How to Program in Unity: Hierarchical State Machine Refactor [Built-In Character Controller #5] 

I did the Unity Junior Programmer course, I'm at the last small game for my portfolio. Saw this pop up and thought oh let me check this out. Now I feel like a Freshman Programmer V_V. I get the point of doing this though, it's similar to what I do with having parent and children for my enemies in the game: I have the parent that contains the code everything uses and the children that do things specific to that object. But HSM is a new frontier and your use of getters and setters is... prolific, I'm happy I already knew about them or my head might have exploded. Definitely need to re-watch this or actually go back to the first in this series. I am shocked you aren't at 100k subs yet. The YT algorithm gods haven't descended on this channel yet I guess.

Man. This was hard, but I'm glad you're tackling complex issues like this, I feel like most other youtube tutorial channels are afraid to make videos on topics like this. Also your presentation was top notch. Thanks for taking the time to make this video.

Hey all! I'm so excited to share this new tutorial where we go over a player-based hierarchical state machine. Most of the state machine tutorials that I've found have covered AI and have just been single state, so hopefully you find this helpful when making more complex character controllers. The next video lined up is the first Cinemachine tutorial voted for by the Patrons! As always, thank you so much for watching and I hope this helps you on your game dev journeys! Cheers! 🍻 -Nicky

I still can't believe the amount of effort you put in on these videos. Cant wait!!

I thought of and implemented a small refactor that should provide a nice performance boost to the code. When you use the StateFactory, you're creating a new instance of each state to be applied. It clearly works great, but discarding those classes after you don't need them anymore causes some work for Garbage Collection, which can cause issues down the road. So I went back and in the constructor of the factory I create an instance of each state and store them in a dictionary. Then instead of returning a new state, I just fetch the same state from the dictionary. If you do that, and move the initialize substate method to the Enter functions of the states, then everything works the same. You could even go a step further and have the switch state method take in a state enum instead of having different methods for each state. I'm pretty sure this disqualifies the factory as a factory, but I'm not experienced enough to know the actual name. I should also mention that this ONLY works because the states work entirely off of the data provided by the context. if the states themselves held some sort of data, this would require some extra logic to maintain. Love these videos, btw! I look forward to the next one!

This is a damn fine tutorial. More people should know about your channel. You're like an advanced Brackey's spiritual successor.

I have a few recommendations 1. Make the states inherit from Scriptable objects. This way you can add different configurations for a specific state. If you game have some "buff" system you can have the states take their stats (like movement speed etc) from the scriptable object, and then you can switch the current state in run time to buffed version and vice versa. You don't need the state factory, all the states are pre-configured. 2. create a "unique name" for each state (states that differ in configurations will have the same name you will see later why) and make a dictionary that holds a name and the scriptable object in context. The player will try to switch states using the name of the new state only, and the level above in the hierarchy will hold the dictionary. This is good because you can have more states, like dodging, climbing ladder, dash, fly, swim ... each of those "know" when they need to be active, when they need to be shut, each can hold its own configurations and functions (in the scriptable object) 3. Add events - (mostly applied to shooters) if you want an action (like shooting) to depend on state, make an event to be fired off the base FSM component (the outmost one that is always in the scene) that when a state changes it fires "OnStateChange()" with information of the new state, make the weapon subscribe to it. and then if the weapon can only shoot on certain states you can use if(state is StateThatEnablesShooting) canShoot=true ... 4. Separate the input system from the context. Create a class of InputHandler that will take in the inputs and process them, this way you can put constrains on the input itself before it reaches the controller. Why do you need it? let's say you want to enter a driving state and you don't want to "hard steer" left and right. You want to simulate a wheel turning and slerp between (0,1) to (0,-1) and you want to reuse the movement (that takes direction from the data) you will need to apply another layer of processing. Another thing is that you might want to change sprint to toggle - first click would enter the state, second exit, you would probably want to pre-process the data outside of the classes (if we are following SOLID we don't want the class to also manage the input types). Overall very very powerful design. It takes a lot of work to get it to work at first, but the amount of work on expanding that is next to nothing. When comparing it to celeste's controller I wanna see the brave guy that will try to implement some new functionality in there.

