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Document Summary: This is a complete glossary of all the Unreal Ed terms you will ever need to know (and a few more for good measure).

Document Changelog: Last updated by Jason Lentz (DemiurgeStudios?), for creation purposes. Original author was Jason Lentz (DemiurgeStudios?).

A - B - C - D- E - F - G - H - I, J & K - L - M - N & O - P - Q & R - R - S - T - U - V - W - X, Y & Z


Actor - An object that can be placed or spawned in the world. This includes such things as the Players, StaticMeshes, Emitters, ZoneInfos, Sounds, etc. For a detailed explanation of all the Actor Properties, see the ActorVariables document.

ActorX - An exporting plugin used for exporting skeletal meshes and their animations into files that Unreal Ed can import. For more about the ActorX plugin, see the ActorX document (downloads are also available there)

Additive BSP - BSP space that has been added to a subtracted BSP space. Additive BSP is solid, impenetrable space within the game environment. See BSP.

AI - (Artificial Intelligence) a term used to describe the behavior and apparent thought process of computer controlled characters. This can include things as simple as non interactive scripted sequences to things as complex as computer characters that learn from player actions and adapt.

AI Controller - A class that defines how a computer controlled characters or a group of computer controlled characters behave. For more about AI Controllers, see the AIControllers doc.

Alpha Channel - An extra channel in a texture that allows for not only transparency but also translucency in a texture. To use an Alpha Channel one must have the texture's bAlphaTexture property set to True. For more on Alpha Channels, see the UnrealTexturing document.

AmbientSound - An actor that when placed in the level will loop a sound file selected from the Sound Browser. For more on AmbientSounds, see the ExampleMapsSounds document.

Anim/Animation - Movement created for a 3D model with bones that allows it to move in game. The Animations are stored in .PSA files and several can be imported for a single skeletal mesh.

Antiportal - A volume that obscures parts of the scene from the renderer. If the player camera's view is blocked by an Antiportal, the rendered will not draw what is on the other side of the Antiportal. For more on Antiportals, see the LevelOptimizationAntiportals document.


Beam Emitter - An individual emitter that stretches a texture into long strips and emits these strips in a pattern that can be designed in within the Unreal Editor. For more on information on Beam Emitters, see the BeamEmitter document.

Blocking Volume - A volume that can be created in the Editor that will block players as well as other actors, but it will not block zero extent trances. For more on Blocking Volumes, see the Volumes Tutorial document.

Bot - A computer controlled player that has its own AI.

Browser - One of the tabbed menus that one can use to view various aspects of the editor. The various Browsers include the Texture Browser, Actor Browser, Meshes Browser, Animations Browser, StaticMeshes? Browser, Prefab Browser, Groups Browser, Sounds Browser, and Music Browser. For more on these Browsers, see the Unreal Ed Interface document.

Brush - Any geometry created from the Brush Primitive tools on the left side of the Unreal Editor including the red Builder Brush. For more on Brushes see that BspBrushesTutorial document.

Build - The act of compiling the level so that it can perform all of the necessary precalculations such as lighting, path generation, and resolving geometry. Also known as Rebuilding,
          - The version of the Unreal Editor. For example: "UT2K3 uses the 2136 Build of the Engine. For more information on the various Builds of the Unreal Engine, see the UnrealFamilyTree? document.

Builder Brush - The red Brush that one can use to subtract out or add in BSP volumes to the level. For more on the Builder Brush, see that BspBrushesTutorial document.

BSP - Binary Space Partitioning (sometimes refered to as CSG ) is a data structure that is used to organize objects within a space of the level. While it is not semantically correct to use this term to refer to geometry, it is loosely accepted as referring to the geometry created with the builder brush. For more on BSP, see that BspBrushesTutorial document.
      In simpler words, BSP is a type of geometry that can be added or subtracted from a level to sculpt the space of the environment.

BSP Holes - Inexplicable breaks in the BSP geometry where subtractive and additive BSP spaces spill into each other. They can occur in highly complicated BSP additions/subtractions. In addition to slowing down the frame rate of a scene, they have been known cause other more strange problems including but not limited to disappearing staticmeshes and invisible player blocking walls.


Camera - The view that the player sees from in game as well as in the Unreal Editor. In the orthogonal viewports, one can see the Camera for the perspective view shown as an eye.

