Unreal Engine 5 Tutorial - AI Part 3: Perception System

In Part 3 we look at how the perception system works and how we can set up the sight sense and use it for our behaviour tree.
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[@jonexotic282]

ok few things for those struggling. I found these three things helped me...... 1, in Thirdperson Blue Print, add the "AI Perception Stimuli Source". 2, AI Perception, register as source for senses and select sight. 3, In the AI's Controller, under AIPerception, Detection By Affiliation, check all the boxes (enemies, neutrals, friendlies)

[@kirill2525]

im using the first person thing and i cant get anything to work. please help, ive been at this for days. it sees me but just isnt updating to chase me

[@antivirus3052]

Add "AI Perception Stimuli Source" component to your FPS Character. Make sure you have "move to" set as TargetActor, which you have implemented in your AI Controller. @@kirill2525

[@SyraeTheHealer]

@@kirill2525 You also need to change the type of the 'Get Sense Class for Stimulus' to the normal sight one, not the config one

[@draicor]

You managed to explain something complex and now it feels a lot easier to comprehend, amazing work!

[@N00BleSouP24]

thanks for making these videos! its much appreciated

[@katiekaliber]

Thank you for all these video's, ive been learning so much from them. Appreciate the effort homie

[@Rayza-73]

This is so cool, such good content - thanks dude.

[@alekvillarreal3470]

Thank you! I was having trouble never losing the target but its all working now thanks to you!

[@wowee766]

Great tutorial Ryan really appreciate these videos you make it a lot easier to understand :)

[@ztormsink5931]

Very Very Nice tutorial, well explained. I learn Behaviors Tree today. I was avoiding it for a long time. I was not ready I guess.

[@fms9999]

This is great Ryan thank you so much

[@vizorsnix]

you are a legend. thank you for the tutorials

[@coltish]

You are a true legend!

[@amkorousagi]

Thank you so much

[@rucicailia3355]

thx ,it helped a lot

[@themaciej420]

love you man

[@nassemalsabah5610]

Thank you.

[@Propserousworld]

yo ryan i was wondering if maby you could make a series on room generation and procedure generation cause i know that you explain everything in detail

[@MagistroFF]

big thx its worked brother

[@michaellutz4154]

One thing I would ask to see is setting up a child actor to this setup that uses ranged attacks only but uses the same behavior tree and ai controller so we can see the versatility I got mine to work somewhat between the two but this is the first time I've set up ai using behavior trees and their is alot more to it than the basic set up I had through just BPs and child BPs

[@javacpp2525]

If On Target Perception Updated event is not called for you try next: In AI_NPC blueprint select AIPerception component, look the Details: AIPerception - Senses Config - Sense - Detection by Affiliation. Try different values of the checkmarks. Detect Enemies doesn't work for me. I set Detect Neutrals to true to get On Target Perception Updated event to be called. Maybe there is a way to set who is the enemy and who is not?

[@thesisko2065]

Thank you for your videos! I'm learning ue5 piece by piece and AI is like a whole another animal. And here I thought the anim graphs and blendspaces got confusing 🤣 these are good videos though for diving into and starting to learn. Thanks again!

[@2020Tech4U]

I had no issue's with the instructions like some of the others. Maybe I messed up in a good way? lol It works so I'm happy

[@njaalt1064]

Hi @RyanLaley I feel it makes more sense to use player -> get actor location for when you set the last known location value. I got some REALLY weird behaviour when I did what you did. The last known location would be in very odd places

[@NikEki-1337]

Affirmative. Did like you told i.o. using Stimulus Receiver Location. Before that with what was on the tutorial, AI was immediately skipping the MoveToLastLocation task and gointo to the MoveToRandomLocation sequence.

[@rifat.ahammed]

Great

[@KittehBit]

I am curious about why its nessesary/good practice(?) to set the base class for the TargetActor key on the blackboard. Can someone who knows enlighten me? Is it just good practice or what can be an issue if its not set to actor?

[@ICE0124]

This might help someone but if the enemy isnt following you try replacing the 2 get player character blocks in the Handle Sight Function with Get Player Pawn blocks and it fixed it for me after 2 hours of troubleshooting.

[@leonelsandoval987]

It didn't work for me, and I used both "get player character" and "get player pawn". I'm fucked.

