feat: added basic window, input & drawing

Platforms/Desktop/Desktop.csproj

@@ -10,6 +10,7 @@
     <AssemblyName>MyUniverse</AssemblyName>
   </PropertyGroup>
   <PropertyGroup>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <ApplicationManifest>app.manifest</ApplicationManifest>
     <ApplicationIcon>Icon.ico</ApplicationIcon>
   </PropertyGroup>
@@ -26,20 +27,16 @@
     </EmbeddedResource>
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="MonoGame.Framework.DesktopGL" Version="3.8.2.1105" />
-    <PackageReference Include="MonoGame.Content.Builder.Task" Version="3.8.2.1105" />
     <PackageReference Include="nulastudio.NetBeauty" Version="2.1.5" />
+    <PackageReference Include="SDL3-CS" Version="3.3.7" />
+    <PackageReference Include="Silk.NET.OpenGL" Version="2.23.0" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="../../Engine/Engine.Integration/Engine.Integration.LiteNetLib/Engine.Integration.LiteNetLib.csproj" />
+    <ProjectReference Include="../../Engine/Engine.Integration/Engine.Integration.Yaml/Engine.Integration.Yaml.csproj" />
     <ProjectReference Include="../../Shared/Shared.csproj" />
   </ItemGroup>
 
-  <ItemGroup>
-    <MonoGameContentReference Include="../../Shared/Content/Content.mgcb">
-      <Link>Content/Content.mgcb</Link>
-    </MonoGameContentReference>
-  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="../../Shared/Shared.csproj" />
     <ProjectReference Include="../../Engine/Engine.Integration/Engine.Integration.Yaml/Engine.Integration.Yaml.csproj" />

Platforms/Desktop/Engine.Integration.SDL3/CameraController2D.cs

@@ -0,0 +1,31 @@
+using Engine.Core;
+
+using SDL3;
+
+namespace Engine.Integration.SDL3;
+
+public class CameraController2D : Behaviour2D, IFirstFrameUpdate, IUpdate
+{
+    private Sdl3KeyboardInputs keyboardInputs = null!;
+    private ICamera2D camera = null!;
+
+    public void FirstActiveFrame()
+    {
+        keyboardInputs = Universe.FindRequiredBehaviour<Sdl3KeyboardInputs>();
+        camera = BehaviourController.GetRequiredBehaviourInParent<ICamera2D>();
+    }
+
+    public void Update()
+    {
+        if (keyboardInputs.IsPressed(SDL.Keycode.W)) Transform.Position += Transform.Up * Universe.Time.DeltaTime * 100f;
+        if (keyboardInputs.IsPressed(SDL.Keycode.A)) Transform.Position += Transform.Left * Universe.Time.DeltaTime * 100f;
+        if (keyboardInputs.IsPressed(SDL.Keycode.S)) Transform.Position += Transform.Down * Universe.Time.DeltaTime * 100f;
+        if (keyboardInputs.IsPressed(SDL.Keycode.D)) Transform.Position += Transform.Right * Universe.Time.DeltaTime * 100f;
+
+        if (keyboardInputs.IsPressed(SDL.Keycode.Q)) Transform.Rotation += Universe.Time.DeltaTime * 45f;
+        if (keyboardInputs.IsPressed(SDL.Keycode.E)) Transform.Rotation -= Universe.Time.DeltaTime * 45f;
+
+        if (keyboardInputs.IsPressed(SDL.Keycode.R)) camera.Zoom += Universe.Time.DeltaTime * 15f;
+        if (keyboardInputs.IsPressed(SDL.Keycode.F)) camera.Zoom -= Universe.Time.DeltaTime * 15f;
+    }
+}

Platforms/Desktop/Engine.Integration.SDL3/ISdl3EventProcessor.cs

@@ -0,0 +1,8 @@
+using SDL3;
+
+namespace Engine.Integration.SDL3;
+
+public interface ISdl3EventProcessor
+{
+    void Process(SDL.Event sdlEvent);
+}

Platforms/Desktop/Engine.Integration.SDL3/Sdl3Camera2D.cs

@@ -0,0 +1,86 @@
+using Engine.Core;
+
+namespace Engine.Integration.SDL3;
+
+public class Sdl3Camera2D : Behaviour, ICamera2D, IFirstFrameUpdate, ILastFrameUpdate, IPreDraw
+{
+    public Event<Sdl3Camera2D> OnViewMatrixChanged { get; } = new();
+    public Event<Sdl3Camera2D> OnProjectionMatrixChanged { get; } = new();
+    public Event<Sdl3Camera2D> OnViewportChanged { get; } = new();
+    public Event<Sdl3Camera2D> OnZoomChanged { get; } = new();
+
+    private IWindow window = null!;
+    public ITransform2D Transform { get; private set; } = null!;
+
+    public Matrix4x4 ProjectionMatrix
+    {
+        get;
+        private set
+        {
+            if (field == value)
+                return;
+
+            field = value;
+            OnProjectionMatrixChanged.Invoke(this);
+        }
+    } = Matrix4x4.Identity;
+
+    public Matrix4x4 ViewMatrix
+    {
+        get;
+        private set
+        {
+            if (field == value)
+                return;
+
+            field = value;
+            OnViewMatrixChanged.Invoke(this);
+        }
+    } = Matrix4x4.Identity;
+
+    public float Zoom
+    {
+        get;
+        set
+        {
+            float newValue = Math.Max(0.1f, value);
+
+            if (field == newValue)
+                return;
+
+            field = newValue;
+            OnZoomChanged.Invoke(this);
+        }
+    } = 1f;
+
+    // TODO This causes delay since OnPreDraw calls assuming this is called in in Update 
+    public Vector2D ScreenToWorldPosition(Vector2D screenPosition)
+    {
+        Vector2D worldPosition = Vector2D.Transform(screenPosition, Transform);
+        return worldPosition;
+    }
+
+    public Vector2D WorldToScreenPosition(Vector2D worldPosition)
+    {
+        Vector2D screenPosition = Vector2D.Transform(worldPosition, Transform);
+        return screenPosition;
+    }
+
+    public void LastActiveFrame() => Transform = null!;
+    public void FirstActiveFrame()
+    {
+        window = BehaviourController.UniverseObject.Universe.FindRequiredBehaviour<IWindow>();
+        Transform = BehaviourController.GetRequiredBehaviour<ITransform2D>();
+    }
+
+    public void PreDraw()
+    {
+        ProjectionMatrix = Matrix4x4.CreateOrthographicViewCentered(window.Size.X, window.Size.Y);
+
+        ViewMatrix = Matrix4x4.Identity
+            .ApplyScale(Transform.Scale.X.Max(Transform.Scale.Y))
+            .ApplyScale(Zoom)
+            .ApplyRotationZ(-Transform.Rotation * Math.DegreeToRadian)
+            .ApplyTranslation(new Vector3D(-Transform.Position.X, -Transform.Position.Y, 0f));
+    }
+}

