ShadeC EVO has memory leaks and I wouldn't recommend using it. As far as I know, it doesn't have vegetation shaders. As I'm new to shaders in general, I can't migrate unity shader to the acknex, maybe txesmi might help, as he is a shader guru
Glad to hear that ENABLE_FRAME helped out. I would also recommend to not use while loops in general, but ENABLE_FRAME for cosmetics and on_frame for game mechanics.