How do you properly get unique instances of ISharedComponentData?

I tried EntityManager.GetAllUniqueSharedComponentDatas() but it's weird that I'm getting one even when I haven't made any. Then on the next frame, it becomes 2, then 3, and so on. Why is it increasing?

 

As to your question of how it keeps increasing, I think that you need to clear your List at the end of the OnUpdate() or before calling EntityManager.GetAllUniqueSharedComponentDatas() again. (I'm guessing that you are calling ot from OnUpdate)

I am having a similar issue where it returns more than 1 when it's only attached to 1 GameObject. Here are some simple test code I created that shows the issue.

Code (CSharp):

1. [System.Serializable]
2. public struct TestData : ISharedComponentData
3. {
4.     //Returns 2
5.     //public Object value;
6.     //Returns 2
7.     //public string value;
8.     //Returns 1
9.     //public int value;
10.     //Returns1
11.     public bool value;
12. }
13.  
14. public class TestComponent : SharedComponentDataWrapper<TestData> { }

Code (CSharp):

1. public class TestSystem : ComponentSystem
2. {
3.     private readonly List<TestData> cachedTestData = new List<TestData>(3);
4.     private ComponentGroup componentGroup;
5.  
6.     protected override void OnCreateManager(int capacity)
7.     {
8.         componentGroup = GetComponentGroup(typeof(TransformMatrix), typeof(TestData));
9.     }
10.  
11.     protected override void OnUpdate()
12.     {
13.         EntityManager.GetAllUniqueSharedComponentDatas(cachedTestData);
14.         Debug.Log("cachedUniqueSharedSpriteRenderer: " + cachedTestData.Count);
15.  
16.         for (int i = 0; i != cachedTestData.Count; i++)
17.         {
18.             TestData testData = cachedTestData[i];
19.             if (testData.value == null)
20.             {
21.                 Debug.Log("Index: " + i + " is null");
22.                 continue;
23.             }
24.             Debug.Log("Index: " + i + " is not null");
25.         }
26.  
27.         cachedTestData.Clear();
28.     }
29. }

Does anyone know why with some type fields the count it returns is not the same?

 

I see. That's good to know.

There's still one weird behaviour. Why do I get one instance even if I haven't called any AddSharedComponentData()?

 

It always seems to include the default instance. You can start indexing at 1 to skip it if you need (usually it doesn't matter).

 

That won't work. If I run the code that is posted above attached to a single entity it returns the count as 1 (correct value), but if I change the type of value to either string or any Object based type. It will return the count as 2 (while the Entity Debug still only points to 1 Entity).

 

I'm not really sure what you just said to be honest.

What I suggested is exactly what Unity does in their own demos.

https://github.com/Unity-Technologi...s/Assets/GameCode/Samples.Boids/BoidSystem.cs

Code (CSharp):

1.             EntityManager.GetAllUniqueSharedComponentDatas(m_UniqueTypes);
2.        
3.             var obstaclePositions = m_ObstacleGroup.GetComponentDataArray<Position>();
4.             var targetPositions   = m_TargetGroup.GetComponentDataArray<Position>();
5.        
6.             // Ingore typeIndex 0, can't use the default for anything meaningful.
7.             for (int typeIndex = 1; typeIndex < m_UniqueTypes.Count; typeIndex++)
8.             {

They skip index 0 because it's mostly meaningless

GetAllUniqueSharedComponentDatas returns all SharedComponentDatas + default(T) which is always index 0

 

I think this has something to do with the wrapper. If you remove the wrapper and load the reference some way other than the inspector (as obviously you cannot use the inspector if you get rid of the wrapper), does the count go back down to 1?