init

.gitignore

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+.idea/
+AvaloniaOpenTK/bin/
+AvaloniaOpenTK/obj/

AvaloniaOpenTK.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AvaloniaOpenTK", "AvaloniaOpenTK\AvaloniaOpenTK.csproj", "{9DF7318A-20CB-4172-B798-D1619F9615F8}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{9DF7318A-20CB-4172-B798-D1619F9615F8}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9DF7318A-20CB-4172-B798-D1619F9615F8}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9DF7318A-20CB-4172-B798-D1619F9615F8}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9DF7318A-20CB-4172-B798-D1619F9615F8}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal

AvaloniaOpenTK/App.axaml

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+<Application xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="AvaloniaOpenTK.App"
+             xmlns:local="using:AvaloniaOpenTK"
+             RequestedThemeVariant="Default">
+             <!-- "Default" ThemeVariant follows system theme variant. "Dark" or "Light" are other available options. -->
+
+    <Application.DataTemplates>
+        <local:ViewLocator/>
+    </Application.DataTemplates>
+  
+    <Application.Styles>
+        <FluentTheme />
+    </Application.Styles>
+</Application>

AvaloniaOpenTK/App.axaml.cs

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+using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Data.Core;
+using Avalonia.Data.Core.Plugins;
+using System.Linq;
+using Avalonia.Markup.Xaml;
+using AvaloniaOpenTK.ViewModels;
+using AvaloniaOpenTK.Views;
+
+namespace AvaloniaOpenTK;
+
+public partial class App : Application
+{
+    public override void Initialize()
+    {
+        AvaloniaXamlLoader.Load(this);
+    }
+
+    public override void OnFrameworkInitializationCompleted()
+    {
+        if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+        {
+            // Avoid duplicate validations from both Avalonia and the CommunityToolkit. 
+            // More info: https://docs.avaloniaui.net/docs/guides/development-guides/data-validation#manage-validationplugins
+            DisableAvaloniaDataAnnotationValidation();
+            desktop.MainWindow = new MainWindow
+            {
+                DataContext = new MainWindowViewModel(),
+            };
+        }
+
+        base.OnFrameworkInitializationCompleted();
+    }
+
+    private void DisableAvaloniaDataAnnotationValidation()
+    {
+        // Get an array of plugins to remove
+        var dataValidationPluginsToRemove =
+            BindingPlugins.DataValidators.OfType<DataAnnotationsValidationPlugin>().ToArray();
+
+        // remove each entry found
+        foreach (var plugin in dataValidationPluginsToRemove)
+        {
+            BindingPlugins.DataValidators.Remove(plugin);
+        }
+    }
+}

AvaloniaOpenTK/AvaloniaOpenTK.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+    <PropertyGroup>
+        <OutputType>WinExe</OutputType>
+        <TargetFramework>net8.0</TargetFramework>
+        <Nullable>enable</Nullable>
+        <BuiltInComInteropSupport>true</BuiltInComInteropSupport>
+        <ApplicationManifest>app.manifest</ApplicationManifest>
+        <AvaloniaUseCompiledBindingsByDefault>true</AvaloniaUseCompiledBindingsByDefault>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <Folder Include="Models\"/>
+        <AvaloniaResource Include="Assets\**"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Avalonia" Version="11.2.1"/>
+        <PackageReference Include="Avalonia.Desktop" Version="11.2.1"/>
+        <PackageReference Include="Avalonia.Themes.Fluent" Version="11.2.1"/>
+        <PackageReference Include="Avalonia.Fonts.Inter" Version="11.2.1"/>
+        <!--Condition below is needed to remove Avalonia.Diagnostics package from build output in Release configuration.-->
+        <PackageReference Include="Avalonia.Diagnostics" Version="11.2.1">
+            <IncludeAssets Condition="'$(Configuration)' != 'Debug'">None</IncludeAssets>
+            <PrivateAssets Condition="'$(Configuration)' != 'Debug'">All</PrivateAssets>
+        </PackageReference>
+        <PackageReference Include="CommunityToolkit.Mvvm" Version="8.2.1"/>
+        <PackageReference Include="OpenTK" Version="5.0.0-pre.13" />
+    </ItemGroup>
+</Project>

