[compiz] Blurring behind windows

[Mirco Müller]

Am Mittwoch, den 03.01.2007, 11:43 +0100 schrieb julio at lepi.org:

> Another trick than would probably be 1/ much more good looking and 2/ less
> cpu-intensive than convolution (or at least as cpu-intensive) would be to
> blend several (let say 9) textures of what is behind the window, each one
> with a very low alpha, but each one with an offset of one pixel in each
> direction :
>  __________________
> |_|_|_|______|_|_|_|
> |_|_|_|______|_|_|_|
> |_|_|_|______|_|_|_|
> | | | |      | | | |
> | | | |      | | | |
> | | | |      | | | |
> |_|_|_|______|_|_|_|
> |_|_|_|______|_|_|_|
> |_|_|_|______|_|_|_|
> |_|_|_|______|_|_|_|
> 
> Hmmm I'm not sure my english and my ascii art skills are enough to make
> myself clear, but anyway, here it is ;)
> Would it be possible ?

	That would kill the texture-fillrate. Just imagine this with a
maximized terminal-window, at e.g. 1920x1200. You would have to do 9
passes for a 1920x1200 texture... on only one window. Most people have a
few more (ok maybe not all that large and transparent, but still). I
assume that this makes most cards crawl. And not even multitexturing
would help that much. One still would have to upload the same texture
multiple times for each change of the "area behind the window".

	An approach like this, would it be implemented, has the potential to
render a system nearly unresponsive (or at least very sluggish) if the
user happens to open a few terminals (setup with transparency) and
starts maximizing them.

	I would not recommend to follow that path, although it will likely
achieve the intended blurred looks.

Best regards...

Mirco "MacSlow" Müller

-- 
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