Behavior trees and controller input

Unreal Engine Programming & Scripting
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#1

I am trying to read controller inputs from behavior tree nodes.
I know this may be strange to you but I find it very usefull the use behaviour trees to organize player interface.

My main problem is that when I want to add the action event to my task’s blueprint the “Action Events” category is not available. I guess that makes sense since behavior trees do not have an input component.

Any idea?

Thanks,
Erwan

Edit: In the pawn’s event graph it is possible to access such event but not in the task’s event graph.
Also I have tried to use custom events but they don’t allow me to target the task precisely. Also I would like to have many tasks listening to such events.

#2

Try casting Owner Actor to whatever class you’re controlling with your BT and then extract InputComponent from it. I’m not familiar with input mechanics at all, so if taking a hold of InputComponent turns out to be impossible you can always just call functions on the actor your control with the BT.

Cheers,

–mieszko

#3

Try casting Owner Actor to whatever class you’re controlling with your BT and then extract InputComponent from it.
You mean in the task’s c++ code I need to get the input component of the controlled actor and read inputs from there? By using BindInput for example?

#4

Calling functions from the BT task on actors in the game is what I am doing already.

However I don’t seem to find any way of getting a hold on the input component from the task for the simple reason that there is no GetOwnerActor type function in UBTNode.

My problem is that I cannot catch controller events (input events) from a BT Node

#5

First of all I need information on what are you using to implement your BT nodes, C++ or BP? But regardless, one thing to note about our BT implementation is that nodes as (generally speaking) “skeletons” and operate on given contest (expressed by BehaviorTreeComponent instance in case of C++ or Owner Actor in BP).

#6

Would anyone know how to retrieve the AAIController from a UBTNode ? From there I could get the possessed pawn.

#7

Like I said, UBTNodes are skeletons and as such don’t have information on any specific AI since a single BT node instance is being used by all AIs using the same BT asset. You get a “context” as BehaviorTreeComponent reference (or pointer, depending on the version you’re using) when functions are being called on given BT node instance for a specific AI (the owner of BehaviorTreeComponent instance).

#8

Note: This question is not resolved yet… why was is marked as resolved ?

nodes as (generally speaking)
“skeletons” and operate on given
contest (expressed by
BehaviorTreeComponent instance in case
of C++ or Owner Actor in BP).

Thanks for pointing that out! So I wrote that bit of code:
AAIController *const aiController = OwnerComp->GetAIOwner();
APawn *const pawn = aiController->GetPawn();
UInputComponent *const inputComponent = static_cast< UInputComponent * >( pawn->GetComponentByClass ( UInputComponent::StaticClass() ) );

But inputComponent is null. I managed to trace it and it seems to be because the pawn is not possessed by a AAPlayerController.
It would seem I would have to write a specialised class inheriting from character which manually calls CreatePlayerInputComponent().

What do you think?

#9

Like I said, I don’t know much about Input code, but the BT part has been solved. I suggest you created a new thread regarding the details of your input question.

#10

Okay thanks!