C Glossary

C Glossary#

Vertex #: A point where two or more lines intersect. Polygon shapes have the same number of vertices as sides, e.g., a triangle has three vertices.
Array #: A linear data structure where elements are arranged sequentially.
Buffer #: A region of memory used to store data temporarily whilst it is transferred from one place to another.
Vertex Array Object (VAO)#: A container object for storing any data and attributes related to a vertex, e.g., co-ordinates, texture co-ordinates, normal vectors etc.
Vertex Buffer Object (VBO)#: The buffer where the values of the vertex attributes are stored, e.g., \(x\), \(y\) and \(z\) co-ordinates of the vertices.
Graphics Processing Unit #: The hardware used by a computer to output graphical information to the display.
Fragment #: A pixel or collection of pixels.
Shader #: A program that is performed on the GPU that determines how fragments as displayed on the screen.
Vertex shader #: A shader program that is used to transform the current vertex to the screen space.
Fragment shader #: A shader program that is used to calculate the colour of the fragment.
Uniform #: A global shader variable that remains constant for all vertices and fragments.
RGB #: A colour model where the colour is defined by levels of red, green and blue.
RGBA #: A colour model where colours are defined by levels of red, green and blue in addition to an opacity value Alpha.
Texture #: A 2D image that is mapped onto a polygon in the screen space.
Textel #: An individual pixel in a texture.
Texture co-ordinates #: The co-ordinates of a pixel (textel) in the texture.
Texture wrapping #: Controls how textures are repeated across a surface of a polygon.
Texture filtering #: Controls how the colour of a fragment is obtained from the texture.
Mipmap #: A duplicate of a texture and successively smaller resolution.
Vector (math)#: An object that has length and direction.
Matrix #: A rectangular array of elements, e.g., numbers.
Transformation #: The process of changing an object, e.g., changing its position, orientation, size etc.
Origin #: A point in a space with all zero co-ordinates.
Normalized Device Co-ordinates (NDC)#: A 3D right-handed co-ordinate system used by OpenGL where the camera is assumed to be at the origin pointing down the \(z\)-axis.
Translation #: Moving a point or set of points in a space by the same vector.
Scaling #: Changing the distance between a point or set of points from the origin.
Rotation #: Changing the orientation of a point or set of points.
Composite transformations #: The combination of a sequence of transformations.
Unit cube #: A cube with sides of length 2 parallel to the co-ordinate axes where the vertex co-ordinates are combinations of \(-1\) and \(1\).
Model space #: The space in which an individual 3D model is defined (also known as object space).
World space #: The space which contains the objects that make up the virtual world.
View space #: A transformed world space such that the camera is at the origin pointing down the \(z\)-axis.
Screen space #: A transformed view space that represents what is to be displayed on the screen.
Model matrix #: A transformation matrix used to transform from the model space to the screen space.
View matrix #: A transformation matrix used to transform from the world space to the view space.
Projection matrix #: A transformation matrix used to project the view space onto the screen space.
Z buffer #: A buffer containing the \(z\) co-cordinate of the nearest surface to the viewer (also known as a depth buffer).
Depth test #: A test applied to each fragment where only fragments that are closer than those currently stored in the Z buffer are computed by the shaders. Used to remove hidden surfaces.
Orthographic projection #: Transformation from the view space to the screen space where the \(z\) co-ordinate is ignored.
Perspective projection #: Transformation from the view space to the screen space which accounts for the distance of objects from the camera.
Field of View (FOV)#: The angle between the top and bottom edges of the screen space.
Aspect #: The width-to-height aspect ratio of the screen.
Near projection plane #: A plane parallel to the \(x\) and \(y\) axes that defines the nearest points to the camera shown in the screen space.
Far projection plane #: A plane parallel to the \(x\) and \(y\) axes that defines the furthest points to the camera shown in the screen space.
Pitch, roll and yaw #: Euler angles used for the rotations in the \(x\), \(y\) and \(z\) axes respectively.
Back face culling #: The removal of any surface whose normal vector is pointing away from the camera (known as back facing).
Local illumination model #: A lighting model where the colour of a surface is only determined by light emanating directly from light sources (also known as direct illumination).
Global illumination model #: A lighting model where the colour of a surface is determined by light emanating from light sources and that reflected off other surface in the scene (also known as indirect illumination).
Phong’s lighting model #: A local illumination model where the colour of a fragment is determined by summing ambient, diffuse and specular lighting models.
Ambient reflection #: A simplified model of the light reflected off of all objects in the scene.
Diffuse reflection #: A reflection model for light reflecting off rough surfaces.
Specular reflection #: A reflection model for light reflecting off smooth surfaces.
Attenuation #: The loss of light intensity over distance.
Normal map #: A texture map containing information for the normal vectors across a surface.
Tangent space #: A 3D space defined using orthogonal tangent, bitangent and normal vectors.
Tangent vector #: A vector pointing along a surface.
Bitangent vector #: A vector pointing along a surface that is orthogonal to the tangent vector.
Normal vector #: A vector pointing perpendicularly away from a surface.
Orthogonal #: At right angles to \(\ldots\)
TBN matrix #: The transformation matrix used to transform to the tangent space.
Specular map #: A texture map containing the levels or specular reflection across a surface.
Quaternion #: A 4D object consisting of a real part and three imaginary parts.
SLERP #: Spherical Linear intERPolation used to interpolated between points on a sphere.