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2.5D

Used to describe raycasting engines, such as Doom or Duke Nukem. The maps are generally drawn as 2D bitmaps with height properties but when rendered gives the appearance of being 3D.

3D

Used to describe raycasting engines, such as Doom or Duke Nukem. The maps are generally drawn as 2D bitmaps with height properties but when rendered gives the appearance of being 3D.

3D

Refers to the ability to move in the X, Y and Z axis and also rotate around the X, Y, and Z axises.

 

A

Axis-aligned Bounding Box (AABB)

A form of a bounding box where the box is aligned to the axis therefore only two points in space are needed to define it. AABB’s are much faster to use, and take up less memory, but are very limited in the sense that they can only be aligned to the axis.

Albedo

An albedo is a physical measure of a material’s reflectivity, generally across the visible spectrum of light. An albedo texture simulates a surface albedo as opposed to explicitly defining a colour for it.

Alpha Blending

Assigning varying levels of translucency to graphical objects, allowing the creation of
things such as glass, fog, and ghosts. This can be accomplished by using alpha channels.

Alpha Channel

The optional channel of image data in a texture file that can be used as a transparency map, height map, specular map, etc. The format of the alpha channel is usually 8 bits per pixel (256 colors), though certain file formats support different bit depths.

Alpha Testing

A method for creating transparency by checking the alpha value of a given pixel.

Animatic

An animated storyboard which is used to refine timing, cameras, composition, when a complex shot is needed and static images have trouble making intention clear. When needed, low-resolution animated 3d scenes are used, intermixed with the remaining 2D storyboard panels.

Anisotropic Filtering

A texture filtering method, specifically for non-square filtering, usually of textures shown in radical perspective. Generally speaking, anisotropic improves clarity of images with severely unequal aspect ratios.

Anti-aliasing (AA)

Removes the stair-stepping or jaggies which occur at the edges of polygons or between the texels on the polygons. The way this works is by interpolating the pixels at the edges to make the difference between two color areas less dramatic.

Artificial Intelligence (AI)

A set of computer instructions or algorithms designed to simulate the actions of an intelligent being to the extent necessary to meet the design requirements of a game.

ASCII

An acronym for the American Standard Code for Information Interchange, which is an encoding method for text, based on the English alphabet.

Aspect Ratio

A number that describes the shape of a rectangle texture, whether it’s tall or wide. To calculate an aspect ratio, either divide the width by the height, or write it out as width:height. 

 

B

Back Buffer

A secondary surface where the current frame’s graphics are stored before they are transferred to the primary display surface.

Backface Culling

The process of removing the unseen polygons that face away from the camera in the game. These surfaces are usually not needed (except sometimes for shadow casting). Doing so can dramatically speed up the rendering of a polygonal scene.

Bezier Spline

This type of spline provides the ability to make a curved line using very few points. The two endpoints of the curve are called anchor points. The other points, which define the shape of the curve, are called handles, tangent points, or nodes.

Billboard

A term commonly used in games to describe a camera-facing plane. This is a polygon with a texture using transparency, that rotates on various axes to always face the player. Billboards are commonly used for particles, trees, grass, clouds, and UI elements.

Bit depth

This value defines the amount of color information an image holds. Typically 1-bit is two colors
(black and white), 2-bit is four colors, 4-bit is sixteen, 8-bit is 256 colors, and 16-bit is 65536 colors.

Bitmap

An image file, such as JPG, TIF, PSD, and BMP.

Binary Space Partition (BSP)

A BSP tree subdivides 3D space with 2D planes to help speed up sorting. In game development, BSP usually means using solid modeling techniques to carve the basic surfaces of a game level.

Bloom

A post-processing effect which simulates bright light sources overwhelming a camera or the eye, creating a halo around the brightest parts of a scene.

BMP

A Bitmap file type used in game development, for storing source files. This is an intermediary format for use outside of a game engine. Usually then imported and converted into a different in-game format.

Bounding Box

A simplified approximation of the volume of a model, most commonly used for collision detection. It is common place to find referenced in code axis-aligned bounding box (AABB) and oriented
bounding box (OBB).

