Rename and mouse cursor support

fix scroll input
handle gui side, move and closed events

.gitmodules

@@ -13,3 +13,6 @@
 [submodule "Nerfed.Runtime/Libraries/dav1dfile"]
 	path = Nerfed.Runtime/Libraries/dav1dfile
 	url = https://github.com/MoonsideGames/dav1dfile.git
+[submodule "Nerfed.Runtime/Libraries/ImGui.NET"]
+	path = Nerfed.Runtime/Libraries/ImGui.NET
+	url = https://github.com/ImGuiNET/ImGui.NET.git

Nerfed.Runtime/Engine.cs

@@ -1,7 +1,7 @@
-using System.Diagnostics;
 using Nerfed.Runtime.Audio;
 using Nerfed.Runtime.Graphics;
 using SDL2;
+using System.Diagnostics;
 
 namespace Nerfed.Runtime;
 
@@ -39,6 +39,8 @@ public static class Engine
     private const string WindowTitle = "Nerfed";
     //..
 
+    private static Gui.GuiController Controller;
+
     internal static void Run(string[] args)
     {
         Timestep = TimeSpan.FromTicks(TimeSpan.TicksPerSecond / TargetTimestep);
@@ -65,11 +67,17 @@ public static class Engine
 
         AudioDevice = new AudioDevice();
 
+        Controller = new Gui.GuiController(GraphicsDevice, MainWindow, Color.DarkOliveGreen);
+        Controller.OnGui += () => {
+            ImGuiNET.ImGui.ShowDemoWindow();
+        };
+
         while (!quit)
         {
             Tick();
         }
 
+        Controller.Dispose();
         GraphicsDevice.UnclaimWindow(MainWindow);
         MainWindow.Dispose();
         GraphicsDevice.Dispose();
@@ -146,6 +154,7 @@ public static class Engine
                 ProcessSDLEvents();
 
                 // Tick game here...
+                Controller.Update((float)Timestep.TotalSeconds);
 
                 AudioDevice.WakeThread();
                 accumulatedUpdateTime -= Timestep;
@@ -154,6 +163,7 @@ public static class Engine
             double alpha = accumulatedUpdateTime / Timestep;
 
             // Render here..
+            Controller.Render();
 
             accumulatedDrawTime -= framerateCapTimeSpan;
         }

Nerfed.Runtime/Gui/GuiClipboard.cs

@@ -0,0 +1,50 @@
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace Nerfed.Runtime.Gui;
+
+public static unsafe class GuiClipboard
+{
+    private static IntPtr clipboard;
+    private static readonly Dictionary<Delegate, IntPtr> pinned = new Dictionary<Delegate, IntPtr>();
+
+    public static readonly IntPtr GetFnPtr = GetPointerTo(Get);
+    public static readonly IntPtr SetFnPtr = GetPointerTo(Set);
+
+    private static unsafe void Set(void* userdata, byte* text)
+    {
+        int len = 0; while (text[len] != 0) len++;
+        string str = Encoding.UTF8.GetString(text, len);
+        SDL2.SDL.SDL_SetClipboardText(str);
+    }
+
+    private static unsafe byte* Get(void* userdata)
+    {
+        if (clipboard != IntPtr.Zero)
+        {
+            NativeMemory.Free((void*) clipboard);
+            clipboard = IntPtr.Zero;
+        }
+
+        string str = SDL2.SDL.SDL_GetClipboardText();
+        int length = Encoding.UTF8.GetByteCount(str);
+        byte* bytes = (byte*)(clipboard = (nint)NativeMemory.Alloc((nuint)(length + 1)));
+
+        Encoding.UTF8.GetBytes(str, new Span<byte>(bytes, length));
+        bytes[length] = 0;
+        return bytes;
+    }
+
+    // Stops the delegate pointer from being collected
+    private static IntPtr GetPointerTo<T>(T fn) where T : Delegate
+    {
+        if (pinned.TryGetValue(fn, out nint ptr))
+        {
+            return ptr;
+        }
+
+        ptr = Marshal.GetFunctionPointerForDelegate(fn);
+        pinned.Add(fn, ptr);
+        return ptr;
+    }
+}

