[compiz] Blur bugs and slowdown :(

[David Reveman]

On Tue, 2007-02-27 at 20:34 +0100, Bellegarde Cedric wrote:
> I now use blur plugin thanx to window matching feature, thanx David ;)
> 
> I have some bugs:
> http://hibbert.univ-lille3.fr/~cbellegarde/blur_4xbilinear_bug.png
> 
> Here, i have some artefacts bugs with 4xbilinear. This blur mode is fast! May 
> be a Nvidia drivers bug...

I can't reproduce that. Does you driver support
GL_ARB_texture_non_power_of_two?

> 
> http://hibbert.univ-lille3.fr/%7Ecbellegarde/blur_gaussian_fast.png
> 
> Here, an amarok big window with just desktop, moving window is fast.
> 
> http://hibbert.univ-lille3.fr/~cbellegarde/blur_gaussian_slow.png
> 
> Here same amarok window with a fullscreen window under it (basket already have 
> blur enabled), moving amarok is slow.

Well, there's at least two times as much work involved to render and
blur those two windows so this isn't really a surprise.

> 
> Don't know really why it's slow... Maybe amarok window blur basket window that 
> already blur desktop window. This may explain the slowdown... I'm really not 
> sure :(

Yes, you have multiple levels of blur here. The blurring behind the
amarok window depends on the blurring behind the window below. We're not
blurring windows here, we're blurring whatever is rendered behind the
windows, which is a lot harder than just blurring a window or texture.

- David