Tutorial/Discussion: Unity's New ECS (Entity Component System) - #1

[@quill18creates]

ARG! I forgot to add the credits properly to the video. So much fail. I don't want to take it down now that it's gone live though -- I'll make it up with something else.

[@Ebonmourn]

i would of liked to see you actually flesh out the example of the fetching and show the difference in timing to run for each one.

[@lee1davis1]

No one has explained the differences with structs and classes as well as you just did in this video. Kudos!

[@shannonrowe9402]

Wow, this was exceptionally well explained. Really helped to clarify the concepts around ECS. Great stuff!

[@Drecon84]

I've been looking a little bit at Data Oriented Design and I was a bit confused about how to actually apply it. This video was exactly what I needed to make the concepts useful. Thank you for a clear and concise explanation and I'm interested to see where all of this ends up going in the future.

[@nikosnikolaidis3762]

Nice! very stoked to see ECS on this channel.

[@PeppoMusic]

Woa that intro has way too much energy for me right after just waking up. But cool stuff! I'll look forward to you uploading more of this and will definitely watch this later. I've been looking into how to implement the ECS paradigm into my projects to improve their efficiency at a larger scale.

[@hongpinglo]

Hope part 2 out soon

[@hellohaos]

Hope so =)

[@theral056]

Any second now! I'm sure!

[@shaunhall7894]

Very educational. The presentation from beginning to end kept me engaged. Subscribed.

[@PeterF590]

Nice lecture, looking forward to your future ECS videos. Having done ECS for many years I think that the most important (and creative) part of ECS is "Dynamic behaviour composition". I.E. The WizardSystem only process entities who have a WizardComponent so when adding or removing the WizardComponent it changes the entity's to have the Wizard behaviour or not. The separation of data and behaviour also makes ECS a good candidate for server side database storage and network serialisation. Imo Unity JobSystem is an advanced optimisation topic for ECS and would be easier to grasp when one understands ECS itself. Dynamic behaviour composition gets complicated with the JobSystem because a synchronous system (aka a BarrierSystem) is needed process the async ECS command queue

[@drzacha]

Please, more! I love you (mainly your tutorials), and it helps me a lot.

[@deusxyz]

This is a great tutorial. Reminds me of the older school days of programming in high school.

[@Dragonmaster047]

I strongly disagree with the struct are 99.9% like classes in C# statement. In C++, ok only difference is the default member visibility, I'd give you that. But in C# there are so many cases where just changing struct to class or vica versa breaks the whole algorithm/program. You should probably make it clear that the "structs are just values" sentiment only holds as long as you're using plain structs (not implementing interfaces) with just ValueType members and only if you keep them in variables that do not get autoboxed. Otherwise people will find them self in a world of hurt when they realise the difference between class and struct is not just pass by value/pass by reference! Other than that love your videos keep it up :)

[@Hoffmanpack]

Dragonmaster047 idk wtf u just said I'm worries now

[@G4M5T3R]

Randy Hoffman TL:DR struct != class unless in C++ (but not really, but close enough)

[@theral056]

So stoked for an intro to ECS! Amazing

[@purpl3grape]

I was thinking about how in a way, the Universe calculates it's 'entities'. In some ways, it's a bit like ECS where how it just acts on what forces it needs to, and the macro result precipitates from the culmination of all the micro calculations.

[@TheBelrick]

Quill you could be a uni lecturer you are so good at explaining this.

[@Nightlurk]

20 years later, people learn how to program the way people were programming before people learned how to program OOP...

[@mdo]

This statement is annoyingly accurate.

[@Nightlurk]

:) este

[@Sylfa]

Sure, but 1 year after that this new thing is on the rise, Object Oriented Programming, its really sweet. (This swing back and forth has happened before and will happen again, its nothing new)

[@deusxyz]

xD

[@jussivalter]

partically right. But ECS is not that old architectural style (maybe a bit over a ten year old??). And ECS isn't actually programming paradigm as OOP is. And in terms of paradigms, I think that old paradigms like procedural or functional are the ways people tend to code mostly before OOP. Also ECS was/is mainly used for game development.

[@piotrszuflicki1527]

Will you create the tutorial of Pure ECS?