Nerfed.Runtime/Gui/GuiController.cs

@@ -0,0 +1,710 @@
+// ImGuiController with docking and viewport support for MoonWorks/Refresh.
+// Based on the example im ImGui.NET and MoonWorksDearImGuiScaffold.
+
+using ImGuiNET;
+using Nerfed.Runtime.Graphics;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace Nerfed.Runtime.Gui;
+
+internal class GuiController : IDisposable
+{
+    public event Action OnGui;
+
+    private readonly string shaderContentPath = Path.Combine(System.AppContext.BaseDirectory, "Assets", "Shaders");
+
+    private readonly GraphicsDevice graphicsDevice;
+    private readonly Window mainWindow;
+    private readonly Color clearColor;
+
+    private readonly Platform_CreateWindow createWindow;
+    private readonly Platform_DestroyWindow destroyWindow;
+    private readonly Platform_GetWindowPos getWindowPos;
+    private readonly Platform_ShowWindow showWindow;
+    private readonly Platform_SetWindowPos setWindowPos;
+    private readonly Platform_SetWindowSize setWindowSize;
+    private readonly Platform_GetWindowSize getWindowSize;
+    private readonly Platform_SetWindowFocus setWindowFocus;
+    private readonly Platform_GetWindowFocus getWindowFocus;
+    private readonly Platform_GetWindowMinimized getWindowMinimized;
+    private readonly Platform_SetWindowTitle setWindowTitle;
+
+    private readonly ResourceUploader resourceUploader;
+    private readonly GraphicsPipeline imGuiPipeline;
+    private readonly Shader imGuiVertexShader;
+    private readonly Shader imGuiFragmentShader;
+    private readonly Sampler imGuiSampler;
+    private readonly GuiTextureStorage textureStorage = new GuiTextureStorage();
+    private readonly Dictionary<Window, GCHandle> windows = new Dictionary<Window, GCHandle>(16);
+
+    private Texture fontTexture = null;
+    private uint vertexCount = 0;
+    private uint indexCount = 0;
+    private Graphics.Buffer imGuiVertexBuffer = null;
+    private Graphics.Buffer imGuiIndexBuffer = null;
+    private bool frameBegun = false;
+
+    public GuiController(GraphicsDevice graphicsDevice, Window mainWindow, Color clearColor, ImGuiConfigFlags configFlags = ImGuiConfigFlags.NavEnableKeyboard | ImGuiConfigFlags.DockingEnable | ImGuiConfigFlags.ViewportsEnable)
+    {
+        this.mainWindow = mainWindow;
+        this.graphicsDevice = graphicsDevice;
+        this.clearColor = clearColor;
+
+        resourceUploader = new ResourceUploader(graphicsDevice);
+
+        ImGui.CreateContext();
+
+        ImGuiIOPtr io = ImGui.GetIO();
+        io.DisplaySize = new Vector2(mainWindow.Width, mainWindow.Height);
+        io.DisplayFramebufferScale = Vector2.One;
+
+        ShaderCreateInfo vertexCreateInfo = new ShaderCreateInfo {
+            ShaderStage = ShaderStage.Vertex,
+            ShaderFormat = ShaderFormat.SPIRV,
+            UniformBufferCount = 1,
+        };
+        imGuiVertexShader = new Shader(graphicsDevice, Path.Combine(shaderContentPath, "imgui-vertex.spv"), "main", in vertexCreateInfo);
+
+        ShaderCreateInfo fragCreateInfo = new ShaderCreateInfo {
+            ShaderStage = ShaderStage.Fragment,
+            ShaderFormat = ShaderFormat.SPIRV,
+            SamplerCount = 1,
+            
+        };
+        imGuiFragmentShader = new Shader(graphicsDevice, Path.Combine(shaderContentPath, "imgui-frag.spv"), "main", in fragCreateInfo);
+
+        imGuiSampler = new Sampler(graphicsDevice, SamplerCreateInfo.LinearClamp);
+
+        imGuiPipeline = new GraphicsPipeline(
+            graphicsDevice,
+            new GraphicsPipelineCreateInfo
+            {
+                AttachmentInfo = new GraphicsPipelineAttachmentInfo(
+                    new ColorAttachmentDescription(
+                        mainWindow.SwapchainFormat,
+                        ColorAttachmentBlendState.NonPremultiplied
+                    )
+                ),
+                DepthStencilState = DepthStencilState.Disable,
+                MultisampleState = MultisampleState.None,
+                PrimitiveType = PrimitiveType.TriangleList,
+                RasterizerState = RasterizerState.CW_CullNone,
+                VertexInputState = VertexInputState.CreateSingleBinding<Position2DTextureColorVertex>(),
+                VertexShader = imGuiVertexShader,
+                FragmentShader = imGuiFragmentShader,
+            }
+        );
+
+        BuildFontAtlas();
+
+        io.ConfigFlags = configFlags;
+        //io.MouseDrawCursor = true;
+
+        if (!OperatingSystem.IsWindows())
+        {
+            io.SetClipboardTextFn = GuiClipboard.SetFnPtr;
+            io.GetClipboardTextFn = GuiClipboard.GetFnPtr;
+        }
+
+        ImGuiPlatformIOPtr platformIO = ImGui.GetPlatformIO();
+        ImGuiViewportPtr mainViewport = platformIO.Viewports[0];
+        mainViewport.PlatformHandle = mainWindow.Handle;
+        GCHandle handle = GCHandle.Alloc(mainWindow);
+        mainViewport.PlatformUserData = (IntPtr)handle;
+        AddWindow(mainWindow, mainViewport, handle);
+
+        unsafe
+        {
+            createWindow = CreateWindow;
+            destroyWindow = DestroyWindow;
+            getWindowPos = GetWindowPos;
+            showWindow = ShowWindow;
+            setWindowPos = SetWindowPos;
+            setWindowSize = SetWindowSize;
+            getWindowSize = GetWindowSize;
+            setWindowFocus = SetWindowFocus;
+            getWindowFocus = GetWindowFocus;
+            getWindowMinimized = GetWindowMinimized;
+            setWindowTitle = SetWindowTitle;
+
