Can't access LinkedEntityGroup

I'm trying to make a system that gets all entities with OptimizeTag and removes unnecessary components from them.

For some reason I can't get the LinkedEntityGroup, but the Entity Debugger shows that all entities with OptimizeTag has LinkedEntityGroup.

Accessing the LinkedEntityGroup throws this error: InvalidOperationException: The NativeArray has been deallocated, it is not allowed to access it.

Any idea why is this happening?

Code (CSharp):

1. using Unity.Entities;
2. using Unity.Mathematics;
3. using Unity.Rendering;
4. using Unity.Transforms;
5. using Hash128 = Unity.Entities.Hash128;
6.  
7. public class OptimizeSystem : ComponentSystem
8. {
9.     protected override void OnUpdate()
10.     {
11.  
12.         Entities.ForEach((Entity entity, ref OptimizeTag optimizeTag) =>
13.         {
14.             var linkedEntityGroup = EntityManager.GetBuffer<LinkedEntityGroup>(entity);
15.  
16.             for(int i = 0; i < linkedEntityGroup.Length; i++)
17.             {
18.                 var childEntity = linkedEntityGroup[i].Value;
19.                 EntityManager.AddComponent(childEntity, typeof(Static));
20.                 EntityManager.AddComponent(childEntity, typeof(Frozen));
21.                 EntityManager.RemoveComponent(childEntity, typeof(Translation));
22.                 EntityManager.RemoveComponent(childEntity, typeof(Rotation));
23.                 EntityManager.RemoveComponent(childEntity, typeof(LocalToParent));
24.                 EntityManager.RemoveComponent(childEntity, typeof(Child));
25.                 EntityManager.RemoveComponent(childEntity, typeof(Parent));
26.                 EntityManager.RemoveComponent(childEntity, typeof(PreviousParent));
27.              
28.                 if(EntityManager.HasComponent<RenderMesh>(childEntity))
29.                 {
30.                     EntityManager.AddSharedComponentData(childEntity, new FrozenRenderSceneTag
31.                     {
32.                         SceneGUID = new Hash128 { Value = new uint4(1, 0, 0, 0) }
33.                     });
34.                 }
35.  
36.                 // Remove OptimizeTag, after the object is finished
37.                 EntityManager.RemoveComponent(childEntity, typeof(OptimizeTag));
38.             }
39.         });
40.     }
41. }

 

You're doing structural changes, which invalidate all direct references to any component data. You can easily see it if put debugger in to your for loop, it will print only first iteration (and second if you put it before

linkedEntityGroup[i].value

line). In your case

linkedEntityGroup

buffer invalidated right in first

EntityManager.AddComponent

call. You can use ECB for defer synch point after loop, or just do

ToNativeArray

after

GetBuffer

thus you get copy and not reference which wouldn't be invalidated.