Unreal Engine AI Tutorial #1 - AI Guard Part One

[@yr1520]

This tutorial was absolutely fantastic. 5/5, would watch again.

[@adamgascoine]

Great job of explaining this system. Nice work mate!

[@GaryParkin]

Thank you for the tutorial. I just found your channel. I find it interesting that the Unreal engine has not changed that much in 6 years. Tutorials written long ago are still very much valid, unlike the Unity ones. Not knocking Unity, but I pulled my hair out with compatibility issues.

[@zoombapup]

Its a good and bad thing really. Good in that old knowledge still works, but bad because there should be better and easier ways of doing these things by now. UE is a very weird technology platform, but right now its the best option if you are a core C++ developer doing AI related work.

[@coolboy7369]

Hello there, I just want to share something that i encountered, maybe it could help new followers having same problems. After setting everything exactly like your tutorial (great one btw ^^) my character wasn't moving to the Target Point, even if my NavMesh was correctly set, at least in the editor view. After wandering for a while i have checked the "Rebuild at Runtime" tick in the "RecastNavMesh", and the Guard finally started running ! I still don't know why without checking this it's not working though. Another thing, to be able to use the blackboard key, you need to set the "Base class" of the key to actor, the default one won't work.

[@younlee9690]

OMG!!! about the key thingy!! You saved my life!!

[@GaryParkin]

Holy crap! I was stumped on this. Thank you so much for the info!!! I thought it was because of my newer version. (4.25.3)

[@kevinnisbet5648]

great tutorial but had a bit of trouble finding the Guard Target under the default tab (on ue4) @19:45

[@bharath-frizz6710]

DID U FIND IT?

[@BurtonPosey]

Thanks so much for the tutorial series! I'm just digging into Unreal after 6 years of Unity. I've been trying to find a place where you might have addressed it, but did you ever address the rotational behavior of the character when using MoveTo? My character is snapping directly to face the target destination. I can't seem to find the right settings to get it to turn over time.

[@zoombapup]

I believe that is a property of the movement component. So its likely a value on there. Unreal is a bit of a strange beast compared to Unity, but both are pretty solid toolsets in the scheme of things. Have fun!

[@BurtonPosey]

Awesome. Thank you for the help and encouragement!

[@SMKKNIEP]

Unfortunately I bumped into a problem at 20:19, cant seem to find the 'Guard Target' field under the 'Default' Tab. Have looked everywhere :( Most likely because I am having a newer version then the tutorial. When running the game at the end it does not go to the target point, please help

[@zoombapup]

Make sure you click the little eye icon next to the variable so that it becomes public. It only shows up there if you make it public.

[@SMKKNIEP]

zoombapup Thank you so much! really appreciate your quick response!! Keep up the good work!

[@manowargoblin]

Following this great tutorial. Bug still in 4.10.1 is when you create a character and edit it - it just shows blank - no graph or variables. To get around this, toolbar select useClassDefaults - this will show it's a data only actor. Then exit & enter again it should be ok. I also had to check orient movement to rotation to get the guard to at least face the right direction

[@jojoelongoria3447]

Nice video, mine wouldn't work at first but it was because my target was not touching the nav mesh.oops

[@hyperatomart8]

Another tutorial down, working perfectly so far!

[@gon222000]

Thanks for you reply. I know what you are saying, and I'm feeding it like the player character. I may be overlooking something, but I don't know what it is. Can you show me a picture of the blueprint where I have to set the speed?

[@kingniwashi]

Is there a way to set the TargetPoint (what you're doing at 19:48) automatically when the character is spawned?

[@zoombapup]

+kingniwashi Yeah, you could search for the target point when you get the begin play event in the AIController blueprint and set it there. FindObjectsOfClass or some such is the node. You would basically determine which target you want by iterating the available ones and looking for the closest say. Do that on begin play.

[@kingniwashi]

+zoombapup Thanks for your quick reply! I managed to insert the node (I suppose it's called Get All Actors Of Class) into the AIController blueprint, now I just have to figure out how to change said value... Guess I'll take a break until tomorrow, after 10 hours of learning the engine my brain reached its daily maximum capacity ;)

[@shaicruz176]

At 19:45 I cannot find "GuardTarget" on my character but I did follow it up....please help

[@zoombapup]

Make you you click the little eye next to the variable to make it public. It should show up on your character then.