+            platformIO.Platform_CreateWindow = Marshal.GetFunctionPointerForDelegate(createWindow);
+            platformIO.Platform_DestroyWindow = Marshal.GetFunctionPointerForDelegate(destroyWindow);
+            platformIO.Platform_ShowWindow = Marshal.GetFunctionPointerForDelegate(showWindow);
+            platformIO.Platform_SetWindowPos = Marshal.GetFunctionPointerForDelegate(setWindowPos);
+            platformIO.Platform_SetWindowSize = Marshal.GetFunctionPointerForDelegate(setWindowSize);
+            platformIO.Platform_SetWindowFocus = Marshal.GetFunctionPointerForDelegate(setWindowFocus);
+            platformIO.Platform_GetWindowFocus = Marshal.GetFunctionPointerForDelegate(getWindowFocus);
+            platformIO.Platform_GetWindowMinimized = Marshal.GetFunctionPointerForDelegate(getWindowMinimized);
+            platformIO.Platform_SetWindowTitle = Marshal.GetFunctionPointerForDelegate(setWindowTitle);
+
+            ImGuiNative.ImGuiPlatformIO_Set_Platform_GetWindowPos(platformIO.NativePtr, Marshal.GetFunctionPointerForDelegate(getWindowPos));
+            ImGuiNative.ImGuiPlatformIO_Set_Platform_GetWindowSize(platformIO.NativePtr, Marshal.GetFunctionPointerForDelegate(getWindowSize));
+        }
+
+        io.BackendFlags |= ImGuiBackendFlags.HasMouseCursors;
+        io.BackendFlags |= ImGuiBackendFlags.HasSetMousePos;
+        io.BackendFlags |= ImGuiBackendFlags.PlatformHasViewports;
+        io.BackendFlags |= ImGuiBackendFlags.RendererHasViewports;
+    }
+
+    public void Update(float deltaTime)
+    {
+        if (frameBegun)
+        {
+            ImGui.Render();
+            ImGui.UpdatePlatformWindows();
+        }
+
+        UpdatePerFrameImGuiData(deltaTime);
+        UpdateInput();
+        UpdateCursor();
+        UpdateMonitors();
+
+        frameBegun = true;
+        ImGui.NewFrame();
+
+        OnGui?.Invoke();
+
+        {   // Debug
+            ImGuiIOPtr io = ImGui.GetIO();
+            ImGui.Text($"mouse pos: {io.MousePos}");
+        }
+
+        ImGui.EndFrame();
+    }
+
+    private void UpdatePerFrameImGuiData(float deltaSeconds)
+    {
+        ImGuiIOPtr io = ImGui.GetIO();
+        io.DisplaySize = new Vector2(mainWindow.Width, mainWindow.Height);
+        io.DisplayFramebufferScale = new Vector2(1, 1);
+        io.DeltaTime = deltaSeconds; // DeltaTime is in seconds.
+    }
+
+    private void UpdateInput()
+    {
+        ImGuiIOPtr io = ImGui.GetIO();
+
+        if ((ImGui.GetIO().ConfigFlags & ImGuiConfigFlags.ViewportsEnable) != 0)
+        {
+            // For viewports we use the global mouse position.
+            _ = SDL2.SDL.SDL_GetGlobalMouseState(out int x, out int y);
+            io.MousePos = new Vector2(x, y);
+        }
+        else
+        {
+            // Without viewports we need to use the relative position.
+            //_ = SDL2.SDL.SDL_GetMouseState(out int x, out int y);
+            io.MousePos = Mouse.Position;
+        }
+
+        io.MouseDown[0] = Mouse.IsButtonDown(MouseButton.Left);
+        io.MouseDown[1] = Mouse.IsButtonDown(MouseButton.Right);
+        io.MouseDown[2] = Mouse.IsButtonDown(MouseButton.Middle);
+        
+        io.MouseWheel = Mouse.GetWheel();
+
+        io.AddKeyEvent(ImGuiKey.A, Keyboard.IsKeyDown(Key.A));
+        io.AddKeyEvent(ImGuiKey.Z, Keyboard.IsKeyDown(Key.Z));
+        io.AddKeyEvent(ImGuiKey.Y, Keyboard.IsKeyDown(Key.Y));
+        io.AddKeyEvent(ImGuiKey.X, Keyboard.IsKeyDown(Key.X));
+        io.AddKeyEvent(ImGuiKey.C, Keyboard.IsKeyDown(Key.C));
+        io.AddKeyEvent(ImGuiKey.V, Keyboard.IsKeyDown(Key.V));
+
+        io.AddKeyEvent(ImGuiKey.Tab, Keyboard.IsKeyDown(Key.Tab));
+        io.AddKeyEvent(ImGuiKey.LeftArrow, Keyboard.IsKeyDown(Key.Left));
+        io.AddKeyEvent(ImGuiKey.RightArrow, Keyboard.IsKeyDown(Key.Right));
+        io.AddKeyEvent(ImGuiKey.UpArrow, Keyboard.IsKeyDown(Key.Up));
+        io.AddKeyEvent(ImGuiKey.DownArrow, Keyboard.IsKeyDown(Key.Down));
+        io.AddKeyEvent(ImGuiKey.Enter, Keyboard.IsKeyDown(Key.Enter));
+        io.AddKeyEvent(ImGuiKey.Escape, Keyboard.IsKeyDown(Key.Escape));
+        io.AddKeyEvent(ImGuiKey.Delete, Keyboard.IsKeyDown(Key.Delete));
+        io.AddKeyEvent(ImGuiKey.Backspace, Keyboard.IsKeyDown(Key.Backspace));
+        io.AddKeyEvent(ImGuiKey.Home, Keyboard.IsKeyDown(Key.Home));
+        io.AddKeyEvent(ImGuiKey.End, Keyboard.IsKeyDown(Key.End));
+        io.AddKeyEvent(ImGuiKey.PageDown, Keyboard.IsKeyDown(Key.PageDown));
+        io.AddKeyEvent(ImGuiKey.PageUp, Keyboard.IsKeyDown(Key.PageUp));
+        io.AddKeyEvent(ImGuiKey.Insert, Keyboard.IsKeyDown(Key.Insert));
+
+        io.AddKeyEvent(ImGuiKey.ModCtrl, Keyboard.IsKeyDown(Key.LeftControl) || Keyboard.IsKeyDown(Key.RightControl));
+        io.AddKeyEvent(ImGuiKey.ModShift, Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift));
+        io.AddKeyEvent(ImGuiKey.ModAlt, Keyboard.IsKeyDown(Key.LeftAlt) || Keyboard.IsKeyDown(Key.RightAlt));
+        io.AddKeyEvent(ImGuiKey.ModSuper, Keyboard.IsKeyDown(Key.LeftSuper) || Keyboard.IsKeyDown(Key.RightSuper));
+
+        ReadOnlySpan<char> input = Keyboard.GetTextInput();
+        if (!input.IsEmpty)
+        {
+            foreach (char c in input)
+            {
+                if (c == '\t')
+                {
+                    break;
+                }
+
+                io.AddInputCharacter(c);
+            }
+        }
+    }
+
+    private void UpdateCursor()
+    {
+        ImGuiIOPtr io = ImGui.GetIO();
+        
+        if ((io.ConfigFlags & ImGuiConfigFlags.NoMouseCursorChange) != 0)
