Usage of Group 4 in Hand - MuJoCo XML

[aswinkumar1999]

I am learning MuJoCo modeling , I was going through the MJCF files of the Hand robot and noticed that in robotics/assets/hand/robot.xml lots of geoms used the class DC_HAND which is declared as group 4 in shared.xml.

I understand I can enable them in the MuJoCo simulator by toggling the group settings , but I don't understand the reasoning behind them. What is the purpose of group 4 ? Why we do need robot0:C_xyz when we have robot0:V_xyz.

I found a similar question in the MuJoCo forum , but it did not seem to answer my question.

[jkterry1]

PR #2762 is about to be merged, introducing V4 MuJoCo environments using new bindings and a dramatically newer version of the engine. If this issue still persists with the V4 ones, please create a new issue for it.