Components¶

Components are reusable pieces of functionality you attach to actors. The two roots:

Base	Has transform?	Examples
`UActorComponent`	No	`UMovementComponent`, `UAbilitySystemComponent`, audio non-spatial
`USceneComponent`	Yes	`UStaticMeshComponent`, `UCameraComponent`, `UWidgetComponent`

Categories¶

Rendering¶

UStaticMeshComponent
USkeletalMeshComponent
UInstancedStaticMeshComponent / UHierarchicalInstancedStaticMeshComponent (ISM/HISM)
UDecalComponent
UWidgetComponent — UMG in 3D space
USceneCaptureComponent2D / Cube
UPostProcessComponent
UNiagaraComponent

Collision / Physics¶

UBoxComponent, USphereComponent, UCapsuleComponent
UPrimitiveComponent (base for collide-able shapes)
URigidBodyComponent / UPhysicsConstraintComponent

Movement¶

UMovementComponent (base)
UCharacterMovementComponent
UProjectileMovementComponent
UFloatingPawnMovement
UChaosVehicleMovementComponent

Audio¶

UAudioComponent
UAmbientSoundComponent

AI¶

UBlackboardComponent
UBehaviorTreeComponent
UAIPerceptionComponent
UPathFollowingComponent

Camera¶

UCameraComponent
UCineCameraComponent
USpringArmComponent

Gameplay¶

UAbilitySystemComponent (GAS)
UHealthComponent (custom pattern)
UInventoryComponent (custom pattern)

Special¶

UTextRenderComponent — 3D text
UArrowComponent — editor visualization
UBillboardComponent — facing-camera sprite

Attachment¶

SceneComponent has a parent → child tree. Attach with:

ChildComp->AttachToComponent(ParentComp, FAttachmentTransformRules::KeepRelativeTransform);

Or AttachToSocketName for skeletal mesh sockets.

Replication¶

Components don't automatically replicate. Mark bReplicates = true on the component, and the owning Actor must also be replicated.

Creating in C++¶

UStaticMeshComponent* Mesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("Mesh"));
SetRootComponent(Mesh);

Creating from Blueprint¶

+ Component in the BP editor. Choose any registered component class.

Custom components¶

UCLASS(ClassGroup=(Custom), meta=(BlueprintSpawnableComponent))
class MYGAME_API UHealthComponent : public UActorComponent
{
    GENERATED_BODY()
public:
    UPROPERTY(EditAnywhere, BlueprintReadWrite) float Max = 100.f;
    UPROPERTY(BlueprintReadOnly, ReplicatedUsing=OnRep_Current) float Current = 100.f;
    UFUNCTION() void OnRep_Current();
};

Performance¶

Each ticking component costs main-thread time. Disable Tick on components that don't need it.
ISM/HISM consolidates thousands of meshes into one draw call — huge win for PCG-spawned content.
WidgetComponent in 3D space rasterizes UMG to a render target every frame it changes — pin it to manual redraws if static.