Glossary

A

Actor An Actor is any object that can be placed into a level. Actors are a generic Class that support 3D transformations, such as translation, rotation, and scale. Actors can be created (spawned) and destroyed through gameplay code (C++ or Blueprints). In C++, AActor is the base class of all Actors.

Answer Hub A searchable database of reported bugs, suggestions and questions about working with UE4. You can also submit your own bug reports, and ask and ansewer questions.

B

Blueprint Editor The Blueprint Editor is a node-based graph editor that acts as your primary tool for creating and editing the visual scripting node networks that make-up Blueprints.

Blueprint Blueprints are special assets that provide an intuitive, node-based interface that can be used to create new types of Actors and script level events; giving designers and gameplay programmers the tools to quickly create and iterate gameplay from within Unreal Editor without ever needing to write a line of C++ code.

C

Character A Character is a subclass of a Pawn Actor that is intended to be used as a player character. The Character subclass includes a collision setup, input bindings for bipedal movement, and additional code for movement controlled by the player.

Class A Class defines the behaviors and properties of a particular Actor or Object used in the creation of an Unreal Engine game. Classes are hierarchical, meaning a Class inherits information from its parent Classes (the Classes it was derived or “sub-classed” from) and passes that information to its children. Classes can be created in C++ code or in Blueprints.

Component A Component is a piece of functionality that can be added to an Actor. Components cannot exist by themselves, however when added to an Actor, the Actor will have access to functionality provided by the Component.

Content Browser The Content Browser is the primary area of the Unreal Editor for creating, importing, organizing, viewing, and modifying content assets within Unreal Editor.

Content Cooking Content Cooking is the process of converting content from the internal formats used by Unreal Editor, such as PNG for texture data or WAV for audio, to the formats used by each individual platform; either because the platform uses a proprietary format, does not support the format Unreal uses to store the asset, or a more memory/performance-effective format exists.

Controller Controllers are non-physical Actor Classes that can possess a Pawn or Character to control its actions.

D

Details Panel The Details panel contains information, utilities, and functions specific to the current selection in the viewport; such as transform edit boxes for moving, rotating, and scaling Actors, editable properties for the selected Actors, and quick access to additional editing functionality (depending on the types of Actors selected in the viewport).

E

Editor Preferences The Editor Preferences window is used to modify settings that control the behavior of Unreal Editor with respect to controls, viewports, source control, auto-saving, and more.

Event Events are the starting point for Blueprint execution and only have an ouput Exec node. You may create Custom Events that can be called through Blueprint code as well.

F

Function Executable method defined either through code or through the Blueprint Editor that has at least one output parameter or return a value.

G

Game Mode The GameMode Class is responsible for setting the rules of the game that is being played. The rules can include how players join the game, whether or not a game can be paused, level transitions, as well as any game-specific behavior (for example, win conditions).

Gameplay Framework The basic gameplay classes include functionality for representing players, allies, and enemies; as well as for controlling these avatars with player input or AI logic. There are also classes for creating heads-up displays and cameras for players. Finally, gameplay classes such as GameMode, GameState, and PlayerState set the rules of the game. Gameplay classes also track how the game and the players are progressing.

Global Asset Picker The Global Asset Picker (Ctrl-P) is a fast-access means of editing assets or bringing them into your levels. In some ways, it is similar to the Content Browser but without limiting itself to the current folder you have selected in the Asset Tree. Not only can you pull assets specific to your game, but also anything from Engine, like lights or sound emitters. Because it offers all available assets in a list format, it is not intended to be used as means for browsing. Instead, it’s perfect for those moments when you know the asset (or asset type) you need and just want to quickly type part of its name into the Search Line.

H

HUD A HUD is a “heads-up display”, or the 2D on-screen display that is common in many games.

L

Launcher A UE4 application that allows you to manage your Unreal Engine 4 installations, Marketplace content, and other plugins. The Launcher also hosts the Community tab, Learning tab, and the Modding tab allowing access to a wealth of information.

