Texture Projectors

One of the main difficulties involved in texture mapping is that a rectangular map must often be applied to a non-rectangular region. In the case of a sphere, this is done by mapping uv- coordinates of texture space to the sphere's longitude and latitude.

Mapping strategies of this sort map surface coordinates to texture space coordinates by going through an intermediate mapping space. The topology of the mapping space is determined by the mapping mode. Most mapping modes require an object called a projector to perform mapping.