How to use the "opengl" qt rendering backend instead of "raster"?

[Duncan]

René J.V. Bertin posted on Mon, 21 May 2018 10:46:39 +0200 as excerpted:

>>Whenever I cause a redraw of a KDE-5 application, I always see a lot of
>>cycles spent in software rendering/blending loops - even for operations
>>which can be easily done with OpenGL (blits with alpha).

>>The kde page "KDE Mailing Lists" only shows this list - and a separate
>>list for developers.
>>Is there a separate list for plasma questions?
> 
> I don't think there is, but your question is technical enough to pose on
> a developers' list even if you're doing any Plasma development yourself.
> This particular list is mostly driven by users; I answered because
> experience leads me to expect you will probably not get much more
> helpful feedback here.
> But you'd do good to figure out what those software rendering loops are
> actually drawing.

Agreed.  Any time you're talking about seeing cycles spend in software 
rendering/blending loops, you're in developer territory.  Both RJVB and I 
are reasonably advanced users, gentooers used to building from source, 
even live-git sources, and applying patches, etc, but speaking for myself 
at least (RJVB can speak for himself), I'm not a dev, and while I can 
generally follow such discussions, and have followed the plasma list and 
the (largely) pre-commit discussion there at times, there's little I 
could actually contribute in the way of a useful answer, other than to 
point you to the plasma-devel list (which, FWIW, I followed as I do this 
one, via news.gmane.org 's list2news service).

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman