hm ... thanks for your thoughts .. i think the angle between two vectors can be calculatet with the dotproduct divided with the magnitude of the vectors.... my problem is that i don't know how to tell the shader to look at EACH adjacent vector. thank you maybe i am askig the wrong questions ... basicly i just want to do what the groupsop method edward metioned does, but in shading context with a smooth falloff.... some further suggestions would be great