This video is certainly a step up in difficulty from the last ones. Feels like it went from algebra straight to rocket science in terms of complexity. Gonna be rewatching this one quite a few times. Thanks for taking the time to make these videos.

I needed to see this. Recently wrote a monster state machine like you referenced in the beginning. Now I'm refactoring it and it feels great. You're very good at breaking down each step so I've learnt some basic principles & habits aswell. I can't thank you enough, keep it up. Liked and subed.

This video made me sub to your Patreon. I'm from Brazil so Patreon is kinda expensive to back on, but the effort and quality on this video is incredible, one of the best tutorials on RU-vid. I love how you're not shy of explaining more complex topics, most Unity tutorials don't really dive into programming, but this tutorial is incredible not only for Unity but for programming overall. Thank you for this!

Excellent tutorial! Just for the record, you explain genuinely well, with ease, precision and conciseness. Keep up the great work, you'll see your community growing fast for sure!

This is exactly what i needed, i have been doing C# for years and had a hard time with figuring out how to structure a project so it stayed clean the further i got in, i had this idea in my head that statemachines was the answer but i was unsure of how to implement it in unity, thank you for a very nice in depth tutorial :)

Expertly visualized. Expertly explained. To the point, concise & articulate. You value - - our time. Thank you. Subscribed!

I just used this in my game. Amazing stuff, thank you so much! :) Although, I did add a little to it that I recommend others do, also. For example, this code as it is doesn't run the EnterState or ExitState on the SubState when changing state to another Root State. For example, when going to the Jump State it will call the function from EnterState to Initialize a substate, but that substate's Enter function is never called. EnterState is only ever called on the Sub States when calling SwitchState, like going from the Walk state to the Run state for example. To implement this just do these basic things. In the PlayerBaseState script, just add this line of code to the SetSubState function "_currentSubState.EnterState();". This will cause the Enter state to be called. Although you'll get the EnterState being called twice when calling SwitchState from Idle to Walk etc. So to fix this just move the line "newState.EnterState();" to inside the if(_isRootState) conditional. Full code is such... protected void SwitchState(PlayerBaseState newState){ // Current State exits ExitState(); if(_isRootState) { // Call exit on substate as we move to new root state if(_currentSubState != null) _currentSubState.ExitState(); // Call new States enter state newState.EnterState(); // Switch current state of context _ctx.CurrentState = newState; } else if(_currentSuperState != null) { // set new substate _currentSuperState.SetSubState(newState); } } protected void SetSuperState(PlayerBaseState newSuperState){ _currentSuperState = newSuperState; } protected void SetSubState(PlayerBaseState newSubState){ _currentSubState = newSubState; newSubState.SetSuperState(this); // Call enter state for substate when entering it _currentSubState.EnterState(); }

Great video, I have had so much trouble with HSM since the beginning of my time in Unity. Your tutorials make a complex topic very digestible. Thanks so much for your time!

Hey man, I just wanted to say a huge thank you for posting this video! After sitting in front of my computer many days and rewatching this video like a bunch of times, I finally was able to implement the hierarchical state I needed thanks to you. Thank you, thank you, thank you! :)

I love how this channel videos are very aligned with the games I like to make. Great job, Nicky!

Dude, you are just amazing...your videos are even better and explain more than Unity's official tutorials...Keep up the good work sir...please dont leave youtube ever...

I am trying to make my first game and I wanted to learn about this state machine topic. The first time that I watched this video I took notes and didn't try coding anything. Going through the video I found things that I didn't quite understand at first but I just continued to try and understand as much as possible. After watching the video I tried coding a state machine for an object that I want in my game and I had the lightbulb moment several times! Everything is starting to make much more sense now that I pushed myself to figure out something that I didn't quite understand yet. Thank you for this video!

This is what I've been looking for, thanks. Keep up with the amazing series!

Overall great video. thumbnail, Communication, Diagrams, Audio Cues, Flow. Keep it up man, you'll be the next Brackey's in no time!

The quality on these videos is exceptional. Awesome video thanks a bunch.

Thank you saved me a lot of time trying to browse videos for an actual working one

this channel is just magic, very nice content dude. Really looking forward to all the new content coming

You are amazing, I just switch to soft softs and I am loving everytNice tutorialng about it. It much easier then my last program.