Platforms/Desktop/Engine.Integration.SDL3/Sdl3GameInputs.cs

@@ -1,17 +1,16 @@
 using System;
 using System.Collections.Generic;
 
-using Microsoft.Xna.Framework.Input;
-
 using Engine.Core;
-using Engine.Integration.MonoGame;
 using Engine.Systems.Input;
 
 using MyUniverse.Shared.Behaviours.Abstract;
 
-namespace MyUniverse.Platforms.Desktop;
+using SDL3;
 
-public class DesktopInputs : Behaviour, IEnterUniverse, IExitUniverse, IGameInputs
+namespace Engine.Integration.SDL3;
+
+public class Sdl3GameInputs : Behaviour, IGameInputs, IFirstFrameUpdate
 {
     public IButtonInputs<IGameInputs.Button>.InputEvent OnAnyButtonPressed { get; } = new();
     public IButtonInputs<IGameInputs.Button>.InputEvent OnAnyButtonReleased { get; } = new();
@@ -19,23 +18,23 @@ public class DesktopInputs : Behaviour, IEnterUniverse, IExitUniverse, IGameInpu
     private readonly Dictionary<IGameInputs.Button, IButtonInputs<IGameInputs.Button>.InputEvent> OnPressed = new(256);
     private readonly Dictionary<IGameInputs.Button, IButtonInputs<IGameInputs.Button>.InputEvent> OnReleased = new(256);
 
-    private readonly Dictionary<IGameInputs.Button, Keys> keyMappingReversed = [];
-    private readonly Dictionary<Keys, IGameInputs.Button> keyMapping = new() {
-        { Keys.Space, IGameInputs.Button.Interact }
+    private readonly Dictionary<IGameInputs.Button, SDL.Keycode> keyMappingReversed = [];
+    private readonly Dictionary<SDL.Keycode, IGameInputs.Button> keyMapping = new() {
+        { SDL.Keycode.Space, IGameInputs.Button.Interact }
     };
 
-    private KeyboardInputs keyboardInputs = null!;
+    private Sdl3KeyboardInputs keyboardInputs = null!;
 
-    public void EnterUniverse(IUniverse universe)
+    public void FirstActiveFrame()
     {
-        keyboardInputs = BehaviourController.GetOrAddBehaviour<KeyboardInputs>();
+        keyboardInputs = BehaviourController.GetOrAddBehaviour<Sdl3KeyboardInputs>();
         keyboardInputs.OnAnyButtonPressed.AddListener(AnyPressCallback);
         keyboardInputs.OnAnyButtonReleased.AddListener(AnyReleaseCallback);
 
-        foreach ((Keys key, IGameInputs.Button button) in keyMapping)
+        foreach ((SDL.Keycode key, IGameInputs.Button button) in keyMapping)
             keyboardInputs.RegisterOnPress(key, PressCallback);
 
-        foreach ((Keys key, IGameInputs.Button button) in keyMapping)
+        foreach ((SDL.Keycode key, IGameInputs.Button button) in keyMapping)
             keyboardInputs.RegisterOnRelease(key, ReleaseCallback);
     }
 
@@ -44,14 +43,14 @@ public class DesktopInputs : Behaviour, IEnterUniverse, IExitUniverse, IGameInpu
         keyboardInputs.OnAnyButtonPressed.RemoveListener(AnyPressCallback);
         keyboardInputs.OnAnyButtonReleased.RemoveListener(AnyReleaseCallback);
 
-        foreach ((Keys key, IGameInputs.Button button) in keyMapping)
+        foreach ((SDL.Keycode key, IGameInputs.Button button) in keyMapping)
             keyboardInputs.UnregisterOnPress(key, PressCallback);
 
-        foreach ((Keys key, IGameInputs.Button button) in keyMapping)
+        foreach ((SDL.Keycode key, IGameInputs.Button button) in keyMapping)
             keyboardInputs.UnregisterOnRelease(key, ReleaseCallback);
     }
 
-    private void PressCallback(IButtonInputs<Keys> sender, IButtonInputs<Keys>.ButtonCallbackArguments args)
+    private void PressCallback(IButtonInputs<SDL.Keycode> sender, IButtonInputs<SDL.Keycode>.ButtonCallbackArguments args)
     {
         if (!keyMapping.TryGetValue(args.Button, out IGameInputs.Button button))
             return;
@@ -62,7 +61,7 @@ public class DesktopInputs : Behaviour, IEnterUniverse, IExitUniverse, IGameInpu
         @event.Invoke(this, new(button));
     }
 
-    private void ReleaseCallback(IButtonInputs<Keys> sender, IButtonInputs<Keys>.ButtonCallbackArguments args)
+    private void ReleaseCallback(IButtonInputs<SDL.Keycode> sender, IButtonInputs<SDL.Keycode>.ButtonCallbackArguments args)
     {
         if (!keyMapping.TryGetValue(args.Button, out IGameInputs.Button button))
             return;
@@ -73,13 +72,13 @@ public class DesktopInputs : Behaviour, IEnterUniverse, IExitUniverse, IGameInpu
         @event.Invoke(this, new(button));
     }
 
-    private void AnyReleaseCallback(IButtonInputs<Keys> sender, IButtonInputs<Keys>.ButtonCallbackArguments args)
+    private void AnyReleaseCallback(IButtonInputs<SDL.Keycode> sender, IButtonInputs<SDL.Keycode>.ButtonCallbackArguments args)
     {
         if (keyMapping.TryGetValue(args.Button, out IGameInputs.Button button))
             OnAnyButtonPressed?.Invoke(this, new(button));
     }
 
