Getting ready with ECS - All ComponentType must be known at compile time

Unity Engine
,
1

Hello,

I finally decided to try the new ECS system.
I’m quite new with this technology so be patient with me.

I tried a very simple example to understand how it work :

I got a simple component :

public class Rotator : MonoBehaviour
{
    public float Speed;
}

And a simple system :

public class RotatorSystem : ComponentSystem
    {
        public struct Components : IComponentData
        {
            public Rotator Rotator;
            public Transform Transform;
        }

        protected override void OnUpdate()
        {
            EntityQuery entityQuery = GetEntityQuery(ComponentType.ReadWrite<Components>());
            NativeArray<Components> components = entityQuery.ToComponentDataArray<Components>(Allocator.Temp);

            float deltaTime = Time.DeltaTime;
            foreach (Components component in components)
            {
                component.Transform.Rotate(0.00f, component.Rotator.Speed * deltaTime, 0f);
            }

            components.Dispose();
        }
    }
}

The purpose is to rotate 3 cubes on the scene. So very simple…
The problem is that, I start with an error :

ArgumentException: Tutorial_ECS.RotatorSystem+Components contains a field of Tutorial_ECS.Rotator, which is neither primitive nor blittable.

If I run the scene :

ArgumentException: Unknown Type:Tutorial_ECS.RotatorSystem+Components All ComponentType must be known at compile time. For generic components, each concrete type must be registered with [RegisterGenericComponentType].

I tried to add :

[assembly: RegisterGenericComponentType(typeof(RotatorSystem.Components))]

But It does not seems to work.

Anybody can explain me what i’m doing wrong ?

Update : I use Entities V5.0.1

Sato

1 Like
2

As the error tells you, the fields of your IComponentData must be primitive or blittable.

You should have an Authoring version and an ECS version for your components, like this:

public class RotatorAuthoring : MonoBehaviour
{
    public float Speed;
}

public struct RotatorData : IComponentData
{
    public float Speed;
}

And assign the respective values during conversion.

Take a look on the ECS samples on the GitHub, there is no better place to get started: GitHub - Unity-Technologies/EntityComponentSystemSamples

3

Ok, so i tried something like this :

public class Rotator_Authoring : MonoBehaviour, IConvertGameObjectToEntity
{
    public float Speed;

    public void Convert(Entity entity, EntityManager dstManager, GameObjectConversionSystem conversionSystem)
    {
        Rotator_Data data = new Rotator_Data
        {
            Speed = Speed,
        };

        dstManager.AddComponentData(entity, data);
    }
}

public struct Rotator_Data : IComponentData
{
    public float Speed;
}

public class RotatorSystem : ComponentSystem
{
    EntityQuery _group;

    protected override void OnCreate()
    {
        _group = GetEntityQuery(typeof(Rotation), ComponentType.ReadOnly<Rotator_Authoring>());
    }

    protected override void OnUpdate()
    {
       
    }
}

But how can I access the transform (Rotation) to rotate my cubes ?
I can retrieve the data from Rotator_Data but there is no example with EntityQuery to do it

By the way thank you for the answer and the example :stuck_out_tongue:

4

In the link there is an example of something similar:

https://github.com/Unity-Technologies/EntityComponentSystemSamples/blob/master/ECSSamples/Assets/HelloCube/1.%20ForEach/RotationSpeedSystem_ForEach.cs

You should access the component Rotation (as you already seems to be doing), in ECS the Transform was broke into smaller components (Translation, Rotation and Scale).

5

Ok, thank you, I think I finally understand the way to use it.
Instead of giving the reference of the entire transform, we use the reference of it rotation.

Thanks for the example and the explaination:)

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