D18377: Update blur to be more natural

fredrik added a comment.


  In D18377#400171 <https://phabricator.kde.org/D18377#400171>, @anemeth wrote:
  
  > I tried experimenting what fredrik suggested without luck so far. 
  >  @fredrik @zzag is this the correct approach? This gives the exact same result as not using sRGB textures.
  
  
  Basically yes, but it's important to keep in mind that the framebuffer contents are effectively sRGB even though the framebuffer format is not.
  So in other words, GL_FRAMEBUFFER_SRGB must be disabled when doing the initial copy from the framebuffer to the first sRGB texture, so the gamma curve is not applied twice.

REPOSITORY
  R108 KWin

REVISION DETAIL
  https://phabricator.kde.org/D18377

To: anemeth, #vdg, #kwin, davidedmundson, zzag
Cc: fredrik, abetts, Petross404, rapiteanu, filipf, rooty, ngraham, kwin, jraleigh, GB_2, mkulinski, ragreen, jackyalcine, Pitel, iodelay, bwowk, ZrenBot, lesliezhai, ali-mohamed, hardening, jensreuterberg, sebas, apol, mart