Update mujoco-py to MuJoCo 2.1

[nimrod-gileadi]

MuJoCo has been updated to version 2.1 (see announcement).

Activation keys are no longer required, and there are some minor API changes. This PR updates code generation to support the API changes, and removes code related to the activation key.

I also updated README.md, assuming there will be a new version of mujoco-py on PyPI, 2.1.

[vwxyzjn]

@nimrod-gileadi this is amazing work! if this repo is no longer maintained, does it make sense put a free-mujoco-py on PyPi so that people can directly install it? It should also be possible to directly include the free mujoco binary as part of the pypi wheel file.

[nimrod-gileadi]

@vwxyzjn, are you interested in mujoco-py in the context of Gym, or would you be a direct user of mujoco-py?

The MuJoCo team and I are trying to figure out what to do about this: from talking to @jkterry1 (see his post openai/gym#2456), there are some issues with mujoco-py that make it hard for gym to upgrade.

We are thinking of making official MuJoCo python bindings that we can maintain long term. As you say, automatically getting a mujoco binary would make installation much simpler for users.

[vwxyzjn]

Hey, @nimrod-gileadi thanks for the quick response. I am interested in the context of Gym. Actually, I have just made a quick demo release. Try executing

python -m venv venv
source venv/bin/activate
pip install gym
pip install free-mujoco-py
python -c "import mujoco_py;import gym;env=gym.make('HalfCheetah-v2')"

The source code is at nimrod-gileadi#1. For convenience, the release automatically includes the MuJoCo binaries so there's no need to download it.

[araffin]

@vwxyzjn I made a @googlecolab notebook if you want to try it online (it requires one env reload): https://colab.research.google.com/drive/1KGMZdRq6AemfcNscKjgpRzXqfhUtCf-V?usp=sharing

[matthiasplappert]

LGTM, thanks for contributing this. Will merge.

[paantya]

#648

[Krishnendu1984]

Kindly tell how to render in colab with this half cheetah beaacuse when i am writing env.render() it is showing GLFW error