A high-performance Entity Component System framework for Unity, designed for deterministic simulation, recording/playback, and Burst/Jobs.

Full docs: svermeulen.github.io/trecs

Getting Started · Glossary · Samples · FAQ · Trecs vs Unity ECS

Status: Trecs is a 0.x release. While it is functional and reasonably well-tested, the API is still evolving and future updates are likely to include many breaking changes.

• Cache-friendly storage. Components live in contiguous structure-of-arrays buffers grouped by tag set.
• Composable building blocks. Aspects bundle component access; sets give sparse subsets without restructuring storage; templates declare entity blueprints with inheritance and partitions; SharedPtr / UniquePtr let components reference heap data.
• Burst and Jobs out of the box. A source generator emits job structs and chains JobHandle dependencies from the components you read and write — no manual wiring.
• Deterministic by construction. Fixed-timestep simulation, seeded RNG, isolated input, and built-in snapshot / record / replay with desync detection.
• Editor tooling. A live entity inspector and a record / scrub / fork timeline window for diagnosing transient bugs.

// 1. Components — unmanaged structs holding per-entity data
public partial struct Position : IEntityComponent { public float3 Value; }
public partial struct Velocity : IEntityComponent { public float3 Value; }

// 2. A tag — a zero-cost marker
public struct PlayerTag : ITag { }

// 3. A template — the entity blueprint
public partial class PlayerEntity : ITemplate, ITagged<PlayerTag>
{
    Position Position;
    Velocity Velocity;
}

// 4. A system — logic that runs over matching entities
public partial class MovementSystem : ISystem
{
    [ForEachEntity(typeof(PlayerTag))]
    void Execute(ref Position position, in Velocity velocity)
    {
        position.Value += velocity.Value * World.DeltaTime;
    }
}

// 5. Build and run
var world = new WorldBuilder()
    .AddTemplate(PlayerEntity.Template)
    .AddSystem(new MovementSystem())
    .BuildAndInitialize();

// In a MonoBehaviour:
void Update()    => world.Tick();
void OnDestroy() => world.Dispose();

World inside a system body is a source-generated property — your access into the running world for that phase. See Getting Started for the full walkthrough, or the Glossary for a one-stop reference of the terminology.

Requires Unity 6000.3+.

With the openupm-cli:

openupm add com.trecs.core

Or add the scoped registry to Packages/manifest.json manually:

{
  "scopedRegistries": [
    {
      "name": "package.openupm.com",
      "url": "https://package.openupm.com",
      "scopes": ["com.trecs"]
    }
  ],
  "dependencies": {
    "com.trecs.core": "0.2.0"
  }
}

In Window → Package Manager, click + → Add package from git URL and enter:

https://github.com/svermeulen/trecs.git?path=UnityProject/Trecs/Assets/com.trecs.core

The project includes 17 samples covering everything from basic entity creation to complex simulations with Burst jobs. To try them, clone the repo, open UnityProject/Trecs in Unity 6000.3+, and run Assets/Samples/Core/Main.unity. See the samples docs for details.

Trecs was originally based on Svelto.ECS by Sebastiano Mandalà.

MIT