Thank you guys for attention)
Steven i was using this model at the very first time.
Yarfapet i am already using such model right now.
But this is all about LOS using, i'm looking for solution without it atm.
[quote="Steven":3t2t7ilv]I had a little play, you sparked an idea[/quote:3t2t7ilv]
Well Steven, here's another idea, which gpu consumption goes in geometrical progression (that's why i've dropped it), but in some cases may come handy. Great for precise calculating of visible-invisible area. Here's a cap [url:3t2t7ilv]http://www.box.net/shared/bkjyg0894s[/url:3t2t7ilv]
also you need this effect to work (it flips aplha pixels with opaque ones)