A triangle fan is a primitive in 3D computer graphics that saves on storage and processing time. It describes a set of connected triangles that share one central vertex. If N is the number of triangles in the fan, the number of vertices describing it is N+2. This is a considerable improvement over the 3N vertices that are necessary to describe the triangles separately. The graphics pipeline can take advantage by only performing the viewing transformations and lighting calculations once per vertex.