Thanks Nicky! Helped me so much this series.

Wow, just wow! One of the best Unity tutorial i have ever seen

This is awesome! Definitely refactoring my player and monster controllers now and will mention this video in my next one :)

Really cool! 🙂 Your channel definitely needs more views!

There are so many comments already so not sure if it's was already mention; But the HandleGravity method should also be included on the groundstate (where it checks if the player is onground or not, like falling off from a stair or so). Thanks for all your vids, it's one of the best explained tutorials I've ever seen. While I'm already an advance programmer, it always nice to learn some different ways on how things could be implemented.

I didn't even thought about implementing StateMachine for player character controller. Thanks for video!

Oh my god! Finally I could understand State Machine. Thank you so much, I am very happy with the code refactoring. I came from JAVA world and I made a mess up with my code. Really appreciated

Thank you! So glad I found this video. My player code just got 10x cleaner

This is one od the best and most usefull tutorials ever Made!

I can't believe literally no one is talking about how satisfying Nice tutorials voice softs.

Ayyyy Thanks for helping get to know the Software! I just downloaded it in hopes of making resetupes and originals. Props to you for

I will be rewatching this video for months, thanks nick

Incredible video. I always had issues when we have "conditional states" that can be used any time, like Die State, we can die while walking, while jumping, while idle etc. Well, one condition wont hurt. But having greater than one causes issues. I thought i was on Complete FSM level, but seeing Hierarchical made me think why i didnt know this before.

This is the exact thing I was looking for!!! Thanks!!!

Subscribed. I needed this. Thank you

by any ans, but I can make what I envision, and that's the greatest gift to . You are, without a doubt, an expert teacher. You may

This is the best free software Ive seen. Respect.

it worked! thank you so much!!

Can't wait for the next episode

Thank you man for sharing this stuff

As always, awesome job bro! 🤜🤛

So informative, thanks a lot!

I have watched this video 2 times. The first time i was confused. And this time, i am proud that i can understand this. This may not look like much, but, i am glad that my 6 month of learning does not waste any of my time.

Oh my gosh. You are amazing. Now I can say that I'm a game developer. Thanks to you.

Huge THANKS for this video!!! This is AWESOME!!! 👍

I've written several FSM/HSM implementations, but thought I'd give this architecture a try because it's far less complicated than those I've written. Made a few changes, but the primary is that my OnExit method is an IEnumerator and when switching states, I yield until it's exited. The makes it easier to do things like waiting for an animation to finish before exiting. I also am using ScriptableObjects to configure each state. For example, if you have multiple playable characters, each state can utilize properties of the current character scriptable object.

the moment we all have been waiting for

Im glad you have the luxury of optimizing with State Machines, I'm having trouble getting the animation to kick in at all. I got run to animate thanks to Jason Weinman's Navmesh animator in the Player object hierarchy. Thanks for your jump script, it helped me crack jumping better than Brackeys' outdated tutorials. Subscribed. You rock dude!! Thanks! Im pretty sure what I did wrong was not implicitly adding a animator component in the Inspector. Clearly My animator is attached to the player, it should be somewhere in the inspector. The problem is since I started not using the animator in an inspector from the beginning, adding it after the fact does not rectify the problem. Its similar to when you make mistakes assigning scripts to the player object instead of the game model. Those errors in organizing are hard to correct, and it is quicker to start over from scratch or at a much earlier build. Gotta love it!!

You're the man mate! Thank you so much.

THANK YOU SO MUCH FOR THIS VIDEO

thanks, it actually let me through so i could download it.

You will definitely become the top 1 who makes cracks

i didnt expect it to work wow thank you so much bro

Respect to your good work, thanks a lot

This helped a lot thank you

Great job buddy, keep it up!

I am sure that Unity technology will use your videos in Unity Learn one day or they will put them in their RU-vid channel. Explanation is clear and well illustrated. Thank you very much. Please, don't forget Ledge grabbing in your coming videos. Thanks!

you are the best teacher, bro

Casi 4 días con esta clase. Valió cada momento.