-    private void AnyPressCallback(IButtonInputs<Keys> sender, IButtonInputs<Keys>.ButtonCallbackArguments args)
+    private void AnyPressCallback(IButtonInputs<SDL.Keycode> sender, IButtonInputs<SDL.Keycode>.ButtonCallbackArguments args)
     {
         if (keyMapping.TryGetValue(args.Button, out IGameInputs.Button button))
             OnAnyButtonPressed?.Invoke(this, new(button));
@@ -121,15 +120,15 @@ public class DesktopInputs : Behaviour, IEnterUniverse, IExitUniverse, IGameInpu
 
     public bool IsPressed(IGameInputs.Button button)
     {
-        if (!keyMappingReversed.TryGetValue(button, out Keys key))
+        if (!keyMappingReversed.TryGetValue(button, out SDL.Keycode key))
             throw new($"{Enum.GetName(button)} is not mapped correctly");
 
         return keyboardInputs.IsPressed(key);
     }
 
-    public DesktopInputs()
+    public Sdl3GameInputs()
     {
-        foreach ((Keys key, IGameInputs.Button button) in keyMapping)
+        foreach ((SDL.Keycode key, IGameInputs.Button button) in keyMapping)
             keyMappingReversed.Add(button, key);
     }
 }

Platforms/Desktop/Engine.Integration.SDL3/Sdl3KeyboardInputs.cs

@@ -0,0 +1,87 @@
+using System.Collections.Generic;
+
+using Engine.Core;
+using Engine.Systems.Input;
+
+using SDL3;
+
+namespace Engine.Integration.SDL3;
+
+public class Sdl3KeyboardInputs : Behaviour, ISdl3EventProcessor, IButtonInputs<SDL.Keycode>
+{
+    public IButtonInputs<SDL.Keycode>.InputEvent OnAnyButtonPressed { get; } = new();
+    public IButtonInputs<SDL.Keycode>.InputEvent OnAnyButtonReleased { get; } = new();
+
+    private readonly Dictionary<SDL.Keycode, IButtonInputs<SDL.Keycode>.InputEvent> OnPressed = new(256);
+    private readonly Dictionary<SDL.Keycode, IButtonInputs<SDL.Keycode>.InputEvent> OnReleased = new(256);
+
+    private readonly FastList<SDL.Keycode> currentlyPressedKeys = [];
+
+    public void RegisterOnPress(SDL.Keycode key, IButtonInputs<SDL.Keycode>.InputEvent.EventHandler callback)
+    {
+        if (!OnPressed.TryGetValue(key, out IButtonInputs<SDL.Keycode>.InputEvent? delegateCallback))
+        {
+            delegateCallback = new();
+            OnPressed.Add(key, delegateCallback);
+        }
+
+        delegateCallback.AddListener(callback);
+    }
+
+    public void UnregisterOnPress(SDL.Keycode key, IButtonInputs<SDL.Keycode>.InputEvent.EventHandler callback)
+    {
+        if (OnPressed.TryGetValue(key, out IButtonInputs<SDL.Keycode>.InputEvent? delegateCallback))
+            delegateCallback.RemoveListener(callback);
+    }
+
+    public void RegisterOnRelease(SDL.Keycode key, IButtonInputs<SDL.Keycode>.InputEvent.EventHandler callback)
+    {
+        if (!OnReleased.TryGetValue(key, out IButtonInputs<SDL.Keycode>.InputEvent? delegateCallback))
+        {
+            delegateCallback = new();
+            OnReleased.Add(key, delegateCallback);
+        }
+
+        delegateCallback.AddListener(callback);
+    }
+
+    public void UnregisterOnRelease(SDL.Keycode key, IButtonInputs<SDL.Keycode>.InputEvent.EventHandler callback)
+    {
+        if (OnReleased.TryGetValue(key, out IButtonInputs<SDL.Keycode>.InputEvent? delegateCallback))
+            delegateCallback.RemoveListener(callback);
+    }
+
+    public bool IsPressed(SDL.Keycode button) => currentlyPressedKeys.Contains(button);
+
+    public void Process(SDL.Event sdlEvent)
+    {
+        switch ((SDL.EventType)sdlEvent.Type)
+        {
+            case SDL.EventType.KeyDown:
+                SDL.Keycode currentlyPressedKey = sdlEvent.Key.Key;
+                if (IsPressed(currentlyPressedKey))
+                    return;
+
+                currentlyPressedKeys.Add(currentlyPressedKey);
+
+                if (OnPressed.TryGetValue(currentlyPressedKey, out IButtonInputs<SDL.Keycode>.InputEvent? pressCallback))
+                    pressCallback?.Invoke(this, new(currentlyPressedKey));
+
+                OnAnyButtonPressed?.Invoke(this, new(currentlyPressedKey));
+                return;
+
+            case SDL.EventType.KeyUp:
+                SDL.Keycode previouslyPressedKey = sdlEvent.Key.Key;
+                if (!IsPressed(previouslyPressedKey))
+                    return;
+
+                currentlyPressedKeys.Remove(previouslyPressedKey);
+
+                if (OnReleased.TryGetValue(previouslyPressedKey, out IButtonInputs<SDL.Keycode>.InputEvent? releaseCallback))
+                    releaseCallback?.Invoke(this, new(previouslyPressedKey));
+
+                OnAnyButtonReleased?.Invoke(this, new(previouslyPressedKey));
+                return;
+        }
+    }
+}

