Singletons Pattern

So it feels wasteful to loop over every entity looking for what you know will be a Singleton. (Perhaps under the hood it has every entity type split out so it's looping over an array of one element which isn't really an issue?)

I made:

Code (CSharp):

1. using Unity.Entities;
2. using Unity.Tiny;
3.  
4. namespace Krunk
5. {
6.     public struct SingletonsComponent : IComponentData
7.     {
8.         [EntityWithComponents(typeof(Dir4Component))]
9.         public Entity playerEntity;
10.         [EntityWithComponents(typeof(MapComponent))]
11.         public Entity mapEntity;
12.     }
13. }

Added this to the Configuration, and then dragged the two entities for my player and map into these slots. (Side note: even though those were defined with EntityWithComponents, it would let me drag them into the wrong slots by accident. Seems like it should have rejected the drag if the required components weren't present?)

Then later when I try to use them:

Code (CSharp):

1.             var singletons = World.TinyEnvironment().GetConfigData<SingletonsComponent>();
2.             Entity mapEntity = singletons.mapEntity;
3.             MapComponent map = EntityManager.GetComponentData<MapComponent>(mapEntity);
4.             Translation lclPos = EntityManager.GetComponentData<Translation>(mapEntity);
5.  

It starts throwing exceptions trying to extract the components:

 

They are in my starting MainScreen that's set to always be loaded. I just dragged them from the hierarchy window over to the inspector window.

 

i don't feel like such a noob now, thanks!

 

Actually I think it might be a load order issue. OnCreate and OnStartRunning both seem to be called before the entities in my main scene are live. I added logs for OnCreate and OnStartRunning.