Missing function in python binding.

[xkiixkii]

Intro

Hi!

I am a student tring to use MuJoCo to create a reinforcement learning environment for stacking deformable objects.

My setup

MuJoCo Version: 3.1.6
OS: Ubuntu 22.04.4 x86_64
Using mujoco python binding

My question

I want to spawn some soft objects on some random positions at runtime.
My intended method is to convert MjModel to Mjspec, add these soft objects, and then recompile it back to MjModel. However, I found that the exposed Python API does not provide the mj_copyBackfunction, and some other functions mentioned in the documentation are also not exposed in the Python API. Is there any other way to achieve the same effect as the mj_copyBack `function?"

Minimal model and/or code that explain my question

No response

Confirmations

• I searched the latest documentation thoroughly before posting.
• I searched previous Issues and Discussions, I am certain this has not been raised before.

[yuvaltassa]

My intended method is to convert MjModel to Mjspec

This is not possible, and not what mj_copyBack does. You need to start with an mjSpec, modify that, and compile to mjModel when required.

The whole copyback functionality is a remnant from before mjSpec existed and doesn't really makes sense anymore. There is now no reason to modify mjMode. We'll probably delete it in the future.