OpenGL Canvas or Not

[Enrico Guarnieri]

I've just recompiled git and with the texture buffer option active the
performances skyrocket! The difference is impressive, it's super fast and
stable! Thank you so much!

>"Ah, bah... I only got reports of Krita breaking for people because of
that option. I can revert it, of course. The problem remains that I haven't
got a representative set of test hardware, no nvidia, no radeon, so I only
test on Intel GPUs's"*
*

These problems are typical in a Windows environment too with integrated
nvidia/ati gpu for notebook, "cheap" version of major release hardware and
poor drivers. Usually professional applications scan for problematic
hardware and drivers and go automatically in software mode in these cases.
However this solution is not 100% reliable, so producers release list of
certified hardware and drivers for a specific software application. For
this reason many painting programs don't use an opengl canvas at all to
keep maximum compatibly but they're really fast with their viewport
movements in software mode.

>"Ubuntu 12.04 doesn't provide VC librairies afaik  ( and also got a lot of
librairies outdated, might also be a problem to follow Git master. )  ; you
probably already built VC yourself ; but if not your CPU ( a strong one )
might gain a big improvement of performances. For the 'buntus , I made this
script by the past to auto build VC 7.0 Git master :
https://raw.github.com/Deevad/compilscripts/master/vc-install.sh "

Yes, David I compiled Vc by myself. ^^

>"I always experienced Qpainter (CPU canvas) to get more slower for
continuous zoom or continuous rotation ; it's true it's really smooth with
GPU ; and smoother with an Intel GPU and libre driver. ( I discovered it in
our London trip on Boud's computer ; then I bought the week after the same
hardware :D )"

I know, I tried... It's really fast with old Intel GPUs too.

>"As Boudewijn linked ; a bug report is open about it :
https://bugs.kde.org/show_bug.cgi?id=313502
Trilinear is always blury ; at any zoom level. Qpainter(CPU) is a bit less
blury.
Choosing "Bilinear" is actually the best option ; from 100% to 50% you'll
match the Gimp/Mypaint/Azdrawing quality.
Above 50% ( 33% , 25%, 17%, 12% ) ; the Bilinear filter will bug ; and the
rendering will be bad ( total aliasing ). Equal to 'Nearest'.
I adapted my workflow to paint using mostly 50% as a workaround. And when I
do sketch/line art at 25% , I have a workaround changing the code , as I
explain on the bug report."

Thanks for the information! I were using the trilinear filtering because
thin lines disappeared at certain zoom levels, but I didn't pay attention
enough to this 50/25% zoom level matter. I'll check it again!

Thank you very much for your hard work, Boudewijn, Dmitri and Krita's team!
^^
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