Bug 311698

Summary:	Windows Blur Upon Desktop Switching On nVidia Video Chip With FXAA Enabled
Product:	[Plasma] kwin	Reporter:	Mikiya Okuno <mikiya.okuno>
Component:	effects-window-management	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	normal
Priority:	NOR
Version:	4.9.3
Target Milestone:	---
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	Texts blur Texts don't blur without FXAA

Description Mikiya Okuno 2012-12-14 16:05:16 UTC

When FXAA feature is enabled on nVidia video chip with proprietary driver, contents of windows blur after desktop switching. The problem can be solved by refreshing (repainting) windows by doing any actions (e.g. select/deselect texts in it).

Reproducible: Always

Steps to Reproduce:
1. Enable FXAA on nvidia-settings
2. Turn "Keep window thumbnails" to "Never"
3. Turn "Keep window thumbnails" to "Only for Shown Windows"
4. Switch desktop
Actual Results:  
Window contents blur

Expected Results:  
Window contents are shown as is

Comment 1 Mikiya Okuno 2012-12-14 16:06:24 UTC

Created attachment 75831 [details]
Texts blur

Comment 2 Mikiya Okuno 2012-12-14 16:09:17 UTC

Created attachment 75832 [details]
Texts don't blur without FXAA

Comment 3 Thomas Lübking 2012-12-14 16:28:35 UTC

That's not a bug - you're keeping a full screen antialiaser active and it does exactly what it's supposed to do (everytime glXSwapBuffer is invoked)

It also has a performance impact, so you basically don't want to use it with a WM at all (notably not, since well'll likely have to swap buffers for effective vsyncing)

So far there's unfortunately not env to control that behavior in the driver (so we cannot toggle off FXAA for you)

*** This bug has been marked as a duplicate of bug 307003 ***

Comment 4 Mikiya Okuno 2012-12-15 00:45:45 UTC

Thomas,

Thank you for your comment. My question is why such blur goes away after repaint. If KWin cannot turn FXAA off, it should always ON even after repainting, shouldn't it? Are foreground window painted in 2D (non-OpenGL fashon)?

Comment 5 Martin Flöser 2012-12-15 00:57:56 UTC

> Thank you for your comment. My question is why such blur goes away after
> repaint. If KWin cannot turn FXAA off, it should always ON even after
> repainting, shouldn't it? Are foreground window painted in 2D (non-OpenGL
> fashon)?
Buffer swapping is only performed during fullscreen effects. For normal 
operations only the relevant areas are copied. KWin cannot know that FXAA is 
turned on and therefore cannot react to it.