+        {
+            return;
+        }
+
+        ImGuiMouseCursor imGuiCursor = ImGui.GetMouseCursor();
+
+        if (imGuiCursor == ImGuiMouseCursor.None || io.MouseDrawCursor)
+        {
+            SDL2.SDL.SDL_ShowCursor(0);
+        }
+        else
+        {
+            nint sdlCursor = imGuiCursor switch
+            {
+                ImGuiMouseCursor.Arrow => SDL2.SDL.SDL_CreateSystemCursor(SDL2.SDL.SDL_SystemCursor.SDL_SYSTEM_CURSOR_ARROW),
+                ImGuiMouseCursor.TextInput => SDL2.SDL.SDL_CreateSystemCursor(SDL2.SDL.SDL_SystemCursor.SDL_SYSTEM_CURSOR_IBEAM),
+                ImGuiMouseCursor.ResizeAll => SDL2.SDL.SDL_CreateSystemCursor(SDL2.SDL.SDL_SystemCursor.SDL_SYSTEM_CURSOR_SIZEALL),
+                ImGuiMouseCursor.ResizeNS => SDL2.SDL.SDL_CreateSystemCursor(SDL2.SDL.SDL_SystemCursor.SDL_SYSTEM_CURSOR_SIZENS),
+                ImGuiMouseCursor.ResizeEW => SDL2.SDL.SDL_CreateSystemCursor(SDL2.SDL.SDL_SystemCursor.SDL_SYSTEM_CURSOR_SIZEWE),
+                ImGuiMouseCursor.ResizeNESW => SDL2.SDL.SDL_CreateSystemCursor(SDL2.SDL.SDL_SystemCursor.SDL_SYSTEM_CURSOR_SIZENESW),
+                ImGuiMouseCursor.ResizeNWSE => SDL2.SDL.SDL_CreateSystemCursor(SDL2.SDL.SDL_SystemCursor.SDL_SYSTEM_CURSOR_SIZENWSE),
+                ImGuiMouseCursor.Hand => SDL2.SDL.SDL_CreateSystemCursor(SDL2.SDL.SDL_SystemCursor.SDL_SYSTEM_CURSOR_HAND),
+                ImGuiMouseCursor.NotAllowed => SDL2.SDL.SDL_CreateSystemCursor(SDL2.SDL.SDL_SystemCursor.SDL_SYSTEM_CURSOR_NO),
+                _ => SDL2.SDL.SDL_CreateSystemCursor(SDL2.SDL.SDL_SystemCursor.SDL_SYSTEM_CURSOR_ARROW),
+            };
+            SDL2.SDL.SDL_SetCursor(sdlCursor);
+            SDL2.SDL.SDL_ShowCursor(1);
+        }
+    }
+
+    private unsafe void UpdateMonitors()
+    {
+        ImGuiPlatformIOPtr platformIO = ImGui.GetPlatformIO();
+        Marshal.FreeHGlobal(platformIO.NativePtr->Monitors.Data);
+        int videoDisplayCount = SDL2.SDL.SDL_GetNumVideoDisplays();
+        IntPtr data = Marshal.AllocHGlobal(Unsafe.SizeOf<ImGuiPlatformMonitor>() * videoDisplayCount);
+        platformIO.NativePtr->Monitors = new ImVector(videoDisplayCount, videoDisplayCount, data);
+
+        for (int i = 0; i < videoDisplayCount; i++)
+        {
+            _ = SDL2.SDL.SDL_GetDisplayUsableBounds(i, out SDL2.SDL.SDL_Rect usableBounds);
+            _ = SDL2.SDL.SDL_GetDisplayBounds(i, out SDL2.SDL.SDL_Rect bounds);
+            _ = SDL2.SDL.SDL_GetDisplayDPI(i, out float ddpi, out float hdpi, out float vdpi);
+            ImGuiPlatformMonitorPtr monitor = platformIO.Monitors[i];
+            float standardDpi = 96f; // Standard DPI typically used
+            monitor.DpiScale = hdpi / standardDpi;
+            monitor.MainPos = new Vector2(bounds.x, bounds.y);
+            monitor.MainSize = new Vector2(bounds.w, bounds.h);
+            monitor.WorkPos = new Vector2(usableBounds.x, usableBounds.y);
+            monitor.WorkSize = new Vector2(usableBounds.w, usableBounds.h);
+        }
+    }
+
+    public void Render()
+    {
+        if (!frameBegun)
+        {
+            return;
+        }
+
+        frameBegun = false;
+
+        if ((ImGui.GetIO().ConfigFlags & ImGuiConfigFlags.ViewportsEnable) != 0)
+        {
+            ImGui.Render();
+            ImGui.UpdatePlatformWindows();
+            ImGuiPlatformIOPtr platformIO = ImGui.GetPlatformIO();
+
+            for (int i = 0; i < platformIO.Viewports.Size; i++)
+            {
+                ImGuiViewportPtr vp = platformIO.Viewports[i];
+                Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+
+                if (!window.Claimed)
+                {
+                    continue;
+                }
+
+                UpdateImGuiBuffers(vp.DrawData);
+
+                CommandBuffer commandBuffer = graphicsDevice.AcquireCommandBuffer();
+                Texture swapchainTexture = commandBuffer.AcquireSwapchainTexture(window);
+
+                if (swapchainTexture != null)
+                {
+                    RenderCommandLists(commandBuffer, swapchainTexture, vp.DrawData);
+                    graphicsDevice.Submit(commandBuffer);
+                    //graphicsDevice.Wait();
+                }
+            }
+        }
+        else
+        {
+            ImGui.Render();
+
+            if (!mainWindow.Claimed)
+            {
+                return;
+            }
+
+            ImDrawDataPtr drawDataPtr = ImGui.GetDrawData();
+            UpdateImGuiBuffers(drawDataPtr);
+
+            CommandBuffer commandBuffer = graphicsDevice.AcquireCommandBuffer();
+            Texture swapchainTexture = commandBuffer.AcquireSwapchainTexture(mainWindow);
+
+            if (swapchainTexture != null)
+            {
+                RenderCommandLists(commandBuffer, swapchainTexture, drawDataPtr);
+                graphicsDevice.Submit(commandBuffer);
+                graphicsDevice.Wait();
+            }
+        }
+    }
+
+    private unsafe void UpdateImGuiBuffers(ImDrawDataPtr drawDataPtr)
+    {
+        if (drawDataPtr.TotalVtxCount == 0 || drawDataPtr.CmdListsCount == 0)
+        {
+            return;
+        }
+
+        if (drawDataPtr.TotalVtxCount > vertexCount)
+        {
+            imGuiVertexBuffer?.Dispose();
+
+            vertexCount = (uint)(drawDataPtr.TotalVtxCount * 1.5f);
+            imGuiVertexBuffer = Graphics.Buffer.Create<Position2DTextureColorVertex>(
+                graphicsDevice,
+                BufferUsageFlags.Vertex,
+                vertexCount