AvaloniaOpenTK/Controls/BaseOpenTKControl.axaml

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+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             x:Class="AvaloniaOpenTK.Controls.BaseOpenTKControl">
+</UserControl>

AvaloniaOpenTK/Controls/BaseOpenTKControl.axaml.cs

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+// BaseOpenTKControl.axaml.cs
+
+using System;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+using Avalonia.OpenGL;
+using Avalonia.OpenGL.Controls;
+using OpenTK;
+using OpenTK.Graphics;
+using OpenTK.Graphics.OpenGL;
+
+namespace AvaloniaOpenTK.Controls;
+
+public partial class BaseOpenTKControl : OpenGlControlBase
+{
+
+    private int _vao;
+    private int _vbo;
+
+    private readonly float[] _verts =
+    {
+        0.0f, 0.5f,
+        -0.5f, -0.5f,
+        0.5f, -0.5f
+    };
+
+public BaseOpenTKControl()
+    {
+        InitializeComponent();
+    }
+    
+    protected override void OnOpenGlInit(GlInterface gl)
+    {
+        GLLoader.LoadBindings(new AvaloniaBindingsContext(gl));
+        GL.ClearColor(new(0.2f, 0.4f, 0.8f, 1.0f));
+        
+        _vao = GL.GenVertexArray();
+        GL.BindVertexArray(_vao);
+        
+        _vbo = GL.GenBuffer();
+        GL.BindBuffer(BufferTarget.ArrayBuffer, _vbo);
+        
+        GL.BufferData(BufferTarget.ArrayBuffer, _verts.Length * sizeof(float), _verts, BufferUsage.StaticDraw);
+        
+        GL.EnableVertexAttribArray(0);
+        GL.VertexAttribPointer(0, 2, VertexAttribPointerType.Float, false, 2 * sizeof(float), 0);
+        
+        GL.BindVertexArray(0);
+    }
+
+    protected override void OnOpenGlRender(GlInterface gl, int fb)
+    {
+        var width = (int)Bounds.Width;
+        var height = (int)Bounds.Height;
+        GL.Viewport(0, 0, width, height);
+        GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
+        
+        GL.BindVertexArray(_vao);
+        GL.DrawArrays(PrimitiveType.Triangles, 0, 3);
+        
+        GL.BindVertexArray(0);
+    }
+
+    protected override void OnOpenGlDeinit(GlInterface gl)
+    {
+        GL.DeleteBuffer(_vbo);
+        GL.DeleteVertexArray(_vao);
+    }
+    
+    private class AvaloniaBindingsContext : IBindingsContext
+    {
+        private readonly GlInterface _gl;
+        
+        public AvaloniaBindingsContext(GlInterface gl)
+        {
+            _gl = gl;
+        }
+        
+        public IntPtr GetProcAddress(string procName)
+        {
+            return _gl.GetProcAddress(procName);
+        }
+    }
+}
+

AvaloniaOpenTK/Program.cs

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+using Avalonia;
+using System;
+using System.Collections.ObjectModel;
+
+namespace AvaloniaOpenTK;
+
+sealed class Program
+{
+    // Platform-specific options to be passed to AppBuilder.Configure.
+    private static Win32PlatformOptions _win32PlatformOptions = new()
+    {
+        RenderingMode = new Collection<Win32RenderingMode>() { Win32RenderingMode.Wgl }
+    };
+    
+    private static X11PlatformOptions _x11PlatformOptions = new()
+    {
+        RenderingMode = new Collection<X11RenderingMode>() { X11RenderingMode.Egl },
+        WmClass = "AvaloniaOpenTKApp"
+    };
+    
+    private static MacOSPlatformOptions _macOSPlatformOptions = new()
+    {
+        ShowInDock = true
+    };
+    
+    // Initialization code. Don't use any Avalonia, third-party APIs or any
+    // SynchronizationContext-reliant code before AppMain is called: things aren't initialized
+    // yet and stuff might break.
+    [STAThread]
+    public static void Main(string[] args) => BuildAvaloniaApp()
+        .StartWithClassicDesktopLifetime(args);
+
+    // Avalonia configuration, don't remove; also used by visual designer.
+    public static AppBuilder BuildAvaloniaApp()
+        => AppBuilder.Configure<App>()
+            .UsePlatformDetect()
+            .WithInterFont()
+            .UseSkia()
+            .With(_win32PlatformOptions)
+            .With(_x11PlatformOptions)
+            .With(_macOSPlatformOptions)
+            .LogToTrace();
+}

