Unreal Engine 5.3.2: State Trees Demystified (Global tasks, Parameters, etc)

Have you ever wished you could have state trees in unreal engine? want to know about their #parameters or #globaltasks well with the recent addition to UE5 we can! check this video out to learn more
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#engine 5 tutorial
#State tree ue5
#Ue5 tutorial
#Unreal engine 5 tutorial
#unreal engine 5
#State trees
#Unreal engine 5 ai
00:00 Intro
00:28 Project setup
00:55 State tree setup
01:45 Context actors
02:30 Parameters
04:00 Adding state tree to actor
04:40 Evaluators
07:10 Global Tasks
09:00 Tasks
11:40 Transitions
15:40 State Types
17:00 More on Transitions
19:40 Details on Tasks
21:30 How the state tree works in my AI
23:00 Full Breakdown of State Types
26:00 State Selection Behavior
28:00 Showing off my AI ships using state trees
#State tree global tasks
#State tree parameters
#State tree unreal engine
#Ue5 ai tutorial
#Ue5.3.2 ai

[@AJGameDev]

subscriber 999! lol one to go! Thank you for this demystification. Behavior trees have been just way too rigid for me so I was mad curious about this and this was incredibly helpful and insightful. Thanks man!

[@Spacemarine658]

Thank you! Glad to hear it ♥️

[@Cazaq]

This was really useful. Thank you for taking the time to make it!

[@Spacemarine658]

Thank you for the compliment 🤗 I'm glad I could help!

[@JasonWelch]

Awesome. Helped me understand them better. I've been working on a custom version of this in a Unity project based on the Unreal docs, and a few things just weren't super clear to me.

[@Spacemarine658]

Glad to hear it!

[@SuperLordee]

Thank you that was very helpful!

[@dyotoorion1835]

Yo yo SpaceMarine! :-) Thanks for the tutorial! Great stuff!

[@Spacemarine658]

Thanks man glad you liked it!

[@dyotoorion1835]

@@Spacemarine658 Cheers mate! I'm learning about State Trees cos we're using them in one of my freelance Unreal game projects. This video's super helpful!

[@omegablast2002]

awesome thank you for the guide!

[@Spacemarine658]

Thank you for watching! I'm glad you enjoyed it!

[@someth1ngstube]

LInked state is linked to subtree node and when Linked becomes active Subtree becomes active as well. I assume it's done to flatten the strcture if you have deep hierarchy of states. Unfortunately it doesn't allow injection of external state trees.

[@Spacemarine658]

Make sense I'm sure that would be handy for subtrees

[@DuneGames-fg3gk]

When you say "you change the enum" it switches states - what causes the state change? I've tried changing the enum value via bp, and the evaluator should be picking up the new value - yet the state change doesn't change.

[@tjrizvi251]

Good video! Only thing would be maybe shrink down your video and maybe move it to like the bottom right or something

[@Spacemarine658]

Yeah unfortunately I have to move it around basically every video to try and cover as little of the important stuff as possible 👍 I have shrunk it a bit further in recent videos thanks for the feedback!

[@tjrizvi251]

Sorry I meant to the bottom left. But yeah, I get it. Definitely some good information here@@Spacemarine658

[@tjrizvi251]

Any ideas for getting the enemy to check its own stats? Im assuming maybe under global variables?@@Spacemarine658

[@ShamaxGD]

I really like the way your blueprints look. What plugin or option do you use for that?

[@Spacemarine658]

Electronic nodes it's like a 12$ plugin totally worth it the creator is super helpful and updates the plugin quickly

[@Spacemarine658]

www.unrealengine.com/marketplace/en-US/product/electronic-nodes

[@gmdg5844]

First of all, great Tutorial, it helped me a lot! I used State Tees in a 3 months project. And I found myself and designers much more confortable, but there are something I could not find out: 1) As far as you know a custom StateTree task can be written in C++? 2) There is a way to inform about the current active states and activation of transitions (hence a delegate or event dispatcher)?

[@Spacemarine658]

Glad you liked it 🤘 and afaik yes to both

[@user-rd1og6fy8z]

Really useful! I have a question though, I'm trying to use the subtree type in an state, but I'm not able to select anything, do you happen to know how it works?

