How To Build An Event System in Unity

[@MortMort]

This channel needs more love

[@ElegantWaster]

This is really great and very concise. You have quickly become my favourite Game Dev channel on here.

[@GameDevGuide]

Wow, thank you! That really means a lot. I'm trying hard to strike a good balance between informative and entertaining. I'm presenting a lot of things I think go undeserved by a lot of other channels, and honestly my content for these videos are mostly from things I'm using day to day during development - stuff I wish I'd learned\heard about when I was first getting started. So I'm really glad you're finding it useful! Thanks for the kind words! 😊

[@tsvetansumerski7231]

I've been watching videos on events for days and this is the only video that actually explained it well enough for me to understand, thank you!

[@simoxeh]

I've been trying forever to understand events. I finally think I understand it. May you have many blessed days and may your descents know nothing but happiness

[@AetherXIV]

I like how you explain the concept first. It actually helps to teach us how to code, not just show us what you did.

[@Seb_Ibrahim]

Your content is amazing. I'm so tired of the same beginner how-to stuff that ends up being a pile of spaghetti code and can't really be used in medium to large projects. This was much needed. Thank you and keep the videos coming! ❤️🙏🏼

[@vintoncerf7562]

This system is not performant since he is id checking for every single door in the scene. Let's say we have 1000 doors in the scene. The id checking code will run 1000 times whenever a single door is opened. In other words, we say the following to the computer: You: "Hey dude can you open this door for me please?" PC: Wait pal, first I need to know which door is that what's the id? You: The id of the door is 0. PC: Ok just wait while I'm comparing that value to all thousand doors.

[@2n974]

@@vintoncerf7562 that's not true at all

[@vintoncerf7562]

@@2n974 why?

[@MaikoYT]

@@vintoncerf7562 If you want to make sure the right object handles an event, you can assign the event to a delegate in a Dictionary. Then, when the event is triggered, you can specify which object to call the function on using its instance ID. This way, you can make sure that the function is only called on the specific object you want.

[@Chocochoco22]

I've been watching so many Event tutorials and for some reason after this tutorial, everything that I watched started making sense now

[@Sevendogtags]

How do you not have like a 100k subs already? Your videos are so nice and high quality! Thanks!

[@Jay12321Jay]

Just thought the same... Strange!

[@MassimoRough]

Have you already shared this video so he would get closer to 100k?

[@zakkaioken2812]

That's because they don't upload often enough uwu

[@MassimoRough]

Zak Kaioken 2 how do you measure that?

[@zakkaioken2812]

@@MassimoRough measure it by quality / content / count / topic / focus if you're not making good content on topics people care about fast enough, enough times, you will not grow that fast. people call it the KZbin algorithm, but, the fact is, if people care they will share.

[@Antman261]

THANK YOU! I come from a web dev background and build a lot of event-driven and/or event-sourced distributed systems. I've just started building a game as a hobby. SO, naturally, I decided to punish myself early and went looking for an event-based implementations in Unity. The first few forum posts and packages I came across made me doubt the entire approach, but this is precisely the kind of clean, simple, straightforward thing I LOVE! Thank you!

[@roderickmorgan2115]

I've got to echo all the comments below, this is one of the quickest, clearest and most aesthetically pleasing dev tutorials I've seen on youtube.

[@michaelsissons234]

Utterly fantastic, most tutorials available on youtube have serious pacing and clarity issues, and yet you made it look effortless.

[@KarasawaL30]

Been learning C# on my own for a year now and so far, your videos have been the best for concise, step by step explanations. A lot of guides don't take the beginner mindset into account, and simply push forward into glossing over and including a lot of extra concepts that end up making things harder to understand. Cheers!

[@DannyBoy443]

I don't like that either. I'm beginning to think that this channel (and others, if I'm being honest) don't think its a good idea to do the basics because it isn't sexy or too low level and boring. Which if that's the case, I disagree with wholly lol

[@JordanLiver]

I’ve watched this several times and finally pushed myself to use it during a game jam. It worked so well for what I needed! Thanks for the concise explanation and example! It really helped me grow as a programmer.

[@alexbukk556]

This is the BEST Unity event tutorial I've seen so far! I've been looking around for some practical, example based tutorials for understanding both the general use case and implementation details for event systems. It's a shame I had to watch so many other tutorials before I found this one, that in 5 min covered more than the previous five tutorials I've watched combined. Keep up your good work, and THANKS for this awesome video :)

[@hamzazahid4705]

IT WORKED, THANKS I'VE BEEN LOOKING FOR THIS FOREVER, BUT NO TUTORIAL COULD EXPLAIN IT AS YOU DID

[@charmaebritania9406]

It really worked for me after I look and try some tutorials, yours is the one that worked. Owe you a lot.