AvaloniaOpenTK/ViewLocator.cs

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+using System;
+using Avalonia.Controls;
+using Avalonia.Controls.Templates;
+using AvaloniaOpenTK.ViewModels;
+
+namespace AvaloniaOpenTK;
+
+public class ViewLocator : IDataTemplate
+{
+    public Control? Build(object? param)
+    {
+        if (param is null)
+            return null;
+
+        var name = param.GetType().FullName!.Replace("ViewModel", "View", StringComparison.Ordinal);
+        var type = Type.GetType(name);
+
+        if (type != null)
+        {
+            return (Control)Activator.CreateInstance(type)!;
+        }
+
+        return new TextBlock { Text = "Not Found: " + name };
+    }
+
+    public bool Match(object? data)
+    {
+        return data is ViewModelBase;
+    }
+}

AvaloniaOpenTK/ViewModels/MainWindowViewModel.cs

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+using OpenTK.Mathematics;
+
+namespace AvaloniaOpenTK.ViewModels;
+
+public partial class MainWindowViewModel : ViewModelBase
+{
+    public string Greeting { get; } = "Avalonia OpenTK!";
+
+    public int OpenTKViewportSizeX { get; } = 800;
+    public int OpenTKViewportSizeY { get; } = 800;
+}

AvaloniaOpenTK/ViewModels/ViewModelBase.cs

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+using CommunityToolkit.Mvvm.ComponentModel;
+
+namespace AvaloniaOpenTK.ViewModels;
+
+public class ViewModelBase : ObservableObject
+{
+}

AvaloniaOpenTK/Views/MainWindow.axaml

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+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="using:AvaloniaOpenTK.ViewModels"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:controls="clr-namespace:AvaloniaOpenTK.Controls"
+        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+        x:Class="AvaloniaOpenTK.Views.MainWindow"
+        x:DataType="vm:MainWindowViewModel"
+        Icon="/Assets/avalonia-logo.ico"
+        Title="AvaloniaOpenTK">
+
+    <Design.DataContext>
+        <!-- This only sets the DataContext for the previewer in an IDE,
+             to set the actual DataContext for runtime, set the DataContext property in code (look at App.axaml.cs) -->
+        <vm:MainWindowViewModel/>
+    </Design.DataContext>
+
+    <StackPanel x:Name="MainPanel" HorizontalAlignment="Center" VerticalAlignment="Center">
+        <TextBlock Text="{Binding Greeting}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
+        <controls:BaseOpenTKControl Width="{Binding OpenTKViewportSizeX}" Height="{Binding OpenTKViewportSizeY}"/> 
+    </StackPanel>
+
+</Window>

AvaloniaOpenTK/Views/MainWindow.axaml.cs

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+using Avalonia.Controls;
+
+namespace AvaloniaOpenTK.Views;
+
+public partial class MainWindow : Window
+{
+    public MainWindow()
+    {
+        InitializeComponent();
+    }
+}

AvaloniaOpenTK/app.manifest

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+<?xml version="1.0" encoding="utf-8"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <!-- This manifest is used on Windows only.
+       Don't remove it as it might cause problems with window transparency and embedded controls.
+       For more details visit https://learn.microsoft.com/en-us/windows/win32/sbscs/application-manifests -->
+  <assemblyIdentity version="1.0.0.0" name="AvaloniaOpenTK.Desktop"/>
+
+  <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
+    <application>
+      <!-- A list of the Windows versions that this application has been tested on
+           and is designed to work with. Uncomment the appropriate elements
+           and Windows will automatically select the most compatible environment. -->
+
+      <!-- Windows 10 -->
+      <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}" />
+    </application>
+  </compatibility>
+</assembly>