[Flightgear-devel] notice: users of bumblebee on Linux should use "primus" rendering bridge, instead of "virtualgl"

[Hamza A. <ham...@li...>]

Hi,

recently i'm not able to allow an OSG app utilizing multi sampling to run without errors, if i had to ran this app through the command "/usr/bin/optirun" to enable Nvidia graphics, an error occurs:

Error: Not able to create requested visual.
GraphicsWindow has not been created successfully.

when if i used a "primus" rendering bridge, with the command "/usr/bin/optirun -b primus", the app runs flawlessly with multi sampling.

the default rendering bridge used when the error occurs is "virtualgl", where that can be changed in /etc/bumblebee/bumblebee.conf.

i mentioned an OSG app because it's not related to FG, although FG is affected by it when MSAA is enabled, it does occur with the minimal attached OSG example. in FG it simply Sigfaults, in the example it never runs, both will output the same error provided FG's --log-level=Debug.

so not only does primus as rendering bridge, offers better performance, but also avoids this error. I'v sent this to the OSG mailing-list, i'm not sure what triggers this when multi sampling is enabled and "virtualgl" is used.

here's some relevant info:

Ubuntu 14.04

libgl1-mesa-dri=10.1.3-0ubuntu0.4 (provides i915 Intel driver)
libgl1-mesa-glx=10.1.3-0ubuntu0.4 (provides /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1.2.0)
libgl1-mesa-dev=10.1.3-0ubuntu0.4 (provides symlink to the above in /usr/lib/x86_64-linux-gnu/libGL.so)
nvidia-346=346.82-0ubuntu0.2 (provides Nvidia driver)
bumblebee=3.2.1-93 (provides optirun and /etc/bumblebee/bumblebee.conf)

this is just for reference, but if someone would let me know what exactly multi sampling does to instancing a GraphicsContext that it Sigfaults when used with "virtualgl", i would appreciate it.

p.s: compile example with: "g++ multisample.cpp -losg -losgViewer -g -o multisampletest"

Thanks
Hamza