[@joaquinfraustoalfarorocco8177]

let me tell you, this just leveled up my overall coding pipeline, simple, concise a work of art this tutorial

[@MrBsehratmaannking]

im a CS master student who was always quite interested in game dev but in my bachelor and master we havent learned so much about game dev and looking at unity, i always felt somewhat overwhelmed with all the custom functions in unity. Just found your channel today and it gives me a nice starting point to at least see all the options in unity

[@kartiktiwari2008]

The event system was doing my head in. But you solved it in 8 minutes amazing stuff!

[@lesthodson2802]

"An object known of as the subject" *distant linguistical screeching*

[@stephenbacunot4334]

You are a living god among n, a legend worthy of praise. What you've uploaded here, will echo into eternity!

[@mahimagupta8283]

It's truly astounding how easy the internet makes learning these days. Thanks for the tutorial, my guy.

[@512Squared]

One of the clearest Dev tutors on KZbin! I love how you anticipate questions and problems, as well as giving a bit of top-level background to the code/unity concepts you are invoking. Top job fella!

[@ironsfamily6]

This was amazing. I think I need to come back when I'm not so sleep deprived, do a little background research, and try this out for myself to get the full benefit, but I didn't know about this functionality and never thought about programming this way. This is incredible. Thanks!

[@rickloyd8208]

After a week, I came back here to say THANK YOU! This pattern is awesome, I just used it in an upcoming project, everything looks easy to understand, clean and safe!

[@ast_rsk]

The quality of this channel is unreal. Keep it up! If you're looking for suggestions on topics, it would be great to get some insight on project planning, scoping, and starting small for new developers (those most likely to find your videos useful).

[@xuanhungdo7285]

Welp, this was one of the most helpful videos for GameDev in unity. Clean, fast and simple tutorial. Great job!

[@goodusername4901]

he goes faster than a minecraft dream speedrun but it's very helpful!

[@user-dm5qi4nb6l]

I'm having trouble digesting all this about patterns, and now you just made a key subject easy to understand, I really appreciate that.

[@kristianthaler6525]

I was here months ago and didn't get it at all, now it's super clear to me. Progress.

[@owencoopersfx]

This is an excellent tutorial. I would like to point out though that in this example you actually can eliminate the Singleton by instead making GameEvents a static class and making all its methods also static. The only times you need a Singleton are when you need to create/destroy/track runtime data/objects. If all you’re doing is managing events, you don’t need the Singleton. Hope this helps people.

[@alicanted]

It took me a little while to wrap my head around this concept, but as my project grew bigger I really needed something like this! Now that I finally understand it I use it all the time! Thank you for explaining it properly and clearly!!!

[@twomanstudio3249]

I'm working on a project right now and this video really saved me! Thank you so much!

[@TuberTugger]

This stuff is gold! I've watched a handful of your videos now and I'm astounded by how useful they are. Please keep up the good work.

[@pusadev2001]

I FINALLY UNDERSTAND HOW TO CREATE AN EVENT SYSTEM THANKS TO YOU (All Caps intended) 😍😎💯💯

[@heatherelroy9534]

This was great. To the point. Quick typing. No extra fluff. Loooove it.

[@JDoerp]

I’ve been trying to achieve exactly what this video has explained for four days and not been able to until now. Earned a subscriber. First time I’ve come across your channel. Thank you!

[@tricky_fat_cat]

I used to use a C# events before I learned about Unity events, but your video gives a new look on them. Thank you.

[@gadgetboyplaysmc]

UnityEvents are pretty slow

[@nemlinkacompany7577]

I love your content. Fast + clean + VERY usefull.... I never saw channel like this (most are too unprepared) I really wish you success

[@nickolas6060]

Finally someone that explains this clearly! Many thankd👍👍

[@mauco4037]

Maybe I am a bit late to thank you, but your video saved me hours of suffering... Thanks a lot! Keep up your good work!

[@psinjo]

I want to thank you for the simple tutorial, it was pretty short, to the point, and showed off the syntax + a decent implementation (along with parameters) keep up the good work!

