SpawnEmitterAtLocation — spawn a legacy Cascade particle system

Legacy Cascade system. Prefer Niagara (SpawnSystemAtLocation) for new projects.

Health and damage system with ApplyDamage and EventAnyDamage

Dealing damage: Event → ApplyDamage(TargetActor, BaseDamage, InstigatorController, DamageCauser, DamageTypeClass). Receiving: EventAnyDamage → Damage output → Subtract_FloatFloat(CurrentHealth, Damage) → FClamp(Result, 0, MaxHealth) → SET CurrentHealth → Branch(CurrentHealth <= 0) → True: DestroyActor. Initialize CurrentHealth=MaxHealth in BeginPlay.

SetLifeSpan — set actor lifetime before auto-destroy

0 = live forever.

Health regeneration over time with timer

Pattern: Variables RegenRate(float)=5.0, RegenDelay(float)=3.0, RegenTimerHandle. On damage received: ClearTimer(RegenTimerHandle) → SET timer(RegenDelay, RegenTick, looping=true). RegenTick function: Branch(Health < MaxHealth) → True: SET Health = FClamp(Health + RegenRate*DeltaSeconds, 0, MaxHealth). False: ClearTimer.

Asset reference points to a Blueprint that no longer exists

Why: Some node or variable hardcoded a reference to BP_{name}, but that file was deleted or moved. The Asset Registry can't resolve it. Fix: Either: (a) re-create BP_{name} if accidentally deleted (Content Browser → right-click → Blueprint Class), or (b) update the reference to point at the correct existing Blueprint, or (c) make the reference soft (TSoftObjectPtr) so missing assets don't fail compilation.

ApplyDamage — deal damage to a target actor

UGameplayStatics::ApplyDamage. Triggers EventAnyDamage on target.

Respawn system that moves player to spawn point after death

Pattern: On Health<=0 → DisableInput(PC) → PlayMontage(DeathAnim) → Delay(DeathAnimDuration) → GetActorOfClass(PlayerStart) → TeleportTo(SpawnPoint.Location, SpawnPoint.Rotation) → SET Health=MaxHealth → EnableInput(PC). For checkpoint: store last checkpoint location variable, update on overlap with checkpoint triggers.

CreateDynamicMaterialInstance — create a runtime-editable material copy

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

ApplyPointDamage — deal point damage with hit info

Pickup and collectible system with overlap trigger

Pattern: Pickup actor with SphereCollision(overlap), StaticMesh visual. OnComponentBeginOverlap → CastTo PlayerCharacter → Success: call AddScore/AddItem interface on player → PlaySoundAtLocation → SpawnEmitterAtLocation → DestroyActor(self). Set collision to OverlapOnlyPawn for performance.