Bump Mapping

A process of rendering polygons that gives them an illusion of depth.

 

C

Camera

typically the camera in a game is the player’s view into the game scene. Cameras can also be used
for other views in the game level, for example a virtual security camer can use “render to texture“ to show the player alternate views of a game level.

Cartesian Coordinate

The standard coordinate system. With three dimensions, there are three scalars, x, y, and z used to represent a point at a given distance from a reference point, the origin.

Cel Shading

A technique which causes rendered objects to look as though they are hand-drawn, cartoon
images.

Channel

Commonly used to describe a color component that makes up an image. A 24-bit image can have
red, green, and blue channels. 32-bit images have room for a fourth channel, commonly known as an alpha channel.

Child

Any node in a hierarchy that is attached to another node.

Clipping Plane

This plane throws away polygons on the other side of it. This can dramatically speed up the rendering of a polygonal scene, since unneeded polygons can take up valuable processing power.

Collision Detection

The systematic check to see if any intersections are occurring between significant polygons. A common method to optimize collision detection is to use a bounding box to simplify collision
shapes.

Compile

Programmers have to convert source code, written in a high-level language such as C++, into
object code (aka Assembly), so that a microprocessor can run the application.

Concave

Defined where any two points can be connected by a line that goes outside the shape. When
visualized the shape takes the formation of the letter C.

Convex

Defined where any two points can be connected by a line that goes outside the shape. This is a
shape without indentations and is the opposite of a concave surface.

Corona

Artifacts that appear around a bright light source. Often in circular or star like shapes.

Cross-product

Commonly utilized to compute something known as a surface normal. As by the cross product formula, a normal is simply a vector that is perpendicular to some plane. In graphics, this plane is
usually a polygon of some type.

Cube Mapping

an alternative to sphere mapping used in environment mapping, cube mapping gets a ‘screenshot’ looking in 6 different directions and arranges them in a rolled out cube. When applied, the object appears to reflect the environment around it.

 

D

Depth Cueing

Scene effect to make objects that are farther away from the camera are rendered with a
lighter color so that they are given the illusion of distance.

Dithering

Process of creating an illusion of more colors than are really available in the current color depth
by creatively arranging individual pixel patterns.

Draw Call

These calls are based on how many objects are drawn to the screen. A good way to think about
this is 1 material = 1 draw call, and an object with 4 materials = 4 draw calls. This can grow exponentially when incorporating the lighting and shadows in a scene.

Draw Order

the way to define what polygons are drawn in a game engine. Back-to-front draw order means the furthest polygons are drawn first, and the rest are drawn on on top of another, with the last to draw being the one that appears to be in front. This can also be referred to as “sort priority” regarding transparent polygons as well.

Dynamic Lighting

The definition of dynamic lighting is a light source that is updated every frame, as you’d want for moving lights and for characters that move amongst various light sources. The opposite of dynamic lighting is “baked” lighting through lightmapping.

 

E

Engine

A game engine is what converts all the game assets into the display on your computer screen. Game engines often come with a level editor and other tools which help artists create content that work well in the engine.

Environment Probe

An effect where an object reflects its surroundings, much like chrome.

Expression

An expression is a formula used to create procedural animation, often using mathematical elements like sine and cosine. Expressions can automate and greatly speed up repetitive animation tasks.

 

F

Face

Face is another name for a Polygon. This term can be used specifically for a single triangle or more generally for a multi-triangle polygon.

Facial Action Coding System (FACS)

A system to taxonomize human facial movements by their appearance on the face, Movements of individual facial muscles are encoded by FACS from slight different instant changes in facial appearance. It is a common standard to systematically categorize the physical expression of emotions, and it has proven useful to psychologists and to animators alike.

Field of View (FOV)

The FOV is usually defined by its width in degrees. A typical FOV in games is around 60 degrees, although players enjoy being able to change the FOV themselves.

Flat Shading

Assigning only one color shade per face.

