SUMMARY In the brush engine, the curve under the "sharpness" option doesn't do anything. Maybe because you can't have a stroke half sharp (in which case, just remove it or grey it out, it's confusing), maybe because you can and it doesn't work. STEPS TO REPRODUCE 1. Open the brush editor. 2. Check "Sharpness", then "Enable Pen Pressure" 3. Play with the curve there (you can try different values for Brush Tip > Auto > Fade, too), and watch the brush preview in the upper left OBSERVED RESULT No change whatsoever EXPECTED RESULT some change SOFTWARE/OS VERSIONS Linux/KDE Plasma: Fedora 27
It actually does something: it changes the way how the subpixel precision is interpretted. This was tackled in https://phabricator.kde.org/D8543 but that one was never finished. Not sure what to do with this report for now :/
I can try and finish it, seems to be almost complete.
We can confirm it Fix is on the way Working differential: https://phabricator.kde.org/D20423
fixed by c29bc6579685530c9ef113bc416e6ae2008545f2