The Nature Demo on this page http://www.ati.com/developer/demos/r8000.html does some simple animation of a field of grass using a few Taylor Series sine waves. The lighting is done by using the same sum of sines to lerp between yellow and green, rather than actually do any lighting math. The details are discussed in the first ShaderX book (www.shaderx.com) in a chapter called "Animated Grass with Pixel and Vertex Shaders" by John Isidoro and Drew Card. There is nothing really sophisticated going on here...just a simple way to give a sense of motion that looks something like a field of animated grass...
Let me know if you want the actual shader code.
From: Andrey Iones [mailto:email@example.com]
Sent: Wednesday, January 28, 2004 1:40 PM
Subject: [Algorithms] Grass animation
Can anyone share the experience of grass field animation using vertex shaders?
Project Leader PhD in Computer Science