When playing nexuiz (nexuiz-sdl) on Plasma on Wayland, the mouse input in XWayland is often inaccurate. Sometimes the mouse "jumps", resulting in an uncontrollable movement, I would describe it as a ~180° degree movement. Another issue is that the mouse is getting slower or is even blocked when continuously trying to move e.g. to the right side. I noticed this behavior as well in several proprietary games. Linux 4.17.2 wayland 1.15 xwayland 1.20.0 libinput 1.11.1 sdl2 2.0.8 Plasma 5.13.1 kwin-git 5.14 (2018-06-24) kwayland-git 5.14 (2018-06-24)
Related bugs https://bugs.kde.org/show_bug.cgi?id=395815 https://bugs.kde.org/show_bug.cgi?id=388885
The linked bugs are only partially related. I've tested the fix, but the mouse "jump" is still there either in the game and in the menu. It is impossible to control the mouse as of this bug.
I've tested the patch of the other 2 bug reports further. The mouse "jump" only happens if I play in a borderless window mode in my full monitor resolution. So the mouse seems to reach virtually an edge and then the mouse makes this jump from one place to another. If I switch to fullscreen, the input works well. The other issue regarding a slow and stuck mouse, that I've noticed before, seems to be gone completely.
I've tested this again and there is still an issue with the mouse input in Nexuiz on Plasma Wayland. The mouse starts to jump uncontrollable if I reach in the menu the top or if I move in the game to much into one direction. Linux 4.9 wayland 1.16 xwayland 1.20.3 libinput 1.12.2 sdl2 2.0.8 Plasma 5.14.2 KDE Frameworks 5.51 Qt 5.12 beta 3
Should have mentioned this, nexuiz-sdl is still depending on XWayland. I couldn't enforce Wayland with SDL_VIDEODRIVER=wayland.
I have the same problem on my system with game in fullscreen mode. Cursor jumps on screen when moved from bottom to top or from right to the left side on the screen. When cursor reaches the top or left edges, it jumps on the screen. Such behavior does not occur on X11. Operating System: Arch Linux KDE Plasma Version: 5.14.2 Qt Version: 5.12.0 KDE Frameworks Version: 5.51.0 Kernel Version: 4.18.16-arch1-1-ARCH
Still mouse jumps in the main menu of nexus or during gameplay with Plasma 5.16 Beta. Linux 5.1.4 wayland 1.17 xwayland 1.20.4 libinput 1.13.2 sdl2 2.0.9 Plasma 5.15.90 Wayland KDE Frameworks 5.58 Qt 5.13 beta
Still mouse jumps in the main menu of nexus and during gameplay with Plasma 5.17 Beta. Operating System: Arch Linux KDE Plasma Version: 5.16.90 KDE Frameworks Version: 5.62.0 Qt Version: 5.14.0 Kernel Version: 5.3.6-arch1-1-ARCH OS Type: 64-bit AMD GPU
This bug was reported against an outdated version of KWin. We have made many changes since the. If the issue persists in newer versions can you reopen the bug report updating the version number.