Behavior Trees had been used by a lot of developers as a way to model AI. One advantage of this technique is improved readability and maintainability, specially when compared with solutions based on state machines, which is a living heel to work with.
If u want to know more about it i recommend this article → click here ←
So… i’m developing this tool for modeling AI with behavior trees in Unity. It is, of course, a work in progress, but i don’t fell like hiding the tool until its done, my intention is to release it for free on the next couple of days.
I never send anything to the asset store, u guys think its cool to submit a unfinished product??
Anyway… here is some SS
The tool window is a node based editor that allow you to use various kinds of nodes to build your behaviors.
Free!?!? I’ve been wanting to do something like this for a project I was doing in the past. I just seems so much easier to not only read, but to make changes to. If you coded AI in C#, it’d be really strange to want to change some of the structure, or some weights/properates as you would have to move code around.
I would love to try this out soon, as well as look at a public repo
Cool… i am glad to hear that… i’m working on that demo scene and also on a simple documentation so i can release the code and package as soon as possible…
Just letting you guys know that a quick guide is up on the repository for any of you interest on download the tool.
Is a simple guide/tutorial to introduce basic concepts of BeeHIVE.
hello Nilo,
first congrats and thanks for making such a thing.
I’m looking at it and don’t understand what’s going on
this looks like something I would use for Ai (and it uses things like distance check, triggerenter, raycast which is good) and would use physical movement with capsule collider (not character controller)
and it would be a shame if I wouldn’t use because I don’t get the concept.
the “food” scene is very much like waypoint-example. I think it should be more simple so beginners could build upon it / see what’s going on (the food transform is hiddenininspector which doesnt help).
so I see there’s 4 things can be chosen in node (foodonsight, lookforfood, eat, wander) which are handled in aicontroller.cs too.
for me this looks like 2 levels of enums. okay, reading into the article a bit more
but where is the selector node controlled? I dont see any conditional selection in aicontroller.cs. (is it just behind the scenes?)
okay so sum it up a bit: I see this (the behavior tree) as the higher structure of decision making while the controller script (+other scripts) work it out and do decisions on their own, is that right?
how about if a decision (or a result) made in a script, I want to effect behaviour? (example: 3 transforms detected, but one tag overrides others, so I dont want to lookFor, but Flee (?)) I see there are conditions in aicontroller.cs, but those conditions are under BH_Status…
I think making simple examples would help. I hope this develops into a compact solution.
hi dibdab… thx so much for the feedback…
I updated the repo with a simple example / tutorial, you can check that out. https://github.com/NiloFV/BeeHIVE
i will try to cover a few things that maybe can help you understand the tool.
Lets divide the workflow on 3 parts, just for simplicity
User Controller: This is not part of the tool, that is your regular controller that you would implement in your game, fps, plataformer (you name it), using whatever technique you want, like character controllers, or physics, pretty much anything u like.
BeeHiveAgent : script that you will also create, but this time you will make it inherit from BeeHiveAgent. In this script, you will create a bridge that connects the User Controller to the rest of the system. You can do that by ‘translating’ the User Controller actions to methods that returns a BH_Status(more about that on the tutorial), that way the behavior tree can interpret them.
Node Editor : The window where u can drag nodes around. After you are done with the first two parts, you can use this editor to actually create the decision logic for your ai. I’m writing the part of the documentations that explains what exactly each node does, but for now, the article i mentioned (http://www.gamasutra.com/blogs/ChrisSimpson/20140717/221339/Behavior_trees_for_AI_How_they_work.php) cover really well. The rock star node is the leaf, which holds references of the methods created in your BeeHiveAgent. When a tree reach a leaf, it will execute his method and process its return value. The selector node is like a OR gate, and the sequence is like a AND gate, these tree can already create a lot of stuff.
If i understand your question right, you are a bit confused on how the selector node are controlled on the demo scene, that node its actually the root of the tree, since there is no connections going in, only going out, to the the systems assume that is the root when it builds the actual tree.
So putting in fewer words, this system wont create functionality for your game, like ray cast or anything like that, the functionality is created by the user and than translated into a format that can be evaluated and executed by the system, and the node editor its tool for modeling the decision making.
I hope this help a little bit, and please don’t hesitate on contact me if u have any more trouble with the tool, and dont forget to check the repo again for the tutorial.
See ya
that’s the only place BallIsAbove is referenced, right?
now the behaviour tree looks like this
now I don’t understand much of it.
