Question Doesn't filtering (eg: WithAll) remove the performance benefit?

I have been having a hard time getting into ECS, i can't seem to understand how some behaviours work that will give me an advantage over my custom code, eg:

• 100000 entities with a Position component
• 100 random of those entities with Position components with also a Translation component that will change the Position in a system.

The translation component may have a linear memory layout in this case but if the Position components are across multiple chunks/much apart from each other... wouldn't it loose the performance part everyone talks about due to components not being linear in memory?

 

While the Position components may be spread across multiple chunks because there are so many, they are grouped in batches linearly inside each chunk. There is a little bit of a performance cost with jumping between chunks, but most of the linear memory gains remain valid.

 

Thanks for the answer, but what do you mean by this and how can it be faster than having a NativeArray<Position> and NativeArray<int> PositionIndexesToTranslate.

 

Let's say that each chunk has a max capacity of 100 entities.
Chunk A will hold an array of 100 positions and an array of 100 translations. Chunk B will hold an array of 100 positions. Chunk C will also hold an array of 100 positions...