Rendering Problem for gym>=0.25.0

[zjowowen]

Hi!

OpenAi gym remove the rendering.py for supporting pygame.
"from gym.envs.classic_control import rendering" would fail in environment.py.

openai/gym#2599

[thomashirtz]

Oh, that is not good ...
I saw the conversation on gym, it doesn't seem to exist any fix, is there ?
e.g. openai/gym#2806 (comment)

[zjowowen]

No, there seems to have no available rendering API in the latest gym==0.25.1.
They decided to remove it to support and suggest using pygame.
However, there certainly would be learning and transfer time costs for recoding the rendering method.

By the way, it's really amazing that gym, of such great popularity, has not upgraded to 1.0.0 yet, which means that they still hold the right to change their API as they want.
Anyway, such changes would certainly cause troubles to rl environment depending on it.

I am currently a mantainer of RL library opendilab DI-engine. My recent work is to upgrade the denpendency of gym for DI-engine from 0.20.0 to 0.25.0.
https://github.com/opendilab/DI-engine/pull/434
Some other interesting rl environments meet the same rendering trouble as your gym-hybird does, such as slimevolleyball.