Level A Level is a user defined area of gameplay. Levels are created, viewed, and modified by placing, transforming, and editing the properties of the Actors it contains. In the Unreal Editor, each Level is saved as a separate .umap file, which is also why you will sometimes see them referred to as Maps.

Level Editor Tools for viewing and editing levels. Container for many Editor functions.

Level Sequence The Level Sequence is an Actor that acts as a “container” for your cinematic scenes and must be created in order to begin working inside the Sequencer Editor.

Level Streaming The Level Streaming feature makes it possible to load and unload map files into memory as well as toggle their visibility during play. This makes it possible to have worlds broken up into smaller chunks so that only the relevant parts of the world are taking up resources and being rendered at any point. If done properly, this allows for the creation of very large, seamless levels that can make the player feel as if they are playing within a world that dwarfs them in size.

Lightmass Lightmass is the static global illumination system which creates lightmaps with complex light interactions, such as area shadowing and diffuse interreflection from stationary and static lights.

M

Map Map is a synonym for Level (see Level)

Marketplace The Marketplace is an online store built into the UE4 Launcher that allows the communnity to buy and sell UE4 content.

Material A Material is an asset that can be applied to a mesh to control the visual look of the scene. At a high level, it is easiest to think of a Material as the “paint” that’s applied to an object. But even that can be a bit misleading, since a Material literally defines the type of surface from which your object appears to be made. You can define its color, its shininess, its transparency, and much more.

Material Editor The Material Editor provides the ability to create shaders for geometry, using a node-based graph interface.

Material Instance Material Instances are child Materials that use parameters to change the appearance of a Material without incurring an expensive recompilation of the Material.

Middleware Middleware is applications that provide out of the box funcitonality to extend applications either as a standalone application or a plugin.

Modes Modes are tools that change the primary behavior of the Level Editor for a specialized task, such as placing new assets into the world, creating geometry brushes and volumes, painting on meshes, generating foliage, and sculpting landscapes.

Modes Panel The Modes panel provides access to the Editor Modes’s settings and tools.

O

Object The base building blocks in the Unreal Engine are called Objects, containing a lot of the essential “under the hood” functionality for your game assets. Just about everything in Unreal Engine 4 inherits (or gets some functionality) from an Object. In C++, UObject is the base class of all objects; it implements features such as garbage collection, metadata (UProperty) support for exposing variables to the Unreal Editor, and serialization for loading and saving.

P

Packaging The purpose of packaging is to test your full game instead of a single map, or to prepare your game for submission/distribution.

Pawn A Pawn is an Actor that can be an “agent” within the world. Pawns can be possessed by a Controller, they are set up to easily accept input, and they can do a variety of player-like things. Note that a Pawn is not assumed to be humanoid.

Physically Based Rendering (PBR) Physically based rendering (PBR) refers to the concept of using Roughness, Base Color and Metalness to accurately represent real-world materials.

Play in Editor (PIE) Play In Editor allows you to play the current level directly from the editor, so that you can test gameplay functionality, including player controls and level events triggered by players’ actions.

Player The player is the actual human being that is interacting without your application.

PlayerController A PlayerController is the interface between the Pawn and the human player controlling it. The PlayerController essentially represents the human player’s will.

PlayerState A PlayerState is the state of a participant in the game, such as a human player or a bot that is simulating a player.

Plugin Plugins enable you to add entirely new features and to modify built-in functionality without modifying the engine code directly, such as adding new menu items and tool bar commands to the editor, or even adding entirely new features and editor sub-modes.

Post-Process Effect Post-Process Effects enable artists and designers to tweak the overall look and feel of the scene by applying effects including bloom (HDR blooming effect on bright objects), ambient occlusion, and tone mapping to the rendered scene before displaying it in the viewport.