Fog

Fog makes objects become more and more the same color as they recede into the distance. This is similar to real fog, except that game fog is a perfect gradient, whereas real fog usually has some wispy qualities to it. Heavy fogging in a game is used to disguise the far clipping plane.

Forward Kinematics (FK)

A method of manipulating objects in a hierarchy where the animator positions objects and the program calculates the positions and orientations of the objects below it in the hierarchy.

Frames Per Second (FPS)

A measure of animation display rate. Not to be confused with the genre First Person Shooter.

Frame Buffer

What a video card uses to store the images it renders, while it is rendering them. When it is
done rendering, it sends the completed frame to your monitor and starts building the next frame.

Frame Rate

Measures how fast the game is being rendered. Generally if the frame rate is lower than 30
frames per second, then the game will seem “choppy” and unresponsive.

Frustum

A term from traditional photography, the shape that the camera creates when projected into the
scene. This pyramidal shape defines the limits of what the viewer can see, so it is used to calculate clipping, collisions, Fog, etc.

 

G

Geometry

Geometry is commonly used to define all polygonal objects in a game. Also called a mesh.

GIF

Graphics Interchange Format. A format for saving graphics that usually uses a 8-bit (256 color)
indexed bitmap.

Gimbal Lock

A problem encountered when one tries to rotate using the 3 axises where one ends up rotating in the wrong direction after several rotations.

Gouraud Shading

Also known as intensity interpolation. A shading model where the light intensity is calculated at each of the vertices, and is interpolated across the polygon.

GUI

Graphical User Interface.

 

H

HDR

Real world lighting contains a high range of luminance values. HDR, or High Dynamic Range lighting, is essentially a technique that exceeds the normal computer graphics color range of 0 to 255, allowing for more realistic lighting models.

Height Map

A method often used to create 3D landscapes, height maps contain a grid of points that are
given height values and the landscape is rendered by building polygons out of them.

Hierarchy

Existing where each node can trace its lineage up through this upside-down tree, back though
parents to the root. If you choose any parent, then you can call its collection of children a branch of the tree.

HUD

Heads-Up-Display. This means status information which are always visible like health or ammo information.

 

I

Indexed Color

When color information is stored in a look up table that contains the colors red, green and
blue information.

Interpolation

The process of determining from two or more values what the “in-between” values should be. Interpolation is used with animation and with textures, particularly texture filtering.

Inverse Kinematics (IK)

The process of creating realistic positioning of a complex object, such as an arm, based on the positioning of a lower-level node in the skeletal hierarchy, such as the twisting of a hand. This process works in the reverse of forward kinematics.

 

J

JPEG

A bitmap file type used in game development. This format is often used for web games, because it
can be highly compressed for faster download. After the download it is usually converted into a different in-game format to use in the game.

 

L

Lerp

An abbreviation for Linear Interpolation.

Light Mapping

Traditionally, light maps store the color and brightness of pre-baked lighting. The Diffuse map is applied to the mesh with no lighting, and the light map is then multiplied against it, darkening the diffuse where the light map has shadows.

 

M

Mapping

This can either mean texturing or it can mean creating texture coordinates.

Material

A set of parameters that determine the textures, color, shininess, smoothness, etc. for a surface. A
material is the user interface for a shader; the shader controls how the surface is rendered, while the material merely stores the user-adjusted settings for the shader.

Material IDs

Used to split a model’s surface into multiple Materials. Normally a model can only use a single material. However a number can be assigned to sets of polygons which each correspond to a particular material.

Memory

The amount of quickly-retrievable space for storing the assets currently being used by the game.
Games use a number of different types of memory, but game artists are mostly concerned with RAM. The biggest question for the artist is how much RAM is available for textures.

Mesh

Another word for geometry, or polygon.

Mip Mapping

To render a texture more smoothly in a game, it is resized multiple times to make “mips,” which are smaller versions of the texture. These smaller versions are swapped or blended with the original texture as the texture recedes in the scene.

Morph

An animated 2D or 3D effect that makes one texture or geometry smoothly transform into another.
When used with models, all the shapes must have exactly the same vertex count, and vertex order. The individual mesh shapes are called blend shapes, or morph targets.

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