Page "Texture mapping" Paragraph 3

A texture map is applied ( mapped ) to the surface of a shape or polygon.

This process is akin to applying patterned paper to a plain white box.

Every vertex in a polygon is assigned a texture coordinate ( which in the 2d case is also known as a UV coordinate ) either via explicit assignment or by procedural definition.

Image sampling locations are then interpolated across the face of a polygon to produce a visual result that seems to have more richness than could otherwise be achieved with a limited number of polygons.

Multitexturing is the use of more than one texture at a time on a polygon.

For instance, a light map texture may be used to light a surface as an alternative to recalculating that lighting every time the surface is rendered.

Another multitexture technique is bump mapping, which allows a texture to directly control the facing direction of a surface for the purposes of its lighting calculations ; it can give a very good appearance of a complex surface, such as tree bark or rough concrete, that takes on lighting detail in addition to the usual detailed coloring.

Bump mapping has become popular in recent video games as graphics hardware has become powerful enough to accommodate it in real-time.