to "mark" hundreds of entities with a tag for .ForEach, do u use AddComponent

i know i can give empty tag to hundreds of entities with for loop and .AddComponent but was wondering if there is better way?

 

Add a IComponentData with a bool field and set true or false as needed.

 

If you know your entities (i.e. can express their subset with an EntityQuery), use one of the methods in EntityManager that take an EntityQuery; or you can fill a NativeArray with them in your loop, and after the loop set the Tag on them:

Code (CSharp):

1. entityManager.AddComponent(EntityQuery, ComponentType)
2. entityManager.AddComponent(NativeArray<Entity>, ComponentType)

These methods are much faster than individually adding the components, e.g. through a CommandBuffer or inside a non-burst loop.

All structural changes require a sync point, so using this way is the most efficient way to make use of the CPU resources here if you depend on the structural change.

If you don't depend on the structural change, writing a boolean flag into a ComponentData can be a way to go ahead, but you will lose the innate ability of ECS to filter your Entities and only work on those you care about (meanign you need to have a conditional inside each loop testing for said flag)