[@shaicruz176]

zoombapup Thank you sir :)

[@Tueborgame]

zoombapup I'm running into the same issue (version 4.6.1), and I've got the eye as green but there is no GuardTarget or "Default" menu selection in the "Default" Tab. Any thoughts what else might cause it to not show up?

[@zoombapup]

Strength in Numbers Studios Hmm, the variable appearing should be automatic once you click the eye icon to make the variable public. The only other thing I can think of is that it is being placed in a different named section. If you go to the property view for the object in the scene, try using the search filter and put the name of the variable you created in there. It should show up. If not, maybe record me a video of how you have it setup and I'll respond with a way to fix it.

[@Tueborgame]

zoombapup Oh, I found it, thank you. I didn't realize you had to put the Character into the level and select the character. I was trying to find it on the Defaults tab of the Class BP. I was hoping to be able to simply drag out X number of these AI driven pawns and not have to set their Target on each one. Thank you very much tho for the very fast response. It is greatly appreciated.

[@shingAMarie]

Thanks for explaining what Unreal did not in their tutorial!!

[@gon222000]

I've been able to follow the tutorial all along, but I can't make the character use the blendspace to move. It stays at "idle", even when moving. I guess it has something to do with the "speed" variable (it stays at 0, even when moving), but I have no idea. Any idea?

[@zoombapup]

gon222000 Speed is basically the velocity of the character. So if you feed that into the anim instance you should be able to update the blend space properly. Have a look at how the various template characters do it. Its all just fed into the animation blueprint.

[@iskarr9g51]

Could you tell me how to get a behavior tree in Unreal 4.9.1 because there is no behavior tree nor a blackboard in it. They have removed it from the miscellaneous section.

[@studzman9587]

+Oni Donovan When you bring up the menu to create a blueprint, you have to scroll all the way down to "Artificial Inteligence," they are both in there.

[@philiptallentire2724]

When defining the blackboard key name in the AICharacterGuard blueprint. How would you go about defining multiple black board keys for the character AI so the character can move to different waypoints decided by the behavior tree?

[@zoombapup]

You generally wouldn't decide that in the behavior tree, rather you would decide that in an evaluation method. In the latest UE versions you would do that in the EQS system. Watch the sentry gun tutorials to see how that works. Otherwise, you could add each choice into the character as an array and have a task that chose the "best" one from the array.

[@philiptallentire2724]

zoombapup Thanks for your reply. I mean to have multiple waypoints that the character walks to using the 'Move to' task in the behavior tree. The path will be predetermined and run in a cycle in the behavior tree. Just at the moment I can only define one target position in the AICharacterGuard blueprint. Hope this makes more sense.

[@zoombapup]

Philip Tallentire If you watch the later videos in the series, it will show you an example of doing waypoints with optional paths. The blackboard itself isn't really setup very well to handle multiple options, so what most people do is store the options in either the character or the AIController and then use a task to select from those options. But a better way is the EQS system once it gets out of experimental status.

[@philiptallentire2724]

zoombapup OK will check that out, thanks for your help!

[@ThLekkas]

As i try to replicate the example of the tutorial i can't find some of the components that are mentioned (ex. AI Demo Character). Is this because of the version of the unreal engine? (I currently have version 4.7.3). Any help would be greatly appreciated

[@zoombapup]

ThLekkas The AI Demo character is just a character I made that duplicated the third person character from the third person character demo, calling it AI Demo Character as I copied it. Essentially AI characters are exactly the same as player characters but they use an AIController rather than an PlayerController.

[@Megalomaniakaal]

When I added the Move To to the behavior tree it did not fill out the target automagically, and in fact the drop-down list is completely empty. How do I tie the AI bots Behavior Tree and Blackboard together, am I missing something?

[@Megalomaniakaal]

Felix Kütt *DERP* forgot to set the active blackboard. Ouch, did my table met my forehead very suddenly and with great force once I realized that.

