Hello,

I can see 3 different composit types in KDE 4.11: OpenGL 3.1, OpenGL 2.0 and OpenGL 1.2.

What is the difference between these OpenGL version? Do certain special effects require some special OpenGL version? In other words, if you enable "only" OpenGL 1.2 will some desktop effects not be available? Or is the different OpenGL types just a performance issue?

Thank you.

Major difference between GL 1.2 and 2/3 is that the latter use glsl while 1.2 operates on the fixed function pipeline with some ARB shaders. Some specialities won't work/as good with ARB shaders, but it's mostly a HW capability issue (older chips perform lousy on glsl)

GL 3 is mostly relevant for using the core profile (minus legacy cruft of the GL spec) - it's relevant for EGL and some drivers *may* perform better if you tell them that they can skip tons of GL code that nobody uses anymore.

If you've an older IGP (intel 915 etc) you rather want to use GL 1.2 (or maybe kwin_gles) - otherwise GL 2.1
You can try 3.1 on GLX, but be careful with it: https://bugs.kde.org/show_bug.cgi?id=327310

Rule of thumb: if kwin preselection works for you, don't touch

I have an older Geforce G210M laptop GPU from around 2009.

I now tried OpenGL 1.2 and I saw one improvement: in kmix I have enabled to play a sound when I change volume. It plays kind of short clicks when changing the volume. Now with OpenGL 1.2 kmix plays the notification sound just as expected. When using OpenGL3 backend kmix does not play the notification sound. Thus, OpenGL 1.2 seems to give me a smooter experience. Now I try if OpenGL 2.0 also makex kmix working fine, then I may use OpenGL 2.0. YOu just feel better with higher version numbers, who wants 1.2 if you can have 2.0

That sounds extremely unlikely. Did you verify that by changing it back and forth a few times?

Does the sound go over the GPU (hdmi)?
Do you use the nvidia blob or nouveau?

luebking wrote:Does the sound go over the GPU (hdmi)?
Do you use the nvidia blob or nouveau?

No sound over HDMI, I use the close source blob. And yes, my assumption actually was wrong.....

Proper working of kmix has nothing to do with kwin settings.

I guess it is more a question of correct starting order. When kmix starts after pulseaudio daemon, the feedback click sound is being played. But if kmix gets started before pulseaudio, the feedback sound is not being played when changing volume.

When I loggen in KDE I can close kmix and start kmix again, it plays the feedback sound. But, this is a very minor thing, no reason to worry much about.