Question Check if entity has aspect

How do I check if an entity I already have a reference to has a given aspect? There are equivalents for components such as

SystemApi.HasComponent

but there is no

HasAspect

or

TryAspect

.

Seems like the API is not here yet. Any workarounds?

 

Only way I can think of is to just try-catch the aspect creation, but that seems weak

 

Check against queries. If there's a match - there's an aspect.

 

@xVergilx as I said, I already have a reference to the entity from previous transformations. In this case, one of my entities has a buffer of entities it can see. Now I want to check which of these entities are "Food" by checking whether they have the "Food-aspect". So basically I have a

Entity[]

and want to foreach where

FoodAspect

.

 

Seems like this was asked before and is being worked on.

 

I found a solution for now

Code (CSharp):

1. [BurstCompile]
2. private static IEnumerable<ComponentType> RequiredComponents<T>(this IAspectCreate<T> create, bool isReadonly)
3.   where T : IAspect
4. {
5.   var list = new UnsafeList<ComponentType>(10, Allocator.Temp);
6.   create.AddComponentRequirementsTo(ref list, isReadonly);
7.  
8.   foreach (var type in list)
9.   {
10.     yield return type;
11.   }
12.  
13.   list.Dispose();
14. }
15.  
16. [BurstCompile]
17. public static bool TryAspect<TAspect>(this EntityManager entityManager, Entity entity, bool isReadonly, out TAspect aspect)
18.   where TAspect : unmanaged, IAspect, IAspectCreate<TAspect>
19. {
20.   var create = new TAspect();
21.  
22.   foreach (var component in create.RequiredComponents(isReadonly))
23.   {
24.     if (entityManager.HasComponent(entity, component)) continue;
25.     aspect = default;
26.     return false;
27.   }
28.  
29.   aspect = entityManager.GetAspect<TAspect>(entity);
30.   return true;
31. }

 

Another option is to prefilter (or filter later) outputs of the system - ensure required components exist for the data in the stored buffer. This way you can do this in a separate job without stalling the main thread. Use ComponentLookup / BufferLookup to perform checks and remove no longer valid data.