[@servicewithasmile9665]

Why when I try to place the "AI controller class" to my controller, it just pulls back to "none"? Doesn't even try to switch, just lets me click and only displays none. I am on version 4.9.2

[@zoombapup]

+Tyler Wilson Make sure it is actually an AIController based class you are using and not something else (for instance if you've misnamed something), it will likely check the type of the class when you assign it in the editor, so it must be rejecting that.

[@Felipedotcom]

I've got a really basic question. Is it a good idea to use AI, behaviour tree, and all these stuff for Paper2D games?, or should I use only blueprints and basic stuff for it?. Is this too much consuming for a device like a phone, or tablets?

[@zoombapup]

The behavior tree implementation should be better than trying to do the same kind of thing using blueprints. So I don't see why it wouldn't be OK for Paper2D usage. Just remember that the MoveTo nodes won't work with it (they're for moving a character movement component around). At the very least the behavior tree can tick the services at a slower speed to give you some way of performance tweaking on mobile. Let me know how you get on though, seems like an interesting challenge!

[@Felipedotcom]

zoombapup Thanks a lot for your quick answer, I will give it a try! :). Great tutorials btw

[@studzman9587]

To anyone whos having trouble finding the AI blueprints (Behavior tree, blackboard) in the newer versions, it's now under a menu called "Artificial Intelligence," you have to scroll all the way to the bottom of the New Blueprint menu!

[@PonzooonTheGreat]

I don't know what I have done wrong but nothing happens when I begin play. He doesn't move.

[@zoombapup]

Try running it and look at the behavior tree as it runs. You should see different values in the blackboard values in the bottom right and it should show you which part of the tree is actually running. Did you make sure to add the navmeshbounds volume? if you go to show in the world window and check AI debug, then press P, do you see the green mesh for the navmesh?

[@TheCreakyChair]

I had the same issue, missed setting target at 19:44. Nice work,still confused why my Nav Mesh does not show green, but EH.. Keep it up.

[@OperatorRazz]

Duncan Steele If you can't see your green NavMesh, press "P" on your keyboard or go under Show -> Navigation.

[@demitrikambouris2716]

When I search assets such as "ai demo chacacter" as shown in the video, my results do not much yours and therefore I cannot find nor access ai demo character....why would this be?

[@zoombapup]

Its just the name I gave my character blueprint class. Yours might be called something else. If you load the third person template and copy the player character and call it "ai demo character" you'll have the same thing.

[@demitrikambouris2716]

Ahh it's as simple as that, thanks pal for the reply, it is a big help.

[@jozseflaszlo7445]

Hello, am I missing something? I'm following step by step but I seem to be missing the misc category when creating a BT or BB, I can't even find a way to create one :( using ver. 4.5

[@zoombapup]

Its under miscellaneous in 4.6.1 so I am guessing its the same in 4.5, in those videos I was using 4.4.3 and maybe the BT was still in experimental. Have a look under all the categories and you should find Behavior Tree and Blackboard in them. Try the miscellaneous one.

[@jozseflaszlo7445]

That's the thing, I see it in the video, but when I click the category is missing :(

[@zoombapup]

***** What categories do you see? I'm doing the same in 4.6.1 and its the last category in the list.

[@jozseflaszlo7445]

zoombapup I see the exact thing as in the video only without the misc category! :(

[@zoombapup]

***** Hmm, that is very odd. There are a number of items under the miscellaneous category, so you might want to verify your install of 4.5 (there's a verify option in the launcher). Or try getting 4.6.1 and seeing if you get the same thing?

[@Stormsson]

zoombapup Maybe i'm a bit late ,but why do you setup the blackboard defaults in the character instead of the aicontroller ? is there a design reason ?

[@zoombapup]

More of a convention than anything. AIController is basically there to create the instance of the "brain" in terms of the BT and the blackboard naturally sits with the behavior tree. The character is more like the body in this relationship. With the BB as more of the memory of the brain.

[@Stormsson]

zoombapup Thank you for your answer and your videos. These are very difficult topics ,and know how is very rare

[@zoombapup]

Stormsson Always happy to help.