[@codingTheFuture]

Great video! Do you plan on do one of your game making series using ECS with the C# job system?

[@mcgeufer]

And now for something completely different: Would you mind to do a RPG-Stat system with an ECS approach? I kinda wonder how the would work. Like how to gouvern different bonuses on stats and so on. Edit: I'm on it and it turns out the whole thing is less complicated then expected.

[@SoloparafocasxD]

I was wondering if I want to implement a kind of search algorithm for my array struct, could that have a negative impact in terms of performance?

[@Sylfa]

Technically they don't use "bool[] alive" in ECS but rather have a "int alive" that keeps track of how many of the items are alive, then to kill an item you do: data[i] = data[alive-1]; alive -= 1; This way you skip the unsafe stack push and save an array lookup on every iteration.

[@theonewhohonks9675]

Hey quill, if you still have the files from this, could you add a deltatime measurement to calculate the difference in time between the two styles? That seems like it'd help quantify the difference between the two.

[@shmafoo]

Hey quill, did some reading of tutorials and example code, watched other videos regarding ECS & the job system. I have yet to write such code myself but just from reading it feels somehow more natural and logical to do it this way. Also it might actually result in not having two systems one usually needs and I wanted to know if you can confirm it at this point or what your view on this is: As this whole thing is data driven, the need for a classic event system (like you have shown in the other tutorial videos) or object pool managers is not there. Instead of creating an event and have some other object listen to it, simply create data and the rest will happen automatically due to the systems checking for existing data all the time. Also, as the data is stored in a continuous chunk of memory all the time, the thing with the object pools is obsolete as it's kind of part of the whole thing incidentally. At least if full ECS only is used and not hybrid ECS. Can this be viewed as correct or can you please share your thoughts on this? Thanks! :) /Edit: Also I think it might be even faster to write the code in the end, once you got a hang of it.

[@ThoughtExperiment]

Hey Quill18, any update on the other parts of this?

[@amber9040]

Is ECS really mostly about performance though?

[@ozgurakpinar_gr]

Not really. It is very helpful for "separation of concerns" (not in class level but in system level) and overall architectural design (of your game) is more closer to software development best practices.

[@henrikse55]

Please correct me if I'm wrong but aren't everything references by default in C#? As far as I understand in C# everything is a reference, you are by default never working with pointers as they are not safe in itself and to my understanding to use actual pointers you are required to use enable "allow unsafe code" and encapsulate your code with the unsafe keyword.

[@JordanSwapp]

henrikse55 you're correct, not the same thing, though similar in concept wrapped in some protective love because of the CLR. Pointers are to a memory address and not type safe generally speaking. In c# a reference points to an object, the reference can be moved in memory (garbage collector, sizing of arrays without using fixed) and the type is guaranteed and validated with the exception of using the unsafe keyword.

[@JordanSwapp]

To address "everything references by default" is actually not true, parameters are passed by value with respect to reference type parameters they are reference types. This is why keywords like out/ref exist.

[@quill18]

Not everything is a reference -- that's why I talked about Value types (which are not references). As for pointers: I use the word pointer here because it helps to emphasize that reference types are "pointing" to some randomly assigned memory in the heap. Mechanically, references and pointers work differently (and C# uses reference types), but in practical terms for this discussion the difference is moot.

[@filipsalen2561]

At 5:40 he say that doing 4 things in 4 threads are faster then doing 4 things in 1 thread. Why is that? Or have I missed something imprtant? :)

[@anarchoyeasty3908]

Lets say every task takes 20ms to complete. If you have them all in 1 thread you have to wait for each one to finish before kicking off the next task. Thus all 4 tasks will take 80ms total to complete. However, if you split up those same 4 tasks into 4 different threads, that means that the tasks can be done at the same time. Thus it will only take 20ms to complete all 4 tasks.

[@filipsalen2561]

Thanks for the answer, Ah I was thinking of a single core processor

[@anarchoyeasty3908]

It's actually still the case even on a single core processor. Modern processors all have tons of threads on them, allowing for parallel processing on a single core. If a single thread takes up all the resources then the other tasks won't happen an exactly the same time, but it will try it's best to do more than one thing at once.

