServer : LiteNetLibCommunicatorBase, INetworkCommunicator
     public INetworkCommunicatorServer SendToClient<T>(IConnection connection, T packet, PacketDelivery packetDelivery) where T : class, new()
     {
         netDataWriter.Reset();
-        netPacketProcessor.Write(netDataWriter, packet);
 
-        if (Manager.ConnectedPeerList.FirstOrDefault(p => p.Id.CompareTo(connection.Id) == 0) is not NetPeer netPeer)
+        if (Manager.ConnectedPeerList.FirstOrDefault(p => p.Id.ToString().CompareTo(connection.Id) == 0) is not NetPeer netPeer)
             throw new($"Peer {connection} couldn't be found.");
 
+        if (packet is INetworkPacketEncrypted) // TODO performance improvements 
+        {
+            netDataWriterEncrypted.Reset();
+            netPacketProcessor.Write(netDataWriterEncrypted, packet);
+            byte[] encryptedData = cryptor.Encrypt(netDataWriterEncrypted.CopyData());
+
+            netDataWriter.Put(true);
+            netDataWriter.PutBytesWithLength(encryptedData);
+        }
+        else
+        {
+            netDataWriter.Put(false);
+            netPacketProcessor.Write(netDataWriter, packet);
+        }
+
         switch (packetDelivery)
         {
             case PacketDelivery.ReliableInOrder: netPeer.Send(netDataWriter, DeliveryMethod.ReliableOrdered); break;
@@ -75,6 +90,23 @@ public class LiteNetLibServer : LiteNetLibCommunicatorBase, INetworkCommunicator
         netDataWriter.Reset();
         netPacketProcessor.Write(netDataWriter, packet);
 
+        if (packet is INetworkPacketEncrypted)
+        {
+            netDataWriterEncrypted.Reset();
+
+            logger?.Log($"Encrypted Packet Sending");
+            netPacketProcessor.Write(netDataWriterEncrypted, packet);
+            byte[] encryptedData = cryptor.Encrypt(netDataWriterEncrypted.CopyData());
+            netDataWriter.PutBytesWithLength(encryptedData);
+            netDataWriter.Put(true);
+        }
+        else
+        {
+            logger?.Log($"Regular Packet Sending");
+            netPacketProcessor.Write(netDataWriter, packet);
+            netDataWriter.Put(false);
+        }
+
         switch (packetDelivery)
         {
             case PacketDelivery.ReliableInOrder: Manager.SendToAll(netDataWriter, DeliveryMethod.ReliableOrdered); break;

Engine.Integration/Engine.Integration.LiteNetLib/PacketCryptor.cs

@@ -0,0 +1,26 @@
+using System.Security.Cryptography;
+using System.Text;
+
+namespace Engine.Systems.Network;
+
+public class PacketCryptor // TODO performance improvements 
+{
+    private readonly Aes aes = null!;
+
+    private readonly ICryptoTransform encrpytor = null!;
+    private readonly ICryptoTransform decryptor = null!;
+
+    public byte[] Encrypt(byte[] data) => encrpytor.TransformFinalBlock(data, 0, data.Length);
+    public byte[] Decrypt(byte[] data) => decryptor.TransformFinalBlock(data, 0, data.Length);
+
+    public PacketCryptor(string key, string initializationVector)
+    {
+        aes = Aes.Create();
+
+        aes.Key = Encoding.UTF8.GetBytes(key);
+        aes.IV = Encoding.UTF8.GetBytes(initializationVector);
+
+        encrpytor = aes.CreateEncryptor();
+        decryptor = aes.CreateDecryptor();
+    }
+}

Engine.Integration/Engine.Integration.MonoGame/Behaviours/MonoGameCamera2D.cs

@@ -5,7 +5,7 @@ using Engine.Core;
 
 namespace Engine.Integration.MonoGame;
 
