Need Help with Initializing AIPerception and getting enemy to switch players on the fly.

Development Programming & Scripting C++
1
  1. I cannot for the life of me figure out how to get UAIPerceptionComponent to function in c++. This is how I Initialize it in the SZombieAIController.cpp but it never shows up on the AIController in the editor (yes the SZombieAIController.h is set up too).


#include "Perception/AIPerceptionComponent.h"

ASZombieAIController::ASZombieAIController(const class FObjectInitializer& ObjectInitializer)
	: Super(ObjectInitializer)
{
	PerceptionComponent = ObjectInitializer.CreateDefaultSubobject<UAIPerceptionComponent>(TEXT("PerceptionComp"));
	
	

}
  1. I have been banging my head on the wall trying to figure out how to get a zombie to update and change targets on the fly. I tried in blueprint because it was the only way to get the AIPerception to work but gave up and came back to C++ which I am more comfortable with. Basically I need to do this:

PsuedoCode



//should this be on Tick?

if(PlayersAreInLineOfSight) //using perception system?
{
//create an array of all players in Line of Sight
//Find the closest player to the zombie
//Set that as the enemy in the AI Behavior Tree
}
else
{
//create an array of all players in the game world
//Find the closest player to the zombie
//Set that players as the enemy in the AI Behavior Tree
}

The behavior tree has a moveto component that will move the zombie to the set target player.

So the above works in blueprint fine as long as you just want to search once. But what I need the zombie to do is constantly search for the player, update the player target, and move towards this new target. I assumed I could use eventTick but the problem I am having is that I am not sure the best way to abort out of the MoveTo in the behavior tree to update the new target (always moves towards the first target set). So I am moving back to C++ and once again trying to get things set up here.

So, to summerize, I need to:

1)Perceive players in LOS (Using PerceptionSystem)
2)Update the target
3)update which target to move to in the behavior tree.

There is something I am missing here (likely a decorator) but I am not sure what to do about it.

PS: There needs to be a ton more C++ AI tutorials that are relevant to 2016 and current versions of UE4. Right now its pretty pathetic.

2

I think you need to set up senses for the component, here is how i did it in my AI controller maybe it can help you.

.h



	virtual void ActorsPerceptionUpdated(const TArray<AActor*>& UpdatedActors);

	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "AI")
        UAISenseConfig_Sight *sightConfig;

	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "AI")
	UAIPerceptionComponent *aiPerception;

.cpp



AUnitAIController::AUnitAIController(const FObjectInitializer &ObjInit)
{	
	aiPerception = GetAIPerceptionComponent();
	aiPerception = CreateDefaultSubobject<UAIPerceptionComponent>(TEXT("AIPerception Component"));
	sightConfig = CreateDefaultSubobject<UAISenseConfig_Sight>(TEXT("Sight Config"));
	sightConfig->DetectionByAffiliation.bDetectEnemies = true;
	sightConfig->DetectionByAffiliation.bDetectNeutrals = true;
	sightConfig->DetectionByAffiliation.bDetectFriendlies = true;
	aiPerception->ConfigureSense(*sightConfig);
}

void AUnitAIController::ActorsPerceptionUpdated(const TArray<AActor*>& UpdatedActors)
{
	for (AActor *actor : UpdatedActors)
	{
	     //do something
        }
}

The ActorsPerceptionUpdated is only called when something is changed (when characters enters or leaves your perception).

3

Thank you, any idea on how to update an AI’s target on the fly (as in while it is moving towards it’s original target)?

4

You could hold on to the pointer to the actor that you get in the UpdatedActors array and then update the target in OnTick. Or you could use a UPawnSensingComponent that is a kind of “simpler” version of the AIPerceptionComponent and has it’s own update interval, and do the stuff there.

5

I am in the process of moving my perception logic from my pawn to the AIController. I have it working fine on the pawn, but getting an error when I try to add a second sense when I came upon this.

I think the second line of this code wipes out the results of the first? I use the second line in my pawn where it works. But only the first line in my AIController.
aiPerception = GetAIPerceptionComponent();
aiPerception = CreateDefaultSubobject<UAIPerceptionComponent>(TEXT(“AIPerception Component”));

Trying to figure out why I get an accessviolation in the AIPerceptionComponent.cpp when I add the second sense.
PerceptionComp->ConfigureSense(*Sight);
PerceptionComp->ConfigureSense(*Hear); <—triggers the error.

This post helped me get on the right track.

6

Here’s how I setup the Perception inside my AIController class:

Create a Blueprint derived from your AIController, then add the PerceptionComponent inside that blueprint. If you configure your Pawn to use your Blueprint AIController, your Tasks, Services etc. can now in C++ access the Perception via aiController->GetPerceptionComponent() . The PerceptionComponent variable in the AIController class searches for all occurances of a UAIPerceptionComponent class, which includes blueprints.



void AAIController::PostRegisterAllComponents()
{
	Super::PostRegisterAllComponents();

	// cache PerceptionComponent if not already set
	// note that it's possible for an AI to not have a perception component at all
	if (PerceptionComponent == NULL || PerceptionComponent->IsPendingKill() == true)
	{
		PerceptionComponent = FindComponentByClass<UAIPerceptionComponent>();
	}
}