ECS Deep Dive blog post

A few weeks ago, I had the great pleasure to attend a very informative presentation about the inner workings of the ECS framework titled: ECS Deep Dive.

I wrote down an blog post summarising this talk: https://rams3s.github.io/blog/2019-01-09-ecs-deep-dive/

Enjoy!

 

This was pleasure to read.



Really nice content.
Definitely good article for anyone who starts journey with ECS.

Not sure if is critical in this state, but I miss mentioning about Injections. Yes they are on the way go away.
But maybe omitted for a reason, while targeting future ECS evolution?

 

Thank you for the kind words.

Indeed, Fabrice informed me they were on their way out so I removed their mention

 

Hi ozirus, thank you for the generous contribution

 

This is a great article, it explains everything very well. It should be the first article people read about ECS. Thank you!

 

Great article. My only complaints is the use of GetComponentDataArray and a quick example of chunk iteration and/or IJobChunk would have been great (though you do link to it!)

Again though, great article.

 

May I ask, what is wrong with GetComponentDataArray in the article?
I assume is the lack of example to the job? Or perhaps something different?

 

Because, at least the last I heard, it's being removed.

 

Interesting. What is the replacement/alternative to GetComponentDataArray?

 

Use IJobProcessComponentData and chunk iteration (IJobChunk).

https://forum.unity.com/threads/api-usability.550450/#post-3679534

 

Uh I just get scared and quickly checked, but I realized, I use GetComponentDataFromEntity. Hence my confusion since they looks similar. I understand from the attached post, GetComponentDataFromEntity is not to be removed?

 

GetComponentDataFromEntity is fine. It is quite different.

 

https://github.com/Unity-Technologi...er/Documentation/reference/chunk_iteration.md
Just curious about chunk iteration but in the context of JobComponentSystem(looking at docs)... All querying code is done in OnUpdate right (so nothing in OnCreateManager except EntityArchetypeQuery creation)?

 

Yeah, needs to be done every on update because the chunks becomes dirty anytime a chunk is changed.

I find the documentation you linked actually quite confusing, it makes it more complicated than it should be.
It also doesn't even reference IJobChunk.

Maybe I'll write a small example for people tomorrow.

 

Thank you for this nice feedback. I'll update the post a bit later today.

 

I agree that any additional info on IJobChunk/chunk iteration would be extraordinarily useful especially since GetComponentDataArray is apparently on its way out.

 

I wrote a little article where I basically wrote the same logic three different ways

• Iterating chunks in ComponentSystem
• Using IJobChunk
• Using IJobProcessComponentData

I'm not much of a writer and this is the first thing I've ever written so not sure how much use it will be to people. I personally learn a lot better reading source code and so I put an emphasis on that over the actual writing.

Anyway maybe someone will find it useful, https://www.bovinelabs.com/ecs-hello-world/

 

Really nice written. Well done. Glad you add BurstCompile.

Not sure how helpful that would be @tertle , but you could attach article to following topic
Please give me a simpler sample.

 

Way ahead of you, it's already there lol

 

Oh lol, I must be really short sighted

 

Hi. Thank you for that fantastic blog post.

Question. Is the presentation made by Fabrice Lété online somewhere? According to slides the talk was called "UniteLA 2018 - ECS deep dive" but i have been not been able to find it anywhere.

 

If you got each day LA 2018 schedule, you may be able to find, on one of 1-3 days. Check playlist.

 

Thanks. I checked and still no result. The only talk listed by him was ECS Track: Streaming and Serialization one.

Really strange mystery Oh well at least the blog covers it pretty well.

 

You are a better writer then you think. Love how simple and to the point the article is. And you show the entire example and explain a lot of it through comments, which is great. Most article show tidbits of the code and endlessly talk about it which is really annoying.

 

I think it was presented during a private (non recorded) session.

 

Thanks for the very nice blog post @tertle. I updated mine according to your remarks and added a link to your article for a more complete reference.

 

@ozirus

• This is a very nice write up and I hope it gets added to the Unity Documentation Thread that is tagged (@Joachim_Ante)
• A great addition to your article would be (1) a deep dive into jobs in a similar fashion, (2) a deep dive into native containers

A lot of info is already out there from the power users like @tertle, @5argon & @eizenhorn who share generously - but you summarized the ECS part very nicely. I would point anyone new to ECS to your Introduction.

Great contribution!

 

Hi!

Great article! Thank you!

You wrote:

I highlighted in bold the thing I am interested in. I am not sure what you meant by that. Did you mean that one Entity which, lets say, has 10 data fields(structs) could be split into, lets say, 2 chunks: the first one strores first 5 fields, and the second one the other 5 fields?

Thank you in advance.

 

Thanks for the feedback!

I guess I'll have to rephrase this if it's not clear.

An entity is never split across multiple chunks. If an entity is composed of 10 components, each chunk of its archetype will contain 10 arrays, 1 per component type. Depending on the number of components in the archetype, a chunk will thus be able to store more or less entities.

Does it make more sense? If yes, I'll update the article accordingly.

 

Oh.. Yes. Now it is clear.

Thank you!