+            );
+        }
+
+        if (drawDataPtr.TotalIdxCount > indexCount)
+        {
+            imGuiIndexBuffer?.Dispose();
+
+            indexCount = (uint)(drawDataPtr.TotalIdxCount * 1.5f);
+            imGuiIndexBuffer = Graphics.Buffer.Create<ushort>(
+                graphicsDevice,
+                BufferUsageFlags.Index,
+                indexCount
+            );
+        }
+
+        uint vertexOffset = 0;
+        uint indexOffset = 0;
+
+        for (int n = 0; n < drawDataPtr.CmdListsCount; n++)
+        {
+            ImDrawListPtr cmdList = drawDataPtr.CmdLists[n];
+
+            resourceUploader.SetBufferData(
+                imGuiVertexBuffer, 
+                vertexOffset, 
+                new Span<Position2DTextureColorVertex>(cmdList.VtxBuffer.Data.ToPointer(), cmdList.VtxBuffer.Size),
+                n == 0
+            );
+
+            resourceUploader.SetBufferData(
+                imGuiIndexBuffer,
+                indexOffset,
+                new Span<ushort>(cmdList.IdxBuffer.Data.ToPointer(), cmdList.IdxBuffer.Size),
+                n == 0
+            );
+
+            vertexOffset += (uint)cmdList.VtxBuffer.Size;
+            indexOffset += (uint)cmdList.IdxBuffer.Size;
+        }
+
+        resourceUploader.Upload();
+    }
+
+    private void RenderCommandLists(CommandBuffer commandBuffer, Texture renderTexture, ImDrawDataPtr drawDataPtr)
+    {
+        Vector2 pos = drawDataPtr.DisplayPos;
+
+        RenderPass renderPass = commandBuffer.BeginRenderPass(
+            new ColorAttachmentInfo(renderTexture, false, clearColor)
+        );
+
+        renderPass.BindGraphicsPipeline(imGuiPipeline);
+
+        // It is possible that the buffers are null (for example nothing is in our main windows viewport, then we exixt early but still clear it).
+        if (imGuiVertexBuffer == null || imGuiIndexBuffer == null)
+        {
+            commandBuffer.EndRenderPass(renderPass);
+            return;
+        }
+
+        Matrix4x4 projectionMatrix = Matrix4x4.CreateOrthographicOffCenter(
+            pos.X,
+            pos.X + drawDataPtr.DisplaySize.X,
+            pos.Y + drawDataPtr.DisplaySize.Y,
+            pos.Y,
+            -1.0f,
+            1.0f
+        );
+        TransformVertexUniform vertexUniform = new TransformVertexUniform(projectionMatrix);
+
+        renderPass.BindVertexBuffer(imGuiVertexBuffer);
+        renderPass.BindIndexBuffer(imGuiIndexBuffer, IndexElementSize.Sixteen);
+
+        commandBuffer.PushVertexUniformData(in vertexUniform);
+
+        uint vertexOffset = 0;
+        uint indexOffset = 0;
+
+        for (int n = 0; n < drawDataPtr.CmdListsCount; n++)
+        {
+            ImDrawListPtr cmdList = drawDataPtr.CmdLists[n];
+
+            for (int cmdIndex = 0; cmdIndex < cmdList.CmdBuffer.Size; cmdIndex++)
+            {
+                ImDrawCmdPtr drawCmd = cmdList.CmdBuffer[cmdIndex];
+
+                Texture texture = textureStorage.GetTexture(drawCmd.TextureId);
+
+                if (texture == null)
+                {
+                    Log.Error("Texture or drawCmd.TextureId became null. Fit it!");
+                    continue;
+                }
+
+                renderPass.BindFragmentSampler(new TextureSamplerBinding(texture, imGuiSampler));
+
+                float width = drawCmd.ClipRect.Z - (int)drawCmd.ClipRect.X;
+                float height = drawCmd.ClipRect.W - (int)drawCmd.ClipRect.Y;
+
+                if (width <= 0 || height <= 0)
+                {
+                    continue;
+                }
+
+                renderPass.SetScissor(
+                    new Rect(
+                        (int)drawCmd.ClipRect.X - (int)pos.X,
+                        (int)drawCmd.ClipRect.Y - (int)pos.Y,
+                        (int)drawCmd.ClipRect.Z - (int)drawCmd.ClipRect.X,
+                        (int)drawCmd.ClipRect.W - (int)drawCmd.ClipRect.Y
+                    )
+                );
+
+                renderPass.DrawIndexedPrimitives(vertexOffset, indexOffset, drawCmd.ElemCount / 3);
+
+                indexOffset += drawCmd.ElemCount;
+            }
+
+            vertexOffset += (uint)cmdList.VtxBuffer.Size;
+        }
+
+        commandBuffer.EndRenderPass(renderPass);
+    }
+
+    private unsafe void BuildFontAtlas()
+    {
+        ResourceUploader resourceUploader = new ResourceUploader(graphicsDevice);
+
+        ImGuiIOPtr io = ImGui.GetIO();
+
+        io.Fonts.GetTexDataAsRGBA32(
+            out nint pixelData,
+            out int width,
+            out int height,
+            out int bytesPerPixel
+        );
+
+        Texture fontTexture = resourceUploader.CreateTexture2D(
+            new Span<byte>((void*)pixelData, width * height * bytesPerPixel),
+            (uint)width,
+            (uint)height
+        );
+
+        resourceUploader.Upload();
+        resourceUploader.Dispose();
+
+        io.Fonts.SetTexID(fontTexture.Handle);
+        io.Fonts.ClearTexData();
+
+        textureStorage.Add(fontTexture);    // <-- The fontTexture seems to get lost after some time (CG?).
+        this.fontTexture = fontTexture;     // <-- So we also keep a reference to make sure it doesn't happen.
+    }
+
+    #region Window
+    private void CreateWindow(ImGuiViewportPtr vp)
+    {
+        // TODO: Handle all flags.
+        ScreenMode screenMode = vp.Flags.HasFlag(ImGuiViewportFlags.NoDecoration) ? ScreenMode.WindowedBorderless : ScreenMode.Windowed;
+        bool systemResizable = !vp.Flags.HasFlag(ImGuiViewportFlags.NoDecoration);