[@brodiemorris2081]

@@leonelsandoval987did you ever fix your problem? i can’t seem to find what my mistake was

[@user-bg4lv6xc1w]

​@@leonelsandoval987 this is a bit late of a response, but have you set the "detection by affiliation" to enemy neutral and friendly? Idk I missed to do that. I'm suing the two "Get player Character" blocks in the handle sight, but it wouldn't follow my character because I didn't set the detection be affiliation. Hope this helps.

[@SupercapeGames]

Thanks for that (: - 20:13

[@elgatonet]

The values ​​that I set at 200 for the spectator point and near clipping, leave them at 0, it gives fewer errors

[@Rlifshitz19]

Do you have any reference or an example of what doin this in C++ looks like? Or when building these systems is it more standard to build them in Blueprints?

[@brandonstam626]

Is it at all possible to make the Sight Radius a variable? I want to be able to change it at runtime or per Actor, but I can't access the variable via blueprint.

[@RickHenderson]

Oof debugging this is super tricky when you're first getting started.

[@revan9903]

Very nice tutorial series and very helpful. One thing that I noticed is that you always look up the Bahaviour Tree/Blackboard in the content browser instead of switching directly with the buttons in the top right. Is there is special reason for that or just a habit? :D

[@KaitheArtGuy]

I want to make my NPC adjust their speed based on the player speed/proximity. I followed the tutorial, and my NPC only runs at the set speed, regardless of how fast the player is moving or how far away. Is there a way to do that in a Behavior Tree, or is that a blueprint feature?

[@randallmiller3162]

I have an issue. In the Function, my Get Sense Class For Stimulus is returning AI Sense Sight, not AI Sight Config so it's not matching and is always false. In my AI Perception Index, it is AI Sight Config, is there something i'm missing causing the Get Sense Class for Stimulus not returning the AI Sight Config?

[@SHADOWonlyForGamers]

Hey, good video. In singleplayer the perception works just fine but when i change it to multiplayer and start with to player just one gets focused. Has anyone an idea why or what to change to make the ai follow both player?

[@elantrauma]

LastKnownLocation and TargetLocation are both invalid. Im well over an hour diagnosing the problem. The dude detects me but doesn't chase. I'm going to start over and if I missed something, I'll post the result. Update: Went back, redid the AI_NPC, and at 16:00 in the video, my guy is following me now. He didn't do that the first time around and I figured it was because I didn't define LastKnownLocation yet. I don't know which node it was, but while I was rebuilding Handle Sight Sense, 1 or 2 of the nodes have the same name but serve a different function. This is something I'm noticing following these tutorials. I'm new at UE5 and I knew going into this it's going to be trial by fire trying to figure out at least the basics.

[@HeartsintheWind]

How do we set up detection by allies enemies neutral? What do these settings do how and why

[@JOnRMbO07]

How did you open the debug section? I can't open it either. i have laptop.

[@marcomoutinho7611]

In UE4, you could see the lines while editing (wireframe like) the sense parameters, in UE5, not anymore?

[@diazwatson]

Thanks Ryan for sharing this content, one question: I agree this approach gives a way more granular control BUT is it not easier to use the Pawn Sensing Component that comes OOB with Unreal?

[@michaellutz4154]

At least in my experience pawn sensing doesn't have as much control and isn't as dynamic as this is but pawn sensing is easier to set up

[@NabrocTheGreat]

Watch Behavior tree very much in control of what AI is doing as well. Lol, I missed something there and AI did behave as set, just not as expected.

[@employerslave]

how can I add 2d sound when he see and chase me? it should play fade in and when he lose me (it doesn't mean that he lost sight, it means he can not see and hear me anymore) the music should fade out. can anybody help?

[@zhaohuanxiao9543]

Sorry, i want to know why in 8:10 time, i cant find my 'get blackborad' ?

[@lmbits1047]

I think you forgot to mention you have to have the stimuli source set in the player character BP otherwise you won't get sensed. I had to add the AIPerceptionStimuliSource component and then on the right side panel enable Auto Register as Source with the array element of AISense_Sight. Only then it worked for me.

[@RyanLaley]

If your player character derives from the character class you don't have to add this component. It is already an auto registered class.

[@lmbits1047]

@@RyanLaley I see I didn't know that but I guess it's good to have that bit of info for anyone who can run into this issue like me. Thanks for the tip and the videos.