Platforms/Desktop/Engine.Integration.SDL3/Sdl3TriangleBatch.cs

@@ -0,0 +1,269 @@
+using System;
+using Engine.Core;
+using Engine.Systems.Graphics;
+using SDL3;
+using Silk.NET.OpenGL;
+
+namespace Engine.Integration.SDL3;
+
+public class Sdl3TriangleBatch : Behaviour, ITriangleBatch, IFirstFrameUpdate
+{
+    private GL gl = null!;
+    private readonly uint MaxVertices = 1024;
+    private uint vao;
+    private uint vbo;
+    private uint shader;
+
+    private uint vertexIndex = 0;
+    private VertexPositionColor[] vertices = new VertexPositionColor[1024];
+
+    private Matrix4x4 view = Matrix4x4.Identity;
+    private Matrix4x4 projection = Matrix4x4.Identity;
+    private Sdl3Window sdl3window = null!;
+    private ICamera? camera = null!;
+    private nint glContext;
+
+    public void FirstActiveFrame()
+    {
+        sdl3window = BehaviourController.GetRequiredBehaviourInParent<Sdl3Window>();
+        camera = BehaviourController.GetRequiredBehaviourInParent<ICamera>();
+        nint window = sdl3window.Window;
+
+        SDL.GLSetAttribute(SDL.GLAttr.ContextMajorVersion, 3);
+        SDL.GLSetAttribute(SDL.GLAttr.ContextMinorVersion, 3);
+        SDL.GLSetAttribute(SDL.GLAttr.ContextProfileMask, (int)SDL.GLProfile.Core);
+        SDL.GLSetAttribute(SDL.GLAttr.DoubleBuffer, 1);
+
+        glContext = SDL.GLCreateContext(window);
+        if (glContext == nint.Zero)
+            throw new Exception(SDL.GetError());
+
+        SDL.GLMakeCurrent(window, glContext);
+
+        gl = GL.GetApi(procName => SDL.GLGetProcAddress(procName));
+        gl.Viewport(0, 0, (uint)sdl3window.Size.X, (uint)sdl3window.Size.Y);
+        vertices = new VertexPositionColor[MaxVertices];
+
+        // --- GL objects ---
+        vao = gl.GenVertexArray();
+        vbo = gl.GenBuffer();
+
+        gl.BindVertexArray(vao);
+        gl.BindBuffer(BufferTargetARB.ArrayBuffer, vbo);
+
+        unsafe
+        {
+            gl.BufferData(
+                BufferTargetARB.ArrayBuffer,
+                (nuint)(MaxVertices * sizeof(VertexPositionColor)),
+                null,
+                BufferUsageARB.DynamicDraw
+            );
+
+            // position
+            gl.EnableVertexAttribArray(0);
+            gl.VertexAttribPointer(
+                0,
+                3,
+                VertexAttribPointerType.Float,
+                false,
+                (uint)sizeof(VertexPositionColor),
+                (void*)0
+            );
+
+            // color
+            gl.EnableVertexAttribArray(1);
+            gl.VertexAttribPointer(
+                1,
+                4,
+                VertexAttribPointerType.Float,
+                false,
+                (uint)sizeof(VertexPositionColor),
+                (void*)(3 * sizeof(float))
+            );
+
+            gl.BindVertexArray(0);
+        }
+
+        shader = CreateShader();
+    }
+
+    public void Draw(Triangle triangle, ColorRGBA colorRGBA)
+    {
+        if (vertexIndex + 3 >= vertices.Length)
+            Flush();
+
+        Vector2D A = triangle.A;
+        Vector2D B = triangle.B;
+        Vector2D C = triangle.C;
+
+        Vector4D c = new Vector4D(colorRGBA.R, colorRGBA.G, colorRGBA.B, colorRGBA.A) / 256f;
+
+        vertices[vertexIndex++] = new()
+        {
+            Position = new Vector3D(A.X, A.Y, 0f),
+            Color = c
+        };
+
+        vertices[vertexIndex++] = new()
+        {
+            Position = new Vector3D(B.X, B.Y, 0f),
+            Color = c
+        };
+
+        vertices[vertexIndex++] = new()
+        {
+            Position = new Vector3D(C.X, C.Y, 0f),
+            Color = c
+        };
+    }
+
+    public void Begin(Matrix4x4? view = null, Matrix4x4? projection = null)
+    {
+        this.view = view ?? camera?.ViewMatrix ?? Matrix4x4.Identity;
+
+        if (projection != null)
+            this.projection = projection.Value;
+        else
+            this.projection = camera?.ProjectionMatrix ?? Matrix4x4.CreateOrthographicViewCentered(sdl3window.Size.X, sdl3window.Size.Y);
+
+        vertexIndex = 0;
+        SDL.GLMakeCurrent(sdl3window.Window, glContext);
+        gl.ClearColor(sdl3window.BackgroundColor.R / 256f, sdl3window.BackgroundColor.G / 256f, sdl3window.BackgroundColor.B / 256f, 1f);
+        gl.Clear(ClearBufferMask.ColorBufferBit);
+    }
+
+    public void End()
+    {
+        Flush();
+
+        SDL.GLSwapWindow(sdl3window.Window);
+    }
+
+    private void Flush()
+    {
+        if (vertexIndex == 0)
+            return;
+
+        gl.UseProgram(shader);
+
+        int viewLoc = gl.GetUniformLocation(shader, "uView");
+        int projLoc = gl.GetUniformLocation(shader, "uProjection");
+
+        unsafe
+        {
+            Span<float> temp = stackalloc float[16];
+
+            CopyTo(view.Transposed, temp);
+            fixed (float* v = temp)
+                gl.UniformMatrix4(viewLoc, 1, false, v);
+
+            CopyTo(projection.Transposed, temp);
+            fixed (float* p = temp)
+                gl.UniformMatrix4(projLoc, 1, false, p);
+
+            gl.BindVertexArray(vao);
+            gl.BindBuffer(BufferTargetARB.ArrayBuffer, vbo);
+
+            fixed (VertexPositionColor* ptr = vertices)
+            {
+                gl.BufferSubData(
+                    BufferTargetARB.ArrayBuffer,
+                    0,
+                    (nuint)(vertexIndex * sizeof(VertexPositionColor)),
+                    ptr
+                );
+            }
+        }
+
+        gl.DrawArrays(PrimitiveType.Triangles, 0, vertexIndex);
+
+        vertexIndex = 0;
+    }
+
+    public static void CopyTo(Matrix4x4 m, Span<float> destination)
+    {
+        if (destination.Length < 16)
+            throw new ArgumentException("Destination span must have at least 16 elements.");
+
+        destination[0] = m.M11;
+        destination[1] = m.M12;
+        destination[2] = m.M13;
+        destination[3] = m.M14;
+
+        destination[4] = m.M21;
+        destination[5] = m.M22;
+        destination[6] = m.M23;
+        destination[7] = m.M24;
+
+        destination[8] = m.M31;
+        destination[9] = m.M32;
+        destination[10] = m.M33;
+        destination[11] = m.M34;
+
+        destination[12] = m.M41;
+        destination[13] = m.M42;
+        destination[14] = m.M43;
+        destination[15] = m.M44;
+    }
+
+    private uint CreateShader()
+    {
+        const string vertexSrc = """
+        #version 330 core
+        layout (location = 0) in vec3 aPosition;
+        layout (location = 1) in vec4 aColor;
+
+        uniform mat4 uView;
+        uniform mat4 uProjection;
+
+        out vec4 vColor;
+
+        void main()
+        {
+            gl_Position = uProjection * uView * vec4(aPosition, 1.0);
+            vColor = aColor;
+        }
+        """;
+
+        const string fragmentSrc = """
+        #version 330 core
+        in vec4 vColor;
+        out vec4 FragColor;
+
+        void main()
+        {
+            FragColor = vColor;
+        }
+        """;
+
+        uint vs = CompileShader(ShaderType.VertexShader, vertexSrc);
+        uint fs = CompileShader(ShaderType.FragmentShader, fragmentSrc);
+
+        uint program = gl.CreateProgram();
+        gl.AttachShader(program, vs);
+        gl.AttachShader(program, fs);
+        gl.LinkProgram(program);
+
+        gl.DeleteShader(vs);
+        gl.DeleteShader(fs);
+
+        return program;
+    }
+
+    private uint CompileShader(ShaderType type, string src)
+    {
+        uint shader = gl.CreateShader(type);
+        gl.ShaderSource(shader, src);
+        gl.CompileShader(shader);
+        return shader;
+    }
+
+    struct VertexPositionColor
+    {
+        public Vector3D Position;
+        public Vector4D Color;
+
+        public const int SizeInBytes = (3 + 4) * sizeof(float);
+    }
+}

