Resolved Queries what's the mindset now?

EntityQueryBuilder is the recommended method for creating queries because it's fully Burst-compatible and can be used in Burst-compiled ISystems. ComponentType[] is a managed array and cannot be used in Burst-compiled code, and it generates managed objects that have to be cleaned up by the GC.

All query APIs now funnel into ultimately using an EntityQueryBuilder, so it's most efficient just to use that API directly.

Removing all the ComponentType[] APIs prior to the 1.0 release was not feasible and would have broken many user projects, but it's a good idea to move over to using EntityQueryBuilder as the others may be deprecated in the future.

 

Correct. The short explanation is that the sourcegen for using an idiomatic foreach requires that you use SystemAPI.Query, and the query types must be known at compile time. If you want to use a premade query, you could write an IJobChunk, but that's a bit more code.

Also correct, Query takes at least one generic argument. For example if you want to iterate over every entity that has a certain empty component, you can use a discard argument, so that you don't accidentally try to access the empty component, which would give an error.

Code (CSharp):

1. struct TagComponent : IComponentData {};
2. struct IntComponent : IComponentData
3. {
4.     int Value;
5. };
6.  
7. public void OnUpdate()
8. {
9.     // Normally, you'd specify an empty component in WithAll, so that it doesn't
10.     // require a variable in the tuple
11.     foreach (var (transform, entity) in
12.         SystemAPI.Query<LocalTransform>().WithAll<TagComponent>().WithEntityAccess())
13.     {
14.         // OK
15.     }
16.  
17.     // If you only want to query an empty component, you can provide it as the
18.     // generic argument to Query and discard it in the tuple
19.     foreach (var (_, entity) in SystemAPI.Query<TagComponent>().WithEntityAccess())
20.     {
21.         // OK
22.     }
23. }

IComponent access defaults to RefRO, so that you don't inadvertently create a write-dependency when you don't need one.

From https://docs.unity3d.com/Packages/c...anual/systems-systemapi-query.html#query-data

Code (CSharp):

1. float deltaTime = SystemAPI.Time.DeltaTime;
2.  
3. foreach (var (transform, speed) in SystemAPI.Query<RefRW<LocalTransform>, RotationSpeed>())
4.     transform.ValueRW = transform.ValueRO.RotateY(speed.RadiansPerSecond * deltaTime);

 

Yes, that's correct. Using RefRO avoids the copy and also provides safety against trying to write to the component.

Omitting RefRO use value semantics. It will give you a copy of the component. You can modify the copy, but it won't be written back to the chunk data.

Either way, the component dependency will be registered as read-only and only complete write jobs for the component before running the body of the foreach.