D9848: Updated the blur method to use the more efficient dual kawase blur algorithm.

[Alex Nemeth]

anemeth added inline comments.
Restricted Application edited projects, added Plasma; removed KWin.

INLINE COMMENTS

> fredrik wrote in blur.cpp:145
> Okay, I see what you mean. I think this is a trade-off between two undesirable effects though, because the clamping causes abrupt changes near the edges of the blurred region when a window is moved. You can see this effect pretty clearly in the video you attached when the blur strength is set to strong. It really comes down to what you think is worse though.
> 
> But my concern here is that a fullscreen texture consumes at least 8 MB of VRAM with an HD monitor, and 32 MB with a 4K monitor.
> 
> I think it would be better to copy the framebuffer to m_renderTexture[0], and apply the clamping as a post-processing effect, using m_renderTexture[0] as both the source and destination, and targeting only the region outside the red rectangle for rendering. Using the same texture as both the source and destination is allowed in OpenGL when GL_ARB_texture_barrier or GL_NV_texture_barrier is supported, but unfortunately not in OpenGL ES.
> 
> The taskbar (and other panels) can be identified by calling EffectWindow::isDock().

I checked if I have these extensions. Just to make sure it works I included another extension I know my card supports.

  qCDebug(KWINEFFECTS) << "NV_texture_barrier:" << hasGLExtension("NV_texture_barrier");
  qCDebug(KWINEFFECTS) << "ARB_texture_barrier:" << hasGLExtension("ARB_texture_barrier");
  qCDebug(KWINEFFECTS) << "GL_NV_texgen_reflection:" << hasGLExtension("GL_NV_texgen_reflection");

And the output:

  kwineffects: NV_texture_barrier: false
  kwineffects: ARB_texture_barrier: false
  kwineffects: GL_NV_texgen_reflection: true

If this works so unreliably I don't think we should use this.

REPOSITORY
  R108 KWin

REVISION DETAIL
  https://phabricator.kde.org/D9848

To: anemeth, #plasma, #kwin
Cc: luebking, broulik, romangg, zzag, anthonyfieroni, mart, davidedmundson, fredrik, ngraham, plasma-devel, kwin, #kwin, ZrenBot, progwolff, lesliezhai, ali-mohamed, jensreuterberg, abetts, sebas, apol
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