CollisionCylinder - The cylindrical space around every actor that can be used to determine collisions. For many actors, this setting is by default turned off but for other actors such as the player and triggers, the CollisionCylinder is on be default and detects when other actors collide with it. The height and radius of the CollisionCylinder can be altered under the collision properties tab.

Collision Model - Less complicated geometric volumes that are created along with and stored in a staticmesh. The Collision Model is used to facilitate faster collision calculations than would be possible with just a complex staticmesh. For more on Collision Modles, see the CollisionTutorial document.

Combiner - A type of material that combines two textures or materials and blends them to create a new material. For more on Combiners, see the MaterialsCombiners document.

Console - (a.k.a. command prompt, command line) A field at the bottom of the Unreal Editor that allows one to enter console commands in the editor. For more on the Console, see the Unreal Ed Interface document.

CSG - Constructive Solid Geometry (a.k.a. CSG ) this is a more semantically accurate term for BSP (Binary Space Partitioning). The term CSG refers to the geometry created with the builder brush. For more on CSG, see that BspBrushesTutorial document.

Cubemap - A Cubemap is required to create an environment map which can be used to create the appearance of a reflective material. To learn more about Cubemaps, see the MaterialsEnvironmentMaps document.

Cull - To hide from the rendered, or in other words, to have the rendered not draw something.


Decolayer - A layer in the terrain that can be used to generate a set random pattern of staticmeshes that will fade in and out over distance as well as remain attached to the terrain and have their scale and orientation randomly skewed per instance of the staticmesh. For more on Decolayers see the CreatingDecoLayers document.

Deintersect - An action that will leave the remainder of builder brush selection that is in negative/subtracted space. For more on using the Deintersect button, see the Intro to Unreal Ed document.

Demiurge - A Platonic deity who orders or fashions the material world out of chaos.

Distance Fog - A property of a zone that allows the level to be culled out after a certain distance by blending far off geometry with a solid color causing it to appear as if the geometry is disappearing into the atmosphere.

Drag Grid - (a.k.a. Grid) A toggle that allows one to snap certain actors (such as staticmeshes, movers, and brushes) to a grid in the Unreal Editor. The Drag Grid size can be adjusted by powers of 2 going from as low as 1 to as high as 4096. To learn more about the Drag Grid, see the Unreal Ed Interface and Worldflow and Modularity documents.

DXTC - (a.k.a. DirectX Texture Compression ) A method of texture compression that is the primary algorithm for texture compression in the Unreal Editor. To see more about DXTC see the TextureComparison document.


Emitter - (a.k.a. Particle System) An actor that can spawn a series of other actors such as staticmeshes and sprites as particles to achieve various special effects. Emitters can be used in conjunction with each other to create "Particle Systems." To learn more about Emitters, see the EmittersReference and ParticleSystems documents.

EnvMap - (a.k.a. EnvironmentMap) A type of material which can be used to create the appearance of a reflective material. To learn more about EnvMaps, see the MaterialsEnvironmentMaps document.

Event - A call that certain actors can listen for that will cause them to initiate some action. Events can be called from triggers, movers, emitters, and from code.


Face - One side of a BSP object. A Face is made up of two triangles.

Fake Backdrop - A surface property that can be assigned to BSP faces that allow those faces to be seen as a skybox. To see how the Fake Backdrop surface property is used, see the Sky Zone Example Maps document.

FinalBlend - A material that allows one to control how another material blends with the scene in the ZBuffer. For more about FinalBlends, see the MaterialsFinalBlend document.

FluidSurface - (a.k.a. FluidSurfaceInfo ) A dynamic sheet that is divided into small quads that react to encroaching actors as if it were a liquid. To learn more about FluidSurfaces, see the FluidSurfaceTutorial document.

Fog Volume - Much like distance fog, volumes can also create a fog effect that allows objects in the distance to fade to an opaque color.

FPS - (Frames Per Second) A measure of the rate at which pictures are shown for a motion video. Television runs at roughly 30 FPS, film usually runs at 24 FPS, while games often have variation in their FPS.
          - (First Person Shooter) A style of game that depicts the scene from a first person perspective and the primary interaction with the world is a gun of some sort.


