ECS. Bug or feature.

Unity Engine
,
1

Hello! I discovered some strangeness. If we instantiate the object in the old-fashioned way (UnityEngine.Object) and it has the necessary components, then ComponentSystem correctly finds the corresponding groups of objects (example code below):

public class SomeManager : MonoBehaviour
{
    public GameObject prefab;

    void DoStuff()
    {
        Instantiate(prefab);
    }
}

public class SomeSystem : ComponentSystem
{
    struct SomeGroup
    {
        public ComponentArray<SomeOldComponent> SomeOldComponent;
        public EntityArray              Entity;
        public int                      Length;
    }

    [Inject] SomeGroup someGroup;

    protected override void OnUpdate()
    {
        Debug.Log(someGroup.Length); // <- if "prefab" (higher) has Some Component then Length more than 0
    }
}

If we first instantiate an object and then add a component to it, then ComponentSystem does not see this object:

public class SomeManager : MonoBehaviour
{
    public GameObject prefab;

    void DoStuff()
    {
        GameObject tmp = Instantiate(prefab);
        tmp.AddComponent<SomeOldComponent>();
    }
}

public class SomeSystem : ComponentSystem
{
    struct SomeGroup
    {
        public ComponentArray<SomeOldComponent> SomeOldComponent;
        public EntityArray              Entity;
        public int                      Length;
    }

    [Inject] SomeGroup someGroup;

    protected override void OnUpdate()
    {
        Debug.Log(someGroup.Length); // <- if "prefab" (higher) hasn't Some Component, and we add them after Instantiate, then Length equal 0
    }
}
2

There is no auto sync. You have to add the components to the entity as well through the EntityManager

3

Then, with Instantiate, the objects would not be added to the group, which means that with Instantiate (old-school style) there is a synchronization point and can also be in the old-school addition of the component. And I advise you to pay attention to the code - it does not use ECS instantiate.

4

The GameObjectEntity Component adds all ECS Components of that GameObject at Start/Awake Method (don’t know exactly) to the ECS.

You can take a look into this component by clicking the GameObjectEntity in the inspector. It will show up the GameObjectEntity.cs script in the Project view.

5

You did not understand a bit (or I incorrectly explained), I’m aware of how GameObjectEntity works (adds components to EntityManager in OnEnable), I’m just talking about why Unity did not add an event to add a component that would catch the change in the composition of the object’s components for hybrid approach.

6

We are planning to add support for it. But it requires new events to be exposed in the core engine.

1 Like
7

Hopefully I can see the components of Game Object at Inspector and the components of Entity at Entity Debugger sync seamlessly soon.

8

That’s all I wanted to hear! Look forward to. Thank you! And we are waiting for the release of 2018.1 :slight_smile: :slight_smile: As I suspect, b14 can not wait until the release (you said that in the new version of the ECS will be “out of the box” and will not need a “specific version”) :slight_smile: