Need Tangent

Hi @all,
I’m not sure if this is the right forum, but it seems to be a mathematical problem.
I need the tangent in a vertex shader. But I can the normal and the vertex position only. How can I calculate the tangent at that point?
I think that OpenGL SL does not provide a build-in function to deliver the tangent, or?

I cross posted this topic here:
But its in german, sorry. Just for your knowlegde.

You have to precalculate the tangents using texture coordinate information from adjacent vertices. Then send the tangents to a vertex program using a generic attribute array. Here’s some code that will determine the tangent direction at each vertex of a mesh:

– Eric Lengyel

Thanx Eric that will help.