Unreal Editor notes for Unity developers

This page is a supplement for developers moving from Unity to Unreal Engine 5 (UE5). For implementation examples, start with the Showcase.

Editor terms and where data is saved

Unity	UE5	Purpose
Scene	Level	File that stores placement, lighting, and GameMode. The Showcase uses Showcase.umap.
Hierarchy	World Outliner	Where to find Actors placed in a Level.
GameObject	Actor	A game object that can be placed in a Level.
MonoBehaviour	Actor / Actor Component	Game logic on an Actor, or a feature attached to an Actor.
Prefab	Actor Class / Child Actor	Reusable Actor class. It can be placed as a Child Actor inside a parent Actor.
Inspector	Details	Where to edit savable properties of the selected Actor / component.
Play	Play In Editor (PIE)	Execution mode that runs a copy of the Editor World.

The Showcase places zone Actors such as Z1_Bowling in the Level. Pins, the Shark, and Targets are Child Actors owned by a zone. Adjust position, rotation, and scale primarily through the Child Actor slot Transform in the parent zone’s Details, rather than on an internal mesh.

Editor World and PIE World

UE5 PIE does not run the Level being edited directly. It creates and runs a copy of the Editor World (the PIE World).

Edit and save the Level
  → Editor World
  → Start PIE
  → BeginPlay / physics / Tick run in the copied PIE World
  → Stop PIE
  → Return to the saved Editor World values

Objects knocked over by physics, spawned projectiles, and component values changed at runtime during PIE are not written back to the Level after it stops. To keep a placement change, stop PIE, select the Actor in the Outliner, edit it in Details, then save with Ctrl+S.

To inspect an Actor or component during PIE, change the World Outliner’s world selector to Play World. You can inspect Child Actors and runtime values set by BeginPlay there. Press Tab in the Showcase to toggle mouse-cursor capture in PIE.

C++ initialization timing

In Showcase C++, when a value is created affects what is visible in the Editor.

Timing	Main purpose	Editor / PIE behavior
constructor	Create default components and default properties	Always appears in the component tree.
OnConstruction	Build derived visuals from properties	Also runs when the Actor is placed or its properties change.
BeginPlay	Start input, physics, and runtime setup for Child Actors	Set only after PIE starts.
Tick	Per-frame motion and state updates	Runs only during PIE.

Z1 Pins, the Z3 Shark, and Z5 Targets receive their Hapbeat Event Map / entry ID from the zone in BeginPlay. This ensures that Child Actors follow the zone’s Event Map override. If you change the parent zone Actor’s Event Map / entry in Details during PIE, the Showcase rewires existing Child Triggers so the change applies from the next fire.

Transforms calculated by OnConstruction, such as mesh corrections and previews, are derived values. Moving an internal mesh directly can be recalculated when a parent Actor property changes or when the asset reloads. The Showcase treats the public properties on the zone / Child Actor slot as the source of truth.

After changing C++

Ordinary Details / Event Map edits apply after saving and restarting PIE. C++ changes require a build. In particular, changes to constructor-created components, default values, or the Class Default Object (CDO) may not reach existing Level instances through Live Coding alone. In that case, close the Editor, perform a normal build, and reopen it.