Introduction to AI in Unreal Engine

Unreal Engine provides one of the most comprehensive built-in AI frameworks of any game engine, with behavior trees, environment queries, perception, and navigation all integrated out of the box.

UE5 AI Architecture

Unreal's AI system follows a controller-pawn architecture. The AI Controller is the "brain" that controls a Pawn (the physical character). This separation allows you to swap AI logic independently from character movement and visuals.

Core AI Components

AI Perception System

The AI Perception System gives NPCs simulated senses. Instead of directly checking distances or line-of-sight in gameplay code, you configure perception components that automatically track stimuli.

• Sight: Configurable field of view, range, and age (how long remembered). Supports peripheral vision vs focused vision.
• Hearing: React to noise events with configurable range and loudness thresholds.
• Damage: Automatically perceive sources of damage.
• Touch: Physical contact detection.
• Custom senses: Create project-specific senses (smell, radar, telepathy).

// MyAIController.h
#include "AIController.h"

UCLASS()
class AMyAIController : public AAIController
{
    GENERATED_BODY()

public:
    AMyAIController();

protected:
    virtual void OnPossess(APawn* InPawn) override;

    UPROPERTY(EditDefaultsOnly)
    UBehaviorTree* BehaviorTreeAsset;

    UPROPERTY(EditDefaultsOnly)
    UBlackboardData* BlackboardAsset;
};

// MyAIController.cpp
void AMyAIController::OnPossess(APawn* InPawn)
{
    Super::OnPossess(InPawn);

    if (BlackboardAsset)
    {
        UseBlackboard(BlackboardAsset, BlackboardComp);
    }
    if (BehaviorTreeAsset)
    {
        RunBehaviorTree(BehaviorTreeAsset);
    }
}

Blueprint vs C++ for AI