Project A Project is a self-contained unit that holds all of the content and code that make-up an individual game and coincides with a set of directories on your disk.

Project Browser The Project Browser provides an interface for creating new projects, opening your existing projects, or opening sample content like sample games and Showcases.

Project Launcher The Project Launcher tab provides a graphical front-end interface to build, cook, deploy, and launch your game.

Project Settings The Project Settings editor provides access to configuration options that specify information about your project, as well as defining how the engine behaves when running the project.

Property Matrix The Property Matrix enables easy bulk editing and value comparison for large numbers of Objects or Actors by displaying a configurable set of properties for a collection of objects as columns in a table view that can be sorted on any column.

R

Rasterization Rasterization is the process creating rendererd images from vector data. UE4 uses rasterization over Raytracing to achieve interactive frame rates.

Raytracing A technique for generating rendered images by simulating the path of light through the scene. This produces very high quality, but is very computationally expensive.

Real-Time Real-Time refers to applications that resppond to the user's input immediately. This typically requires a response time of less than 1/30 of a second.

Redirector A Redirector provides a reference to the new location of an Asset when it is moved or renamed so that content not loaded at the time of the operation can find the asset.

S

Sequencer Unreal Engine’s cinematic toolset that provides director-level control over cut scenes, dynamic gameplay sequences, and movies.

Simulate In Editor Simulate In Editor enables you to run game logic in the editor viewport so you can inspect, edit, and interact with Actors in the world as the game runs.

Skeletal Mesh Skeletal Meshes are built up of two parts; a set of polygons composed to make up the surface of the Skeletal Mesh, and a hierarchical set of interconnected bones that can be used to animate the polygons.

Skeleton A Skeleton is an asset that holds bone and hierarchy information for a specific type of character or Skeletal Mesh.

Slate UI Framework Slate is a completely custom and platform agnostic user interface framework that is designed to make building the user interfaces for tools and applications, such as Unreal Editor, or in-game user interfaces fun and efficient. It is the core technology UMG is based on.

In UE4, Source Code refers to the C++ code files that makes up UE4. These files are then compiled to create the Editor, Launcher and other UE4 tools.

Spawn Creating a new instance of an Actor, either programmatically at run-time, or manually in the Level Editor at design-time.

Static Mesh A Static Mesh is a piece of geometry that consists of a static set of polygons and are the basic unit used to create world geometry for levels in Unreal Engine 4.

Static Mesh Actor An Actor whose visual representation is a Static Mesh.

Static Mesh Components A Component that adds a Static Mesh to an Actor.

Static Mesh Editor The Static Mesh Editor provides tools for previewing the geometry, collision, and levels of detail of a Static Mesh asset, as well as editing properties, applying Materials, and setting up collision geometry.

T

Texture Textures are images that are mapped to the surfaces that a Material is applied to.

U

Unreal Editor Unreal Editor is the complete suite of tools provided with Unreal Engine that enables developers to build levels, import content, create effects, and much more.

Unreal Motion Graphics (UMG) Unreal Motion Graphics UI Designer (UMG) is a visual UI authoring tool which can be used to create UI elements such as in-game HUDs, menus or other interface related graphics you wish to present to your users.

V

Variable A Variable is an named memory location that can store data such as numbers and text.

Viewport Viewports are your window into the worlds you create in Unreal. They can be navigated just as you would in a game, or can be used in a more schematic design sense as you would for an architectural blueprint.

Volume Volumes are three-dimensional areas within your levels, each of which serve a specific purpose.

W

Widget Blueprint A Widget Blueprint is a specialized Blueprint used by Unreal Motion Graphics (UMG) to provide visual layout and logic editing functionality for widgets.

World A World contains a list of Levels that are loaded. It handles the streaming of Levels and the spawning (creation) of dynamic Actors.

World Outliner The World Outliner panel displays all of the Actors within the scene in a hierarchical tree view that can be filtered and enables selection and modification of Actors directly in the tree.