How to reference sprites in component data?

I have a component like this:

Code (CSharp):

1.     [InternalBufferCapacity(Capacity)]
2.     public struct PlayerConfig : IBufferElementData
3.     {
4.         public const int Capacity = 8;
5.  
6.         public Entity Prefab;
7.         public Sprite Avatar;
8.     }

When I spawn a player, I want to show its avatar in UI that is injected using conversion workflow. But unity complains about Avatar field since it's not blittable. How can I work around this?

 

Sprite is a class and don't inherits UnityEngine.Component, so cannot be used in IComponentData, IBufferElementData or attached to a Entity. For your case, you can configure hybrid prefab with injection to create a hybrid entity using a MonoBehaviour to hold the Sprite. Then reference this hybrid entity in your player entity using some component/dynamic buffer.

This code have a lot more than it needs (and some implicit assumptions), but I think it can give you some grasps about what I said:

Code (CSharp):

1. public struct AvatarReference : IComponentData {
2.     public Entity Value;
3. }
4.  
5. [RequiresEntityConversion, DisallowMultipleComponent]
6. public class AvatarBehaviour : MonoBehaviour, IConvertGameObjectToEntity {
7.     public Sprite Sprite;
8.    
9.     public void Convert(Entity entity, EntityManager dstManager, GameObjectConversionSystem conversionSystem) {
10.         // When referenced by a convert and destroy entity, the prefab will strip all component objects from entity
11.         // This is a hack to keep this component object
12.         dstManager.AddComponentObject(entity, this);
13.     }
14. }
15.  
16. [RequiresEntityConversion, DisallowMultipleComponent]
17. public class PlayerBehaviour : MonoBehaviour, IDeclareReferencedPrefabs, IConvertGameObjectToEntity {
18.     public AvatarBehaviour Avatar;
19.    
20.     public void DeclareReferencedPrefabs(List<GameObject> referencedPrefabs) {
21.         Assert.IsNotNull(Avatar);
22.         referencedPrefabs.Add(Avatar.gameObject);
23.     }
24.    
25.     public void Convert(Entity entity, EntityManager dstManager, GameObjectConversionSystem conversionSystem) {
26.         dstManager.AddComponentData(entity, new AvatarReference {
27.             Value = conversionSystem.GetPrimaryEntity(Avatar)
28.         });
29.     }
30. }
31.  
32. public class ShowAvatarSystem : ComponentSystem {
33.     protected override void OnCreate() {
34.         base.OnCreate();
35.        
36.         RequireSingletonForUpdate<ShowAvatarWindow>();
37.         RequireSingletonForUpdate<AvatarWindow>();
38.     }
39.    
40.     protected override void OnUpdate() {
41.         var showAvatarWindowEntity = GetSingletonEntity<ShowAvatarWindow>();
42.         var avatarReference = EntityManager.GetComponentData<AvatarReference>(showAvatarWindowEntity);
43.         var avatar = EntityManager.GetComponentObject<AvatarBehaviour>(avatarReference.Value);
44.         var avatarWindowEntity = GetSingletonEntity<AvatarWindow>();
45.         var avatarWindow = EntityManager.GetComponentObject<AvatarWindowBehaviour>(avatarWindowEntity);
46.        
47.         avatarWindow.SetAvatar(avatar.Sprite);
48.        
49.         EntityManager.RemoveComponent(showAvatarWindowEntity, typeof(ShowAvatarWindow));
50.     }
51. }
52.  
53. EntityManager.AddComponent(playerEntity, typeof(ShowAvatarWindow));
54.  

[]'s

 

One correction, they can be attached to an entity

EntityManager.AddComponentObject(Entity, object)
EntityManager.GetComponentObject<T>(Entity entity)

Can't be used in burst obviously.

-edit-

to actually answer original question. I tend to just have a collection of, in this case sprites, and store an index on a component data instead.

I like doing this, and did even before I started using ECS because it gives you a lot flexibility in the future to easily allows adding localization, events etc. For example maybe I want to run a Christmas event. I can just load a different set of sprites for the holiday season without having to change any code. I can even push this with asset bundles (or new addressables) without even having to submit to a stores.