unreal-actors-components

Actors and Components - Unreal Engine 5.7

Actors (AActor)

• ALWAYS inherit from AActor for objects in the world
• Use GENERATED_BODY() at the beginning of the class
• Implement BeginPlay() for initialization
• Implement Tick() only if necessary (disable if not using)
• Use UPROPERTY(VisibleAnywhere) for components
• Use UPROPERTY(EditAnywhere) for editable properties in editor

Components (UActorComponent / USceneComponent)

• ALWAYS inherit from UActorComponent or USceneComponent
• Use UActorComponent for logic without position
• Use USceneComponent for components with transformation
• Use USceneComponent as root component when appropriate
• Components must be created in constructor with CreateDefaultSubobject<>()
• Use SetupAttachment() for component hierarchy

Component Creation Pattern

// In constructor (.cpp)
AMyActor::AMyActor()
{
    PrimaryActorTick.bCanEverTick = false; // Disable if not using Tick

    // Create mesh component
    MeshComponent = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("MeshComponent"));
    RootComponent = MeshComponent; // Set as root

    // Create child component
    CollisionComponent = CreateDefaultSubobject<UBoxComponent>(TEXT("CollisionComponent"));
    CollisionComponent->SetupAttachment(RootComponent);
}

Actor Lifecycle

1. Constructor - Create components and default values
2. BeginPlay() - Initialization after spawn in world
3. Tick() - Update every frame (disable if not using)
4. EndPlay() - Cleanup when removed from world

Best Practices

• Disable Tick if not necessary: PrimaryActorTick.bCanEverTick = false;
• Use events instead of Tick when possible
• Components should be self-contained and reusable
• Use GetWorld() to access the world, don't store reference
• Use GetOwner() in components to access the owner Actor