ProjectWorldLocationToScreen — project 3D location to 2D screen coordinates

APlayerController method.

SpawnEmitterAtLocation — spawn a legacy Cascade particle system

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

MakeColor — construct FLinearColor from R G B A

ProjectPointToNavigation — snap a point to the nearest nav mesh

SpawnSystemAtLocation — spawn a Niagara/Cascade particle system

UNiagaraFunctionLibrary::SpawnSystemAtLocation. bAutoDestroy=true for fire-and-forget. Use SpawnSystemAttached to attach to a component.

CreateDynamicMaterialInstance — create runtime modifiable material

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

MakeRotator — construct FRotator from Roll Pitch Yaw

UKismetMathLibrary::MakeRotator. NOT MakeRot.

Procedural mesh placement on terrain using line trace downward

Pattern for snapping object to ground: GetActorLocation → Add Vector(Z=+1000) → as TraceStart. GetActorLocation → Subtract Vector(Z=1000) → as TraceEnd. LineTraceByChannel(Start=TraceStart, End=TraceEnd, TraceChannel=Visibility) → Branch(ReturnValue=true) → BreakHitResult → SetActorLocation(NewLocation=ImpactPoint) → SetActorRotation(NewRotation=MakeRotFromZ(Normal)) [align to surface normal]. MakeRotFromZ takes a 'Z' input Vector and outputs Rotator aligned to that normal.

Performance optimization checklist for Blueprints

1. TICK MANAGEMENT: - Disable tick on static actors (SetActorTickEnabled=false). - Use SetActorTickInterval(0.1-0.5) for AI, non-critical systems. - Prefer event-driven over tick polling where possible. 2. AVOID EVERY-TICK EXPENSIVE CALLS: - GetAllActorsOfClass: cache in BeginPlay, refresh only when needed. - CastTo: cache result in variable after first cast. - GetComponentByClass: call once and store reference. 3. VISIBILITY: - SetActorHiddenInGame + SetActorTickEnabled=false for off-screen actors. - Use LOD (Level of Detail) on meshes. 4. SPAWNING: - Use object pooling for frequently spawned/destroyed actors (bullets, effects). 5. EVENTS OVER POLLING: - Use overlap events instead of periodic distance checks. - Use delegates/dispatchers instead of checking conditions each frame.

Common Blueprint mistakes and how to fix them

MISTAKE 1: Calling GetAllActorsOfClass every Tick. FIX: Cache results in BeginPlay or use delegates/tags instead. MISTAKE 2: Not checking IsValid before using object references. FIX: Always IsValid → Branch → Is Valid before dereferencing. MISTAKE 3: Using hard references to large assets in variables. FIX: Use Soft Object References + AsyncLoadAsset. MISTAKE 4: Tick enabled on many actors doing heavy work. FIX: SetActorTickInterval(0.1) for non-critical logic, or use Timers. MISTAKE 5: Casting to specific class without checking IsValid first. FIX: CastTo has 'Cast Failed' output — always handle it. MISTAKE 6: Modifying array elements by getting then setting a copy. FIX: Use 'Array Set' with index to modify in-place. MISTAKE 7: Creating widget every time it's shown. FIX: Create once → cache reference → show/hide with SetVisibility or Add/RemoveFromParent.