# Tangent Vector

Anisotropic raytraced reflection uses the same tangent vectors as for tangent shading…
I would like to understand, how anisotropic reflection are “realy” working". For that it seems I need a better understanding what`s behind the concept of tangent vectors. Can somebody give a breeve explanation. Links to websides (without many formulars - but many pictures) are wellcomed.

In basic terms, a tangent vector is used to determine the orientation of a face, they’re kinda like two vectors that define the X and Y axes of that face, which can be used to define a co-ordinate system with the tangent X and Y was the ground plane, and the face normal as the Z/up axis. Generally when you’re rendering, it just considers a pixel/point at a time, and it doesn’t have any idea of which way that face is pointing. So if you want directional shading, you need to have some reference for what that direction is, which is encoded in the tangent vectors.

Thank you very much. I found an explanation a little bit more deatiled than yours

What confused me is “tangent”, because it is used in another meaning than normally in mathematic. But anyway - your explanation was very helpfull.

you mean tangens?