Originally posted by bridgman
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The most important fact in this list is, that KWin does not enable any functionality the driver does not claim support for it! Furthermore we have several runtime checks to ensure that our users have a smooth experience even if the drivers are claiming support for extensions they do not support. Many of these checks have been added in the 4.4 and 4.5 release cycle.
Now that I have explained all our checks we did to ensure a smooth user experience, I want to explain how it could happen that there are regressions in 4.5. In 4.5 we introduced two new features which require OpenGL Shaders: the blur effect and the lanczos filter. Both are not hard requirements. Blur effect can easily be turned off by disabling the effect and the lanczos filter is controlled by the general effect level settings which is also used for Plasma and Oxygen animations. Both new features check for the required extensions and get only activated iff the driver claims support for it. So everything should be fine, shouldn?t it?
Now that I have explained all our checks we did to ensure a smooth user experience, I want to explain how it could happen that there are regressions in 4.5. In 4.5 we introduced two new features which require OpenGL Shaders: the blur effect and the lanczos filter. Both are not hard requirements. Blur effect can easily be turned off by disabling the effect and the lanczos filter is controlled by the general effect level settings which is also used for Plasma and Oxygen animations. Both new features check for the required extensions and get only activated iff the driver claims support for it. So everything should be fine, shouldn?t it?
So, all that should be necessary, for now, is for open source drivers to remove the "claimed support" for the new OpenGL extensions that are used by KDE 4.5.
This would have the effect that when using open source drivers in KDE 4.5, the blur effect and the lanczos filter would not be available, but other kwin compositing features would be. This would remove the kwin regressions for KDE 4.5.
Later, when the problematic OpenGL extensions are debugged, the open source driver can once again claim support, and then the kwin blur effect and the lanczos filter would magically be re-instated.
Is this too much of a problem, really?
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