+
+        WindowCreateInfo info = new WindowCreateInfo("Window Title", (uint)vp.Pos.X, (uint)vp.Pos.Y, screenMode, systemResizable, false);
+
+        Window window = new Window(graphicsDevice, info);
+        graphicsDevice.ClaimWindow(window, SwapchainComposition.SDR, PresentMode.Immediate); // What PresentMode do we need?
+
+        GCHandle handle = GCHandle.Alloc(window);
+        vp.PlatformUserData = (IntPtr)handle;
+
+        AddWindow(window, vp, handle);
+    }
+
+    private void DestroyWindow(ImGuiViewportPtr vp)
+    {
+        if (vp.PlatformUserData == IntPtr.Zero) return;
+
+        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+        graphicsDevice.UnclaimWindow(window);
+
+        if (windows.TryGetValue(window, out GCHandle handle))
+        {
+            handle.Free();
+            windows.Remove(window);
+        }
+
+        //graphicsDevice.Wait();
+        window.Dispose();
+
+        vp.PlatformUserData = IntPtr.Zero;
+    }
+
+    private void AddWindow(Window window, ImGuiViewportPtr vp, GCHandle handle)
+    {
+        window.OnResizedEvent += ((win, w, h) => {
+            vp.PlatformRequestResize = true;
+        });
+
+        window.OnMovedEvent += ((win, x, y) =>
+        {
+            vp.PlatformRequestMove = true;
+        });
+
+        window.OnCloseEvent += (win) =>
+        {
+            ImGuiPlatformIOPtr platformIO = ImGui.GetPlatformIO();
+
+            for (int i = 0; i < platformIO.Viewports.Capacity; i++)
+            {
+                ImGuiViewportPtr vp = platformIO.Viewports[i];
+                if(win == (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target)
+                {
+                    DestroyWindow(vp);
+                }
+            }
+        };
+
+        windows.Add(window, handle);
+    }
+
+    private void ShowWindow(ImGuiViewportPtr vp)
+    {
+        if (vp.PlatformUserData == IntPtr.Zero) return;
+
+        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+        SDL2.SDL.SDL_ShowWindow(window.Handle);
+    }
+
+    private unsafe void GetWindowPos(ImGuiViewportPtr vp, Vector2* outPos)
+    {
+        if (vp.PlatformUserData == IntPtr.Zero) return;
+
+        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+        SDL2.SDL.SDL_GetWindowPosition(window.Handle, out int x, out int y);
+        *outPos = new Vector2(x, y);
+    }
+
+    private void SetWindowPos(ImGuiViewportPtr vp, Vector2 pos)
+    {
+        if (vp.PlatformUserData == IntPtr.Zero) return;
+
+        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+        SDL2.SDL.SDL_SetWindowPosition(window.Handle, (int)pos.X, (int)pos.Y);
+    }
+
+    private void SetWindowSize(ImGuiViewportPtr vp, Vector2 size)
+    {
+        if (vp.PlatformUserData == IntPtr.Zero) return;
+
+        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+        SDL2.SDL.SDL_SetWindowSize(window.Handle, (int)size.X, (int)size.Y);
+    }
+
+    private unsafe void GetWindowSize(ImGuiViewportPtr vp, Vector2* outSize)
+    {
+        if (vp.PlatformUserData == IntPtr.Zero) return;
+
+        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+        SDL2.SDL.SDL_GetWindowSize(window.Handle, out int w, out int h);
+        *outSize = new Vector2(w, h);
+    }
+
+    private void SetWindowFocus(ImGuiViewportPtr vp)
+    {
+        if (vp.PlatformUserData == IntPtr.Zero) return;
+
+        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+        //SDL2.SDL.SDL_SetWindowInputFocus(window.Handle);
+        SDL2.SDL.SDL_RaiseWindow(window.Handle);
+    }
+
+    private byte GetWindowFocus(ImGuiViewportPtr vp)
+    {
+        if (vp.PlatformUserData == IntPtr.Zero) return (byte)0;
+
+        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+        SDL2.SDL.SDL_WindowFlags flags = (SDL2.SDL.SDL_WindowFlags)SDL2.SDL.SDL_GetWindowFlags(window.Handle);
+        return (flags & SDL2.SDL.SDL_WindowFlags.SDL_WINDOW_INPUT_FOCUS) != 0 ? (byte)1 : (byte)0;
+    }
+
+    private byte GetWindowMinimized(ImGuiViewportPtr vp)
+    {
+        if (vp.PlatformUserData == IntPtr.Zero) return (byte)0;
+
+        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+        SDL2.SDL.SDL_WindowFlags flags = (SDL2.SDL.SDL_WindowFlags)SDL2.SDL.SDL_GetWindowFlags(window.Handle);
+        return (flags & SDL2.SDL.SDL_WindowFlags.SDL_WINDOW_MINIMIZED) != 0 ? (byte)1 : (byte)0;
+    }
+
+    private unsafe void SetWindowTitle(ImGuiViewportPtr vp, IntPtr title)
+    {
+        if (vp.PlatformUserData == IntPtr.Zero) return;
+
+        Window window = (Window)GCHandle.FromIntPtr(vp.PlatformUserData).Target;
+        byte* titlePtr = (byte*)title;
+        int count = 0;
+        while (titlePtr[count] != 0)
+        {
+            count += 1;
+        }
+        SDL2.SDL.SDL_SetWindowTitle(window.Handle, System.Text.Encoding.ASCII.GetString(titlePtr, count));
+    }
+    #endregion
+
+    public void Dispose()
+    {
+        fontTexture?.Dispose();
+        imGuiVertexBuffer?.Dispose();
+        imGuiIndexBuffer?.Dispose();
+        imGuiFragmentShader?.Dispose();
+        imGuiVertexShader?.Dispose();
+        imGuiPipeline?.Dispose();
+        imGuiSampler?.Dispose();
+        resourceUploader?.Dispose();
+
+        foreach (KeyValuePair<Window, GCHandle> window in windows)
+        {
+            if (window.Key == mainWindow) continue;
+
+            graphicsDevice.UnclaimWindow(window.Key);
+            window.Key.Dispose();
+            window.Value.Free();
+        }
+        windows.Clear();
+    }
+}