G16 - Grayscale 16B image. Terrain uses G16 bitmaps for the heightmaps and alpha layers.

Geometry - Anything constructed out of triangles in the level, such as StaticMeshes, BSP, Terrain, etc.

Grid - See Drag Grid.

Group - (Groups Browser) Actors can be assigned to a Group using the Groups Browser. These Groups can be used to better visually manage all the different actors that can clutter up a scene. To learn more about using these Groups see the GroupsBrowser document.
          - (Package Groups ) A subdivision of assets within a package (such as a texture, staticmesh, and sound packages) that allows for easier management of the assets within the browser.


Hardware Brush - see StaticMesh

HOM - (Hall of Mirrors) An effect where the renderer does not correctly redraw the scene creating a chaotic visual effect similar in appearance to a Hall f Mirrors. This effect can be caused by looking into an antiportal or through a BSP hole in the level.

I , J & K

Impersonator - A third-party tool integrated into Unreal Engine 2.5 that allows one to animate lip synching to character models. For more information on using Impersonator, see the ImpersonatorUserGuide and ImpersonatorTutorial documents. You must contact OC3 to purchase this technology, as it is not included with your Unreal Engine license, and it will stop being available for purchase on August 30th, 2005.

Intersect - An action that will leave only the section of the builder brush that is overlapping with additive BSP geometry. For more on using the Intersect button, see the Intro to Unreal Ed document.

Invisible - A surface property for BSP geometry that will cause surfaces marked as Invisible not to be rendered. Invisible surfaces however will still collide as if they were visible.

KActor - (a.k.a. KarmaActor ) A staticmesh that uses a karma hull and is placed in the world as a KActor. KActors can be knocked around and will collide with other world geometry with realistic physics. To see how to create and import KActors, see the ImportingKarmaActors document.

Karma - The physics engine by Math Engine which is integrated into the Unreal Engine. For more information on Karma, see the IntroToKarma document.

Karma Hull - A simplified 3D model attached to a staticmesh that is not visible in game, but is used for physics and collision calculations. For more about KarmaHulls, see the ImportingKarmaActors document.

Keyframe - A pose in an animation or mover path that is used to interpolate the motion of an animation or of the movement of a mover. To see more info on Keyframes pertaining to movers, see the MoversTutorial document.


Layer - ( Terrain Layer ) Hierarchical levels in the Terrain that allow Textures to be painted on and blended together on the terrain. For more on Layers, see the EditingTerrainLayers document.

Level - See Map

Light - An actor that casts light on the nearby surfaces. For more on using Lights, see the LightingBasics document.

Lightwave - A 3rd party modeling program that can be used for creating intricate staticmeshes and/or skeletal meshes.

LOD - (Level of Detail) A feature that allows the resolution of the geometry to decrease over distance in order to increase the frame rate of a scene (specifically in animated characters). For more on how to use LOD on character models, see the Anim Browser Reference document.

Log - A window that prints out actions either in game or in the editor that shows every action that takes place.


Map - The file that is saved which contains all of the placed actor properties and thus the layout of the entire scene you've created.

Masked - A texture property that uses the alpha channel to determine whether or not a section of the texture is transparent or opaque. Masked textures have no translucency. To use the Masked setting one much have the texture's bMasked property set to False.

Material - A tool used for creating special effects with textures. Materials show up and can be browsed in the texture browser and they are also saved in texture packages. For more on using the different types of Materials see the MaterialTutorial.

Matinee - An in-editor movie making tool that allows one to set up camera paths to create in-game cut scenes and fly bys. For more information on using Matinee, see the MatineeTutorial document.

Max - (3DS Max) A 3rd party modeling program that can be used for creating intricate staticmeshes and/or skeletal meshes.

Maya - A 3rd party modeling program that can be used for creating intricate staticmeshes and/or skeletal meshes.

Mesh Emitter - An individual emitter that emits staticmeshes in a pattern that can be designed within the Unreal Editor. For more information on Mesh Emitters, see the MeshEmitter document.

Meshes - A model created in a 3rd party program that uses vertex animation, although the term "Mesh" is often used interchangeably with the term staticmesh even though they are not the same thing. To see how to import Meshes with vertex animation, see the UnrealVertexAnimation document.

