How to install vpython as backend?

[NirViaje]

Check here first

Common issues

Describe the bug

Traceback (most recent call last):
File "rtb_neo.py", line 51, in
robot.plot(qt.q, backend=args.backend)
File "/home/nirj/miniconda3/lib/python3.8/site-packages/roboticstoolbox/robot/BaseRobot.py", line 2331, in plot
env = self._get_graphical_backend(backend)
File "/home/nirj/miniconda3/lib/python3.8/site-packages/roboticstoolbox/robot/BaseRobot.py", line 2230, in _get_graphical_backend
raise ValueError("unknown backend", backend) # pragma nocover
ValueError: ('unknown backend', 'vpython')

Version information

rtb 1.1.0
python 3.8.10
pip installed vpython 7.6.5

Did you install from PyPI or GitHub?
If PyPI what version number?
If GitHub what commit hash?

Robotics Toolbox depends heavily on two other packages: Swift (3D graphics) and SpatialMath toolbox (underpinning maths utilities). If you think your issue is related to these, then please answer the questions above for them.

To Reproduce
Steps to reproduce the behavior:

1. The shortest, complete, Python script that exhibits the bug.
2. The script output, including error messages.

Expected behavior
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Environment (please complete the following information):

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• Your Python version.

Additional context
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[a-camarillo]

It looks like vpython is not a supported backend.

robotics-toolbox-python/roboticstoolbox/robot/BaseRobot.py

Lines 2175 to 2178 in 7f1bcae

	def _get_graphical_backend(
	self, backend: Union[L["swift", "pyplot", "pyplot2"], None] = None
	) -> Union[Swift, PyPlot, PyPlot2]:
	default = self.default_backend

If vpython is globally installed through pip my suggestion is to try installing rtb in a virtual environment and see if that separation from your global dependencies fixes the issue