-public class MonoGameCamera2D : Behaviour, ICamera2D, IFirstFrameUpdate, IPreDraw
+public class MonoGameCamera2D : Behaviour, ICamera2D, IFirstFrameUpdate, ILastFrameUpdate, IPreDraw
 {
     public Event<MonoGameCamera2D> OnMatrixTransformChanged { get; } = new();
     public Event<MonoGameCamera2D> OnViewportChanged { get; } = new();
@@ -56,7 +56,7 @@ public class MonoGameCamera2D : Behaviour, ICamera2D, IFirstFrameUpdate, IPreDra
         get => _zoom;
         set
         {
-            float newValue = Engine.Core.Math.Max(0.1f, value);
+            float newValue = Math.Max(0.1f, value);
 
             if (_zoom == newValue)
                 return;
@@ -84,22 +84,21 @@ public class MonoGameCamera2D : Behaviour, ICamera2D, IFirstFrameUpdate, IPreDra
         return screenPosition.Scale(EngineConverterExtensions.screenScale);
     }
 
+    public void LastActiveFrame() => Transform = null!;
     public void FirstActiveFrame()
     {
         Graphics = BehaviourController.UniverseObject.Universe.FindRequiredBehaviour<MonoGameWindowContainer>().Window.Graphics;
         Viewport = Graphics.GraphicsDevice.Viewport;
+        Transform = BehaviourController.GetRequiredBehaviour<ITransform2D>();
     }
 
     public void PreDraw()
     {
         MatrixTransform =
             Matrix.CreateTranslation(new Vector3(-Position.X, Position.Y, 0f)) *
-            Matrix.CreateRotationZ(Rotation * Engine.Core.Math.DegreeToRadian) *
+            Matrix.CreateRotationZ(Rotation * Math.DegreeToRadian) *
             Matrix.CreateScale(Transform.Scale.X.Max(Transform.Scale.Y)) *
             Matrix.CreateScale(Zoom) *
             Matrix.CreateTranslation(new Vector3(_viewport.Width * .5f, _viewport.Height * .5f, 0f));
     }
-
-    protected sealed override void InitializeInternal() => Transform = BehaviourController.GetRequiredBehaviour<ITransform2D>();
-    protected sealed override void FinalizeInternal() => Transform = null!;
 }

Engine.Integration/Engine.Integration.MonoGame/Behaviours/MonoGameCamera3D.cs

@@ -5,17 +5,23 @@ using Engine.Core;
 
 namespace Engine.Integration.MonoGame;
 
-public class MonoGameCamera3D : Behaviour, ICamera3D, IFirstFrameUpdate, IPreDraw
+public class MonoGameCamera3D : Behaviour, ICamera3D, IFirstFrameUpdate, ILastFrameUpdate, IPreDraw
 {
     public Event<MonoGameCamera3D, ViewChangedArguments> OnViewChanged { get; } = new();
     public Event<MonoGameCamera3D, ProjectionChangedArguments> OnProjectionChanged { get; } = new();
     public Event<MonoGameCamera3D, ViewportChangedArguments> OnViewportChanged { get; } = new();
-    public Event<MonoGameCamera3D, FieldOfViewChangedArguments> OnFieldOfViewChanged { get; } = new();
+
+    public Event<ICamera3D, ICamera3D.NearPlaneChangedArguments> OnNearPlaneChanged { get; } = new();
+    public Event<ICamera3D, ICamera3D.FarPlaneChangedArguments> OnFarPlaneChanged { get; } = new();
+    public Event<ICamera3D, ICamera3D.FieldOfViewChangedArguments> OnFieldOfViewChanged { get; } = new();
 
     private Matrix _view = Matrix.Identity;
     private Matrix _projection = Matrix.Identity;
     private Viewport _viewport = default;
-    private float _fieldOfView = 1f;
+    private float _nearPlane = 0.01f;
+    private float _farPlane = 100f;
+    private float _fieldOfView = Math.DegreeToRadian * 70f;
+    private bool isRecalculationNeeded = true;
 
     public GraphicsDeviceManager Graphics { get; private set; } = null!;
     public ITransform3D Transform { get; private set; } = null!;
@@ -47,12 +53,6 @@ public class MonoGameCamera3D : Behaviour, ICamera3D, IFirstFrameUpdate, IPreDra
         }
     }
 
-    public Vector3D Position
-    {
-        get => Transform.Position;
-        set => Transform.Position = value;
-    }
-
     public Viewport Viewport
     {
         get => _viewport;
@@ -63,32 +63,52 @@ public class MonoGameCamera3D : Behaviour, ICamera3D, IFirstFrameUpdate, IPreDra
 
             Viewport previousViewport = _viewport;
             _viewport = value;
+            SetForRecalculation();
             OnViewportChanged.Invoke(this, new(previousViewport));
         }
     }
 