[@Caldaron]

Fun fact. Having a prefab setup (door with trigger zone) for this is way easier and doesnt require to call multiple methods to figure out if this is the right door. people are going to use events from now on when it doesnt even make sense.

[@snaileri]

Yea, bad example in the video. Well explained, but people shouldn't use an eventsystem for generic doors.

[@Pietrofonix]

A fair example of how events should be used?

[@cheapgrams2955]

Why not?

[@n1ppe]

​​​@@PietrofonixFor example if there's a level in your game and there's some button or a lever that causes something to happen in some other part of the level (like unlock something or open some door or whatever), you could have an event and listen to it, and then do it when it happens. You could also use events for example when the player collects something and you want to have some kind of an effect on the UI. Basically if you want something to happen somewhere else when something happens. In the example of the video though, you could just have a script on the door that opens it when the player enters the trigger collider, making the event system unnecessary. Sorry for my English :)

[@xoms_4712]

Yeah, i thought of that because of how stupid it is to trigger event on which there could be millions of subscribers on scene, and "fix" with id doesn't make it better, that's why i was looking for how to trigger one exact listener instead of triggering all of them.

[@Fenixmaiden666]

A clear and concise video explaining events. I was self-taught with code, so I had been coding for a while before I started to understand events and how to utilise them. Even after learning about them, I still didn't really use them as I had to step out of my comfort zone. Really good explanation and usage to introduce someone to events though. Kudos!

[@lando6583]

love the video format! I appreciate you speeding up the coding sections and highlighting actual gameplay functionality.

[@rakowumusic5143]

That is so damn well explained. Short and sweet but without leaving out a single thing. You answered all my questions in record time. Thank you for the great video.

[@in801fo5]

The way I differentiated between each object that uses the same script was to subscribe it to the ”OnInteractKeyPress” when the player has entered its trigger, and then unsubscribe it when the player exits its trigger area. So that I don’t have to manually assign an id to every object and its trigger area.

[@ali51717]

as a programmer, I am just looking for design and planning, because I am confident I can write the code. This is why I find it perfect

[@dariussparkes7080]

A brilliantly constructed guide.

[@TheMenkin]

This has become one of my favorite design philosophies for quick prototyping, and even in some production builds over two years. I've used this for two major game jams, and it has amazingly reduced coding time drastically , although it can be a hard concept to grasp for other devs on short time span. I cannot recommend this tutorial enough. If you have trepidations about it, try it out, it might change your world as much as it did mine.

[@sufianahmad7337]

After 7 or 8 videos I finally got a focused video 😊 Thank you

[@ardwennem]

Thanks for this video, I have seen a lot of event systems that didn't implement it with parameters, this was the first one that did! This really makes things a lot easier :)

[@Etocles64]

Wow, what a clear, concise, and informative video. Absolutely amazing work, thank you!!!

[@mehmedcavas3069]

I was looking for months like a tutorial like this. everyone shows an example which makes no sense or don't give even a good example. thanks

[@VladimirDemidovIllusiveMan]

I wish i would have seen this video one month ago when I started my project, now I have a spaghetti of dependencies that i have struggled to maintain in order, but with this I could have had such a great system.

[@VladimirDemidovIllusiveMan]

So, i was using Localization package in unity and it didnt go well with webgl, i decided to make my own translation. I have a binary file with texts, and one static dictionary. all texts in the game should take info from that dictionary. I had no idea how to do this, but this video gave me the perfect one. I connected to every TMPro text (they are the observers? correct me if im wrong) a script with a function that changes the text. When a button to change language is pressed, the dictionary is updated with data from a file, and then an event is generated, every label gets updated with a new text. If i did anything wrong then please tell me, im open to learning new things :) Thank you GDG for an amazing video. Got a sub right then and there :D

[@simoncodrington]

What a great video mate. Love how you've animated it to keep it interesting. Cheers

[@jackpeterson1909]

This is high quality content! You cover topic that's actually important. Thank you

[@kyleme9697]

This is the first Events video I've seen that said anything about unsubscribing from the Events ... seems kinda important :)

[@karim009]

Hi, cool video, but I recommend putting the subscribe/unsubscribe lines of code in the Enable/Disable methods, because unless you call DestroyImmediate you don't really know when the object is destroyed.

[@ChaosCain4]

This really made the way event systems work a lot more clear for me. Thanks a lot, hope you have a good day!