I guess invertor means if is NOT above, ballhitter must go down.
but then the sequence means going from Left to Right, not from Above to Downwards (as I thought).
okay, so then if moveup or movedown is success, it will call pongController.MoveUp() or pongController.Move Down().
okay, maybe I got a bit closer to understanding how it works.
The tree is searched on a Co-routine started by the InitBeeHive method.
Each node return a BH_Status to its parent, to tell him about the result of its execution. It can be Success, Failure or Running. For the leaves, we have to define what they will return, with a method such as the example you posted. The other nodes have a logic on their own. They will return a status based on what their children return to them.
Let’s run this behavior tree step by step to explain this better…
Let’s assume that that ball is bellow the agent.
1.The tree will start by the root, which is the top most node, in this case a selector.
2.The selector will execute its children, from left to right, so the the left-most Sequence node its executed.
3.Left-most Sequence node will also execute its children, first will be the “BallIsAbove” leaf
4.When the three hit a leaf, it will execute the method associated whit it, in this case, the BallIsAbove(), present in PongAI_Finished.cs.
Since we assume that the ball is bellow, the execution will return Failure to the parent.
The parent (Left-most Sequence node), receive that Failure status, and since it act like a AND gate, he already know that its execution can not succeed. So it will not process any further children, and will also return Failure to its parent(selector node).
The selector will receive that Failure status, and since he acts like a OR gate, he only need one of the children to succeed, the first child did not, but there is still hope, so it will keep going. Now it will execute the second child (the right-most sequence node).
The right-most sequence node will execute the Inverter node.
The Inverter node will execute its child, the “BallIsAbove” leaf
“BallIsAbove” leaf will execute the method and will return Failure, because the ball is bellow.
The inverter takes whatever it receives from the child and invert is, in this case, it will take the Failure status and turn into a Success status, and then return to the parent.
The parent(the right-most sequence node) receive the Sucess status and keep going. It execute the next child.
The MoveDown node gets executed, which actually moves the agent, and return Running.
Running its not Sucess, and is not Failure, but his parent its a optimistic guy, so it receives it and takes as a Success.
Since all the children of the right-most sequence node succeed, it will return success to its parent (selector)
The selector receives a success, and one success is all it needs in life, so it will not execute any further.
At that point the agent has been moved down and the tree will be searched again and again. Below is the execution sequence and what each node returned.
SELECTOR (SUCCESS)
LEFT SEQUENCE (FAILURE)
BALLISABOVE (FAILURE)
RIGHT SEQUENCE (SUCCESS)
INVERTER (SUCCESS)
BALLISABOVE (FAILURE)
MOVEDOWN (RUNNING)
Try to follow the tutorial that is on the repo, there i try to guide you on reproducing that ai behavior. By the end you should have a better understanding on how the system is structured.
hi… i’m glad you are interested… i’m still working on it… but i also working on a game, so is not a full time thing with this plugin…
it is totally free, for now you can download from the repo… i plan to release on the asset store as soon as i’m happy with the documentation…
if you try it out i would love to hear about your experience to see what can be done to improve the tool… and if you have any feature request u can throw it here and will try to implement, maybe something to fit a wider range of game structures…
I was looking for behaviour tree for AI, but the thing is, I do not use Monobehaviours for my gameplay. I use pure C# classes, and use gameObjects just as “renderers”.
Now the trees like Behaviour Designer or others, they require the GameObject to have their script attached to it. Which is impossible to use in my architecture.
Then I saw your designer, with the source code, and I wondered if I could try to extend it to fit my architecture. Currently, I have time to try and look into it and come up with something, to use it without any MonoBehaviours. If I can extend it with your permission (I wont distribute it or anything, its just for this project), I will let you know how it goes. If such thing can even be done.
no worries… u can do anything u want as long as the tool is kept free… i will be happy to have other people working on the code… u can make a push request on the repo anytime u want, and we can have a second branch with your version, or if it work both ways it can be merged into a single solution…
and by the way… the code you will find on the repo its mostly front-end stuff… the core is included from a dll, which was compiled from a vs project…
i uploaded the project for you in case u want to take a look at it as well…
Yes, as I said, I will keep the project only to myself, I wont distribute it, since its yours
After hours and figuring out how it all works, I have managed to get it working with my architecture. No need for merging, because It looks like I have made very little changes how its used.
Also, have you considered putting variables or method arguments to nodes like in Behaviour Designer?
yes… it is on my list of features to add… i will try to work some more on the tool on the next few days…will try to add this… and maybe implement a way to import other tress as a single node…
