VR error because scene_scale = 0

[goddard@…]

The following bug report has been submitted:
Platform:        Windows-10-10.0.17763
ChimeraX Version: 0.91 (2019-11-18)
Description
After recentering in VR by pressing grip button, I then pressed trigger button to move structure and the structure vanished and then I got this overflow error.

Log:
UCSF ChimeraX version: 0.91 (2019-11-18)  
© 2016-2019 Regents of the University of California. All rights reserved.  
How to cite UCSF ChimeraX  

> open C:\Users\goddard\Desktop\vrdemos\opioids-vr-2018\ligands\beta-
> endorphin.pdb

Chain information for beta-endorphin.pdb #1  
---  
Chain | Description  
A | No description available  
  

> show atoms

> hide cartoons

> vr true

started SteamVR rendering  
C:\cygwin64\home\goddard\chimerax\ChimeraX.app\bin\lib\site-
packages\chimerax\vive\vr.py:683: RuntimeWarning: overflow encountered in
double_scalars  
return 1/sqrt(x*x + y*y + z*z)  
An error occurred in drawing the scene. Redrawing graphics is now stopped to
avoid a continuous stream of error messages. To restart graphics use the
command "graphics restart" after changing the settings that caused the error.  
  
Traceback (most recent call last):  
File "C:\cygwin64\home\goddard\chimerax\ChimeraX.app\bin\lib\site-
packages\chimerax\core\updateloop.py", line 73, in draw_new_frame  
view.draw(check_for_changes = False)  
File "C:\cygwin64\home\goddard\chimerax\ChimeraX.app\bin\lib\site-
packages\chimerax\core\graphics\view.py", line 166, in draw  
self._draw_scene(camera, drawings)  
File "C:\cygwin64\home\goddard\chimerax\ChimeraX.app\bin\lib\site-
packages\chimerax\core\graphics\view.py", line 214, in _draw_scene  
self._update_projection(camera, vnum)  
File "C:\cygwin64\home\goddard\chimerax\ChimeraX.app\bin\lib\site-
packages\chimerax\core\graphics\view.py", line 811, in _update_projection  
near_far = self.near_far_distances(camera, view_num)  
File "C:\cygwin64\home\goddard\chimerax\ChimeraX.app\bin\lib\site-
packages\chimerax\core\graphics\view.py", line 824, in near_far_distances  
cp = camera.get_position(view_num).origin()  
File "C:\cygwin64\home\goddard\chimerax\ChimeraX.app\bin\lib\site-
packages\chimerax\core\graphics\camera.py", line 58, in get_position  
p = self._position if view_num is None else self.view(self._position,
view_num)  
File "C:\cygwin64\home\goddard\chimerax\ChimeraX.app\bin\lib\site-
packages\chimerax\vive\vr.py", line 752, in view  
t = es.scale_translation(1/self.scene_scale)  
ZeroDivisionError: float division by zero  
  




OpenGL version: 3.3.0 NVIDIA 430.39
OpenGL renderer: Quadro P6000/PCIe/SSE2
OpenGL vendor: NVIDIA Corporation

[Tom Goddard]

After updating the vive bundle I was not able to reproduce this bug.

[Tom Goddard]

Put in code to avoid divide by zero if scene scale becomes 0.