Unreal Engine

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name: Unreal Engine description: Avoid common Unreal mistakes — garbage collection, UPROPERTY macros, replication authority, and asset reference pitfalls. metadata: {"clawdbot":{"emoji":"🎯","os":["linux","darwin","win32"]}}

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Garbage Collection

Raw pointers to UObjects get garbage collected — use UPROPERTY() to prevent

UPROPERTY() marks for GC tracking — without it, pointer becomes dangling

TWeakObjectPtr for optional references — doesn't prevent collection, check IsValid()

NewObject() for UObjects — never raw new, GC won't track it

UPROPERTY and UFUNCTION

UPROPERTY() required for Blueprint access — and for GC tracking

UFUNCTION() for Blueprint callable/events — also required for replication

EditAnywhere vs VisibleAnywhere — edit allows changes, visible is read-only

BlueprintReadWrite vs BlueprintReadOnly — controls Blueprint access level

Actor Lifecycle

BeginPlay after all components initialized — safe to access components

Constructor runs on CDO (Class Default Object) — don't spawn actors or access world

PostInitializeComponents before BeginPlay — for component setup

EndPlay for cleanup — called on destroy and level transition

Tick Performance

Disable tick when not needed — PrimaryActorTick.bCanEverTick = false

Use timers instead of tick + counter — GetWorldTimerManager().SetTimer()

Tick groups for ordering — PrePhysics, DuringPhysics, PostPhysics

Blueprint tick expensive — move hot logic to C++

Replication

Server is authority — clients request, server validates and replicates

UPROPERTY(Replicated) for variable sync — implement GetLifetimeReplicatedProps

UFUNCTION(Server) for client-to-server RPC — must be Reliable or Unreliable

HasAuthority() to check if server — before executing authoritative logic

Role and RemoteRole for network role checks — ROLE_Authority is server

Asset References

Hard references load with parent — bloats memory, use for always-needed

Soft references (TSoftObjectPtr) load on demand — for optional or large assets

LoadSynchronous() or AsyncLoad for soft refs — don't access until loaded

Blueprint class references: TSubclassOf — type-safe class selection

Memory and Pointers

TSharedPtr for non-UObjects — reference counted, auto-deletes

TUniquePtr for exclusive ownership — can't copy, moves only

MakeShared() for creation — single allocation for object and control block

Never mix raw new/delete with smart pointers — choose one pattern

Common Mistakes

Accessing null actor in Blueprint — use IsValid() node before access

PIE (Play In Editor) vs packaged build differ — test shipping build

Hot reload corrupts Blueprints — close editor, build, reopen

GetWorld() null in constructor — world doesn't exist yet, use BeginPlay

Spawning in constructor crashes — defer to BeginPlay or later

FString for display, FName for identifiers — FName is hashed, faster comparison