EnTT Sharp is a C# port of EnTT for C++. EnTT is a lightweight entity-component-system library with a focus on performance and cache friendliness.

This C# port roughly matches version 2.8 of the C++ EnTT library. It does not contain many of the C++ specific helper functions (like type information systems or sane events, etc) which are part of the .NET runtime or can be easily added via external libraries. Referencing libraries is not as painful in C# as it apparently is in C++.

• Introduction
  • Code Example
  • Motivation
  • Performance
• Build Instructions
  • Documentation
  • Tests
• Packaging Tools
• EnTT in Action
• Contributors
• License

The entity-component-system (also known as ECS) is an architectural pattern used mostly in game development. For further details:

• Entity Systems Wiki
• Evolve Your Hierarchy
• ECS on Wikipedia

The EnTT wiki contains helpful

• EnTT C++ FAQ
• EnTT C++ wiki

This project is a faithful port of the C++ version of EnTT without any of the C++ specific helper systems needed in the original version. The EnTT system allows you to define abstract entities, assign tags and components to those entities and finally to iterate the entity and component pools in a fast and cache friendly way.

EnTTSharp has the following features:

• An incredibly fast entity-component system based on sparse sets, with its own pay for what you use policy to adjust performance and memory usage according to the users' requirements.
• Works on POCO objects, no need to pollute your code with library interfaces.
• Optional, attribute-based automatic registration of components and serializers
• 64-Bit Entity Keys, 2^31 entities per registry and 24 bits of additional data per key to allow partitioned key-spaces in distributed systems.
• Snapshop and state serialization support
• Compatible with .NET-Framework 4.7, .NET Core 2.0 (and later) and Unity's C# dialect.

    public readonly struct Position
    {
        public readonly double X;
        public readonly double Y;

        public Position(double x, double y)
        {
            X = x;
            Y = y;
        }
    }

    public readonly struct Velocity
    {
        public readonly double DeltaX;
        public readonly double DeltaY;

        public Velocity(double deltaX, double deltaY)
        {
            DeltaX = deltaX;
            DeltaY = deltaY;
        }
    }

    public static void UpdatePosition(EntityRegistry registry, TimeSpan deltaTime)
    {
        // view contains all the entities that have both a position and a velocty component ...
        var view = registry.View<Velocity, Position>();
        foreach (var entity in view)
        {
            if (view.GetComponent(entity, out Position pos) &&
                view.GetComponent(entity, out Velocity velocity))
            {
                var posChanged = new Position(pos.X + velocity.DeltaX * deltaTime.TotalSeconds,
                                              pos.Y + velocity.DeltaY * deltaTime.TotalSeconds);
                registry.AssignComponent(entity, in posChanged);
            }
        }
    }

    public static void ClearVelocity(EntityRegistry registry)
    {
        var view = registry.View<Velocity>();
        foreach (var entity in view)
        {
            registry.AssignComponent(entity, new Velocity(0,0));
        }
    }

    public static void Main(string [] args)
    {
        var random = new Random();
        var registry = new EntityRegistry();
        registry.Register<Velocity>();
        registry.Register<Position>();

        for (int x = 0; x < 10; x += 1)
        {
            var entity = registry.Create();
            registry.AssignComponent<Position>(entity);
            if ((x % 2) == 0)
            {
                registry.AssignComponent(entity, new Velocity(random.NextDouble(), random.NextDouble()));
            }
        }

        UpdatePosition(registry, TimeSpan.FromSeconds(0.24));
        ClearVelocity(registry);
    }

I ported EnTT-Sharp after looking though many of the existing C# based ECS libraries. The existing libraries (Entidas, SharpECS) are sadly not written with garbage-collector or cache friendliness in mind and proceed to define components and entities mandatorily as reference types.

I do not want to be forced to pay the 20-bytes garbage collector enablement tax the .NET framework imposes on reference types. Unity's ECS system seems to have the right ideas, but after years of working against Unity's bugs I have little trust left to bind myself exclusively to a Unity provided implementation.

I ported EnTT to provide me with a fast way of defining entities and component systems to enable me to work in a more data driven way. The library is intentionally not bound to any game library. The ECS architecture splits the update loop in distinct phases that are small enough to be easily understood and can be individually debugged.

Each system function works on a limited set of data and can be trivially unit tested. EnTT's design cleanly separates the game logic from the library.

I have used this library successfully in both Unity and MonoGame projects. Testing its support for Godot is on the roadmap, I suspect it will work out of the box.

This library can be built via the standard build command

 dotnet build

The core EnTTSharp library has no external dependencies. A NuGet package can be created via

 dotnet pack

Todo: Add release scripts.

Todo

Todo

ToDo. EnTT Sharp will be available via NuGet once it has some better tests and documentation.

EnTTSharp was written initially as a faster alternative to other well known and open source entity-component systems. Requests for features, PR, suggestions and feedback are highly appreciated.

If you find you can help me and want to contribute to the project with your experience or you do want to get part of the project for some other reasons, feel free to contact me directly (you can find the mail in the profile).
I can't promise that each and every contribution will be accepted, but I can assure that I'll do my best to take them all seriously.

If you decide to participate, please see the guidelines for contributing before to create issues or pull requests.
Take also a look at the contributors list to know who has participated so far.

C# code and documentation Copyright(c) 2020 Thomas Morgner
Original code and documentation Copyright (c) 2017-2020 Michele Caini.

Code released under the MIT license. Documentation released under CC BY 4.0.
Logo released under CC BY-SA 4.0.