Update: Still messing around with textures in general trying to get better spec and gloss definition also working on the lighting. feedback is more than welcome.
as you alreday wrote... ompared to "simple" textures, like diffuse, normal, spec, ao... ok, cool i thought they are much more expenisv on the performance...
Thanks guys! @malcolm, I colored the spec and am using Newton's rings as well. Download the material here: https://dl.dropboxusercontent.com/u/499159/glass.tbmat