I have traced it back to the removal of i386 (32-bit) OpenGL (specifically libGLU.so) libraries with Ubuntu 20.04 compared to Ubuntu 18.04. Groundtraffic has 32 bit and 64 bit support, but the 32 bit plugin reside in the plugin's root folder instead of in the 32 bit folder.
The groundtraffic folders are currently organized as follows:
64/win.xpl 64/lin.xpl win.xpl mac.xpl lin.xpl
the groundtraffic plugin folder should therefore be reorganized into the 32 and 64 bit folders so that the 64 bit x-plane finds the correct plugin for its architecture:
groundtraffic in Orbx_A_EGLC on linux: error loading plugin
in X Plane 11 Orbx product BUG REPORTS
Posted · Edited by Reto Stockli
Since upgrading to Ubuntu 20.04 from 18.04 I get this error in Log.txt:
dlerror:Custom Scenery/Orbx_A_EGLC_LondonCity/plugins/groundtraffic/64/lin.xpl:
undefined symbol: __atan2f_finite
dlerror:Custom Scenery/Orbx_A_EGLC_LondonCity/plugins/groundtraffic/lin.xpl: wro
ng ELF class: ELFCLASS32
I have traced it back to the removal of i386 (32-bit) OpenGL (specifically libGLU.so) libraries with Ubuntu 20.04 compared to Ubuntu 18.04. Groundtraffic has 32 bit and 64 bit support, but the 32 bit plugin reside in the plugin's root folder instead of in the 32 bit folder.
The groundtraffic folders are currently organized as follows:
64/win.xpl 64/lin.xpl win.xpl mac.xpl lin.xpl
the groundtraffic plugin folder should therefore be reorganized into the 32 and 64 bit folders so that the 64 bit x-plane finds the correct plugin for its architecture:
64/win.xpl 64/lin.xpl 32/win.xpl 32/lin.xpl mac.xpl
You may omit the 32 bit versions alltogether since X-Plane is now only 64 bit, right?
Reorganizing the plugin folder and removing the 32 bit groundtraffic plugin did solve the problem.
cheers,
Reto