The three virtues of a programmer: Laziness, Impatience, and Hubris. – Larry Wall


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Got a term that isn't described here? Add it to the list (at its appropriate place) and leave the explanation out. Somebody else will fill it in.

Contributors: Please read the Terminology Style Guide. Also please don't add random UnrealScript variable names to this page, it's not intended for that. (Use the Search instead, please.)


Abstract class 
a class which can't be added to a map or spawned in game and is thus only useful as a base class. See Class Syntax.
Accessed None 
UnrealScript warning message, meaning that code attempted to retrieve or alter data via an invalid object reference (also see Log Warnings)
Active brush 
another name for the red builder brush
object in three-dimensional virtual space
implementation, procedure, protocol, or sequence of rules or instructions, (usually for accomplishing a maths-oriented task) that specify the order and kind of arithmetic operations that are used on specified set of data, though technically, a cooking recipe is an example
Alpha Channel 
Information contained within an image file that can be used to determine the intensity of different material properties such as opacity and specularity intensity among other things.
Alpha Map 
An Unreal Tournament Map that is being tested by the mapper, and/or a few other, selected people.
Alpha version 
unfinished software version, not yet feature-complete; not ready for public release.
Series of pre-generated, articulated graphic components that convey character motion or behavior, during a scene display, and are called by the animation subsystem in specific game situations
System of smoothing out jagged edges on the screen. Video card renders at a higher resolution and then tones it down to your current set resolution.
Anisotropic Filtering 
System to improve quality of textures rendered at various angles.
Code expression that usually evaluates to true or false. Utilized to ensure that components behave properly; typically, checks on execution conditions and performance
Variable containing an ordered set of values of the same type, indexed by an integer
Artificial Intelligence; in game development, AI is a code subsystem that controls the behavior of agents (or Bot (UT)s, see Bot Support), objects, and numerous actors; the AI is responsible for realistic, or, intelligent, behavior of opponents during gameplay
synonymous to Property


Base class 
higher level, generalized class; used to define characteristics common to all its subclasses. ScriptedPawn is the base class for Unreal I monsters, for example.
Beta version 
unfinished software version, yet considered feature-complete, that's still in testing stage; not yet ready for public release
Bilinear Filtering 
see Bilinear Filtering.
bitmap file format (with no or lossless compression)
value that is either true or false
An object which describes the relationship of itself to other "bones." Bones usually have vertices attached which move with the bone, thus creating an animation without worrying about the placement of each vertex. See Skeletal Mesh
A computer-controlled player character
The gameplay as specifically related to Bot Support
piece of geometry that builds the virtual space
Binary Space Partition; static data structure method used by game programmers to determine correct front-to-back polygon visibility, so that scenes are rendered realistically
BSP hole 
building bug, yields unwanted invisible obstacles and players falling into geometry and dying


the class in the Unreal engine that is responsible for drawing items directly onto a player's display. The most common use of the canvas is in the creation and modification of a HUD.
see Typecasting
type of an object, an object's class defines how an object is implemented; derived from or instantiated by an object, from which it inherits clearly defined attributes. A class can contain: static data members, objects of another class, pointers and references to types and objects of the same or another class, declarations of another class, member functions, and friend classes. All Classes are listed in the Actor browser.
any linked user (another remote computer terminal, or program, or even another class) of another server, or program, or class is said to be a client of that entity.
software that parses a high-level language, and converts source code to a binary executable program, that will run on Windows, Unix, or some operating system.
method that is automatically called when an object is created; responsible for initializing this object; see Creating Actors And Objects.
Constructive Solid Geometry, the general idea behind building geometry in UnrealED.


code statement that doesn't produce executable code when compiled, but informs the compiler about new variables and functions (and their types, parameters, and so on)
method that is automatically called when an object is destroyed; responsible for releasing resources (memory, sockets, other objects) used by this object; see destroying objects
Dynamic Link Library, file containing native executable code that is bound to another application (or UnrealScript) at runtime
some sort of texture compression mojo. See texture format.
Effects in the map that the map designer put in to make the map more pleasing to the eyes and ears. Examples are Movers, Emitters, and Sounds.


