You know I just found the "Serious Grass" example in AUM58. It just adjusts the roll of the grass object, and that seems to work fine for what I need at this point.

I'm still interested in seeing if this approach will work, but it's not as urgent as it was yesterday.

I'm using the animTree.fx file that comes with GStudio7 in the "code" folder. I'm not sure if it comes in A8.

If you are interested in helping me figure it out (I have very little knowledge of how shaders work) I can send you the file...