[@walkinginspace]

I've double checked everything yet, i still only get sent to idle. I checked for errors and even set the Blackboard condition to "not set" and got an error there, so it must be setting the GuardTarget. When i delete the idle branch, it calls the GoToGuard, but the guard doesn't move to the target....help!

[@zoombapup]

Hmm, so first thing to do, is watch the values in the blackboard as you run. If you keep the BT screen open, does the GuardTarget value get set to something other than null? It should be in the bottom right hand corner of the BT Editor view. Watch what happens with those values and the BT itself and let me know.

[@walkinginspace]

Got it working. I deleted the character out, then placed him back in. When i placed him back in the Guard Target Default wasn't set. I set it and he moved to the right position. Thanks for the great tutorials!

[@zoombapup]

walkinginspace Nice one. Let me know if you hit any other snags.

[@MrDivineWill]

I'm having an issue where even with the blackboard decoration, the Guard target is still never set, as far as I can tell I've followed all your steps, but the idle sequence is always being called

[@zoombapup]

Watch the BT as it runs, does the Guard Target value ever change to anything other than null? If not, place a breakpoint in the AIController that sets the guard target and see why it doesn't get set. Did you use the correct blackboardkeyselector name? Remember its set by name, so check for typo's etc.

[@MrDivineWill]

zoombapup it was incorrect naming, I had mistaken the target node name for the blackboard key selector name, thanks

[@MrDivineWill]

zoombapup but I have noticed now its only moving into that branch for a single frame

[@zoombapup]

MrDivineWill That might just be the distances you have set for the moveto nodes. Have a look at the distances set there, or just continue with the tutorial and go back once its a bit more complete. It does take a bit of tweaking to get it to feel right.

[@MrDivineWill]

zoombapup Ok, will do, thanks again for the help

[@xxDaniel466]

Hi . i dont see the blackboard thing show up when you go to moveTo could you help

[@studzman9587]

+daniel williams When you bring up the menu to create a blueprint, you have to scroll all the way down to "Artificial Inteligence," they are both in there.

[@Quistis99]

Is there a difference between using a blackboard and using a blackboard Data Asset to store your keys? Would there be a particular reason for using one or the other or are they more or less the same?

[@zoombapup]

The blackboard is basically the data asset. You can set which blackboard to use in the behavior tree (top right in the editor at the top is the blackboard to use). I think its just how they called it originally before it got out of experimental. You can create the BT which will automatically create a blackboard for you, or just create the blackboard data asset and then set it in the BT by hand.

[@Quistis99]

Oh I see! Thank you!

[@Garza10001]

Hello, I ran through a problem, I have been following step by step and I can't find my mistake. Every time I simulate the Behavior tree automatically runs the Idle, I have tried everything but I can't seem to fix it.

[@zoombapup]

You should see wether the conditional nodes on the other parts of the tree are failing (they show red). I suggest adding a breakpoint on each subtree under the root and stepping the BT to see what conditions are failing, then check the blueprint code to make sure it is correct. Keep at it though, I've had a number of students make this work so its likely something small you are missing. Being able to debug AI is a vital skill to learn too :)

[@Garza10001]

zoombapup Thanks for the reply. :) Yes my blackboard on "move to guard" is failing. It is red and saying that my GuardTarget is not set. Any Suggestions of how I can make my GuardTarget set? I will double check everything and I will let you know if I fixed my problem, Thank you for taking the time to upload these videos. One question. You said students, do you teach this in a University? Is there a class where I can sign up? I really enjoy these lessons.

[@zoombapup]

GunzPlazing You need to make sure you set the guard target in the details panel of your guard when you place him in your level. If you don't see that property, make sure you set it to "public" in the blueprint for the AIGuardController. I teach game programming and design at the University of Bolton, here in England. www.bolton.ac.uk if you are interested. Let me know how you get on!

[@Garza10001]

zoombapup Yes I am very interested. I didn't see this option but by any chance do you offer any online courses? I live in the United States.