+    public float NearPlane
+    {
+        get => _nearPlane;
+        set
+        {
+            float previousNearPlane = _nearPlane;
+            _nearPlane = value.Max(0.0001f);
+            SetForRecalculation();
+            OnNearPlaneChanged.Invoke(this, new(previousNearPlane));
+        }
+    }
+
+    public float FarPlane
+    {
+        get => _farPlane;
+        set
+        {
+            float previousFarPlane = _farPlane;
+            _farPlane = value.Max(NearPlane);
+            SetForRecalculation();
+            OnFarPlaneChanged.Invoke(this, new(previousFarPlane));
+        }
+    }
+
     public float FieldOfView
     {
-        get => _fieldOfView;
+        get => _fieldOfView * Math.RadianToDegree;
         set
         {
-            float newValue = Math.Max(0.1f, value);
+            value = value.Max(0.1f) * Math.DegreeToRadian;
 
-            if (_fieldOfView == newValue)
+            if (_fieldOfView == value)
                 return;
 
             float previousFieldOfView = _fieldOfView;
-            _fieldOfView = newValue;
+            _fieldOfView = value;
+            SetForRecalculation();
             OnFieldOfViewChanged.Invoke(this, new(previousFieldOfView));
         }
     }
 
-    public Engine.Core.Quaternion Rotation
-    {
-        get => Transform.Rotation;
-        set => Transform.Rotation = value;
-    }
-
     // TODO This causes delay since OnPreDraw calls assuming this is called in in Update 
     public Ray3D ScreenToWorldRay(Vector2D screenPosition)
     {
@@ -104,28 +124,61 @@ public class MonoGameCamera3D : Behaviour, ICamera3D, IFirstFrameUpdate, IPreDra
 
     public Vector2D WorldToScreenPosition(Vector3D worldPosition) => Viewport.Project(worldPosition.ToVector3(), _projection, _view, Matrix.Identity).ToVector3D();
 
+    public void LastActiveFrame() => Transform.OnTransformUpdated.RemoveListener(SetDirtyOnTransformUpdate);
     public void FirstActiveFrame()
     {
+        Transform = BehaviourController.GetRequiredBehaviour<ITransform3D>();
         Graphics = BehaviourController.UniverseObject.Universe.FindRequiredBehaviour<MonoGameWindowContainer>().Window.Graphics;
         Viewport = Graphics.GraphicsDevice.Viewport;
+
+        Transform.OnTransformUpdated.AddListener(SetDirtyOnTransformUpdate);
     }
 
+    private void SetDirtyOnTransformUpdate(ITransform3D sender) => SetForRecalculation();
+    private void SetForRecalculation() => isRecalculationNeeded = true;
+
     public void PreDraw()
     {
-        Vector3 cameraPosition = Position.ToVector3();
-        View = Matrix.CreateLookAt(
-            cameraPosition,
-            Transform.Forward.ToVector3() + cameraPosition,
-            Transform.Up.ToVector3()
-        );
-        Projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, Viewport.AspectRatio, 0.1f, 100f);
+        if (!isRecalculationNeeded)
+            return;
+
+        CalculateView();
+        CalculateProjection();
+        isRecalculationNeeded = false;
     }
 
-    protected sealed override void InitializeInternal() => Transform = BehaviourController.GetRequiredBehaviour<ITransform3D>();
-    protected sealed override void FinalizeInternal() => Transform = null!;
+    private void CalculateView()
+    {
+        Vector3 forward = Vector3.Normalize(Transform.Forward.ToVector3());
+        Vector3 up = Vector3.Normalize(Transform.Up.ToVector3());
+        Vector3 right = Vector3.Normalize(Transform.Right.ToVector3());
+        Vector3 position = Transform.Position.ToVector3();
+
+        View = new Matrix(
+            right.X, up.X, forward.X, 0,
+            right.Y, up.Y, forward.Y, 0,
+            right.Z, up.Z, forward.Z, 0,
+            -Vector3.Dot(right, position),
+            -Vector3.Dot(up, position),
+            -Vector3.Dot(forward, position),
+            1
+        );
+    }
+
+    private void CalculateProjection()
+    {
+        float yScale = 1f / (float)Math.Tan(_fieldOfView / 2f);
+        float xScale = yScale / Viewport.AspectRatio;
+
+        Projection = new Matrix(
+            xScale, 0, 0, 0,
+            0, yScale, 0, 0,
+            0, 0, _farPlane / (_farPlane - _nearPlane), 1,
+            0, 0, -_nearPlane * _farPlane / (_farPlane - _nearPlane), 0
+        );
+    }
 
     public readonly record struct ViewChangedArguments(Matrix PreviousView);
     public readonly record struct ProjectionChangedArguments(Matrix PreviousProjection);
     public readonly record struct ViewportChangedArguments(Viewport PreviousViewport);
-    public readonly record struct FieldOfViewChangedArguments(float PreviousFieldOfView);
 }