Platforms/Desktop/Engine.Integration.SDL3/Sdl3Window.cs

@@ -0,0 +1,224 @@
+using System;
+
+using Engine.Core;
+
+using SDL3;
+
+namespace Engine.Integration.SDL3;
+
+public class Sdl3Window : Behaviour, IWindow, IDisposable, IEnterUniverse, IExitUniverse
+{
+    public Event<IWindow, IWindow.StateChangedArguments> OnStateChanged { get; } = new();
+    public Event<IWindow, IWindow.FocusStateChangedArguments> OnFocusStateChanged { get; } = new();
+    public Event<IWindow, IWindow.ModeChangedArguments> OnModeChanged { get; } = new();
+    public Event<IWindow, IWindow.ShowStateChangedArguments> OnShowStateChanged { get; } = new();
+    public Event<IWindow, IWindow.ResizeModeChangedArguments> OnResizeModeChanged { get; } = new();
+
+    public Event<IWindow, IWindow.TitleChangedArguments> OnTitleChanged { get; } = new();
+    public Event<IWindow, IWindow.TargetFpsChangedArguments> OnTargetFpsChanged { get; } = new();
+    public Event<IWindow, IWindow.SizeChangedArguments> OnSizeChanged { get; } = new();
+    public Event<IWindow, IWindow.BackgroundColorChangedArguments> OnBackgroundColorChanged { get; } = new();
+
+    public IntPtr Window { get; private set; } = IntPtr.Zero;
+
+    public WindowState State
+    {
+        get => field;
+        set
+        {
+            if (value == field)
+                return;
+
+            switch (value)
+            {
+                case WindowState.Open: OpenWindow(); break;
+                case WindowState.Closed: default: CloseWindow(); break;
+            }
+
+            WindowState previousState = field;
+            field = value;
+            OnStateChanged.Invoke(this, new(previousState));
+        }
+    } = WindowState.Open;
+
+    public WindowFocusState FocusState
+    {
+        get => field;
+        internal set
+        {
+            if (value == field)
+                return;
+
+            WindowFocusState previousFocusState = field;
+            field = value;
+            OnFocusStateChanged.Invoke(this, new(previousFocusState));
+        }
+    } = WindowFocusState.Unfocused;
+
+    public WindowMode Mode
+    {
+        get => field;
+        set
+        {
+            if (value == field)
+                return;
+
+            if (value is WindowMode.Windowed or WindowMode.BorderlessWindowed)
+            {
+                SDL.SetWindowFullscreen(Window, false);
+                SDL.SyncWindow(Window);
+            }
+
+            if (Window != IntPtr.Zero)
+                switch (value)
+                {
+                    case WindowMode.Windowed: SDL.SetWindowBordered(Window, true); break;
+                    case WindowMode.BorderlessWindowed: SDL.SetWindowBordered(Window, false); break;
+                    case WindowMode.BorderlessFullscreen: SDL.SetWindowFullscreen(Window, true); break;
+                    case WindowMode.Fullscreen: SDL.SetWindowFullscreen(Window, true); break;
+                }
+
+            SDL.SyncWindow(Window);
+
+            WindowMode previousMode = field;
+            field = value;
+            OnModeChanged.Invoke(this, new(previousMode));
+        }
+    } = WindowMode.Windowed;
+
+    public WindowShowState ShowState
+    {
+        get => field;
+        set
+        {
+            if (value == field)
+                return;
+
+            if (Window != IntPtr.Zero)
+                switch (value)
+                {
+                    case WindowShowState.Normal: SDL.RestoreWindow(Window); break;
+                    case WindowShowState.Minimized: SDL.MinimizeWindow(Window); break;
+                    case WindowShowState.Maximized: SDL.MaximizeWindow(Window); break;
+                }
+
+            WindowShowState previousShowState = field;
+            field = value;
+            OnShowStateChanged.Invoke(this, new(previousShowState));
+        }
+    } = WindowShowState.Normal;
+
+    public WindowResizeMode ResizeMode
+    {
+        get => field;
+        set
+        {
+            if (value == field)
+                return;
+
+            if (Window != IntPtr.Zero)
+                switch (value)
+                {
+                    case WindowResizeMode.Fixed:
+                        SDL.SetWindowResizable(Window, false);
+                        break;
+                    case WindowResizeMode.Resizable:
+                    case WindowResizeMode.AspectLocked:
+                        SDL.SetWindowResizable(Window, true);
+                        break;
+                }
+
+            WindowResizeMode previousResizeMode = field;
+            field = value;
+            OnResizeModeChanged.Invoke(this, new(previousResizeMode));
+        }
+    } = WindowResizeMode.Fixed;
+
+    public ColorRGB BackgroundColor
+    {
+        get => field;
+        set
+        {
+            if (value == field)
+                return;
+
+            ColorRGB previousBackgroundColor = field;
+            field = value;
+            OnBackgroundColorChanged.Invoke(this, new(previousBackgroundColor));
+        }
+    } = new ColorRGB(35, 20, 35);
+
+    public string Title
+    {
+        get => field;
+        set
+        {
+            if (value == field)
+                return;
+
+            string previousTitle = field;
+            field = value;
+            OnTitleChanged.Invoke(this, new(previousTitle));
+        }
+    } = nameof(Sdl3Window);
+
+    public Vector2DInt Size
+    {
+        get => field;
+        set
+        {
+            if (value == field)
+                return;
+
+            if (value.Max(Vector2DInt.One) == Vector2DInt.One)
+                throw new Exception($"Window size can not be smaller than 1x1");
+
+            Vector2DInt previousSize = field;
+            field = value;
+            OnSizeChanged.Invoke(this, new(previousSize));
+        }
+    } = Vector2DInt.Zero;
+
+    public void ExitUniverse(IUniverse universe) => CloseWindow();
+    public void EnterUniverse(IUniverse universe)
+    {
+        if (State == WindowState.Open)
+            OpenWindow();
+    }
+
+    private void OpenWindow()
+    {
+        if (!UniverseObject.IsInUniverse)
+            throw new Exception($"{UniverseObject.Name} is not in a universe. The window can not be opened.");
+
+        SDL.WindowFlags windowFlags = 0;
+        switch (Mode)
+        {
+            case WindowMode.Windowed: break;
+            case WindowMode.Fullscreen: windowFlags |= SDL.WindowFlags.Fullscreen; break;
+            case WindowMode.BorderlessWindowed: windowFlags |= SDL.WindowFlags.Borderless; break;
+            case WindowMode.BorderlessFullscreen: windowFlags |= SDL.WindowFlags.Fullscreen | SDL.WindowFlags.Borderless; break;
+        }
+
+        if (!SDL.Init(SDL.InitFlags.Video))
+            throw new Exception($"SDL_Init failed: {SDL.GetError()}");
+
+        Window = SDL.CreateWindow(Title, Size.X, Size.Y, windowFlags | SDL.WindowFlags.OpenGL);
+        if (Window == IntPtr.Zero)
+            throw new Exception($"SDL_CreateWindowAndRenderer failed: {SDL.GetError()}");
+    }
+
+    private void CloseWindow()
+    {
+        if (Window != IntPtr.Zero) SDL.DestroyWindow(Window);
+
+        Window = IntPtr.Zero;
+    }
+
+    public void Dispose()
+    {
+        CloseWindow();
+
+        GC.SuppressFinalize(this);
+    }
+}

