graphics - openGL - creating a bending surface -

I'm studying Open GL for a while, I want to change the effect of the page, but the pages themselves Should "turn", now I am thinking how to turn a surface and animate it in Open GL.

Or with many branches, perhaps a single shader with

Varies in the form of radius and the highest angle. Div class = "post-text" itemprop = "text">

There is a tutorial for iOS that runs through mathematics is the original letter by Xerox PRC.

Hope it helps!