an Actor responsible for creating a particle effect; there are two emitter classes in UT2003: Emitter and xEmitter
the underlying code framework which makes a complex computer program run.
ordered set of numeric constants whose values are automatically assigned during compilation (declared with the enum keyword)
Environment mapping 
dynamic UV mapping of a skin on a mesh, depending on the viewer's relative position, producing a mirror-like effect.
(1) an actor's or trigger's reaction to something, broadcast to actors with matching tags; (2) UnrealScript function called from native code.


see Polygon
a texture Modifier
numerical value capable of storing numbers with digits after the decimal point (like 3.142)
Forward kinematics (FK) 
A term used in skeletal animation, indicating that motion in a skeletal hierarchy (a set of connected bones) is transferred down the hierarchy. Example: rotation applied to a shoulder joint results in rotation of the bones below that joint in the skeletal chain : upper arm, forearm, hands, fingers or claws, etc. See also Inverse kinematics (IK).
Field Of Vision (or: Field Of View)
piece of code with a defined entry point and one or more exit points
Function call 
request for an object to carry out one of its operations. Code command within a program that jumps to a different portion of the code and returns to the statement following the call after executing that code (and may return a data value to it). The function return can be a value, a reference, or a pointer.
Function overriding 
see Overriding
Function prototype 
see Prototype


16 bit grayscale texture. See texture format
the playability of a game or an element of a game or map; it's relative value in terms of play
a way to implement a mod; specifies basic rules for playing the game (e.g. CTF: get enemy flag and touch your own with it); can be further modified through mutators
Garbage collection 
automatic destruction of unreferenced objects (as in Java, Perl or UnrealScript)
Gimbal lock 
occurs when rotations in successive axes make further rotations either impossible or produce undesired results.
Body parts that fly everywhere when you blow somebody up.
Gold Version 
Version released to the public after the Alpha and Beta versions.


Hidden variable 
a variable defined in a class but not accessible in UnrealEd's Actor Properties Window. This is done with the variable syntax var instead of var().
an ordering of things (such as objects, classes, people) in a tree-like structure, where things descend or depend on their superiors. Examples: a family tree, the military chain of command. Superseding values affect preceding values, but not vice versa.
Hall Of Mirrors effect, a rendering bug
Heads-Up Display, rendered on top of the in-game 3D viewport and displaying in-game data like frags, weapons, ammo and scores


program code structure that accomplishes some task or sequence of functions (see also Interface)
relationship among classes wherein one class shares the structure and/or behavior defined in one or more other superclasses
creation of an object from a class, each object having a copy of its own (non-static) data members
a Pawn which is considered responsible for the damage done by one actor to another; an Actor class property; often used for the InstigatedBy or EventInstigator parameters of Trigger() and TakeDamage() functions
numerical value, a whole number without decimals (like 10)
user's or client's perception of an object; object-oriented data abstraction is to provide a clean and efficient interface that allows the user to access the underlying implementation
Inverse kinematics (IK) 
A term used in skeletal animation, indicating that motion in a skeletal hierarchy (a set of connected bones) is transferred up the hierarchy. Example: Positioning a hand bone at the end of a skeletal chain results in joints further up the chain (e.g., forearm and upper arm) being relocated as needed. See also Forward kinematics (FK).
special function that allows iteration over all or a given subset of all objects, using a foreach loop


a NavigationPoint actor indicating a good place for bots to jump to, not from. Also indicates a good point for translocation, double-jump, impact-jump, etc.


a Level Properties setting of the lowest altitude that a Pawn can exist. Lower than this altitude, the Pawn is killed. See also StallZ.


A combination of the lights in the levels, and the light-maps that are overlayed onto walls, giving the impression of lights on those walls.
Linked List 
List consisting of objects where each item has a reference (link) to the next one.
Level Of Detail. Allows high-end machines to display fancy detail (eg weather effects) and low-end machines to just show the essentials. Also allows details to be skipped at farther distances, improving performance. (which allows more details to be shown at closer distances) See, for example, Chain Of Events When Spawning Actors.
text file which the game writes as it executes.


