After installing kivy, I got a wonderful detailed error message:
[WARNING] [WinPygame ] Video: failed (multisamples=2) [WARNING] [WinPygame ] trying without antialiasing [ERROR ] [Window ] Unable to use <pygame> as windowprovider [ERROR ] [Window ] The module raised an important error: 'X11 driver not configured with OpenGL'
It is not only detailed, it is nicely colored (color offline). However, it is wrong.
tunix ~ # grep Loading /var/log/Xorg.0.log | grep nvidia [ 1011.626] (II) Loading /usr/lib/xorg/modules/drivers/nvidia_drv.so tunix ~ # equery -N u x11-drivers/nvidia-drivers | grep OpenGL + + X : Controls whether the X.org driver, OpenGL libraries, XvMC libraries, and VDPAU libraries are installed tunix ~ # nvidia-settings --glxinfo | grep 'direct rendering' direct rendering: Yes
In my case the reason for the error is the missing opengl USE flag of media-libs/libsdl.