Is there ever a reason to use ComponentType.Create over ComponentType.ReadOnly

Hi there,

so I am currently trying to move from [Inject] to GetComponentGroup. I have always wondered if there ever was a use-case to not use Readonly (both when using Inject and GetComponentGroup). As far as I could figure out, changing values in ComponentDataArrays won't have any effect regardless. As far as I can tell you will always have to use SetComponentData to Update Component Data. Am I missing something here?

 

I'm fairly certain you can update entities using ComponentDataArrays (example).

Note: You can also use chunk iteration with component groups now.

 

Indexing cda doesn't return a reference. You have to set the new value separately:

Code (CSharp):

1. var p = positions[i];
2. p.Value += new float3(1, 0, 0);
3. positions[i] = p;

 

Hmm. So is the use case here that if you are mutating data directly like that you have to declare your data with ComponentType.Create, but if you are using PostUpdateCommands.SetComponent you can declare you data with ComponentType.ReadOnly?

 

The CommandBuffer is always executed with exclusive access to all entity data and might do whatever it wants to it. You don't have declare any access method when using a CommandBuffer. Using CDA allows multithreaded access and needs to know which systems may run in parallel without potential race conditions.