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.

[@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!

[@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

[@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.

[@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.

[@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 :)

[@mahimagupta8283]

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

[@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

[@joaquinfraustoalfarorocco8177]

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

[@kartiktiwari2008]

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

[@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!

[@hamzazahid4705]

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

[@stephenbacunot4334]

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

[@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!

[@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!

[@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!

[@kristianthaler6525]

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

[@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).

[@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!!!

[@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.

[@lesthodson2802]

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

[@charmaebritania9406]

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

[@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

[@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.

[@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!

[@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.

[@twomanstudio3249]

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

[@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!

[@nemlinkacompany7577]

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

[@pusadev2001]

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

[@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!

[@heatherelroy9534]

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

[@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.

[@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!

[@nickolas6060]

Finally someone that explains this clearly! Many thankd👍👍

[@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 :)

[@sufianahmad7337]

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

[@lando6583]

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

[@kyleme9697]

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

[@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.

[@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.

[@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

[@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.

[@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

[@simoncodrington]

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

[@ChaosCain4]

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

[@agentrsdg]

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

[@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

[@tomjesten3945]

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

[@jackpeterson1909]

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

[@dariussparkes7080]

A brilliantly constructed guide.

[@Etocles64]

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

[@Aceleo209]

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

[@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.

[@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.

[@ARandomSub]

Uhh this just changed everything for me! Thanks!

[@zakaruPL]

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

[@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´.

[@DannyBoy443]

Your editing is amazing and I get most of what you're saying. But how did you get the doorway to open vertically? I don't see a transform or axis change.

[@troyna77]

using DentedPixel; LeanTween.moveLocalY(gameObject, 1.6f, 1f).setEaseOutQuad(); "moveLocalY" is the vertical Axis. My problem is the door is not being Triggered. I can put the above line of code in the on Start(). and it works, but for some reason,Im missing something.

[@richystocles]

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

[@alicepricesaeibi4282]

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

[@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 :)

[@Bashar3A]

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

[@manugamingcreations1021]

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

[@Ruzakisan]

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

[@08-adityakothari74]

Fantastic tutorial, keep up the great videos!

[@Husmanmusic]

Binging these videos, amazing quality!

[@HeroSnowman]

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

[@zachcantwell]

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

[@Berndr]

best tutorial on event system I seen so far!

[@rCr101990]

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

[@vainiusgames2709]

your video improved my life

[@Oxmond]

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

[@hhhhhhhhhhhhhhhhh159]

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

[@Jagent]

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

[@PauloSamurai]

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

[@gamepod861]

Well done. Keep up the good work and thank you

[@GameDevGuide]

Thank you!

[@jaancaro3829]

I love you

[@sreerone9562]

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

[@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

[@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.

[@indieprogress7170]

Incredible guide. Thanks, man!

[@user-dd9is6iy9m]

This was super helpful, thank you so much!!

[@MNenad]

Very good explanation!

[@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.

[@Zavarzinia]

Thanks for your work! Super helpful.

[@jasonario4781]

This was a great video! Adding this to my toolbox for sure!

[@llorex1]

Great video as always!

[@Xiromtz]

Great video for a simple "event system"! I think it would be important to note the biggest difference between the observer pattern and an event system: An event system should be time decoupled, which your implementation is not. This means the eventsystem would have some sort of queue where events are queued, and at some later point in time the eventsystem would go through that queue and call event subscribers. A great showcase of this pattern is in the book "game programming patterns".

[@immersiveirl6638]

IMHO, the ideal scenario is that the events are handled immediately, but then the handler queues tasks. eg: void myEventHandler(int id) { StartCoroutine(DelayedHandeler(); }

[@Xiromtz]

@@immersiveirl6638 Starting a coroutine doesn't really do anything here. It's a bit of a misconception that coroutines are "parallel", all they do is run in the main thread until a "yield" statement tells it to stop running for this frame or for however long the yield statement tells it to. The optimal solution in Unity would be a simple queue or stack, where a "fire_event" function would add the event to the queue and the class containing the queue would work through events in its update function. The idea is to decouple heavy event handling functions from the caller, but we must also assume events can't be handled immediately. So the use-cases would be something like an achievement or sound system, where a delay of one or two frames is not noticeable. This kind of system might not, for example, work with an input system. If an event is immediately handled, it is nothing more than an observer pattern, albeit cleaner with the use of delegates and such. Nothing bad about it, just nitpicking with terminologies.

[@immersiveirl6638]

@@Xiromtz I understand that a Coroutine is not true parallelism, but dumping the task into a Queue and processing in Update is effectively the same as doing it in the EventHandler... it's still all being done in one frame. Unless you're limiting the number of tasks that get popped from the queue per Update, at which point you should probably be using a Coroutine for style (processing over multiple Updates).

[@Xiromtz]

@@immersiveirl6638 Oh yeah, you mean something like a coroutine that stays alive for the whole duration of execution? I did something similar once and you would be correct, that does sound like the cleaner solution. Using a time budget per frame and thend yielding until the next once the budget is expended sounds like a really good implementation.

[@mementomori7160]

I just witnessed your channel go from 66.5k to 66.6k subscribers. That's a nice number, but should be multiplied by 10(at least)

[@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.