Thanks a lot for all your comments! Please go on giving suggestions as they really help me noticing things that arent that good.

@sivian: i will try your idea with the grass groups out to see how it looks. but we have always to remember that we cant have an unlimited number of grass entities to keep the fps as high as possible. Therefore we always have to find the right detail/fps ratio!

@slin: Yes, i know, the watershader does not look that good. What i really like to have is a reflect/refract shader... if anyone know a free, good looking shader, please tell us... (but it has to work with shade-c)