Map Flow 
Map layout design that promotes smooth, fast and exciting gameplay
color blending type; makes part of a Texture (UT) transparent (see color blending)
rectangular image (bitmap) that can be applied to brush surfaces and meshes or directly drawn on a canvas; also see texture
three-dimensional representation of an Actor in virtual space (like weapons, pickups, players)
function (piece of code) that deals with objects of a given class; defined by the object's class
short for modification; modification of a game can add new rules or content and in UnrealEngine games (like Unreal or Unreal Tournament) a modification can be implemented as a Mutator, a gametype, a total conversion, a player model, a VoicePack, an AnnouncerPack and a few other ways
color blending type; mid-gray is transparent, black and white are opaque (see color blending)
movable Brush (for doors, elevators and visual effects)
a way to implement a mod in UnrealEngine games; mutators usually just change a certain aspect of the game, but there are also mutators with large scale modifications (e.g. weapon mods, competitive mods); mutators are stackable with other mutators to combine their modifications
a special name for a package. Using this tells UnrealEd to embed a resource in the current map file.


unique specifier for an object or class (or something else) in UnrealScript; unlike strings, can't be modified like a string value and may not contain anything except letters, numbers and underscores
Native code 
code that can be interpreted by a computer's processor without any intermediate steps. In Unreal, this is C++ code in DLL files.
a person that's new to and hence unexperienced in something.
same as Newbie, but is contemptuous (is that a good word for them?) about being that. They are sometimes poseurs.
the polys that are seen in Zone/Portal view. They correspond to surface polygons split by BSP cuts. See polygon and node count.
Node count 
a measure of how much rendering work the engine has to perform to display a view of a map. Also the total number of nodes in the name.
Texture(s) that is missing or can not be found. These null textures are given a default texture used by the engine (The green bubbly texture).


Creating code that works but is difficult to understand or work out what it actually does.
abstraction that typically is assigned clearly specified characteristics; in other words, a chunk of data with a certain class associated to it; the class describes the data structure and contains the code that deals with objects of that class
Object Collision Detection
Object Oriented Programming
Overloading (a function
redeclaring and reimplementing a function with the same name as an existing function, but a distinguishable set of parameters (like having two versions of a function, one of them working for float parameters, one of them for integer parameters)
Overriding (a method
redeclaring and reimplementing a method in a subclass
Overwriting (a method
see Overriding (a method)
Constant Actor declared in the Actor class, specifies who or what owns this object. Use native SetOwner( actor NewOwner ); to set the owner.


a file containing resources for Unreal engine games (like code, decorations, sound, music, maps, or all of it)
Pathing or Bot Pathing 
supporting bot navigation of a level (see Bot Support)
look-up table of colors used in a bitmap
The parent class of all creatures and players in Unreal which are capable of high-level AI and player controls.
bitmap file format (with no or lossless compression)
point about which a brush is rotated or scaled.
variable that "points to" an object's memory location; in UnrealScript, all object variables are (typed) pointers, but there's also an unspecific pointer variable type that serves as a placeholder for C++ pointers in native code
either number of polys currently drawn on screen by the engine, or the total number of polygons in the map.
two-dimensional, flat, closed shape in three-dimensional space, like a brush surface. Currently Unreal Tournament only supports convex polygons.
A collection of Actors, such as CSG brushes and/or lights that can be copied and used over and over again in a map. ( Useful for distributing map parts without sacrificing storage space since a .t3d (Unreal Text) file is much smaller than a .ut2 file )
Private (method or property) 
not accessible from outside the class this method or property has been declared in (see Public (method or property))
Probe function 
A function that can be enabled or disabled using the Enable and Disable methods. These functions are usually defined as "events" and are called by native engine code.
individual item of an object's data; defined by the object's class
number, order and types of function parameters
UT2003's replacement for the deprecated Decal class. Allows for projected shadows (ShadowProjector class) and other neat stuff.
Public (method or property) 
accessible from outside the class this method or property has been declared in (see Private (method or property))


a single grid element of terrain.
mathematical entity similar to a complex number. These can be used to represent 3D rotations in a way that eliminates the gimbal lock problem with non-l33t rotational matrices; popular with game programmers for this very reason


Ray tracing 
Calculating the lighting in a level by tracing exactly where the light goes.
red builder brush
subsystem that actually produces the visible scene that is displayed on the computer terminal for players to yell at; consumes the majority of CPU computing capacity
generic term for sending game-relevant data back and forth between a network server and its clients
texture format with three channels (red, green, blue) and 8 bits per channel
texture format with four channels (red, green, blue, alpha) and 8 bits per channel


