Stuck with ECS and reference ICompontentData

Hi, I'm currently working on a project with Unity ECS code. I have now come to a stop with some problem. The problem is that I need to get two different component data from different entity, however same root parent.

For an example:

WheelSystem -> ref WheelData wheel, in VehicleData vehicle

Vehicle: (VehicleData ) (Entity)

- Body (Entity)

- Wheels (Entity)

- FrontLeft:Wheel (WheelData ) (Entity)

In Monobehavior answer would be GetComponentInChildren, right? So how does this work in ECS? I also tried of just linking Entity on IComponentData, which work. However if I Instance prefab with same data, I also need to re-link entity from the beginning. Is there more simpler way or smarter way?

 

There is something called LinkedEntityGroup that is used to represent a hierarchy of entities.
https://docs.unity3d.com/Packages/com.unity.entities@0.11/api/Unity.Entities.LinkedEntityGroup.html
You could make IBufferElementData for your wheels.

 

Something it’s useful to create your game object as you usually would with collider children etc and then drag it into a sub scenes to see how it was converted , even a mock-up of what you want and dragging it into a sub scene can show child parents linked components etc.

 

Okay, thank you for your answer. However should I update the wheel system separate from vehicle system. Or should I update wheel inside vehicle system, geting reference from vehicle data.

 

It depends, you should avoid updating using a reference to other entity. For spinning, I would use separate system.

 

Got it working, thanks. Little bit complicated, but it's working. My ideal with this game it would run around 50-200 vehicles at same time (traffic simulation), as well player vehicle. That's why I need to convert Monobehaviour into DOTS.