[@gpcm9226]

First, thanks for the educational video. But, the scrolling up and down is hell. If you can figure out a way to keep all the lines you are talking about (seems like about 50) on-screen while you are talking about them it would help a LOT. Ideas...most monitors are quite wide so the // text can be kept in a single line. Idea...I can go to full screen mode so a smaller font can be used and it's still very legible. Thanks again

[@play4fun599]

Can I still use the old component system?

[@dartimosthatsit6001]

From what Ive seen so far, it will take some coding to opt into this. You will need to specifically tell Unity to use the code for the system.

[@mdo]

Play4Fun yes. ECS is still in preview. It doesn't even get loaded as a default package when creating a new project. You have to go out of your way to turn it on. You can even use ECS with existing component system. It's called hybrid ECS.

[@jon_do]

Thanks, Quill. You rock!

[@lhorbrum1818]

Thank you for this.

[@easyBob100]

Read "Digital Design and Computer Architecture" if you reeeeeeeeeally wanna know how it works. It even has code examples for FPGAs if you're into that. Build your own lil cpu.

[@MrTastelessVideos]

Just a random thought: wouldn't using Lua also make a huge performance boost? Like; what you covered in the last example part could easily be made in Lua, as far as I am aware. Using Tables and maybe managing Memory-Allocation by hand (by setting unused vars as nil, or flagging and then reusing them) would probably boost a) compilation time (or rather processing time) and b) memory usage and management, wouldn't it? Sry if I'm wrong somewhere, haven't coded proberly in like over a year now *sigh*

[@Norbingel]

I just wanted to learn how to do Unity's rollerball tutorial using ECS... ;D

[@adhochero6619]

yeah, this. an example of how to actually build something and see how it all works together would be beneficial

[@lamkasdev9983]

Every video on start I hear "Hey fox quality here!" xD

[@DJRUDONE]

Almost two years later and this is still not continued. But I think Quill has given up on programming :(

[@shinevisionsv]

Awesome!

[@nahco3994]

In my (limited) experience with the MVC-model, *absolutely none* of the examples available on the internet *really* conform to all those nice, simple, and abstract descriptions of the theoretical model. Add to that the fact that in more than enough cases those nice, simple, and abstract descriptions contradict each other, and you might just get the impression that absolutely nobody *really* seems to know what MVC is all about. It honestly drove me nuts when I tried researching this model for one of my assignments. Some of the best advice I eventually got went kinda like this: "It's an archaic model developed specifically for some 70s hardware. Don't even try to follow it to the letter. Nevertheless, the underlying principle is still very useful for organizing your code. Try to see the bigger picture in there, and forget about the rest."

[@andrewzuo86]

ECS isn't just about CPU cache. It also allows super fast instantiation time.

[@mcgeufer]

Well... We got the bad and we got the good. But where is the ugly?

[@Hoffmanpack]

Just saying get component rigid body is obsolete took me fucking 4 hours to get it right... Fucking 4 yr old tutorials sup quill love ur tutorial s!!!

[@MikoGot]

Yey!

[@santoshparihar6820]

Sir please make a video on using Facebook sdk or api in our game...how to play online with our Facebook friends. Please please ASAP

[@totlyepic]

"The CPU can only work on data in its cache" - Caches don't have to exist. The CPU can only work on data in its registers. Doesn't affect the point you were going for, but it's not technically correct. That said, with basically any modern CPU, it's a moot point. The CPU's only pulling from memory on a cache miss.

[@PHPLanceRU]

Не могу воспринимать его уроки, дёрганные какие-то :)

[@johnjonjhonjonathanjohnson3559]

make a better ecs than unity and laugh at them

[@gregoryfenn1462]

It's a little hard to focus on a video where there is so much talking over a boring slide; something like pictures to illustrate what you're talking about, or pop-up bubbles of relevant thoughts or observations, would help me as a viewer. Your content is good but your pedagogic style is jarring, which is something I wouldn't expect for a channel with 133k subscribers.

[@gregoryfenn1462]

It gets much better after 11:00. But to clarify my criticism, for a semi-formal lecture about the theory behind ECS, or the programming paradigm and computational principles of it, I would have strongly prefered to see you draw-out some thoughts and diagrams on a physical blackboard, without even touching a computer.