Engine.Integration/Engine.Integration.MonoGame/EngineConverter.cs

@@ -41,6 +41,14 @@ public static class EngineConverterExtensions
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static Vector3 ToVector3(this Vector3D vector) => new(vector.X, vector.Y, vector.Z);
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static Matrix ToXnaMatrix(this Matrix4x4 m) => new(
+        m.M11, m.M12, m.M13, m.M14,
+        m.M21, m.M22, m.M23, m.M24,
+        m.M31, m.M32, m.M33, m.M34,
+        m.M41, m.M42, m.M43, m.M44
+    );
+
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static Microsoft.Xna.Framework.Quaternion ToXnaQuaternion(this Core.Quaternion quaternion) => new(quaternion.X, quaternion.Y, quaternion.Z, quaternion.W);
 

Engine.Integration/Engine.Integration.MonoGame/MonoGameWindow.cs

@@ -19,10 +19,12 @@ public class MonoGameWindow : Game
         IsMouseVisible = true;
         Universe = universe ?? new Universe();
 
-        Universe.InstantiateUniverseObject().SetUniverseObject("Window Container")
+        IUniverseObject monogameParent = Universe.InstantiateUniverseObject().SetUniverseObject("MonoGame");
+
+        Universe.InstantiateUniverseObject().SetUniverseObject("Window Container", monogameParent)
             .BehaviourController.AddBehaviour<MonoGameWindowContainer>(this);
 
-        Universe.InstantiateUniverseObject().SetUniverseObject("Content Loader")
+        Universe.InstantiateUniverseObject().SetUniverseObject("Content Loader", monogameParent)
             .BehaviourController.AddBehaviour<LoadContentManager>();
     }
 

Engine.Integration/Engine.Integration.Yaml/Converters/Abstract/IEngineTypeYamlConverter.cs

@@ -8,6 +8,6 @@ namespace Engine.Serializers.Yaml;
 public interface IEngineTypeYamlConverter : IYamlTypeConverter
 {
     YamlSerializer Serializer { get; set; }
-    EntityRegistry EntityRegistry { get; set; }
+    IdentifiableRegistry IdentifiableRegistry { get; set; }
     IProgressionTracker ProgressionTracker { get; set; }
 }

Engine.Integration/Engine.Integration.Yaml/Converters/BehaviourControllerConverter.cs

@@ -36,7 +36,7 @@ public class BehaviourControllerConverter : EngineTypeYamlSerializerBase<IBehavi
             throw new();
         SerializedClass instanceSerializedClass = (SerializedClass)rootDeserializer(typeof(SerializedClass))!;
         ProgressionTracker.Set(isTrackingController ? .5f : ProgressionTracker.Progression, $"Creating {instanceSerializedClass.Type}");
-        behaviourController = (IBehaviourController)instanceSerializedClass.CreateInstance(EntityRegistry);
+        behaviourController = (IBehaviourController)instanceSerializedClass.CreateInstance(IdentifiableRegistry);
 
         string value = parser.Consume<Scalar>().Value;
         if (value.CompareTo(nameof(IBehaviourController.StateEnable)) != 0)

Engine.Integration/Engine.Integration.Yaml/Converters/BehaviourConverter.cs

@@ -36,7 +36,7 @@ public class BehaviourConverter : EngineTypeYamlSerializerBase<IBehaviour>
             throw new();
         SerializedClass instanceSerializedClass = (SerializedClass)rootDeserializer(typeof(SerializedClass))!;
         ProgressionTracker.Set(isTrackingController ? .5f : ProgressionTracker.Progression, $"Creating {instanceSerializedClass.Type}");
-        behaviour = (IBehaviour)instanceSerializedClass.CreateInstance(EntityRegistry);
+        behaviour = (IBehaviour)instanceSerializedClass.CreateInstance(IdentifiableRegistry);
 
         if (parser.Consume<Scalar>().Value.CompareTo(nameof(IBehaviour.StateEnable)) != 0)
             throw new();