[@alicepricesaeibi4282]

As for me, everything is simple and clear. Thank you very much

[@tomjesten3945]

Just found this channel. There is a lot to learn from you. :)

[@blunygeorge]

When I first saw this video I tried this out but didn't understand why it may be a good idea. Today while I was casually implementing my smol game, I came across this problem: I would have had to add a chain of events. "A" happened in class X -> "A" happened in class Y that contains multiple X instances -> "A" happened at YManager class, which manages multiple Y instances. The last two would have been new events. This is just in order for a UI element to know about a specific event that happens in class X. Instead of adding these two new events, for now I went with something similar that the video shows. This way it is a "global event", and there isn't any additional event that only exists to pass further up the event. There isn't an unnecessary chain. Thanks for the idea.

[@ARandomSub]

Uhh this just changed everything for me! Thanks!

[@TheMapaSoft]

Well, I stumble on your video and I must say that is a very naive implementation of an EventSystem.One of the problem I see is the event payload. Each time you add arg to the event, you must change the code everywhere to accommodate the right Action signature. The other one is the tight coupling inside your GameEvents class. As the project goes, the amount of events will increase and your GameEvent class will be packed with all the types for every aspect of your game, UI, gameplay, music , sounds, etc... The last one, is your "none" implementation of a SingletonBehaviour class... Having a lone static method in your gamevent class does not shield you from having multiple instance running, each one overriding your static Instance.

[@faythe03]

What could make the event system better? Why? I'd like to learn

[@psyneur9182]

I agree with you that there is a very tight coupling between the game's events and this class, it does mean this class could become very long (especially considering it will essentially be a list of types and duplicate methods). However, having to change the code when the type of the Action is changed is not a problem, imo. If you don't have to change the code, where is the type safety?

[@Zethneralith]

​@@faythe03 A good example is the Windows Forms event system that uses an EventHandler generic delegate (found in the System namespace). The real magic is in the TEventArgs which, by default, has no properties. This is meant to be expanded upon by inheritance. For example, to create an event that sends information about a collision, you could create a class that looks like this: class CollisionEventArgs : EventArgs { public HitInfo Collision { get; set; } } The signature for the event would look like this: public event EventHandler OnCollision; And can be raised as expected: (assuming hitInfo is defined) CollisionEventArgs args = new CollisionEventArgs(); args.Collision = hitInfo; OnCollision.Invoke(this, args); // Passing "this" for sender as a reference to the object raising the event. Effectively you use the same method shown in the video, but use EventHandlers, instead of Actions. They're both delegates, but EventHandler gives you some extra consistency via the generic type parameter.

[@CEbbinghaus]

This same System could be Implemented Much closer to Unities Event built in Event system using the `Component.BroadcastMessage` Method. Have something like a Trigger Enter call Broadcast Message and suddenly only the single gameobject that Gets Entered has its Event called opposed to Every Door in the entire game

[@TheMapaSoft]

@@faythe03 Hi Valentin, sorry for the delay, Covid-19 stuff.... Well, for me, being a AAA game dev, I prefer a total separation between the sender of the event and the receiver. In C#, you have event, but you need to subscribe to the sender (most of the time). This could be avoided, by having a static class that contains only the C# events you need. It could work. But my preferred way is by using an EventChannel. A channel, which is a Singleton, is only responsible to let the event pass into it. You can listen for any Type of event, when the event comes in, you will be notified via callback. Also, for the event itself, I prefer using a class (struct could works also). It may hold any other types, so the payload is almost free. And on top of that, to minimize the memory fragmemtation, you can pool the events. To give you an example : GameplayChanne.Instance.StartListenFor(OnThisEventCallback).... I can paste code here if you want.

[@manugamingcreations1021]

Thanks a lot! Managed to make a similar thing in Javascript thanks to this tutorial!

[@gabrielcoleman3267]

Overall great tutorial. One thought, Instead of assigning a Unique ID to each script, an easier way would be to get the gameobject.InstanceID, which would save time of needing to make sure each door has a unique ID.

[@NotASpyReally]

yes that's what I thought

[@qwerty81808]

Why bother with any of that? Why not simply pass the GameObject or Component calling the event as a parameter?

[@Gahanun]

The id allows one trigger to open multiple doors and vice versa. + the way you suggest it doesn't work since both the trigger and the door need to have the same id.

