Accessing other Entities within a Job

I have a ForEach job that is going through a set of TargetChange entities when they are created. Within this job I want to be able to access a set of Ship entities so that I can update their targets.

This is what I have put together so far:

Code (CSharp):

1. public class TargetUpdatedSystem : JobComponentSystem
2. {
3.     private EndSimulationEntityCommandBufferSystem endSimCommandBufferSystem;
4.     private EntityQuery m_Group;
5.     public struct TargetUpdatedJob : IJobForEachWithEntity<TargetChangeComponent>
6.     {
7.         public EntityCommandBuffer.Concurrent CommandBuffer;
8.         [DeallocateOnJobCompletion]public NativeArray<Entity> ships;
9.        
10.         public void Execute(Entity entity, int index,ref TargetChangeComponent target)
11.         {
12.             foreach (var v in ships)
13.             {
14.                 Ship s = Unity.Entities.World.DefaultGameObjectInjectionWorld.EntityManager.GetComponentData<Ship>(v);
15.                 s.OrbitTarget = target.Target;
16.             }
17.             CommandBuffer.DestroyEntity(index,entity);
18.            
19.         }
20.  
21.     }
22.     protected override JobHandle OnUpdate(JobHandle inputDeps)
23.     {
24.         var job = new TargetUpdatedJob()
25.         {
26.             ships = m_Group.ToEntityArray(Allocator.TempJob),
27.             CommandBuffer = endSimCommandBufferSystem.CreateCommandBuffer().ToConcurrent()
28.         };
29.  
30.         var jobHandle = job.Schedule(this, inputDeps);
31.         endSimCommandBufferSystem.AddJobHandleForProducer(jobHandle);
32.         return jobHandle;
33.     }
34.    
35.     protected override void OnCreate()
36.     {
37.         m_Group = GetEntityQuery(typeof(Ship));
38.         endSimCommandBufferSystem = World.GetOrCreateSystem<EndSimulationEntityCommandBufferSystem>();
39.         base.OnCreate();
40.     }
41. }
42.  

Lines 12 and 14 are giving me errors right now. This is probably not the correct way to go about accessing this data, I have pieced this together looking through examples and posts I have found here on the forum.

Line 14 gives me an error about ScheduleBatchedJobsAndComplete can only be called from the main thread.

If taken out Line 12 then gives me an error IndexOutOfRangeException: Index 1 is out of restricted IJobParallelFor range [0...0] in ReadWriteBuffer.

 

You need to use a for loop no IEnumarable in NativeArry I think. Some correct me if I’m wrong

 

Changing it to a standard for loop seems to solve part of the problem. The Line 14 error still exists.

 

You can’t use EntityManager inside job (except ExclusiveEntityTransaction). Look at samples and read docs about accessing data inside jobs, or use search, It’s discussed in this forum soooooo many times Search by ComponentDataFromEntity. In addition, looking to your code - it’s definitely not safe if you have many TargetChange entities and iterating through same ships every time it will be race condition when your TargetChange archetype become more than one chunk. If you have only one TargetChange at time - revert you logic which iterate through all ships in parallel and set target for them and in next job in chain just destroy this target by ECB.