Table of Contents

OpenGL Binding Libraries for C# - Research Report

Date: December 2024 Purpose: Evaluate OpenGL binding libraries for a custom cross-platform game engine

Executive Summary

After evaluating Silk.NET, OpenTK, and Veldrid, Silk.NET is the recommended choice for a custom game engine due to its active maintenance, broader API coverage, .NET Foundation backing, and flexible architecture that doesn't impose design decisions.

Library Comparison

Silk.NET

Attribute Value
Repository github.com/dotnet/Silk.NET
Stars 4.8k
Contributors 109
Open Issues 72
Latest Version 2.22.0 (November 2024)
License MIT

Strengths:

  • .NET Foundation project - Guarantees project longevity and governance
  • Broadest API coverage - OpenGL, Vulkan, DirectX, WebGPU, OpenXR, OpenAL, OpenCL, SDL, GLFW, Assimp
  • Active development - Monthly releases, v3.0 under active development
  • Mobile support - Proven on Android and iOS
  • Performance-focused - Hand-optimized JIT assembly generation
  • Source-generated bindings - Type-safe, low overhead

Weaknesses:

  • v2.x in "limited investment" mode as team focuses on v3.0
  • More complex API surface due to breadth of coverage
  • Uses unsafe code extensively (necessary for low-level APIs)

API Example:

using Silk.NET.Windowing;
using Silk.NET.OpenGL;

var options = WindowOptions.Default with
{
    Size = new Vector2D<int>(800, 600),
    Title = "Silk.NET Window"
};

var window = Window.Create(options);
GL gl = null;

window.Load += () => gl = window.CreateOpenGL();
window.Render += dt => { /* rendering code */ };
window.Run();

OpenTK

Attribute Value
Repository github.com/opentk/opentk
Stars 3.5k
Contributors 122
Open Issues 50
Latest Version 4.9.4 (March 2025)
License MIT

Strengths:

  • Mature and battle-tested - 15+ years of development
  • Included math library - Robust Vector, Matrix, Quaternion types
  • GameWindow abstraction - Convenient for simple applications
  • Active v5.0 development - New bindings generator, Vulkan support, pure C# windowing
  • Simpler API - More approachable for beginners

Weaknesses:

  • No mobile support - Desktop only (Windows, Linux, macOS)
  • Narrower scope - OpenGL, OpenAL, OpenCL only
  • v4.x and v5.x are separate codebases with different APIs
  • Community-maintained (no foundation backing)

API Example:

using OpenTK.Windowing.Desktop;
using OpenTK.Mathematics;

public class Game : GameWindow
{
    public Game() : base(
        GameWindowSettings.Default,
        new NativeWindowSettings
        {
            Size = new Vector2i(800, 600),
            Title = "OpenTK Window"
        })
    { }

    protected override void OnRenderFrame(FrameEventArgs args)
    {
        // rendering code
        SwapBuffers();
    }
}

using var game = new Game();
game.Run();

Veldrid

Attribute Value
Repository github.com/veldrid/veldrid
Stars 2.6k
Contributors 53
Open Issues 106
Latest Version 4.9.0 (February 2023)
License MIT

Strengths:

  • Multi-backend abstraction - Vulkan, Metal, D3D11, OpenGL, OpenGL ES from single API
  • Portable shaders - SPIR-V support for write-once shaders
  • Modern design - Command-based architecture like Vulkan/D3D12
  • Allocation-free rendering - Zero GC pressure in hot paths
  • VR support - OpenVR and Oculus integration

Weaknesses:

  • Maintenance concerns - Creator announced in Feb 2023 they can no longer publicly share updates
  • No releases since 2023 - 106 open issues, unclear future
  • Higher abstraction level - Less control than raw OpenGL bindings
  • Active fork exists (ppy.Veldrid) but fragmentation risk

API Example:

using Veldrid;
using Veldrid.StartupUtilities;

var windowCI = new WindowCreateInfo
{
    X = 100, Y = 100,
    WindowWidth = 800, WindowHeight = 600,
    WindowTitle = "Veldrid Window"
};
var window = VeldridStartup.CreateWindow(ref windowCI);

var options = new GraphicsDeviceOptions
{
    PreferStandardClipSpaceYDirection = true,
    PreferDepthRangeZeroToOne = true
};
var graphicsDevice = VeldridStartup.CreateGraphicsDevice(window, options);

while (window.Exists)
{
    window.PumpEvents();
    // rendering code
}

Decision Matrix

Criteria Weight Silk.NET OpenTK Veldrid
Performance High 9 8 8
Maintenance High 9 8 4
Flexibility High 9 7 6
Documentation Medium 7 8 7
Community Medium 8 8 5
Mobile Support Medium 9 3 7
API Coverage Medium 10 6 8
Weighted Score - 8.6 6.9 6.1

Scores: 1-10, higher is better

Recommendations

Primary Recommendation: Silk.NET

For a custom cross-platform game engine, Silk.NET is the best choice:

  1. Doesn't force architecture - Provides raw bindings, lets you build your own abstractions
  2. Future-proof - Supports modern APIs (Vulkan, WebGPU) alongside OpenGL
  3. Foundation backing - Long-term viability guaranteed
  4. Mobile path exists - Android/iOS support when needed

Alternative: OpenTK

Consider OpenTK if:

  • Desktop-only is acceptable
  • You want included math types without external dependency
  • Simpler API surface is preferred
  • You're following LearnOpenGL-style tutorials (better OpenTK coverage)

Avoid: Veldrid

Veldrid is not recommended due to:

  • Uncertain maintenance status since Feb 2023
  • No public releases in nearly 2 years
  • Risk of being stuck on unmaintained library

If you need a multi-backend abstraction layer, consider building a thin one on top of Silk.NET rather than depending on Veldrid.

Integration Notes for KeenEyes

When integrating graphics with the KeenEyes ECS:

  1. Keep graphics decoupled - Graphics should be a system, not core ECS
  2. Component design - Use components for render-relevant data: 
    [Component]
public partial struct Renderable
{
    public int MeshId;
    public int MaterialId;
}

[Component]
public partial struct Transform
{
    public Vector3 Position;
    public Quaternion Rotation;
    public Vector3 Scale;
}
  3. Query for rendering - Let systems gather renderables: 
    foreach (var entity in World.Query<Transform, Renderable>())
{
    // Extract transform and submit draw call
}

Next Steps

  • [ ] Create minimal "hello triangle" with Silk.NET
  • [ ] Benchmark draw call overhead
  • [ ] Prototype RenderSystem for KeenEyes
  • [ ] Evaluate math library options (System.Numerics vs Silk.NET.Maths)

Sources

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