Engine.Integration/Engine.Integration.Yaml/Converters/EngineTypeYamlConverterBase.cs

@@ -12,7 +12,7 @@ public abstract class EngineTypeYamlSerializerBase<T> : IEngineTypeYamlConverter
 {
     protected const string SERIALIZED_SCALAR_NAME = "Properties";
 
-    public EntityRegistry EntityRegistry { get; set; } = null!;
+    public IdentifiableRegistry IdentifiableRegistry { get; set; } = null!;
     public YamlSerializer Serializer { get; set; } = null!;
     public IProgressionTracker ProgressionTracker { get; set; } = null!;
 
@@ -24,7 +24,7 @@ public abstract class EngineTypeYamlSerializerBase<T> : IEngineTypeYamlConverter
         T? result = Read(parser, type, rootDeserializer);
 
         if (result is IEntity entity)
-            EntityRegistry.Add(entity);
+            IdentifiableRegistry.Add(entity);
 
         return result;
     }

Engine.Integration/Engine.Integration.Yaml/Converters/StateEnableConverter.cs

@@ -29,7 +29,7 @@ public class StateEnableConverter : EngineTypeYamlSerializerBase<IStateEnable>
         if (parser.Consume<Scalar>().Value.CompareTo(SERIALIZED_SCALAR_NAME) != 0)
             throw new();
         SerializedClass instanceSerializedClass = (SerializedClass)rootDeserializer(typeof(SerializedClass))!;
-        stateEnable = (IStateEnable)instanceSerializedClass.CreateInstance(EntityRegistry);
+        stateEnable = (IStateEnable)instanceSerializedClass.CreateInstance(IdentifiableRegistry);
 
         parser.Consume<MappingEnd>();
 

Engine.Integration/Engine.Integration.Yaml/Converters/UniverseConverter.cs

@@ -22,7 +22,7 @@ public class UniverseConverter : EngineTypeYamlSerializerBase<IUniverse>
 
         IUniverse universe;
         IStateEnable stateEnable;
-        List<IUniverseObject> universeObjects;
+        IUniverseObject rootUniverseObject;
 
         parser.Consume<MappingStart>();
 
@@ -34,16 +34,16 @@ public class UniverseConverter : EngineTypeYamlSerializerBase<IUniverse>
             throw new();
         SerializedClass instanceSerializedClass = (SerializedClass)rootDeserializer(typeof(SerializedClass))!;
         ProgressionTracker.Set(isTrackingController ? .2f : ProgressionTracker.Progression, $"Creating {instanceSerializedClass.Type}");
-        universe = (IUniverse)instanceSerializedClass.CreateInstance(EntityRegistry);
+        universe = (IUniverse)instanceSerializedClass.CreateInstance(IdentifiableRegistry);
 
         if (parser.Consume<Scalar>().Value.CompareTo(nameof(IUniverse.StateEnable)) != 0)
             throw new();
         stateEnable = (IStateEnable)rootDeserializer(typeof(IStateEnable))!;
 
         ProgressionTracker.Set(isTrackingController ? .5f : ProgressionTracker.Progression, $"Reading universe objects");
-        if (parser.Consume<Scalar>().Value.CompareTo(nameof(IUniverse.UniverseObjects)) != 0)
+        if (parser.Consume<Scalar>().Value.CompareTo(nameof(IUniverse.Root)) != 0)
             throw new();
-        universeObjects = (List<IUniverseObject>)rootDeserializer(typeof(List<IUniverseObject>))!;
+        rootUniverseObject = (IUniverseObject)rootDeserializer(typeof(IUniverseObject))!;
 
         parser.Consume<MappingEnd>();
 
@@ -52,13 +52,12 @@ public class UniverseConverter : EngineTypeYamlSerializerBase<IUniverse>
         stateEnable.Assign(universe);
         universe.Assign(stateEnable);
 