Mirror - A surface property that can be assigned to BSP faces that will allow those surfaces to act as a Mirror in that it will appear to reflect geometry just as a mirror would. To learn more about this surface property, see the MirrorsAndWarpZones document.

Mod - A released game that is largely based on another commercial game (such as Unreal Tournament 2003) but is modified to create a different game play experience.

Modifier - A material that can modify a texture or another material in a variety of ways including (but not limited to) allowing it to pan, waiver, rotate, and scale. For more information on Modifiers, see the MaterialsModifiers document.

Mover - A special staticmesh that can be assigned keyframes within the editor and then assigned to move along a path determined by these keyframes when triggered by an event such as player collision, weapon fire, or a trigger. For more information on Movers, see the MoversTutorial.

Music - Song files that can be added to a level to be played in the background or Triggered after an event. These song files must be in the .ogg file format. To see how to trigger a music file in game, see the ExampleMapsTriggers and TriggersTutorial documents.

myLevel - A special package that cannot be explicitly saved out, but is saved everytime one saves the level. The myLevel package contains both staticmeshes and textures.

N & O

NonZeroExtentTraces - A trace that uses a box traveling along a line to determine collision. In other words, instead of using casting a 2 dimensional line to determine if a line can be drawn between two points, a 3 dimensional box is cast along a line to see what will impede the box.

Notifies - A call that can be placed at any point in a given animation that can trigger another event including but not limited to sounds, particle systems, or uscript functions. Foot steps sounds that are played when a foot reaches the ground in an walk anim are a good example of Notifies. For more information on setting up Notifies, see the AnimNotifies document.

Order - See Sorting.


P8 - A palletized 8 bit texture.

Package - A library of files of a particle type (such as staticmeshes or textures).

Particle System - See Emitter

Particle Emitter - An individual type of Emitter inside a Particle System (such as a Beam Emitter, Mesh Emitter, Spark Emitter, or Sprite Emitter. See Emitter

Pass - One time that the scene is drawn in the renderer. A scene can require several Passes by the renderer before it is drawn to the screen. In other words, if a triangle is requires 3 passes, it is being drawn 3 times by the renderer.

Path Node - A point in a network of lines that determine where a bot can travel to. Path Nodes appear as apples in the editor. For more information on Path Nodes, see the NavigationAI document.

Pawn - A character or class that can navigate (either on its own or by player control) through the level.

Play Map - Running the level in real time as the end user would be running the map.

Player - An actual human user of the map as it is running in real time. (they do exist!)

PlayerStart - A spawn point for a player's pawn or bot in the level.

Portal - (a.k.a. Zone Portal ) A particular type of special brush usually in the form of a sheet that can divide one zone into two different zones. For more information on Portals, see the LevelOptimizationBSP document.

Poly - (a.k.a. Polygon ) A triangle.

Prefabs - Pre-Unreal Ed 3 only - an antiquated geometry type created in the editor often used for objects that can be placed around the level.

Primitive - One of the standard, unaltered BSP shapes that can be created with the tools on the left side of the editor (i.e. cube, curved stair, cylinder, cone, sheet, etc.). For more information on Primitives, see the UnrealEdInterface document.

Projector - An actor that can cast a texture on various types of geometry in the scene. For more information on Projectors, see the ProjectorsTableOfContents document.

Properties - The settings for any actor or texture. To access the Properties of an actor, just press F4 or right click on the actor. To see more about the default actor Properties, see the ActorVariables document.

Q & R

Quad - A set of two triangles that make up a square, easily seen in terrain in wireframe mode.

Ragdoll - A realistic physics simulation applied to character models that allows them to act like limp Ragdolls. For more information on how to set up Ragdolls, see the KarmaAuthoringToolTutorial and KarmaAuthoringTool documents.

Rebuild - See Build

Refpose - ( Reference Pose ) The default position that an animated character is posed in before it is animated (usually the da Vinci pose). For more information on Refposes, see the UnrealModeling document.

Renderer - The part of the Unreal engine that actually draws what the player sees on the screen.

RGBA8 - a Red Green Blue 8 bit image.

Rmode - (a.k.a. Render Mode ) The mode or style in which the scene is drawn (either in a viewport in the Unreal Editor or in game). Rmodes types include but are not limited to wireframe mode, textures only mode, and dynamic light modes (which is the regular Rmode ). For more information about Rmodes, see the LevelOptimizationProfiling document.

