UnityEcsEvents

An event system package for Unity's data-oriented design framework.

What is it?

Events in ECS are a convenient way to communicate short-lived information between systems. An event is just an Entity with a few components on it and this project makes it faster and easier to create them!

Check out the example project here

Installation:

Download by clicking the "Clone or Download" button on the GitHub repo then copy the folders into your "/packages/" folder.

There are two separate packages included:

Entities.Unlocked - Provides access to various internal features of Unity.Entities
UnityEcsEvents - The core events system.

Getting Started:

Here's an example of routing ECS events through to a MonoBehavior:

using Unity.Collections;
using Unity.Entities;
using UnityEngine;
using Vella.Events;

public class HelloWorld : MonoBehaviour, IEventObserver<MyHelloEvent>
{
    public EventRouter EventSource;

    private void Start() => EventSource.Subscribe<MyHelloEvent>(this);

    public void OnEvent(MyHelloEvent e)
    {
        Debug.Log($"Event Triggered in GameObject. Message={e.Message}, Value={e.SomeValue}");
    }
}

public class TestSystem : SystemBase
{
    private EntityEventSystem _eventSystem;

    protected override void OnCreate()
    {
        _eventSystem = World.GetOrCreateSystem<EntityEventSystem>();

        _eventSystem.Enqueue(new MyHelloEvent
        {
            Message = "Hello World",
            SomeValue = 41
        });
    }

    protected override void OnUpdate()
    {
        Entities.ForEach((in MyHelloEvent e) =>
        {
            Debug.Log($"Event Triggered in System. Message={e.Message}, Value={e.SomeValue}");

        }).Run();
    }
}

public struct MyHelloEvent : IComponentData
{
    public NativeString64 Message;
    public int SomeValue;
}

In general you can also:

Create events anywhere with the same syntax - ForEach, Jobs, Managed, in parallel.
Attach DynamicBuffers and Arrays to events.
Cache and re-use an event queue per system.

For more advanced examples have a look at the test project

Package Dependencies:

"com.unity.burst": "1.3.3",
"com.unity.collections": "0.9.0-preview.6",
"com.unity.entities": "0.11.1-preview.4",
"com.unity.test-framework": "1.1.11",
"com.unity.test-framework.performance": "1.3.3-preview",
"com.vella.entities.unlocked": "0.0.3"

Supported Editors:

2020.1.0b14+

Troubleshooting

Unity still has some issues with ASMREF in certain situations, if Unity.Entities doesnt have the Unlocked package compiled with it properly then the usual fix is to go into preferences >> External tools and click 'regenerate project files'.

Acknowledgements

Consider checking out the project that inspired this work here: com.bovinelabs.entities and the Unity forums thread on event systems: here.

jeffvella / UnityEcsEvents