I still havent watched the complete video, And I have already liked it

At 13:20, you can add the readonly modifier to _context field. This way _context can only be assigned on the class constructor (or on its declaration).

Always the good content great work

Thank you for sharing this tutorial

Great tutorial! Thank you :)

Man this video is pure gold for me!! I have made a platformer character controller and was in the process of refactoring it. I was in a dilemma if i want to eventually put all of the controller code in one script, which i know is bad practise but a lot of things depend on each other so it seems a functional way to do that. I have never used a State Machine before but i kinda thought to go that way cause things started to get messy and if i did i needed an option for sub states as the player actions are kinda complicated in that one. I think this might actually work cause in the end you store all the data in one script here. I think this will improve the controller by much and is probably the missing key i needed to complete it and use it in my portfolio.

I think using static actions and early exits in update loop for player controller to be a better implementation than state machines especially if you have combat that relies on animation events for animation completion checks, vfx etc. It also structure the code in component pattern rather than state patter. This allows you to enable and disable parts of the character controller on run time without breaking anything or any errors. Basically I was able to make a similar controller but with 0 dependencies so far. I imagine the only dependency in this implementation would be a scriptable object that contains player stats such as run speed, jump height etc.

drums softing good start learning how to make your own lodies. Good luck bro!

Great video, thanks I really enjoyed it

First of all, thank you for these wonderful tutorials on the new Input System. I love how much detail you put into each one of your videos. While completing this portion of the series, I ran in to a similar issue as others mentioned below. Sometimes it feels like isGrounded isn't working and others it seems like the animations just aren't playing. After several placements of Debug.Log, I was able to determine that the "EnterState()" method of each substate was never being called. My solution to this was to add "newSubState.EnterState();" on the PlayerBaseState.cs class in the protected SetSubState() method, after newSubState.SetSuperState(this); so, the SetSubState method looks like this: protected void SetSubState(PlayerBaseState newSubState) { _currentSubState = newSubState; newSubState.SetSuperState(this); newSubState.EnterState(); } Hope someone finds this useful.

Thank you it works with me

Really, really great video. I've used state machines a lot but I needed a little bit of extra knowledge and this was perfect, not only did you have beginner friendly information, for those who don't know state machines you also had information for more intermediate programmers such as myself. Your videos are to the point but theyre explained well without over flowing people with useless information. I really appreciate this video and I'm about to go and watch your other videos. Thank you.

How did it take me so long to find this video?!?! I've been wracking my brain for about 2 months trying to "modularize" my fps controller. Everything I've tried has failed miserably. I'm yet to try this, but 10min into the video I suddenly feel like I might still have a chance Also, I fkn love Nicky. I've seen a few of your videos before, so much more pleasant to watch than 99% of other game dev/programming tutorials

thank you so much. tNice tutorials helped a lot

Thank you so much for this!

Great video! Thanks!

now i am in a good mood

Needed this ❤️❤️👍

you are the best dude

you are amazing dude! thanks so much

Best tutorial on state machines, would u mind doing a tutorial on climbing/parkour?

Hello there! For my Visual Studio users, Pressing Ctrl + . will give you some helpful auto completes like the constructors.

I love your channel bro! You are a concise teacher. Can you do a tutorial on instantiating a different prefab every time the health meter decreases/ increases every 25%? Can you also do one on playing a different animation each time the health meter decreases/increases every 25% as well?

Worked, thx

Next step I am taking is to incorporate this into Unity 2021 Visual Scripting. I always got confused thinking about character controller state machines because I'm so used to "State Machine" meaning FSM (or at least that is the impression you can get online). I didn't even know about hierarchical state machines (so you can guess how much trouble I've been having with visual scripting). The nice thing about VS is that you can execute code in multiple states in the same state machine simultaneously.

Спасибо , это очень полезно , вы лучший!)

thanks so much man

Big fan of you I was Waiting for your new Videos please keep it up

Damn! This video is a masterpiece

Very helpful..thanks a lot.

This was a great video

dedication to what you want to acNice tutorialeve in life! Stay safe and be wise! Much love!

You are great bro!

it very well! Good Job!

ITS REALLY WORKED LOL THANK YOU DUDE

WORKS 100%