[@zoombapup]

GunzPlazing No, sorry we don't do online courses yet. We *used* to have the technology for it about 10 years ago, but that was before I joined. It all got outdated and unused. The best I can do right now is to put up tutorial videos for the Unreal Engine community.

[@numnaha]

When creating the character blueprint there is no default option to select the target point?

[@zoombapup]

numnaha No, you have to add it. Remember to make it public so you can change it in the editor.

[@numnaha]

zoombapup public you mean the variable?

[@numnaha]

numnaha wow my bad just noticed it xD, thank you for the help and great tutorials :)

[@terryadams7778]

When I'm trying to assign the GuardTarget Blackboard key to the MoveTo function in the behaviour tree - I cannot. I made the blackboard key of type 'Object' but it simply won't do it. If I create a test variable of type Vector then the Move To function in BT is happy with that - but not the Object key used in this tutorial. Can anyone Help??

[@zoombapup]

You need to make the key of type actor rather than object. If I recall, moveto allows either Actor or Vector. So simply choose actor reference instead and you'll be good to go. Most "objects" are of type Actor anyway, but Actor is guaranteed to have a transform, which ultimately is what MoveTo needs to work. I assume that's why they require Actor rather than Object.

[@terryadams7778]

Hi @@zoombapup. Many thanks for your reply. I appreciate it. I know this is years old now. So - in the blackboard I don't see an 'actor' type - Just Object. However in the Character Blueprint I've set the GuardTarget variable in there to type actor - is that what you mean? It looks like the behaviour tree Move To function will not currently accept a key of type object. NOW - if I set the blackboard key to type vector - go back into the behaviour tree - set the key on the move to (because I can now) - then go *back* into the blackboard and set the key back to object - it sticks - and the NPC will actually move correctly. Tell me I'm missing something - I surely feel I am. EDIT: SOLVED: In the blackboard - when you create a key of type Object - you can click the small arrow next to *Key Type* . This gives you a *base Class* setting for that key. Set this to 'Actor' and away you go. The Move To function will then become happy to use that key. Feel like a Git now!

[@zoombapup]

@@terryadams7778 Nice! I just checked this out again (been a while since I looked), but took too long to load up UE4 (had to compile a bunch of shaders). Glad you found it yourself! Yeah, I have no idea why they didn't actually set that as a default, but you'll find a lot of that about UE4 AI stuff is kind of funky.

[@chrisg2716]

I can't get this to work. I have the mesh set up I have the AIController assigned to the character. All of the blueprinting double and triple checks but the character just stands there. My version is 4.11 anyone know what's up?

[@zoombapup]

+Christopher George Did you add some breakpoints in the blueprint code to be sure that it is correctly called? You have to narrow down what isn't working, then we can figure out what might be wrong. Are you sure you have a navmesh in the level (press P do you see it?) take it step by step and isolate what might not be working.

[@KikiKarypidou]

Are you running this on a laptop or desktop?

[@forsakenheros]

I've done everything here step by step, I see the green box, I've copied everything but when I start it up my character doesn't move so I checked what was wrong and everything was simulating but the behavior tree and I have it set up to run the behavioral tree? Is it a problem with the updated unreal engine? I'm stumped XD The default section target is set and everything

[@zoombapup]

I updated a few days ago and ran it and everything works, so I don't think its an update problem. If you have the behavior tree window open, do you see execution events firing in the node graph? If not, check you have done the run behavior tree setup in the AIController and that you have your own AIController set as the one for your character (in the character details page).

[@forsakenheros]

zoombapup Thanks for quick response! I don't know why this fixed it but when I created a new Ai Character, (I choose the 3rd person character the first time, I choose the tutorial one this time) It worked! XD Thanks for the help! I will be keeping up with your videos!