-        ProgressionTracker.Set(isTrackingController ? .9f : ProgressionTracker.Progression, "Registering universe objects");
-        for (int i = 0; i < universeObjects.Count; i++)
+        ProgressionTracker.Set(isTrackingController ? .9f : ProgressionTracker.Progression, "Registering root universe object");
+        for (int i = rootUniverseObject.Children.Count - 1; i >= 0; i--)
         {
-            IUniverseObject uo = universeObjects[i];
-            ProgressionTracker.Set(isTrackingController ? .9f + .1f * ((float)i / universeObjects.Count) : ProgressionTracker.Progression, $"Registering {uo.Name}");
-
-            universe.Register(uo);
+            IUniverseObject uo = rootUniverseObject.Children[i];
+            ProgressionTracker.Set(isTrackingController ? .9f + .1f * ((float)i / rootUniverseObject.Children.Count) : ProgressionTracker.Progression, $"Registering {uo.Name}");
+            universe.Root.AddChild(uo);
         }
 
         ProgressionTracker.Set(isTrackingController ? 1f : ProgressionTracker.Progression, $"Created {instanceSerializedClass.Type}");
@@ -72,7 +71,7 @@ public class UniverseConverter : EngineTypeYamlSerializerBase<IUniverse>
         bool isTrackingController = ProgressionTracker.Progression.ApproximatelyEquals(0f);
         ProgressionTracker.Set(isTrackingController ? .25f : ProgressionTracker.Progression, $"Serializing universe");
 
-        IEnumerable<IUniverseObject> rootUniverseObjects = universe.UniverseObjects.Where(uo => uo.Parent is null);
+        IUniverseObject rootUniverseObject = universe.Root;
 
         emitter.Emit(new MappingStart());
 
@@ -85,8 +84,8 @@ public class UniverseConverter : EngineTypeYamlSerializerBase<IUniverse>
         emitter.Emit(new Scalar(nameof(IUniverse.StateEnable)));
         serializer(universe.StateEnable);
 
-        emitter.Emit(new Scalar(nameof(IUniverse.UniverseObjects)));
-        serializer(rootUniverseObjects);
+        emitter.Emit(new Scalar(nameof(IUniverse.Root)));
+        serializer(rootUniverseObject);
 
         ProgressionTracker.Set(isTrackingController ? 1f : ProgressionTracker.Progression, $"Serialized universe");
         emitter.Emit(new MappingEnd());

Engine.Integration/Engine.Integration.Yaml/Converters/UniverseObjectConverter.cs

@@ -40,7 +40,7 @@ public class UniverseObjectSerializer : EngineTypeYamlSerializerBase<IUniverseOb
             throw new();
         SerializedClass instanceSerializedClass = (SerializedClass)rootDeserializer(typeof(SerializedClass))!;
         ProgressionTracker.Set(isTrackingController ? .3f : ProgressionTracker.Progression, $"Creating {instanceSerializedClass.Type}");
-        universeObject = (IUniverseObject)instanceSerializedClass.CreateInstance(EntityRegistry);
+        universeObject = (IUniverseObject)instanceSerializedClass.CreateInstance(IdentifiableRegistry);
 
         if (parser.Consume<Scalar>().Value.CompareTo(nameof(IUniverseObject.StateEnable)) != 0)
             throw new();

Engine.Integration/Engine.Integration.Yaml/YamlSerializer.cs

@@ -17,14 +17,14 @@ public class YamlSerializer : Core.Serialization.ISerializer
     private readonly YamlDotNet.Serialization.ISerializer serializer = null!;
     private readonly YamlDotNet.Serialization.IDeserializer deserializer = null!;
 
-    private readonly EntityRegistry entityRegistry = null!;
+    private readonly IdentifiableRegistry identifiableRegistry = null!;
     private readonly IProgressionTracker progressionTracker = null!;
 
     private readonly System.Threading.Lock Lock = new();
 
     public YamlSerializer()
     {
-        entityRegistry = new();
+        identifiableRegistry = new();
         progressionTracker = new ProgressionTracker();
 
