You need to explain this a little closer - seems like I don't get it right :) - layer 6 needs alpha, ok. But the other layers, I thought they have their vertex alpha set to zero as long as they don't show up. But now it seems they are all set to non-zero, but are only occluded? How can I optimize it then? I can ask if layer 6 is not zero, ok, but then I still don't know which other layer need to be displayed, unless I show / save them all.
Any hints for me here?
Any hints for me here?