Object pooling pattern for frequently spawned actors like projectiles

Pattern: PoolManager with Array<AActor*> AvailablePool. Init: loop SpawnActor N times → SetActorHiddenInGame(true) → SetActorEnableCollision(false) → Array_Add to pool. GetFromPool: Array_Length > 0 → remove last → SetHidden(false) → SetCollision(true) → SetActorLocation → return. ReturnToPool: SetHidden(true) → SetCollision(false) → Array_Add back.

Blueprint function vs custom event vs macro: when to use each

BLUEPRINT FUNCTION: - Has its own execution context, can have inputs/outputs/return value. - Cannot have Delay, Timeline, or latent nodes inside. - Best for: pure logic, calculations, data transformation. - Can be overridden in child BPs (if not pure). CUSTOM EVENT: - Lives in event graph, can be called like a function. - CAN have Delay, Timeline, latent nodes. - Can be Replicated (Server/Client/Multicast). - No return value. Best for: triggered behavior, RPC calls. MACRO: - Inlined at call site — like a code template. - CAN have multiple exec inputs AND outputs. - CAN contain latent nodes. - Best for: reusable flow patterns (e.g. 'IsValidAndCast' check-and-cast pattern). PURE FUNCTION: checked 'Pure' — no exec pins, evaluated on demand. Best for getters.

string

string

State machine pattern using enum variable and switch

Variables: CurrentState (your EState enum: Idle, Patrol, Chase, Attack, Dead). EventTick or custom Update event → Switch on EState(CurrentState) → Idle: [idle logic] → Patrol: [patrol logic] → Chase: [chase logic] etc. State transitions via custom events: OnEnemySpotted → SetVariable(CurrentState=EState::Chase). OnEnemyLost → SetVariable(CurrentState=EState::Patrol). OnDamaged → Branch(Health<=0) → True: SetVariable(CurrentState=EState::Dead). Key: Switch On Enum node — connect enum variable to the input, each value gets an exec output pin.

Component pattern: create Actor Component BP for reusable logic

CREATE: New Blueprint → parent class UActorComponent (or USceneComponent if needs transform). Add variables (Health, MaxHealth). Add EventBeginPlay (available in component). Add custom events/functions (TakeDamage, Heal, OnDeath). ADD TO ACTOR: In your Actor BP → Add Component → search for your component class. Or: SpawnActorFromClass → GetComponentByClass → CastTo<BP_HealthComponent>. CROSS-COMMUNICATION: In Component's OnDeath → GetOwner → CastTo<BP_Character> → call OnCharacterDied. Or: Component has Event Dispatcher 'OnDied' → owner binds to it. BENEFIT: Reuse HealthComponent on Enemy, Player, Vehicle without code duplication.

Less (float) — A < B

MakeColor — construct FLinearColor from R G B A

Set (Collection)

An unordered collection with unique elements. (The Set node for writing variables is a separate concept — see the entry for 'Set'.)

Replace string — replace occurrences in string

BooleanAND — logical AND

OR=BooleanOR, NOT=Not_PreBool, XOR=BooleanXOR