[@gabrielcoleman3267]

@@Gahanun Well, good point. I made that suggestion without trying it out. However, a modification that I believe will work is if you have a parent GameObject with both the door and the trigger as children. The event system could use the transform.parent as a substitute to the ID, and simply trigger an event if the door's transform.parent is the same as the trigger's transform.parent. I can see however, that this might not be ideal for all scenarios, and simply using an ID might be the optimal solution, if the intention is to do away with directly referencing GameObjects in code.

[@nachostv4217]

@@qwerty81808 Without being an expert on the subject, I'd say passing the entire GameObject would be sending along far more data than is actually needed. I assume it will want to know about everything in the GameObject, so all variables and whatever, this will cause a lot of unneeded CPU instructions (reading from the RAM to get that information) when all you really need to send along is a 16-bit integer.

[@Bashar3A]

Something I've been trying to confused how to do for long time. Thank you! Subscribed

[@agentrsdg]

Really need more content like this which focuses on code and architecture

[@vainiusgames2709]

your video improved my life

[@HeroSnowman]

Your tutorials are so simple and understandable, keep doing this!

[@Ruzakisan]

omg it is the most clean explanation of events and it using in Unity! God bless you +sub

[@Aceleo209]

I spent 13 seconds in this video. Liked the video..subbed and made a comment

[@zakaruPL]

Great quality of video! keep your work doing mate 🤜🤛

[@Oxmond]

Great tutorial! Accurate and clear description and great code. Well done! 👍🤓

[@richystocles]

"swimming in a big bowl of spaghetti code"... you are watching me right !?

[@MikeArcuri]

This was great! My computer science education is 25 years old, and I'm pretty new to C#, but I was able to follow this lesson the first time, get it all working, and understand the basics. It wasn't clear to me why we needed both the public methods and the public events defined in the GameEvents object, but a few edits to try to call the events directly from the TriggerArea objects showed me via C# errors that this isn't allowed.

[@varunshivaram711]

Keep making amazing videos like this to explain kinda complex stuff simple...as an aspiring game dev I loved the video...you deserve more subs, I'll make sure to like,sub, refer, and tweet...keep up the good work.

[@08-adityakothari74]

Fantastic tutorial, keep up the great videos!

[@Berndr]

best tutorial on event system I seen so far!

[@sreerone9562]

Hey Man, thanks for Sharing the knowledge and supporting the community.. Cheers!

[@zachcantwell]

I love your vids man; you're an awesome teacher.

[@hhhhhhhhhhhhhhhhh159]

that was the funniest unity tutorial video i have ever seen :D

[@ivanmoreno25]

Thanks a lot! I was having an issue with Unity crashing when some events happened, so I watched this video to check what was wrong with my code. Your example worked perfectly. Later I realized that the problem was an infinite recursion lol

[@kirtanvinodbhaivekariya413]

Thank you So much for ur ti and support

[@minecraftermad]

if brackeys and such are 10/10 this is 11/5 tbh.. these have helped me so much more with critical things than those channels have :)

[@akaHarvesteR]

When I need subscribers to return data to the event source, what I usually do is set up a query class that I then pass as a parameter on the event. Then responding subscribers can add in their replies as needed to that query. That way you have full control over how to manage potentially multiple responses to your event's ´question´.

[@rCr101990]

This is great, sounds like combining Mediator pattern with Observer using Events and Singleton. Nice

[@PauloSamurai]

after many times, I finally got it! thanks man!

[@Jagent]

Never before have I needed knowledge so badly without realizing it. Thank you for this!

[@user-dd9is6iy9m]

This was super helpful, thank you so much!!

[@rodolfoc.nascimento6301]

Very good explanation, thank you

[@jaancaro3829]

I love you

[@aprilmaemanzan3708]

You really good at explaining thank you

[@Zavarzinia]

Thanks for your work! Super helpful.

[@llorex1]

Great video as always!

[@RegoneFF]

Your video is great and all but I'm not sure this is the best example of an event system. TL;DR Don't be afraid of errors in log, they are here to help you and you will only learn from it for the next time. Longer version I once worked with a guy who had a similar approach to programming where he rather not notice a bug and make everything run "smoothly" with no apparent stuff breaking around than seeing a bug popping 50 times in the log/ crash the game and then fix it or just did the system too dynamic where it shouldn't, like doors or other "static" stuff that doesn't really change through the run. he had such a hard time finding and fixing a single bug.

[@gamepod861]

Well done. Keep up the good work and thank you

[@GameDevGuide]

Thank you!

[@PedroPaulo-ph1hd]

This is really amazing. Thank you!

[@indieprogress7170]

Incredible guide. Thanks, man!