"Sudden Heart Attack Syndrome". Dying for no apparent reason. Sudden cratering is usually caused by BSP holes (see 'BSP hole').
a brush which does not enclose a 3D volume, usually because it's a single polygon.
generic term for simulation or prediction (not authoritative) of game behaviour on network clients
Skeletal animation 
mesh animation by having vertices attached to interlinked bones; see Animation
set of textures that are applied to a mesh (for instance, a Bot (UT), a player or a decoration)
Sky box 
see page
see page
Source (code) 
original high-level computer language code, like C++ or Java, that is compiled into an executable program
UnrealScript command for creating a new Actor
an error condition during map Playtesting where the player character repeatedly dies, as if automatically suiciding.
a Level Properties setting of the highest altitude a flying Vehicle can fly before it's thrust power is deactivated. See also KillZ.
a concept in UnrealScript that allows actors to execute different code in different circumstances. For example, a Bot can be 'Fleeing', 'Attacking', etc. See State and also InitialState
State code 
code that is outside of functions in a state block
Static Mesh 
see page.
ordered arrangement of typed data items; similar to a class in UnrealScript, but can't be referenced (only copied) and doesn't have methods
value of text; for instance, a message somebody typed in
class derived from another class (its base class, or superclass); inherits properties and methods from the superclass unless they're expressly overwritten
see page.
the rule of arranging and ordering commands to form a code. UnrealScript grammar, if you will; see class syntax and function syntax


Texture pixel (as opposed to screen pixel)
Text Parsing 
the act of using a routine or function of some sort to change symbols in a string variable to reflect the values of certain variables, e.g. replacing "%k" in a death message with the killer's name; see Message Placeholder
rectangular image (bitmap) that can be applied to brush surfaces and meshes or directly drawn on a canvas; special type of material
Total conversion 
mod attempting to totally change the underlying game into a different game by providing all-new content (game types, user interface, weapons, maps, models, menus)
follows a straight line through the world, usually until it hits solid geometry. Usually used to determine where bullets hit.
color blending type; black is transparent, white is opaque (see color blending)
An actor in a level which, when touched, will activate some effect, or other event.
converting one type of variable to another (e.g. Float to Integer)


UC file 
An UnrealScript source code file (Unreal Class), readable in any plain-text editor.
UT's and UT2003's sounds format.
UnrealScript execution environment, ucc.exe in the System subdirectory
Unreal Mod installer
UT's music format.
(Texture (UT)) rendered without any lighting applied to it; yields a bright, uniform appearance
USA file 
In Unreal 1, Unreal 2, and OldSkool for UT, a file created to save data from a singleplayer game in progress.
UT2003's UMOD format
Unreal units, used to measure and specify lengths within the engine's virtual space
UV mapping 
two-dimensional application and alignment of a skin on a mesh


memory location with a symbolic name where a program can store information for future retrieval
point in (normally two- or three-dimensional) space; point where polygon edges meet
Vertex animation 
mesh animation by playing a set of different, fixed vertex arrangements (like stop-motion animation in movies); see Animation
Window in UnrealEd which shows one view of the map that is loaded; a class in UnrealScript that represents the local player


collaborative, open project on the web, gathering knowledge on a certain topic
special kind of zone. A WarpZone's portal renders what can be seen from the destination portal, and also teleports players and objects which enter it to the destination portal.


The third axis in a 3D co-ordinate system. In FPS games, this also refers to things (architectural detail, enemies, etc) being above or below the player.
Portion of a map's space that is sectioned off, either to achieve special effects (gravity, water, etc.) or for engine optimization
Zone portal 
Type of polygon (usually built with a sheet brush) which tells the engine where zone boundaries lie.

Related Topics[edit]

Some other pages that may help:


Sweavo: I would have thought UScript's semantics would be better thought of as references rather than pointers, since it's not meaningful to increment a reference, whereas incrementing a pointer has some meaning, albeit ill-defined...? Also since non-native functions are executed in bytecode (aren't they?) then actual pointers (in the hardware sense) are not passed around in executing unrealscript are they? I imagined array indices.

IceCreamYou: I took the liberty of adding a link to my own Key Terms page... I can't guarantee there aren't a few errors, but it is a very complete list.