What's the replacement of PostUpdateCommands in SystemBase?

I have systems that add/remove components on update using PostUpdateCommands. However, this is not available in SystemBase. How is this done now?

 

With an entity command buffer.

Code (CSharp):

1. using Unity.Entities;
2.  
3. public class YourSystem : SystemBase
4. {
5.     private EndSimulationEntityCommandBufferSystem ecbSystem;
6.  
7.     protected override void OnCreate()
8.     {
9.         ecbSystem = World.GetOrCreateSystem<EndSimulationEntityCommandBufferSystem>();
10.     }
11.  
12.     protected override void OnUpdate()
13.     {
14.         var ecb = ecbSystem.CreateCommandBuffer().ToConcurrent();
15.  
16.         Entities.ForEach((Entity e, int entityInQueryIndex, in YourComponent data) =>
17.         {
18.             // Use ecb as appropriate.
19.         }).ScheduleParallel();
20.  
21.         ecbSystem.AddJobHandleForProducer(Dependency);
22.     }
23. }

 

I see. Thanks!

 

But this sync point is executed at the end of the frame, if I want to playback after the some system OnUpdate() ?

 

Code (CSharp):

1. using Unity.Entities;
2. public class YourSystem : SystemBase
3. {
4.  
5.     protected override void OnUpdate()
6.     {
7.         var ecb = new EntityCommandBuffer(Allocator.TempJob);
8.  
9.         Entities.ForEach((Entity e, in YourComponent data) =>
10.         {
11.             // Use ecb as appropriate.
12.         }).Run();
13.  
14.         ecb.Playback(EntityManager);
15.     }
16. }

 

ECB Systems are not just executed at the end of a frame. They are just like any other system, and will be added to the update order based on their [UpdateBefore], [UpdateAfter], and [UpdateInGroup] attributes.

 

Thanks!

 

Thanks!I just need to implement my ecb system and add [UpdateAfter (typeof (xxxSystem))]?

 

Yes, that will work. If you have multiple other systems issuing commands to the ECB system, it might make more sense to position them to [UpdateBefore] the ECB. Whatever makes sense for your setup.

 

Thank you so much!