Vertex (geometry)
In geometry, a vertex is a point where two or more curves, lines, or edges meet. As a consequence of this definition, the point where two lines meet to form an angle and the corners of polygons and polyhedra are verices. (Vertex (geometry) — Wikipedia)
Vertex (computer graphics)
A vertex in computer graphics is a data structure that describes certain attributes, like the position of a point in 2D or 3D space, or multiple points on a surface.
Application to 3D models
3D models are most often represented as triangulated polyhedra forming a triangle mesh. Non-triangular surfaces can be converted to an array of triangles through tessellation. Attributes from the vertices are typically interpolated across mesh surfaces.
Vertex attributes
The vertices of triangles are associated not only with spatial position but also with other values used to render the object correctly. Most attributes of a vertex represent vectors in the space to be rendered. These vectors are typically 1(x), 2(x,y), 3(x,y,z) dimensional and can include a fourth homogeneous coordinate (w). These valuse are given meaning by a material description. In realtime rendering these properties are used by a vertex shader or vertex pipeline.
such attributes can include:
Position: 2D or 3D coordinates representing a position in space
Color: Typically diffuse of specular RGB values, either representing surface colour or percomputed lighting information.
Texture coordinates: Also known as UV coordinates, these control the texture mapping of the surface, possibly for multiple layers.
normal vectors, tangent vectors, Blend weights, Blend shapes…
