Recursive GameObject Prefab Conversion

Hello,

I would like to convert deep hierarchy of components referencing the prefabs to ecs using the new GameObjectConversion systems.

To be specific, In the scene I have a single GameObject with GameWorldComponent referencing array of Zone GameObject Prefabs. Each Zone Prefab has an array of Unit Gameobject Prefabs. Each Unit has component referencing UnitArt GameObject Prefab etc.

Each of GameWorld, Zone, Unit monobehaviour components declares the referenced prefabs, and Convert method to convert to ecs.

When I run GameObjectConversionUtility.ConvertGameObjectHierarchy on the GameWorld gameObject, only zone prefabs are converted, but not the unit prefabs referenced by zone component.

If I understand it correctly, the zone gameObject does not exist in the scene, so it is not picked up by
DeclareReferencedPrefabs Therefore the unit prefabs are not converted.

I am looking for correct approach to this problem.

I tried to call GameObjectConversionSystem.AddReferencedPrefab on UnitPrefab from
ZoneComponent Convert method, but this throws exception.

Code (CSharp):

1. InvalidOperationException: EntityManager.AddComponent/RemoveComponent/CreateEntity/DestroyEntity are not allowed during ForEach. Please use PostUpdateCommandBuffer to delay applying those changes until after ForEach.

For now I am calling the GameObjectConversionUtility.ConvertGameObjectHierarchy on referenced UnitPrefabs in ZoneComponent, but I am not sure about consequences of doing it this way.

Here is the code.

Code (CSharp):

1.  
2. [System.Serializable]
3. public struct GameWorld : ISharedComponentData
4. {
5.   public Entity[] ZonePrefabs;
6. }
7. public class GameWorldComponent : MonoBehaviour, IConvertGameObjectToEntity, IDeclareReferencedPrefabs
8. {
9.   public ZoneComponent[] ZonePrefabs;
10.  
11.   public void Convert(Entity entity, EntityManager dstManager, GameObjectConversionSystem conversionSystem)
12.   {
13.     var world = new GameWorld
14.     {
15.       ZonePrefabs = ZonePrefabs
16.         .Select(zoneComponent => conversionSystem.GetPrimaryEntity(zoneComponent.gameObject))
17.         .ToArray()
18.     };
19.    
20.     dstManager.AddSharedComponentData(entity, world);
21.   }
22.   public void DeclareReferencedPrefabs(List<GameObject> gameObjects)
23.   {
24.     foreach (var zoneComponent in ZonePrefabs)
25.     {
26.       gameObjects.Add(zoneComponent.gameObject);
27.     }
28.   }
29. }
30.   [System.Serializable]
31. public struct Zone : ISharedComponentData
32. {
33.   public Entity[] UnitPrefabs;
34. }
35. public class ZoneComponent : MonoBehaviour, IConvertGameObjectToEntity, IDeclareReferencedPrefabs
36. {
37.   public UnitComponent[] UnitPrefabs;
38.  
39.   public void Convert(Entity entity, EntityManager dstManager, GameObjectConversionSystem conversionSystem)
40.   {
41.     var zone = new Zone
42.     {
43.     /***************************************************************************************
44.     * THIS WILL ONLY CREATE EMPTY ENTITY FOR UNIT, THE UNIT IS NOT CONVERTED
45.     ***************************************************************************************/
46.     UnitPrefabs = UnitPrefabs.Select(unit => conversionSystem.GetPrimaryEntity(unit.gameObject))
47.         .ToArray()
48.    
49.     /****************************************************************************************
50.     * THIS WORKS BUT I DONT LIKE IT
51.     UnitPrefabs = UnitPrefabs.Select(unit =>
52.     GameObjectConversionUtility.ConvertGameObjectHierarchy(unit.gameObject, dstManager.World))
53.         .ToArray()
54.      
55.     ****************************************************************************************/
56.     };
57.    
58.     dstManager.AddSharedComponentData(entity, zone);
59.   }
60.   public void DeclareReferencedPrefabs(List<GameObject> gameObjects)
61.   {
62.     foreach (var unitComponent in UnitPrefabs)
63.     {
64.       gameObjects.Add(unitComponent.gameObject);
65.     }
66.   }
67. }
68.  

 

Thanks for reply.
For now I will use the gameobjects in scene with prefab component added manually, but would be easier for me to work with regular unity prebafs. Did not know about SCD not being supported, I will migrate to IComponentData.