[@Spacemarine658]

It will lock in situations where either you are too deep into a tree or in a location that, that subtree type is required afaik

[@DuneGames-fg3gk]

Great video. Question - when you change the enum you say the state changes, what causes that? I've changed the enum via bp, and the evaluator should be picking it up but the state tree doesn't change. I've an idle/wait state as the default state, and I want when the enum change to then cause a state tree state change. How to do that?

[@Spacemarine658]

It will only change the state tree if you have it setup such that whatever state is active has a tick check that the enum equals the desired state that way if it changes it will fail the tick check and then it will go back to the root and recheck for the desired state

[@DuneGames]

@@Spacemarine658 Thanks for the reply. That sounds like too much work setting that in each state/task. I made a task and put on root state that compares previous vs current state in enter state, and return the check as finish task succeeded. The root node then has a transition of failed to go to root. So far it's working. If I need something more complicated I can make a separate state to handle state changes, like your full stop thing.

[@Spacemarine658]

Nice that's a pretty intriguing way to do it 🤘

[@cosmotect]

Hey!, thanks for the tutorial! So how do you set the AiContextRef variable in the evaluator?

[@Spacemarine658]

So you may have figured it out already but for anyone else who comes along the state tree has a spot for the AI ref specifically in the top left when your first create the tree and it then becomes available to access in the evaluator

[@cosmotect]

@@Spacemarine658 Aye. I later realized how the parameters are passed around through bindings. And that you can't set the ST parameters inside tasks.

[@M-gf9gu]

This may be because my project is on 5.2 but my State Tree Tasks seem to lack an Event Tick. And with my Evaluator, it only fires Event Tick once when the game begins play? It never enters another state because it doesn't update the player actor location from the evaluator. 😵‍💫 Edit: I upgraded my project to 5.3 and the same issues exist! Edit 2: Sorry, I had to create a new State Tree Task BP for it to bring in Event Tick, I thought it would change my existing ones with the upgrade. It does seem to have been a new feature of 5.3 however.

[@ChristopherFranko]

added to my favs. One tip. You use the filler words Actually and Basically alot.

[@Spacemarine658]

Thanks and yeah I've been trying to work on that and script my videos a little more lol I just struggle as I prefer to just turn on the camera and talk away about something xD it tends to feel more natural and authentic but leads to a lot of filler words. Thanks for the feedback! 🤘

[@masterxeni]

Hey, really useful tutorial for the State Trees, been trying to figure things out how to change States based on results and transfer information around, behavior trees felt kinda restrictive for me (I'm making a business management game where AI helps you out) (btw your Patreon url doesn't work, I get 404)

[@Spacemarine658]

Thanks I've been working to understand every single feature in unreal especially the undocumented/poorly documented ones so I can better help others and improve myself thanks for the heads up about the patreon link not working I'll check it out does this one work? I've been working on updating my patreon rewards/posts so if there's anything you'd like to see feel free to post it here, in my DMs on discord 🤘 www.patreon.com/Spacemarine658?

[@Spacemarine658]

Fixed my description btw 😅 thanks for letting me know

[@renisrrenis9225]

hey, do you maybe have an idea how to make that if branch enter condition is not true anymore it would abort child states and go next state? Or something similiar to that? Or the solution is to use different state trees for that like "Patrol/Shoot" and when that abort change need to happen just stop the logic and switch to other tree?

[@Spacemarine658]

You can have different trees and that's not a bad solution especially for complex behaviors but you can have aborts built into the tree so that when the enum changes the tree gets reset

[@renisrrenis9225]

@@Spacemarine658 oh thats smart way to go, thanks for answer.

[@grandprizebigfuzz-musicart2594]

you say they are still experimental but I am not seeing that on my end? Where are they listed as experimental?

[@Spacemarine658]

Howdy! EPIC stopped considering it experimental after the last state tree update in 5.2 but that doesn't mean a whole lot as even beta features can have huge updates the EIS being a recent example the update that moved it out of "beta" and basically to production ready changed huge swaths of the system. So for anything not yet considered feature complete I tend to use experimental out of precaution!

[@Restart-Gaming]

Is this some what the same a behavior trees?

[@Spacemarine658]

They serve similar purposes but in different ways

[@chaosduck608]

In the future please remove the background music, it's very distracting and sometimes difficult to hear what you are saying

[@Spacemarine658]

I've turned it down in future videos I'm still on the fence for removing it as it helps me focus and stay on track while recording and editing but I'll take your feedback into account when I think about it in my next video!

[@timbunnage9513]

​@@Spacemarine658 The music is good!