         SerializerBuilder serializerBuilder = new SerializerBuilder()
@@ -37,7 +37,7 @@ public class YamlSerializer : Core.Serialization.ISerializer
         foreach (IEngineTypeYamlConverter typeConverter in GetEngineYamlTypeConverters())
         {
             typeConverter.Serializer = this;
-            typeConverter.EntityRegistry = entityRegistry;
+            typeConverter.IdentifiableRegistry = identifiableRegistry;
             typeConverter.ProgressionTracker = progressionTracker;
 
             deserializerBuilder = deserializerBuilder.WithTypeConverter(typeConverter);
@@ -66,9 +66,9 @@ public class YamlSerializer : Core.Serialization.ISerializer
     {
         lock (Lock)
         {
-            entityRegistry.Reset();
+            identifiableRegistry.Reset();
             object result = deserializer.Deserialize(configuration)!;
-            entityRegistry.AssignAll();
+            identifiableRegistry.AssignAll();
             return result;
         }
     }
@@ -77,9 +77,9 @@ public class YamlSerializer : Core.Serialization.ISerializer
     {
         lock (Lock)
         {
-            entityRegistry.Reset();
+            identifiableRegistry.Reset();
             object result = deserializer.Deserialize(configuration, type)!;
-            entityRegistry.AssignAll();
+            identifiableRegistry.AssignAll();
             return result;
         }
     }
@@ -88,9 +88,9 @@ public class YamlSerializer : Core.Serialization.ISerializer
     {
         lock (Lock)
         {
-            entityRegistry.Reset();
+            identifiableRegistry.Reset();
             T result = deserializer.Deserialize<T>(configuration);
-            entityRegistry.AssignAll();
+            identifiableRegistry.AssignAll();
             return result;
         }
     }

Engine.Systems/Network/Abstract/INetworkPacketEncrypted.cs

@@ -0,0 +1,3 @@
+namespace Engine.Systems.Network;
+
+public interface INetworkPacketEncrypted : INetworkPacket;

Engine.Systems/Network/ClientBehaviour.cs

@@ -0,0 +1,16 @@
+using Engine.Core;
+
+namespace Engine.Systems.Network;
+
+/// <summary>
+/// Basic client behaviour that finds the <see cref="INetworkCommunicatorClient"/> in the universe in it's first active frame.
+/// <br/> 
+/// Disclaimer: It implements <see cref="IFirstFrameUpdate"/> and <see cref="ILastFrameUpdate"/> in virtual methods.
+/// </summary>
+public class ClientBehaviour : Behaviour, IFirstFrameUpdate, ILastFrameUpdate
+{
+    public INetworkCommunicatorClient Client { get; private set; } = null!;
+
+    public virtual void FirstActiveFrame() => Client = Universe.FindRequiredBehaviour<INetworkCommunicatorClient>();
+    public virtual void LastActiveFrame() => Client = null!;
+}

Engine.Systems/Network/Hasher.cs

@@ -0,0 +1,21 @@
+namespace Engine.Systems.Network;
+
+public static class Hasher
+{
+    public static long FNV1a(string name)
+    {
+        const long fnvPrime = 1099511628211;
+        long result = 1469598103934665603;
+
+        unchecked
+        {
+            foreach (char c in name)
+            {
+                result ^= c;
+                result *= fnvPrime;
+            }
+        }
+
+        return result;
+    }
+}

Engine.Systems/Network/ServerBehaviour.cs

@@ -0,0 +1,16 @@
+using Engine.Core;
+
+namespace Engine.Systems.Network;
+
+/// <summary>
+/// Basic server behaviour that finds the <see cref="INetworkCommunicatorServer"/> in the universe in it's first active frame.
+/// <br/> 
+/// Disclaimer: It implements <see cref="IFirstFrameUpdate"/> and <see cref="ILastFrameUpdate"/> in virtual methods.
+/// </summary>
+public class ServerBehaviour : Behaviour, IFirstFrameUpdate, ILastFrameUpdate
+{
+    public INetworkCommunicatorServer Server { get; private set; } = null!;
+
+    public virtual void FirstActiveFrame() => Server = Universe.FindRequiredBehaviour<INetworkCommunicatorServer>();
+    public virtual void LastActiveFrame() => Server = null!;
+}

Engine.Systems/Network/TypeHasher.cs

@@ -8,18 +8,7 @@ public static class TypeHasher<T>
         get
         {
             if (_fnv1a == 0)
-                unchecked
-                {
-                    const long fnvPrime = 1099511628211;
-                    _fnv1a = 1469598103934665603;
-
-                    string typeName = typeof(T).FullName ?? typeof(T).Name;
-                    foreach (char c in typeName)
-                    {
-                        _fnv1a ^= c;
-                        _fnv1a *= fnvPrime;
-                    }
-                }
+                _fnv1a = Hasher.FNV1a(typeof(T).FullName ?? typeof(T).Name);
 
             return _fnv1a;
         }