Finite State Machines in Godot 4 in Under 10 Minutes

In this video we'll walk though the setup and creation of a Finite State Machine (FSM) in Godot 4.

Finite State Machines are incredibly useful for managing simple states and transitioning between them. For this video we will look at an enemy with the states of wandering, following, and attacking. Then, we'll build the wander and follow states together in Godot.

Resources:

Chapters:
00:00 Intro
00:27 State Explanation
01:06 Wander State
01:28 Finite State Machine
01:59 Godot Time
02:07 Base State Setup
02:28 State Machine Initial Setup
03:55 Idle State Code
04:40 Testing the Idle State
05:08 Follow State Code
05:40 Testing the Follow State
05:58 Transitioning Between States
06:34 Afterthought
07:03 Cow

[lowirq]

If I hadn't known Finite State Machines for years beforehand, I would definitely know by now!
Your concise concept & excellent explanation makes FSMs - an often over-complicated yet rather basic topic - easily understandable by beginners as well as intermediate developers IMHO.

Awesome content quality I have rarely encountered with video tutorials, and especially on YouTube.

Nicely done, keep it up!

[ArksDigital]

I started to notice a lot of traffic coming in from Youtube and I think I just found one of the reasons why. Thanks for linking my sprites. 😊

[rashulsel]

so you are telling me that there is better way to manage code than writing 2000+ lines in single Gdscript?

[MartinB_Art_Design]

Unashamed to admit I set the speed of the video to 0.75 and rewound the video dozens of times.

[Mgbeatz_Icrowdx]

a good tutorial that doesnt start with a 2hours intro, thank you

[Anisometry]

For anyone who is encountering an "invalid call" error, change the .exit() and .enter() at the bottom of the state machine scripts to .Exit() and .Enter(), this fixed all my issues.

[Bitlytic]

UPDATE:
For this video, I wasn't able to release the source code because of paid assets, but I have created a new project for my most recent video and it uses nearly an identical state machine. If source code would help, I highly recommend checking that out:


ERRATA

- For the state class, the Process and Physics_Process functions are different than the built in _process and _physics_process functions. This should be clearer and I recommend using names like state_process and state_physics_process to avoid confusion.

- 3:31, the enter and exit functions called off of current_state and new_state should be capitalized

[Factor]

Please keep doing more Godot tutorials! Even as a total beginner who knows nothing about coding, I was getting something out of this.

[OHTASISAN]

Just wanna say that you did a great job explaining everything. Lots of youtubers often forget to bridge the gap between what they know and what actual beginners know. In the military we used to call it "barney style". Directions given in a way that a child could understand, and under the assumption that an adult could then branch out and use these tools for a complex mission.

[dragons]

I dont even understand state machines yet, I used this purely for knowing how to make something which follows the player. Already its been an incredible help, given a few months of learning I imagine the other parts of this will help me too. For some reason the previous things I'd tried like 'get_root' and copying node path were not working and I don't know why. But this worked, and knowing about groups is good too!

[itsdabenji]

I've watched so many tutorials on state machines and never understood them until now. Thank you very much!

[ShinSpiegel]

I really love this tutorial,
Simple straight to the point and very intuitive.
Thanks for the amazing tutorial.

[Haxses.]

I LOVE your Godot tutorials, I really hope you keep doing them!

[HeraldOD]

Awesome video!
A neat trick for switching states: using the return value from the state's process function instead of signals.
That way, you can have @export variables for each state to define its next potential states, and return them to the state manager that does the switching
This also removes the need for a dictionary!

[allHailKingJulien]

This is the most beautiful explanation of state machine I have come across. Kudos!

[Noah-huxp]

I thought i was starting to get the hang of godot, but now i realize that i am nothing but an absolute beginner.

[josephsavio]

I do not comment that much on YouTube videos. However I wanted to say that I wanted to learn how states machines were implemented on Godot and I never really grasped how. But this video that I found randomly explained perfectly the way. It changed my to make enemy AI. Thank you so much !

[vicentvalls]

Man, this tutorials are amazing. I subscribed and I'm waiting for more.

Thanks

[TheCrybn]

You have made the best Godot tutorials i have seen. You explain everything so clearly. Keep up the good work.

[mateuszhermann]

I was preparing for my engineering thesis using this course, so thank you for the great material. I won't forget to mention it in the bibliography.