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.

Function

A named, reusable subgraph with inputs + outputs. Cleaner than copy-pasting node clusters.

Component

A reusable piece of behavior or geometry attached to an Actor. Static Mesh, Collision, Audio, Camera are all components.

CreateDynamicMaterialInstance — create a runtime-editable material copy

Must call this before SetScalarParameterValue/SetVectorParameterValue. Store the result in a variable for reuse.

CreateDynamicMaterialInstance — create runtime modifiable material

UPrimitiveComponent method. Store result in variable and reuse. Create once in BeginPlay.

Object pooling: reuse actors instead of spawn/destroy

Variables in pool manager (GameMode or Subsystem): Pool (Array<Actor>), PoolClass (TSubclassOf<Actor>). Init: Loop N times → SpawnActorFromClass → SetActorHiddenInGame(true) → SetActorEnableCollision(false) → SetActorTickEnabled(false) → Array Add to Pool. GetFromPool: ForEachLoop(Pool) → GetActorHiddenInGame → Branch(true) → SetActorHiddenInGame(false) → SetActorEnableCollision(true) → SetActorTickEnabled(true) → SetActorLocationAndRotation → Return actor. If none available: SpawnActorFromClass. ReturnToPool: SetActorHiddenInGame(true) → SetActorEnableCollision(false) → SetActorTickEnabled(false) → SetActorLocation(far away or (0,0,-9999)).

Create a Blueprint for a health pickup that restores health when overlapped by the player

Macro

An inline-expanded subgraph. Like a function but each use creates a fresh copy at compile time (faster, but more bytecode).

String

Editable text (Mutable). Use Text for player-facing localized text instead — String is for internal logic.

Create dynamic material and animate a parameter at runtime

Pattern: EventBeginPlay → GetMesh → CreateDynamicMaterialInstance(ElementIndex=0) → SetVariable(DynMat=ReturnValue). Then on Tick or timer: SetScalarParameterValue(ParameterName='Opacity', Value=SinWave). Or for color: SetVectorParameterValue(ParameterName='Color', Value=MakeLinearColor). Key: CreateDynamicMaterialInstance is called on the COMPONENT (GetMesh), not the actor. Must store the result before using Set*ParameterValue. ParameterName MUST match the name in the Material asset exactly.