Nerfed.Runtime/Gui/GuiStructs.cs

@@ -0,0 +1,33 @@
+using Nerfed.Runtime.Graphics;
+using System.Numerics;
+using System.Runtime.InteropServices;
+
+namespace Nerfed.Runtime.Gui;
+
+[StructLayout(LayoutKind.Sequential)]
+public struct Position2DTextureColorVertex(Vector2 position, Vector2 texcoord, Color color) : IVertexType
+{
+    public Vector2 Position = position;
+    public Vector2 TexCoord = texcoord;
+    public Color Color = color;
+
+    public static VertexElementFormat[] Formats { get; } = new VertexElementFormat[3]
+    {
+        VertexElementFormat.Vector2,
+        VertexElementFormat.Vector2,
+        VertexElementFormat.Color
+    };
+
+    public static uint[] Offsets { get; } = new uint[3]
+    {
+        0,
+        8,
+        16
+    };
+}
+
+[StructLayout(LayoutKind.Sequential)]
+public struct TransformVertexUniform(Matrix4x4 projectionMatrix)
+{
+    public Matrix4x4 ProjectionMatrix = projectionMatrix;
+}

Nerfed.Runtime/Gui/GuiTextureStorage.cs

@@ -0,0 +1,35 @@
+using Nerfed.Runtime.Graphics;
+
+namespace Nerfed.Runtime.Gui;
+
+public class GuiTextureStorage
+{
+    private readonly Dictionary<IntPtr, WeakReference<Texture>> pointerToTexture = new Dictionary<IntPtr, WeakReference<Texture>>();
+
+    public IntPtr Add(Texture texture)
+    {
+        if (!pointerToTexture.ContainsKey(texture.Handle))
+        {
+            pointerToTexture.Add(texture.Handle, new WeakReference<Texture>(texture));
+        }
+        return texture.Handle;
+    }
+
+    public Texture GetTexture(IntPtr pointer)
+    {
+        if (!pointerToTexture.TryGetValue(pointer, out WeakReference<Texture> value))
+        {
+            return null;
+        }
+
+        WeakReference<Texture> result = value;
+
+        if (!result.TryGetTarget(out Texture texture))
+        {
+            pointerToTexture.Remove(pointer);
+            return null;
+        }
+
+        return texture;
+    }
+}

Nerfed.Runtime/Gui/Shaders/generate-spirv.bat

@@ -0,0 +1,2 @@
+glslangvalidator -V imgui-vertex.glsl -o imgui-vertex.spv -S vert
+glslangvalidator -V imgui-frag.glsl -o imgui-frag.spv -S frag

Nerfed.Runtime/Gui/Shaders/imgui-frag.glsl

@@ -0,0 +1,13 @@
+#version 450
+
+layout (location = 0) in vec4 color;
+layout (location = 1) in vec2 texCoord;
+
+layout(set = 2, binding = 0) uniform sampler2D Sampler;
+
+layout (location = 0) out vec4 outputColor;
+
+void main()
+{
+    outputColor = color * texture(Sampler, texCoord);
+}

Nerfed.Runtime/Gui/Shaders/imgui-vertex.glsl

@@ -0,0 +1,20 @@
+#version 450
+
+layout (location = 0) in vec2 in_position;
+layout (location = 1) in vec2 in_texCoord;
+layout (location = 2) in vec4 in_color;
+
+layout (set = 1, binding = 0) uniform ProjectionMatrixBuffer
+{
+    mat4 projection_matrix;
+};
+
+layout (location = 0) out vec4 color;
+layout (location = 1) out vec2 texCoord;
+
+void main() 
+{
+    gl_Position = projection_matrix * vec4(in_position, 0, 1);
+    color = in_color;
+    texCoord = in_texCoord;
+}

Nerfed.Runtime/Input/Devices/Mouse.cs

@@ -1,5 +1,5 @@
-using System.Numerics;
-using SDL2;
+using SDL2;
+using System.Numerics;
 
 namespace Nerfed.Runtime;
 
@@ -65,6 +65,8 @@ internal static class Mouse
 
     internal static void Update()
     {
+        wheelX = 0;
+        wheelY = 0;
         Array.Copy(buttonStates, lastButtonStates, buttonStates.Length);
     }
 
@@ -105,8 +107,8 @@ internal static class Mouse
 
     private static void ProcessWheelEvent(ref SDL.SDL_MouseWheelEvent ev)
     {
-        wheelX += ev.x;
-        wheelY += ev.y;
+        wheelX = ev.x;
+        wheelY = ev.y;
     }
 
     private static void ProcessMotionEvent(ref SDL.SDL_MouseMotionEvent ev)

Nerfed.Runtime/Nerfed.Runtime.csproj

@@ -12,6 +12,16 @@
         <Compile Include="Libraries\dav1dfile\csharp\dav1dfile.cs" />
     </ItemGroup>
 
