UserWiki:DavidJCobb/Glitch Glossary

Here is a glossary for glitch-related terms. It is sorted alphabetically.

Actor

Though the term varies from game to game, "actor" is generally used to refer to anything that is not terrain -- any interactive or mobile object, ranging from Grunts to Deployable Lookout Towers to the Master Chief himself. Weapons and vehicles are also actors.

Array

An array is a data structure consisting of a list of numerically-indexed values.

Backface culling

Backface culling is a 3D rendering technique that causes polygons to only be visible from one side. It can also cause polygons to only be solid from one side -- one-way walls.

Bit

A bit is a single zero or one, in binary.

Byte

A byte is eight bits. A variable capable of holding one byte can hold any value between 0 and 255, inclusive; a signed variable can hold between -128 and +128.

Clipping

Used in some circles to refer to a flaw in collision detection. Collision detection checks the current frame of animation for collisions, with no regard for the previous frame. If an object is moving extremely fast, it may be in front of a wall in one frame, and behind the wall in the next frame of animation. As collision detection engines cannot check between frames, the game will never "notice" that the object went through the wall.

Collision

A collision is any contact between two objects, in 2D or 3D games.

Collision detection

Collision detection refers to both the act of detecting a collision and the program or mechanism used to do so.

Collision mesh

A collision mesh is the 3D shape used to check for collisions. Generally, an object's collision mesh is not as ornate or detailed as its actual 3D model; a vase may have a very detailed 3D representation, but its collision mesh may be just a simple cylinder.

Such separate collision meshes are used to simplify physics calculations and collision detections.

Death plane

See kill barrier.

Exception

An exception is any error that occurs during gameplay. Generally, only fatal exceptions -- those that crash the entire game or program -- are noticeable.

Flag

A flag is a simple on/off or true/false value used to signify some state or condition. Specifically, a flag is a variable that holds a single bit.

Hall of mirrors

A rendering glitch that occurs when nothing is drawn on a part of the screen. When this occurs, whatever was on that part of the screen in the previous frame remains there, creating a "hall of mirrors" or "afterimage" effect. An example can be seen in this screenshot from Doom.

Hexadecimal

Hexadecimal, also referred to as hex, is base-16 encoding. It is commonly used as an intermediate numerical form, between binary (base-2) and decimal (base-10). Valid digits in hexadecimal are 0-9 and A-F. In the same way that any data can be represented in binary, any data can be represented in hex.

Hex is typically used for memory addresses and numerical variable values, which is why it is frequently used in cheat code devices. On a side note, it is also used to format colors in HTML and CSS.

Infinite void

An infinite void is the empty space surrounding all levels and all maps in all 3D games. As maps do not have a fixed shape or size, they are always surrounded by voids. In some games, voids have a solid color; in other games, such as Halo 3, voids exhibit a hall of mirrors effect when seen.

Contrary to popular belief, and despite what the name implies, infinite voids are not infinite. In Halo 3, "infinite" voids are cubic, being no larger than 100,000 world units along any of the standard three axes.

Invisible wall

Main article: Invisible Walls

An invisible wall, typically used by developers to block access to certain areas, and to keep the player inside of the level boundaries.

Kill barrier

Main article: Invisible Walls

A kill barrier is a plane or surface that kills the player upon contact. Typically used to facilitate bottomless pits and falling deaths, they are very abundant in Halo, being used to supplement nearly every invisible wall in the game.

Level boundaries

The level boundaries are the edges of the playable area -- that is, the edges of the normal area of a map that the player is allowed to explore. The term is typically used to refer to the collection of invisible walls that surround the playable area.

Loading point

A loading point is a point at which most of the area behind the player is removed from RAM, and the area in front of the player is loaded into RAM. In non-linear games and levels, players can pass back and forth between a loading point, "toggling" the areas on either side. In the Halo series, loading points are indicated by a "Loading... done." message shown above the Motion tracker.

Typically, loading points do not load or unload level geometry, but they do load and unload textures and actors. In most games, bypassing a loading point generally allows a player to access the area beyond it in a semi-loaded state, with most surfaces being invisible and no actors being present.

Halo appears to use a slightly different system, as demonstrated by the ability to access areas that should be unloaded in a usable state using the Time Travel Glitch.

Moonjump

The term "moonjump" is used to refer to any event where an object very rapidly ascends to an astonishing and physically impossible height. Moonjumps occur, for example, in Super Bounces.

Object

In computing, an object is a data structure that is composed of properties. A property can be thought of as a "sub-variable".

Overflow

Numerical overflow occurs when a variable is not large enough to hold its value. Variables are limited in size, so it is possible to store a value larger than what the variable can hold. Variable sizes tend to be powers of two; common limits for unsigned variables are 255 and 65535.

When overflow occurs, it is typically handled in one of the following ways.

• A fatal exception occurs, and an error is thrown.
• The value is rounded to the largest value the variable can hold.
• The value "wraps" around. If a variable that can only hold 255 is assigned a value of 257, the variable's value becomes 1 (257 - 255 - 1).

Polygon

A polygon is a triangular or rectangular shape, typically combined with others to create 3D objects.

Polygon seam

A polygon seam is an edge where two polygons meet. Seams that form large, sharp angles can sometimes be glitched through or even walked on, as though they were a single flat surface.

Sign bit

All numbers are stored in binary -- base-2, zeroes and ones. When a variable needs to hold a negative value, it is given a sign bit -- one of its bits is converted into the sign bit. If the sign bit is a 1, the value is negative; if the sign bit is a 0, the value is positive. The allocation of an extra bit cuts the variable's maximum value in half.

Skybox

A skybox is a 3D shape placed around the level. The shape, typically a cube or a sphere, is given a sky texture to simulate a real environment with a real atmosphere. In Halo 3, skyboxes tend to be far larger than the actual playable area of their containing maps.

String

In computing, a string is a text value.

Stutter

"Stutter" is used to describe the phenomenon in which an object rapidly jumps back and forth between two very close positions. It can often happen when running into a very small, sharp polygon seam.

Variable

A variable is a name that is used to refer to a value, similar to mathematics. In computing, variables are limited in size; if a program attempts to store a value that is too big for the "target" variable to hold, overflow occurs.

Variables can also hold text, lists, and objects.

Void

See infinite void.

Warp

In tile-based games like Pokemon, "warp" is used to refer to invisible objects placed on tiles that cause the player to teleport to another location when stepped on. Doors in such games do not change the player's position; the invisible warps placed over them do.