Question Is it possible to assign a companion game object at runtime after conversion?

I have a multiplayer game with data representing units sync'd between both the client and the server. I'd like the client-side version of the data to be associated with a companion game object responsible for "presenting" the data in the form of an animated model, particle system, etc.

Is there any way to do something like this?

Code (CSharp):

1.     [ClientWorld]
2.     public class UnitPresentationSystem : SystemBase
3.     {
4.         private EndSimulationEntityCommandBufferSystem _endSimulationEcbSystem;
5.  
6.         protected override void OnCreate()
7.         {
8.             base.OnCreate();
9.             _endSimulationEcbSystem = World.GetOrCreateSystem<EndSimulationEntityCommandBufferSystem>();
10.         }
11.  
12.         protected override void OnUpdate()
13.         {
14.             var ecb = _endSimulationEcbSystem.CreateCommandBuffer();
15.  
16.             Entities.WithAll<NeedsPresentationTag>()
17.                 .ForEach((Entity entity, in UnitTag unitData, in Translation translation, in LocalToWorld localToWorld,
18.                     in Rotation rotation) =>
19.                 {
20.                     var conversionSystem = World.GetExistingSystem<GameObjectConversionSystem>();
21.  
22.  
23.                       // This is the part I'm making up / would like to know how to do
24.                     conversionSystem.AddCompanionGameObject(entity, UnitPresentationManager.GetPresentationGameObjectFromPool());
25.  
26.  
27.                     ecb.RemoveComponent<NeedsPresentationTag>(entity);
28.                 })
29.                 .WithoutBurst()
30.                 .Run();
31.         }
32.     }

When a unit is spawned, I want to grab a presentation game object from the pool and assign it to the entity. I'll probably return the game object to the pool after the entity is destroyed.

 

Here's the current / horrible way of doing it. I'm manually syncing the position and rotation to the gameObject using a dictionary. As you might expect it runs incredibly badly

Code (CSharp):

1.         protected override void OnUpdate()
2.         {
3.             // Acquire an ECB for propagating changes to the entity at the end of the frame.
4.             var ecb = _endSimulationEcbSystem.CreateCommandBuffer();
5.  
6.             Entities.WithAll<NeedsPresentationTag>()
7.                 .ForEach((Entity entity, in UnitTag unitData, in Translation translation, in LocalToWorld localToWorld,
8.                     in Rotation rotation) =>
9.                 {
10.                     UnitPresentationManager.Present(entity, translation.Value, rotation.Value);
11.                     ecb.RemoveComponent<NeedsPresentationTag>(entity);
12.                 })
13.                 .WithoutBurst()
14.                 .Run();
15.  
16.             Entities.WithNone<NeedsPresentationTag>()
17.                 .ForEach((Entity entity, in UnitTag unitData, in Translation translation, in LocalToWorld localToWorld,
18.                     in Rotation rotation) =>
19.                 {
20.                     var transform = UnitPresentationManager.Singleton.GameObjects[entity].transform;
21.                     transform.position = translation.Value;
22.                     transform.rotation = rotation.Value;
23.                 })
24.                 .WithoutBurst()
25.                 .Run();
26.         }

 

I'd like to also clarify that I tried using `AddComponentObject` and couldn't quite get it to sync the transforms.

Code (CSharp):

1.             Entities.WithStructuralChanges().WithAll<NeedsPresentationTag>()
2.                 .ForEach((Entity entity, in UnitTag unitData, in Translation translation, in LocalToWorld localToWorld,
3.                     in Rotation rotation) =>
4.                 {
5.                     EntityManager.AddComponentObject(entity, UnitPresentationManager.Present());
6.                     EntityManager.AddComponentData(entity, new CopyTransformToGameObject());
7.                     ecb.RemoveComponent<NeedsPresentationTag>(entity);
8.                 })
9.                 .WithoutBurst()
10.                 .Run();

 

I understand that you want to avoid having the presentation part on server side.
Have you tried the other way around ? Leaving the presentation part on the prefab and removing it only on server. Maybe you could even have a server init system that t changes the prefab entities themselves to avoid doing it for each instantiation.