GLSL - Parallax Shader

(parallax shader, offset mapping, and texel displacement shader)
http://www.opengl.org/sdk/docs/tutorials/TyphoonLabs/Chapter_4.pdf

- We’ve seen two advanced lighting shaders that can add a great deal of complexity and realism to our scenes, but when the camera gets closer to the surface, it becomes evident that the surface is plain. Neither bump mapping nor per pixel lighting can fix that.

-  Here we will learn an amazingly simple and cheap shader that increases the realism of our scenes by giving volume to our surfaces. This shader is known by many names: parallax shader, offset mapping, and texel displacement shader to name a few. We will call this shader “parallax shader” for now.