Platforms/Desktop/Engine.Integration.SDL3/Sdl3WindowManager.cs

@@ -0,0 +1,71 @@
+using System.Collections.Generic;
+using Engine.Core;
+
+using SDL3;
+
+namespace Engine.Integration.SDL3;
+
+public class Sdl3WindowManager : Behaviour, IUpdate, IEnterUniverse, IExitUniverse
+{
+    private readonly BehaviourCollector<Sdl3Window> windows = new();
+    private readonly BehaviourCollector<ISdl3EventProcessor> eventProcessors = new();
+    private readonly Dictionary<nint, Sdl3Window> windowsDictionary = [];
+
+    public Sdl3WindowManager()
+    {
+        windows.OnCollected.AddListener(OnWindowCollected);
+        windows.OnRemoved.AddListener(OnWindowRemoved);
+    }
+
+    private void OnWindowCollected(IBehaviourCollector<Sdl3Window> sender, IBehaviourCollector<Sdl3Window>.BehaviourCollectedArguments args)
+        => windowsDictionary.Add(args.BehaviourCollected.Window, args.BehaviourCollected);
+
+    private void OnWindowRemoved(IBehaviourCollector<Sdl3Window> sender, IBehaviourCollector<Sdl3Window>.BehaviourRemovedArguments args)
+    {
+        windowsDictionary.Remove(args.BehaviourRemoved.Window);
+        if (windowsDictionary.Count == 0)
+            SDL.Quit();
+    }
+
+    public void EnterUniverse(IUniverse universe)
+    {
+        windows.Assign(universe);
+        eventProcessors.Assign(universe);
+    }
+
+    public void ExitUniverse(IUniverse universe)
+    {
+        windows.Unassign();
+        eventProcessors.Unassign();
+    }
+
+    public void Update()
+    {
+        while (SDL.PollEvent(out SDL.Event e))
+            ProcessInternalEvents(e);
+    }
+
+    private void ProcessInternalEvents(SDL.Event sdlEvent)
+    {
+        if (!windowsDictionary.TryGetValue(SDL.GetWindowFromID(sdlEvent.Window.WindowID), out Sdl3Window? window))
+            return;
+
+        for (int i = 0; i < eventProcessors.Count; i++)
+            eventProcessors[i].Process(sdlEvent);
+
+        SDL.EventType eventType = (SDL.EventType)sdlEvent.Type;
+
+        switch (eventType)
+        {
+            case SDL.EventType.WindowRestored: window.ShowState = WindowShowState.Normal; break;
+            case SDL.EventType.WindowMaximized: window.ShowState = WindowShowState.Maximized; break;
+            case SDL.EventType.WindowMinimized: window.ShowState = WindowShowState.Minimized; break;
+
+            case SDL.EventType.WindowFocusGained: window.FocusState = WindowFocusState.Focused; break;
+            case SDL.EventType.WindowFocusLost: window.FocusState = WindowFocusState.Unfocused; break;
+
+            case SDL.EventType.WindowCloseRequested:
+            case SDL.EventType.Quit: Universe.Remove(window.UniverseObject); break;
+        }
+    }
+}