[@MrAdrianSW]

Make sure you recompile the AIGuardCharacter or the new Key wont show up in the editor... Took me 10 minutes to learn that one.... ;)

[@420TheUser]

I am going through this tut, and I am having issues. (maybe because I am in top-down template rather than 3rd person?) I have narrowed it down to the "EnemyCharacter" blueprint that gets the blackboard and sets the keyname to the value of the object value. When I run it, the Behavior tree stays on the idle branch because the blackboard check of "is targetPoint set?" never returns true. This value is not ever getting set because inside the EnemyCharacter bp, something is not working correctly. here is what I have.... puu.sh/gzcZZ/22c75ae9da.jpg

[@420TheUser]

Scratch that... i sussed it. Thanks for the tutorial. It was all setup right, I just was being silly and missed setting the targetpoint pictured here. puu.sh/gzdry/5f6b07b514.png

[@georgew2014]

I have tried to apply the blueprints to the car in the vehicle template. Nothing happens. Has anyone else tried that?

[@zoombapup]

The problem with the vehicle is that it won't work with the MoveTo nodes in the behavior tree (those require a charactermovementcomponent to work). So you'd have to write a custom movement task.

[@gon222000]

Never mind, I realized that I had an error on the blend space itself, that's why it wasn't working. Thanks a lot!

[@BatmanASB]

In case anyone else using 4.7.2 reaches the end, hits play, and has the AI idling for no reason, make sure your NavMesh didn't break. Press "p" while selecting it to see if it draws, and then move it a bit if it doesn't draw the green mesh. Not sure what happened, probably just a minor bug...

[@cesarsc971]

Very good tutorial. Thanks zoombapup.

[@zoombapup]

Cesar SC Glad you liked it! :)

[@Unhigedblade]

Great tutorial, thank you very much!!!

[@DARamosYT]

Man, I thought it wasn't working. My character was just moving too fast for me to notice. Haha

[@iceriverlia712]

Nice Job. Thank you!

[@Bhudiyo]

so are you able to make 1? let me know i am curious

[@Bhudiyo]

i am not able to change the the key inside the tree behave it is just stuck to none

[@Yor312]

Can i use this in version 11? I cant find this ai demo and i use copy of ThirdPersonCharacter, but in this part my Guard Target in not active and i cant set any target kzbin.info/www/bejne/d5DVn42VZ7Wapq8

[@zoombapup]

Try this one, which shows how to update from the old perception system to the new one: kzbin.info/www/bejne/oaCwh6OqqruqrKM

[@Yor312]

Thank you.

[@MsFreedom9111]

Hello Sir .First of all I am sorry that it is not related to your video but It is related to AI so I thought I should ask you I am following the basics of AI video of unreal engine 4 kzbin.info/www/bejne/m6e8dmqqm7yLi7s by Ian Shadden .At 37:54 he tells that Run Behavior Tree node should be at the beginning and if we don't do it then the path node would be none ,but he didn't give any reason .So do I have to set run behavior tree node at the very starting?I mean the run behavior tree node should run after the value has been set .Again sorry for asking .I asked on form but no one replied answers.unrealengine.com/questions/303268/run-behavior-tree-not-setting-path-node.html

[@zoombapup]

+MsFreedom9111 I guess it does need to be run first. The Run Behavior Tree node will cause the BT to actually load the appropriate Blackboard for it to execute as well. So if you set the blackboard value first, its probably either not initialized or is overwritten. Easy enough to test both and see if it works that way, but looking at the code it does read like you should run the behavior tree first. Your best bet is to try it and verify it works that way.

[@MsFreedom9111]

+zoombapup Yup I tried setting and it would not run because the value is set to none and when I ran it first then It worked .Thanks for the fast reply :)

[@DromeG60]

You're currently getting a lot of views from a University trying to finish an assignment :P

[@zoombapup]

Hehe.. well, good luck to everyone on their assignments! ;)

[@ThLekkas]

DromeG60 Not just one! and we can't figure out anything! PLEASE HELP US!!!!!!!!!!!!!!!!!!!! PLEASE!!!!!!!! peace - love

[@zoombapup]

ThLekkas Hehe.. calm down :) what exactly is the problem you're seeing?

[@ThLekkas]

zoombapup I'm ok now. It was just an act of desperation after 18 hours of things not working in unreal. Thanks for your concern and your quick response

[@zoombapup]

ThLekkas No problem, I've got a lab full of my own students melting down about their own projects so I know how you feel.

[@DrDangers]

I love you

[@zoombapup]

Hehe.. thanks.