Root - The primary bone at the top of the hierarchy of a skeletal animation. The Root is what is translated and/or rotated as a character moves through a level.

Rotation Gizmo - An interface for rotating and translating actors. The Rotation Gizmo is only available in the UDN Build. To see how to use the Rotation Gizmo, see the RotationGizmo document.

Rotation Grid - A toggle that allows one to rotate actors about its pivot point at discrete intervals. For more information on using the Rotation Grid, see the UnrealEdInterface and WorkflowAndModularity documents.

Runtime - The mode when the level is actually running and one can interact as a player within the world.
          - A build of the Unreal Engine, available for download on the UnrealEngine2Runtime page.


Script - See Unreal Script

Scripted Sequence - An actor that controls a pawn and dictates what they will do based a series of actions that can be assigned to that pawn. To learn more about ScriptedSequences, See the ScriptedSequenceTutorial document.

Shader - A material that allows one to alter the opacity, specularity, and illumination (among other qualities) of a texture. Shaders are sometimes used to refer to as materials in general. To see more information on Shaders, see the MaterialsShaders document.

Shape Editor - (a.k.a. 2D Shape Editor ) A tool in the Unreal Editor that allows one to create unique BSP brushes. For more information on the Shape Editor, see the ShapeEditor document.

Sheet - A 2D brush often used for creating ZonePortals.

SimpleBoxCollision - A staticmesh collision type that uses NonZeroExtentTraces to calculate collision. For more information on SimpleBoxCollision, see the CollisionTutorial document.

SimpleKarmaCollision - A staticmesh collision type that uses Karma Hulls to calculate collision. For more information on SimpleKarmaCollision, see the CollisionTutorial document.

SimpleLineCollision - A staticmesh collision type that uses ZeroExtentTraces to calculate collision. For more information on SimpleLineCollision, see the CollisionTutorial document.

Skeletal Mesh - A character that can be animated using a skeleton and animations created in a 3rd party modeling program. For more information on setting a Skeletal Mesh, see the SkeletalSetup document.

Skeleton - The bones set up in a 3rd party modeling program for an animated character. For more information on setting a Skeleton for a character in Unreal, see the SkeletalSetup document.

Skin - The texture(s) applied to a mesh (staticmesh, skeletal mesh, etc.)

Skins Array - A field in the properties window that allows one to switch in different skins or textures onto a model. For more information about the Skins Array, see the WorkflowAndModularity document.

Sky Box - A SkyZone that uses a cube to create the illusion of a far off sky. See SkyZone.

Sky Cylinder - A SkyZone that uses a cylinder to create the illusion of a far off sky. See SkyZone.

Sky Dome/Sky Sphere - A SkyZone that uses a sphere to create the illusion of a far off sky. See SkyZone.

SkyZone - A scene that moves with the player's view and shows up behind everything else causing it to appear as if it is extremely far away to give the effect of a distant horizon or sky. For more information on SkyZones, see the ExampleMapsSkyZones document.

Snap - (Referring to Gird Snap ) A feature that aligns geometry to the grid whenever it is moved or rotated.

Sorting - Choosing the order or hierarchy of what the renderer will draw first.

Special Brush - A brush that is added through use of the Add Special Brush button that allows for not only a pull down selection of possible default Special Brushes as well as customizing a unique Special Brush. For more information on Specail Brushes, see the UnrealEdInterface document.

Special Lit - A property of an that allows it to only affect or be affected by "Special Lights." For more information on using the Special Lit setting, see the LightingReference document.

Sprite - A texture applied to a plane (usually used with particle systems).

Sprite Emitter - An individual emitter that emits sprites in a pattern that can be designed within the Unreal Editor. For more information on Sprite Emitters, see the SpriteEmitter document.

StaticMesh - (a.k.a. _Static Mesh _ ) A model created in a 3rd party program that remains stationary in the level when added to a map.

Subtractive BSP - BSP Space that has been subtracted from the solid and/or additive world space. Subtractive BSP is open space in the level that the players can walk around in. See BSP.

Surface - The visible texture of BSP.

Surface Properties - The attributes that can be assigned to a BSP surface. For more information on Surface Properties, see the UnrealEdInterface document.