Platforms/Desktop/Engine.Integration.SDL3/Windowing/IWindow.cs

@@ -0,0 +1,71 @@
+using Engine.Core;
+
+namespace Engine.Integration.SDL3;
+
+public interface IWindow : IBehaviour
+{
+    Event<IWindow, StateChangedArguments> OnStateChanged { get; }
+    Event<IWindow, FocusStateChangedArguments> OnFocusStateChanged { get; }
+    Event<IWindow, ModeChangedArguments> OnModeChanged { get; }
+    Event<IWindow, ShowStateChangedArguments> OnShowStateChanged { get; }
+    Event<IWindow, ResizeModeChangedArguments> OnResizeModeChanged { get; }
+
+    Event<IWindow, TitleChangedArguments> OnTitleChanged { get; }
+    Event<IWindow, TargetFpsChangedArguments> OnTargetFpsChanged { get; }
+    Event<IWindow, SizeChangedArguments> OnSizeChanged { get; }
+    Event<IWindow, BackgroundColorChangedArguments> OnBackgroundColorChanged { get; }
+
+    WindowState State { get; set; }
+    WindowFocusState FocusState { get; }
+    WindowMode Mode { get; set; }
+    WindowShowState ShowState { get; set; }
+    WindowResizeMode ResizeMode { get; set; }
+
+    string Title { get; set; }
+    Vector2DInt Size { get; set; }
+    ColorRGB BackgroundColor { get; set; }
+
+    readonly record struct StateChangedArguments(WindowState PreviousState);
+    readonly record struct FocusStateChangedArguments(WindowFocusState PreviousFocusState);
+    readonly record struct ModeChangedArguments(WindowMode PreviousMode);
+    readonly record struct ShowStateChangedArguments(WindowShowState PreviousShowState);
+    readonly record struct ResizeModeChangedArguments(WindowResizeMode PreviousResizeMode);
+    readonly record struct TitleChangedArguments(string PreviousTitle);
+    readonly record struct TargetFpsChangedArguments(uint PreviousTargetFps);
+    readonly record struct SizeChangedArguments(Vector2DInt PreviousSize);
+    readonly record struct BackgroundColorChangedArguments(ColorRGB PreviousColor);
+}
+
+public enum WindowFocusState
+{
+    Focused,
+    Unfocused
+}
+
+public enum WindowState
+{
+    Open,
+    Closed
+}
+
+public enum WindowMode
+{
+    Windowed,
+    Fullscreen,
+    BorderlessFullscreen,
+    BorderlessWindowed
+}
+
+public enum WindowShowState
+{
+    Normal,
+    Minimized,
+    Maximized
+}
+
+public enum WindowResizeMode
+{
+    Fixed,
+    Resizable,
+    AspectLocked
+}

Platforms/Desktop/Program.cs

@@ -1,16 +1,15 @@
-using Microsoft.Xna.Framework.Graphics;
+using System;
 
 using Engine.Core;
 using Engine.Core.Debug;
 using Engine.Core.Serialization;
-using Engine.Integration.MonoGame;
+using Engine.Integration.SDL3;
 using Engine.Serializers.Yaml;
 using Engine.Systems.Network;
-
-using MyUniverse.Platforms.Desktop;
+using Engine.Systems.Time;
+using MyUniverse.Shared.Behaviours;
 
 Universe universe = new();
-using MonoGameWindow monoGameWindow = new(universe);
 
 ISerializer serializer = new YamlSerializer();
 
@@ -25,12 +24,11 @@ universe.InstantiateUniverseObject().SetUniverseObject("Logger")
 
 IUniverseObject desktopParent = universe.InstantiateUniverseObject().SetUniverseObject("Desktop");
 
-universe.InstantiateUniverseObject().SetUniverseObject("Desktop Inputs", desktopParent)
-    .BehaviourController.AddBehaviour<DesktopInputs>();
+// universe.InstantiateUniverseObject().SetUniverseObject("Desktop Inputs", desktopParent)
+//     .BehaviourController.AddBehaviour<DesktopInputs>();
 
 universe.InstantiateUniverseObject().SetUniverseObject("Visual Managers", desktopParent)
-    .BehaviourController.AddBehaviour<DrawManager>()
-    .BehaviourController.AddBehaviour<LoadContentManager>();
+    .BehaviourController.AddBehaviour<DrawManager>();
 
 /* For Networking
 LiteNetLibClient client = universe.InstantiateUniverseObject().SetUniverseObject("Client").BehaviourController.AddBehaviour<LiteNetLibClient>();
@@ -38,9 +36,102 @@ client.BehaviourController.AddBehaviour<NetworkManager>();
 universe.OnPreUpdate.AddOneTimeListener((_, _) => client.Connect("localhost", 8888));
 */
 
-MyUniverse.Shared.UniverseSource.ApplyClient(universe);
+MyUniverse.Shared.UniverseSource.ApplyCore(universe);
 MyUniverse.Shared.UniverseSource.ApplyUniverse(universe);
 
-monoGameWindow.Graphics.GraphicsProfile = GraphicsProfile.HiDef;
+desktopParent.AddChild(universe.InstantiateUniverseObject().SetUniverseObject("Triangle Batcher").BehaviourController.AddBehaviour<Engine.Systems.Graphics.TriangleBatcher>().UniverseObject);
 