[@ancientnestsoftware]

@@lmbits1047 that info helped me too thanks

[@KittehBit]

@@RyanLaley FYI: I tried following your tutorial with a top down template and the AI didn't see me until i add the AIPerceptionStimuliSource. In my case it worked even without adding any "Register Source for senses" or "auto register as source". Not quite sure how or why, but just adding the component seemed to be enough. ^^;;

[@KittehBit]

And even weirder it continued to work afer being removed.. I dont get this engine XD (but i like it)

[@kristoffseisler2163]

12:06 how do you add TargetActor when its not there in the first place?

[@zlatty88]

Mines not showing either. I double checked that I typed it in the HandleSightSense, compiled and saved. It still won't show.

[@danielgodstix8753]

same, and when added in doesn't seem to connect to the literal name

[@brianlafontaine3111]

Hey Ryan, If you get the chance I could use some help as my LastKnownLocation is just not working. I have been going over it multiple times and no matter how I attempt to change or modify the code it simply will no execute the move to last known location. This is the biggest roadblock at the moment before my friend and I can really start designing levels for our project.

[@draicor]

Its working fine for me mate, make sure your chase sequence is properly setup, with the abort both and also TargetActor Is Set, and both Move To are pointing to the right locations, one to TargetActor and the other to LastKnownLocation.

[@blindphoenix]

did you get it working for you?

[@brianlafontaine3111]

@@blindphoenix I did but my "friend" turned out not to be a good one. Unfortunately because of what he did to the project and the only version I still have the file doesn't open properly so I can't tell you how I fixed it. It was not the way the gentleman above stated for me though. I ended up redoing the entire system using enumeration.

[@kirill2525]

im using the first person thing and i cant get anything to work. please help, ive been at this for days. it sees me but just isnt updating to chase me

[@routegames]

Thanks for tutorial Ryan. But this AI cant see other clients in multiplayer. How we can fix this easily ? He can chase just server...

[@RyanLaley]

This is because the perception event is checking agains the "get player character", for multiplayer you will want to check the class of the actor sensed. I will add an episode about this to the series.

[@dakotayocom7764]

Maybe someone can help me? I am trying to take his code a little farther by having another actor in game that the ai will recognize. I added a stimuli source to the new actor and in the details pannel clicked auto register and added 1 array elem for type : AiSense_Sight. Is there another step I'm missing? As of yet my AI characters just walk past my new object.

[@dakotayocom7764]

Update : I did nothing wrong except turn off debugging. I'm actually not sure how I did that but when I restarted the editor it turned it back on and I could see my actor being noticed.

[@xgamesvideosofficial1667]

How do I access that debug menu on 14:30?? I can't understand which key he means. It would be nice to show an actual image of key bindings on tutorials like this. Also, please slow a bit down. I barely can't follow your tutorials and I have to constantly rewind the video every second to see what you did previously as you scroll the screen all over the place. EDIT: I found the shortcut keys, but it won't show me any debug information. Gosh, what is this a broken engine...

[@SilasMckeeIII]

" ' " he says it at 14:29 i didnt notice till my like 4th time rewatching the part wondering the same thing

[@usa2998]

not sure why sight config was not returning perception but changing it to just sight allowed it to work

[@user-bg4lv6xc1w]

well because the AI Sight Config just stores the index. Since index 0 has a name (AISense_Sight), the index 0 have different configurations for such things as sight radius etc. Since you can add more indexes with different sight senses, you cant add the AI Sight Config.

[@coltwint7505]

what is the key in 14:27

[@TheAntonio322]

yeah im stuck I feel like I followed everything right but no matter what I do it will not go to the last known location. It calculates the value for it and shows it in debug mode but my ai will not walk to it just gets stuck and does not move

[@TheAntonio322]

to anyone it may concern after days of trouble shooting the cause was my character's capsule component idk why this matters but if you ever scaled it up or down put all xyz scale values back to 1 and it will fix the issue

[@rylanmitchell7216]

I have done this code over and over but at 11:54 it has target actor but mine does not show that I have done the code perfectly but it still won’t show.

[@textik5821]

I'm sure this is irrelevant and you've already solved the issue, but the fix is making sure the TargetActor make literal name is identical to the TargetActor in the blackboard. For me, the blackboard's had a space between target and actor, removing that fixed it!