+    <ItemGroup>
+      <ProjectReference Include="Libraries\ImGui.NET\src\ImGui.NET\ImGui.NET.csproj" />
+    </ItemGroup>
+
+    <ItemGroup>
+        <Content Include="Assets\**\*.*">
+            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+        </Content>
+    </ItemGroup>
+
     <PropertyGroup>
         <OutputType>Exe</OutputType>
         <TargetFramework>net8.0</TargetFramework>

Nerfed.Runtime/Window/ScreenMode.cs

@@ -3,6 +3,7 @@ namespace Nerfed.Runtime;
 public enum ScreenMode
 {
     Fullscreen,
-    BorderlessFullscreen,
-    Windowed
+    FullscreenBorderless,
+    Windowed,
+    WindowedBorderless
 }

Nerfed.Runtime/Window/Window.cs

@@ -11,6 +11,10 @@ namespace Nerfed.Runtime;
 /// </summary>
 public class Window
 {
+	public event Action<Window, uint, uint> OnResizedEvent;
+	public event Action<Window, int, int> OnMovedEvent;
+	public event Action<Window> OnCloseEvent;
+
     internal IntPtr Handle { get; }
 	public ScreenMode ScreenMode { get; private set; }
 	public uint Width { get; private set; }
@@ -33,8 +37,6 @@ public class Window
 	public string Title { get; private set;}
 
 	private bool IsDisposed;
-	private System.Action<uint, uint> SizeChangeCallback = null;
-
     private static readonly Dictionary<uint, Window> windowsById = new Dictionary<uint, Window>();
 
 	public Window(GraphicsDevice graphicsDevice, WindowCreateInfo windowCreateInfo)
@@ -54,10 +56,14 @@ public class Window
 		{
 			flags |= SDL.SDL_WindowFlags.SDL_WINDOW_FULLSCREEN;
 		}
-		else if (windowCreateInfo.ScreenMode == ScreenMode.BorderlessFullscreen)
+		else if (windowCreateInfo.ScreenMode == ScreenMode.FullscreenBorderless)
 		{
 			flags |= SDL.SDL_WindowFlags.SDL_WINDOW_FULLSCREEN_DESKTOP;
 		}
+		else if(windowCreateInfo.ScreenMode == ScreenMode.WindowedBorderless)
+		{
+			flags |= SDL.SDL_WindowFlags.SDL_WINDOW_BORDERLESS;
+		}
 
 		if (windowCreateInfo.SystemResizable)
 		{
@@ -104,6 +110,9 @@ public class Window
 			case SDL.SDL_WindowEventID.SDL_WINDOWEVENT_SIZE_CHANGED:
 				window.ProcessSizeChangedEvent(ref ev.window);
 				break;
+			case SDL.SDL_WindowEventID.SDL_WINDOWEVENT_MOVED:
+				window.ProcessMovedChangedEvent(ref ev.window);
+				break;
 			case SDL.SDL_WindowEventID.SDL_WINDOWEVENT_CLOSE:
 				window.ProcessCloseEvent(ref ev.window);
 				break;
@@ -117,16 +126,19 @@ public class Window
 		Width = newWidth;
 		Height = newHeight;
 
-		if (SizeChangeCallback != null)
-		{
-			SizeChangeCallback(newWidth, newHeight);
+		OnResizedEvent?.Invoke(this, Width, Height);
 	}
+
+    private void ProcessMovedChangedEvent(ref SDL.SDL_WindowEvent ev)
+    {
+		OnMovedEvent?.Invoke(this, ev.data1, ev.data2);
     }
 
     private void ProcessCloseEvent(ref SDL.SDL_WindowEvent ev)
 	{
 		Engine.GraphicsDevice.UnclaimWindow(this);
 		Dispose();
+		OnCloseEvent?.Invoke(this);
 	}
 
 	/// <summary>
@@ -140,7 +152,7 @@ public class Window
 		{
 			windowFlag = SDL.SDL_WindowFlags.SDL_WINDOW_FULLSCREEN;
 		}
-		else if (screenMode == ScreenMode.BorderlessFullscreen)
+		else if (screenMode == ScreenMode.FullscreenBorderless)
 		{
 			windowFlag = SDL.SDL_WindowFlags.SDL_WINDOW_FULLSCREEN_DESKTOP;
 		}
@@ -195,14 +207,6 @@ public class Window
 		SDL.SDL_ShowWindow(Handle);
 	}
 
-	/// <summary>
-	/// You can specify a method to run when the window size changes.
-	/// </summary>
-	public void RegisterSizeChangeCallback(System.Action<uint, uint> sizeChangeCallback)
-	{
-		SizeChangeCallback = sizeChangeCallback;
-	}
-
     protected virtual void Dispose(bool disposing)
 	{
 		if (!IsDisposed)

Nerfed.sln

@@ -5,6 +5,8 @@ VisualStudioVersion = 17.10.35013.160
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Nerfed.Runtime", "Nerfed.Runtime\Nerfed.Runtime.csproj", "{98E09BAF-587F-4238-89BD-7693C036C233}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ImGui.NET", "Nerfed.Runtime\Libraries\ImGui.NET\src\ImGui.NET\ImGui.NET.csproj", "{4EC3C399-4E09-4A36-B11E-391F0792C1C8}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -15,6 +17,10 @@ Global
 		{98E09BAF-587F-4238-89BD-7693C036C233}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{98E09BAF-587F-4238-89BD-7693C036C233}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{98E09BAF-587F-4238-89BD-7693C036C233}.Release|Any CPU.Build.0 = Release|Any CPU
+		{4EC3C399-4E09-4A36-B11E-391F0792C1C8}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4EC3C399-4E09-4A36-B11E-391F0792C1C8}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{4EC3C399-4E09-4A36-B11E-391F0792C1C8}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{4EC3C399-4E09-4A36-B11E-391F0792C1C8}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE