Starting VR on Linux gives traceback

[Greg Couch]

The following bug report has been submitted:
Platform:        Linux-4.15.0-36-generic-x86_64-with-debian-buster-sid
ChimeraX Version: 0.8 (2018-10-06)
Description
Doing "vr on" in daily build on Linux on system without vr.

Log:
UCSF ChimeraX version: 0.8 (2018-10-06)  
How to cite UCSF ChimeraX  

vr on

device vr true ↵

Traceback (most recent call last):  
  File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/chimerax/cmd_line/tool.py", line 205, in execute  
    cmd.run(cmd_text)  
  File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/chimerax/core/commands/cli.py", line 2584, in run  
    _used_aliases=used_aliases, log=log)  
  File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/chimerax/core/commands/cli.py", line 3070, in __call__  
    return self.cmd.run(text, _used_aliases=_used_aliases, log=log)  
  File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/chimerax/core/commands/cli.py", line 2562, in run  
    result = ci.function(session, **kw_args)  
  File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/chimerax/vive/vr.py", line 72, in vr  
    start_vr(session, multishadow_allowed, simplify_graphics)  
  File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/chimerax/vive/vr.py", line 154, in start_vr  
    mv.camera = SteamVRCamera(session)  
  File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/chimerax/vive/vr.py", line 236, in __init__  
    self.vr_system = vrs = openvr.init(openvr.VRApplication_Scene)  
  File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/openvr/__init__.py", line 5286, in init  
    initInternal2(applicationType, pStartupInfo)  
  File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/openvr/__init__.py", line 5390, in initInternal2  
    _checkInitError(error.value)  
  File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/openvr/__init__.py", line 5272, in _checkInitError  
    raise OpenVRError("%s (error number %d)" %(getVRInitErrorAsSymbol(error),
error))  
openvr.OpenVRError: b'VRInitError_Init_PathRegistryNotFound' (error number
110)  
  
openvr.OpenVRError: b'VRInitError_Init_PathRegistryNotFound' (error number
110)  
  
File "/home/chimera/chimerax_daily/lib/python3.6/site-
packages/openvr/__init__.py", line 5272, in _checkInitError  
raise OpenVRError("%s (error number %d)" %(getVRInitErrorAsSymbol(error),
error))  
  
See log for complete Python traceback.  
  




OpenGL version: 4.5 (Core Profile) Mesa 18.0.5
OpenGL renderer: AMD TAHITI (DRM 2.50.0 / 4.15.0-36-generic, LLVM 6.0.0)
OpenGL vendor: X.Org

[Tom Goddard]

Need to catch the exception raised by OpenVR.init() and give a more friendly error message saying OpenVR is not installed or could not start.

[Tom Goddard]

Added simple error message saying SteamVR is not installed or failed to start.