[@jellyfish6042]

@@textik5821 Have the same problem but can' find a way to fix it as well X(

[@thefirstblank607]

UE 5.0.1 crashes when i add "move to"

[@JeramiahL]

I have the same issue. Every single time. No matter what BT or how its configured. For those who need a work around, at the moment what I do for "Move To" is create a Task (BTT) for each Move To event. My enemy AI moves to my character by having a sequence that only triggers if the enemy AI senses the player (with "Player" tag) and if it senses the player then it will cancel its roaming and call the task "Enemy AI Move To Player" that runs a simple "AI Move To" with the "Controlled Pawn" node from the event trigger connected to the "Pawn" node on the AI Move To, "Get Player Character" attached to "Target Actor" node, and I made the Acceptance Radius node an editable variable so I can set this on each BT it gets called to (for ranged vs melee attackers - it's a simple means that I'll replace later with a more complex means of AI positioning relative to its target). From the AI Move To I ran "Finish Execute" from the "On Success" and "On Fail" nodes with the "On Success" having its "Success" box checked and the "On Fail" having its "Success" box unchecked. I'm working with more complex move to concepts using the AI Controller (I use the AI Controller for targeting - the less you can do in the BT the less likely it is to break). There's some really cool position finding stuff out there! It's just... there are a LOT of bugs with UE's system where things that should work simply won't and without knowing C++ it's going to be a LONG work around. I do not know C++ hahaha

[@kraulim]

very complicated, i hope one day Unreal change this Blackboard ....

[@epsiloncore9772]

How do I go into Debug? what button do you press?

[@justhere4theoldskool]

Key is '

[@Dylan-zi4po]

My tree completely skips over MoveTo Last known location. Code all the same. Any ideas?

[@GVMuk]

Same Here bud. cant figure this out. went over the code and spellings

[@aledram00]

I think it has to do with the "Observer Abort: Both", maybe? I don't fully understand how it reaches the last known location movement. If you indicate that you abort the self "flow" and also the rest of low priority flows (like moving to last known location), it'd just go back to Roaming. Or maybe I'm understanding it wrongly.

[@HB...]

Yeah. I was unable to find part 2 as well. EDIT: Part 2 was just posted! Thanks Ryan! kzbin.info/www/bejne/npOroqlvpNtrf68&ab_channel=RyanLaley

[@jessejohnson3232]

What if I want to increase the chase speed of the ai when they are chasing the player ?

[@mr.topbottom1448]

Did you ever figure this out?

[@brodiemorris2081]

I think if you increase the BP_NPC’s max walking speed during the chase then reduce it when they are in patrol it should work

[@ianq86]

@@brodiemorris2081 yes, exactly this. i made a "set run" and "set walk" function in my enemy blueprint. in my BT i call a task to either set run or walk on my enemy blueprint depending on whether a boolean is set. make it public and set it in your chase / roam sequence appropriately when calling the task.

[@unmaskeds]

At 13:42, the option to click TargetActor is not available.

[@unmaskeds]

Please help

[@Zatellia]

Create a "New Key" in Black Board and select object, rename it target actor and on the right open the key type and base class set to actor

[@unmaskeds]

All right thanks I will try that

[@unmaskeds]

@@Zatellia Thank you so much! It worked!

[@zlatty88]

@@Zatellia Hero

[@LifeExperienceST]

TargetLocation invalid Help

[@DavidGWilliams1981]

Definitely missing part 2, but part 1 is here: kzbin.info/www/bejne/f3W9mWObpauHiLs

[@BoxTrapGames]

its not chasing me but i followed step by step, i even double checked and everything i have, you have.. help (edit) nvm i thought i was at the end of the video, looked again and realised i have 5mins left, my fault haha, sorry

[@madeeasy7148]

This is so complex

[@niaaxwoll8051]

The character does not move after inviting me. How can I fix this?

[@thelionszen3352]

am i missing something wheres part 1&2

[@DanielSouza-zp9gg]

Doesn't work

[@lordmegatron7263]

WHAT THE FUCK JUST HAPPENED

[@kriswintf2027]

Not work, It didn't even call HandleSightSense function

[@javacpp2525]

Check AIPerception - Senses Config - Sense - Detection by Affiliation. Try different values of the checkmarks. Detect Enemies doesn't work for me. I set Detect Neutrals to true to get On Target Perception Updated event to be called. Maybe there is a way to set who is the enemy and who is not? Let's watch the rest of the video...

[@kriswintf2027]

@@javacpp2525 ​@javacpp2525 Yeap, I did the whole thing, still not call the HandleSightSense function, ……until I follow Gorka Games‘s tutorial, finally, the AI chase me!

[@melevent]

İ missunderstood if succesfully sensed branches until i see this at ue forum. OnTargetPerceptionUpdated(AI Perception), break stimulus, successfully sensed. true = entered sight, false = left sight.

[@insta.trends4153]

target actor is missing