-monoGameWindow.Run();
+Sdl3Window window = Engine.Core.Factory.BehaviourFactory.Instantiate<Sdl3Window>();
+window.Title = "MyUniverse";
+window.Size = new(800, 600);
+window.Mode = WindowMode.Windowed;
+
+Sdl3Window window2 = Engine.Core.Factory.BehaviourFactory.Instantiate<Sdl3Window>();
+window2.Title = "MyUniverse 2";
+window2.Size = new(400, 300);
+window2.Mode = WindowMode.Windowed;
+
+universe.InstantiateUniverseObject().SetUniverseObject("SDL3 Manager", desktopParent)
+    .BehaviourController.AddBehaviour<Sdl3WindowManager>()
+    .BehaviourController.AddBehaviour<Sdl3KeyboardInputs>()
+    .BehaviourController.AddBehaviour<Sdl3GameInputs>();
+
+IUniverseObject windowUO = universe.InstantiateUniverseObject().SetUniverseObject("SDL3 Window", desktopParent);
+windowUO.BehaviourController.AddBehaviour<Transform2D>();
+windowUO.BehaviourController.AddBehaviour<Engine.Systems.Graphics.DrawableShape2D>(Shape2D.Square, new ColorRGB(0, 0, 128));
+windowUO.BehaviourController.AddBehaviour(window);
+windowUO.BehaviourController.AddBehaviour<Sdl3Camera2D>().Zoom = 20f;
+windowUO.BehaviourController.AddBehaviour<Sdl3TriangleBatch>();
+windowUO.BehaviourController.AddBehaviour<CameraController2D>();
+
+IUniverseObject windowUO2 = universe.InstantiateUniverseObject().SetUniverseObject("SDL3 Window 2", desktopParent);
+windowUO2.BehaviourController.AddBehaviour<Transform2D>().Rotation = 45f;
+windowUO2.BehaviourController.AddBehaviour<Engine.Systems.Graphics.DrawableShape2D>(Shape2D.Square, new ColorRGB(128, 0, 0));
+windowUO2.BehaviourController.AddBehaviour(window2);
+windowUO2.BehaviourController.AddBehaviour<Sdl3Camera2D>().Zoom = 20f;
+windowUO2.BehaviourController.AddBehaviour<Sdl3TriangleBatch>();
+windowUO2.BehaviourController.AddBehaviour<LinearRotator>();
+
+// Testing Start
+// TickerStopwatch tickerStopwatch = windowUO.BehaviourController.AddBehaviour<TickerStopwatch>();
+// tickerStopwatch.Period = 5f;
+// tickerStopwatch.OnTick.AddListener(sender =>
+// {
+//     if (window.IsInitialized)
+//         windowUO.BehaviourController.RemoveBehaviour(window);
+//     else
+//         windowUO.BehaviourController.AddBehaviour(window);
+// });
+// tickerStopwatch.Start();
+
+// universe.InstantiateUniverseObject()
+//     .SetUniverseObject("Square")
+//     .BehaviourController.AddBehaviour<Transform2D>()
+//     .BehaviourController.AddBehaviour<Engine.Systems.Graphics.DrawableShape2D>(Shape2D.Square, new ColorRGB(255, 255, 0));
+
+// Testing End
+
+universe.Initialize();
+
+// window.OnRender.AddListener((sender, args) => universe.Draw());
+// window.OnUpdate.AddListener((sender, args) =>
+// {
+//     timeSinceStart += args.TimeSpan;
+//     universe.Update(new(timeSinceStart, args.TimeSpan));
+// });
+
+// window.Run();
+
+DateTime lastRun = DateTime.UtcNow;
+TimeSpan timeSinceStart = new(0);
+
+while (true)
+{
+    DateTime now = DateTime.UtcNow;
+    TimeSpan updateTimeSpan = now - lastRun;
+
+    timeSinceStart += updateTimeSpan;
+    universe.Update(new(timeSinceStart, updateTimeSpan));
+    universe.Draw();
+
+    lastRun = now;
+    System.Threading.Thread.Sleep(1);
+}
+
+// DateTime lastRun = DateTime.UtcNow;
+// TimeSpan interval = new(0, 0, 0, 0, 16);
+// TimeSpan timeSinceStart = new(0);
+
+// universe.Initialize();
+
+// while (true)
+// {
+//     if (lastRun + interval <= DateTime.UtcNow)
+//     {
+//         lastRun += interval;
+//         timeSinceStart += interval;
+//         universe.Update(new(timeSinceStart, interval));
+//     }
+
+//     Thread.Sleep(1);
+// }

Shared/Behaviours/MousePositionerBehaviour.cs

@@ -1,21 +0,0 @@
-using Microsoft.Xna.Framework.Input;
-
-using Engine.Core;
-using Engine.Integration.MonoGame;
-
-namespace MyUniverse.Shared.Behaviours;
-
-public class MousePositionerBehaviour : Behaviour2D, IUpdate, IFirstFrameUpdate
-{
-    private ICamera2D camera = null!;
-
-    public void FirstActiveFrame()
-    {
-        camera = Universe.FindRequiredBehaviour<ICamera2D>();
-    }
-
-    public void Update()
-    {
-        Transform.Position = camera.ScreenToWorldPosition(Mouse.GetState().Position.ToVector2D());
-    }
-}

Shared/Shared.csproj

@@ -12,6 +12,5 @@
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="../Engine/Engine/Engine.csproj" />
-    <ProjectReference Include="../Engine/Engine.Integration/Engine.Integration.MonoGame/Engine.Integration.MonoGame.csproj" />
   </ItemGroup>
 </Project>

Shared/UniverseSource.cs

@@ -1,5 +1,4 @@
 using Engine.Core;
-using Engine.Integration.MonoGame;
 using Engine.Systems.Graphics;
 using Engine.Systems.Tween;
 
@@ -19,33 +18,11 @@ public static class UniverseSource
         coreManagersUO.AddChild(universe.InstantiateUniverseObject().SetUniverseObject("Tween Manager").BehaviourController.AddBehaviour<TweenManager>().UniverseObject);
     }
 
-    public static void ApplyClient(IUniverse universe)
-    {
-        ApplyCore(universe);
-
-        IUniverseObject clientManagersUO = universe.InstantiateUniverseObject().SetUniverseObject("Core Managers");
-        clientManagersUO.AddChild(universe.InstantiateUniverseObject().SetUniverseObject("Triangle Batcher").BehaviourController.AddBehaviour<TriangleBatcher>().UniverseObject);
-        clientManagersUO.AddChild(universe.InstantiateUniverseObject().SetUniverseObject("Sprite Batcher").BehaviourController.AddBehaviour<SpriteBatcher>().UniverseObject);
-        clientManagersUO.AddChild(universe.InstantiateUniverseObject().SetUniverseObject("MonoGame Triangle Batch").BehaviourController.AddBehaviour<MonoGameTriangleBatch>().UniverseObject);
-
-        MonoGameCamera2D camera = universe.InstantiateUniverseObject().SetUniverseObject("Camera")
-            .BehaviourController.AddBehaviour<Transform2D>()
-            .BehaviourController.AddBehaviour<MonoGameCamera2D>();
-
-        camera.Zoom = 20f;
-    }
-
     public static void ApplyUniverse(IUniverse universe)
     {
         universe.InstantiateUniverseObject().SetUniverseObject("Example Object")
            .BehaviourController.AddBehaviour<ExampleBehaviour>();
 
-        universe.InstantiateUniverseObject().SetUniverseObject("MouseObject")
-           .BehaviourController.AddBehaviour<Transform2D>()
-           .BehaviourController.AddBehaviour<LinearRotator>()
-           .BehaviourController.AddBehaviour<MousePositionerBehaviour>()
-           .BehaviourController.AddBehaviour<DrawableShape2D>(Shape2D.CreateNgon(4), new ColorRGB(255, 255, 0)).Priority = 10;
-
         universe.InstantiateUniverseObject()
             .SetUniverseObject("Rotating Triangle")
             .BehaviourController.AddBehaviour<Transform2D>().SetTransform(position: new(10f, 6f), scale: Vector2D.One * 5)