Tag - The name given to a specific actor in the world under the events tab in the actor's properties window.

Targa - A file format for textures that the Unreal Engine can import.

Teleporter - An actor that can instantly send a player from one point in the map to any other point in the map or even a point in another map. For more information on Teleporters, see the ExampleMapsTeleporters document.

Terrain - (a.k.a. TerrainInfo ) A type of geometry in the form of a heavily tessellated sheet than can be deformed and sculpted using the Terrain Editor tool within the Unreal Editor. For more information on using Terrain, see the TerrainTutorial document.

Texture - An image file that can be assigned to geometry in the world. Materials are also sometimes referred to as Textures. For more information on Textures, see the UnrealTexturing document.

Trace - A line (for calculation purposes only) drawn from one point to another (such as from a gun to a target) that is used for determining collision.

Triangle - The smallest renderable building block of world geometry out of which everything in the scene is constructed.

Trigger - An actor that can be activate an event during game play.

Two Sided - A property that can be assigned to a texture and/or a BSP surface that will cause the rendered geometry with the texture applied to it to be seen from either side of the surface.


Ucc Make - A tool to compile UnrealScript. Typing "Ucc Make" into the command line will compile the UnrealScript.

UDN Build - A version of the Unreal Editor that has extra features and bug fixes provided by Epic and the licensee community built into it. For more information on the UDN build see the UDNBuildIntro document.

Umod - (a.k.a. Unreal MOD ) Platform independent archives that allow mod authors to ship their game content to unreal engine gamers. For more information on Umods, see the UmodInstaller document.

UnEdit - A mailing list available to all Unreal licenses that functions as a support group for the entire UnrealEd community. For more information about UnEdit, see the UnEdit document.

Unlit - A property for textures and geometry that allows that texture or geometry to appear full bright independent of how any lights in the scene would be affecting it.

Unreal Developer Network - (a.k.a. UDN )The team that supports the licensees of the Unreal Engine. For more information on the Unreal Developer Network, see the Main page.

UnrealEd - (a.k.a. Unreal Editor ) The editing tool that allows one to create playable interactive worlds.

UnrealScript - A simple coding language native to Unreal that can be used for creating scripted sequences (a series of actions) for AI as well as game events.

URU - (a.k.a. Unreal Rotation Unit; Unreal Unit) The unit of measure for units over distance or rotation in Unreal Ed. Note that in Unreal Rotation Units 16384 = 90�

UT - (a.k.a. Unreal Tournament) One of the titles released using a first generation build of the Unreal Engine. To see other first generation release titles, see the FirstGenerationTitles document.

UT2K3 - (a.k.a. Unreal Tournament 2003) a released title based on a heavily modified Unreal engine build 2110. For more information on UT2K3, see the UnrealTournament2003 page.


Vertex - ( plural Vertices ) One point of a geometry triangle

Vertex Color - A technique for tinting geometry by adding color based on vertices.

Viewport - A display window in the Unreal Editor that can show a front, side, top, or perspective views. For more information on Virewports, see the UnrealEdInterface document.

Volume - A 3D space that can effect various game play features such as movement, visibility, and player damage. For more information on Volumes, see the VolumesTutorial document.


WarpZone - A special zone that contains a WarpZoneInfo that allows players to instantly travel from that _WarpZone to another corresponding WarpZone. For more information on WarpZones, see the MirrorsAndWarpZones document

Wiki - A webpage formatting system that allows for easy and fast online maintenance. The UDN website is Wiki based.

Wiki wiki - Hawaiian for Fast.

X, Y & Z

Zone - An area in the level that is sectioned off by portals for optimization purposes. For more information on Zones, see the LevelOptimizationBSP document.

ZoneInfo - An actor that allows one to alter the properties of the Zone within which it resides.

ZBuffer - The section of video memory in a graphics card that keeps track of which onscreen elements can be viewed and which are hidden behind other objects.

ZeroExtentTraces - A trace that uses a 1 dimensional line traveling between a source and a target to determine collision.

ZFight - A flickery visual artifact that occurs when two surface either occupy the same plane space or are very close to occupying the same plane and space where the visible textures appear to "fight" for visual dominance.

Zone Portal - See Portal