Access SharedComponentData in IJobProcessComponentData possible?

I cant see anything in the unit tests that suggests it is possible.

I suppose I need to go with IJobChunk in these cases, huh?

 

You can’t use SCD directly in job because it’s not part of chunk actually, chunks store only SCD value index (not yet but as Joachim says, Unity doing it for future releases) you only can manipulate SCD index inside job.

 

Huh? It should generally be possible to [ReadOnly] access SCD from inside a job, right?

MeshInstanceRenderer does it too with ArchetypeChunkSharedComponentType.

Code (CSharp):

1.         struct MapChunkRenderers : IJobParallelFor
2.         {
3.             [ReadOnly] public NativeArray<ArchetypeChunk> Chunks;
4.             [ReadOnly] public ArchetypeChunkSharedComponentType<MeshInstanceRenderer> MeshInstanceRendererType;
5.             public NativeMultiHashMap<int, int>.Concurrent ChunkRendererMap;
6.  
7.             public void Execute(int index)
8.             {
9.                 var chunk = Chunks[index];
10.                 var rendererSharedComponentIndex = chunk.GetSharedComponentIndex(MeshInstanceRendererType);
11.                 ChunkRendererMap.Add(rendererSharedComponentIndex, index);
12.             }
13.         };

 

ArchetypeChunkSharedComponentType doesn't work (for me at least) unless you call complete on the job that uses it before returning. Not doing so causes a "The previously scheduled job reads from the NativeArray(system.sharedcomponenttypename)..." error. Just a warning if you encounter that.

You can use a copy of the shared component in a job though, if you happen to know it beforehand, because you can access the shared component data in the main thread(via EntityManager.GetAllUniqueSharedComponentData). In my case I had some entities used as spawn events, each entity has a sharedcomponent that is copied to the spawned entity. Because each unique shared component is it's own chunk I can use that to generate "per-chunk" traits(as several nativelists, one has copies of the shared component) that I want the spawned entities to have, prior to starting the jobs. Then inside an IJobChunk, iterate over the spawner entities and use the chunk/job index to access the arrays I made.

 

That's not accessing the ISharedComponentData, just the index.
You can't use the index to access the ISharedComponentData till outside of the job.

 

There's a new ArchetypeChunk.GetSharedComponentData in preview 23 so maybe that's possible now? I haven't looked at it though.

 

@eizenhorn & @tertle:
Duh! Sorry for that oversight, I get it now. Thanks for clearing it up!

@RecursiveEclipse
Passing a copy to the job was my immediate reaction to this as well.
Thanks for sharing your implementation approach!

@jooleanlogic
Oh nice! I'll have a look at this.