Acessing static variable from Entities.ForEach

Question

I'm trying to create a grid map of my entities' positions

I'm trying to use entities.foreach to grab position data from entities and update a multi hash map like this:

 public class QuadrantSystem : JobComponentSystem
 {
     private EntityQuery query;
 
     public static NativeMultiHashMap<int, SectorData> quadrantMultiHashMap;
 
     protected override JobHandle OnUpdate(JobHandle inputDeps)
     {    
         quadrantMultiHashMap.Clear();
         if (query.CalculateEntityCount() > quadrantMultiHashMap.Capacity)
         {
             quadrantMultiHashMap.Capacity = query.CalculateEntityCount();
         }
 
         var LquadrantMultiHashMap = quadrantMultiHashMap.AsParallelWriter();
         JobHandle hashJobHandle = Entities
             .ForEach((Entity entity, int entityInQueryIndex, in Translation translation) =>
             {
                 int hashMapKey = GetPositionHashMapKey(translation.Value);
                 LquadrantMultiHashMap.Add(hashMapKey, new SectorData
                 {
                     entity = entity,
                     position = translation.Value
                 });
             })
            .WithStoreEntityQueryInField(ref query)
            .Schedule(inputDeps);
 
         return hashJobHandle;
     }

And access it in another system like this:

 [UpdateAfter(typeof(QuadrantSystem))]
 public class WorldRenderer : ComponentSystem
 {
     protected override void OnUpdate()
     {
         Debug.Log(QuadrantSystem.quadrantMultiHashMap.Count());

However unity throws an invalid operation: alt text

Which says " You must call JobHandle.Complete() on the job QuadrantSystem, before you can read from the Unity.Collections.NativeMultiHashMap". However I would have thought [UpdateAfter(typeof(QuadrantSystem))] would solve this problem no?

What am I doing wrong?

Answer 1

Ok I figured it out. The error actually showed the answer. I needed to call JobHandle.Complete() on the job. Here my entire class, updated with using SystemBase instead of JobComponentSystem:

 public struct SectorData
 {
     public Entity entity;
     public float3 position;
 }
  
 //[DisableAutoCreation]
 public class QuadrantSystem : SystemBase
 {
     private EntityQuery query;
  
     public static NativeMultiHashMap<int, SectorData> quadrantMultiHashMap;
  
     public const int quadrantYMultiplier = LevelGeneration.GridLength;
     private const int quadrantCellSize = LevelGeneration.GridWorldSize;
  
     public static int GetPositionHashMapKey(float3 position)
     {
         return (int)(math.floor(position.x / quadrantCellSize) + (quadrantYMultiplier * math.floor(position.y / quadrantCellSize)));
     }
  
     protected override void OnCreate()
     {
         quadrantMultiHashMap = new NativeMultiHashMap<int, SectorData>(0, Allocator.Persistent);
         base.OnCreate();
     }
  
     protected override void OnDestroy()
     {
         quadrantMultiHashMap.Dispose();
         base.OnDestroy();
     }
  
     protected override void OnUpdate()
     {
         quadrantMultiHashMap.Clear();
         if (query.CalculateEntityCount() > quadrantMultiHashMap.Capacity)
         {
             quadrantMultiHashMap.Capacity = query.CalculateEntityCount();
         }
  
         var LquadrantMultiHashMap = quadrantMultiHashMap.AsParallelWriter();
  
         Entities.ForEach((Entity entity, int entityInQueryIndex, in Translation translation) =>
         {
             int hashMapKey = GetPositionHashMapKey(translation.Value);
             LquadrantMultiHashMap.Add(hashMapKey, new SectorData
             {
                 entity = entity,
                 position = translation.Value
             });
         })
         .WithStoreEntityQueryInField(ref query)
         .ScheduleParallel();
  
         this.CompleteDependency();
     }
 }

With basesystem you call this.CompleteDependency(); instead of calling .Complete() on the job.

Acessing static variable from Entities.ForEach

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