get_state and set_state do not involve the pos and quat of the mocap body

[zichunxx]

Hi Robosuite team,

I constructed an arena including a mocap body whose pose should be reset at the beginning of each episode.

However, I found set_state and get_state in binding_utils.py only save and load data.qpos and data.qvel:

robosuite/robosuite/utils/binding_utils.py

Lines 1140 to 1155 in eafb81f

	def get_state(self):
	"""Return MjSimState instance for current state."""
	return MjSimState(
	time=self.data.time,
	qpos=np.copy(self.data.qpos),
	qvel=np.copy(self.data.qvel),
	)
	def set_state(self, value):
	"""
	Set internal state from MjSimState instance. Should
	call @forward afterwards to synchronize derived quantities.
	"""
	self.data.time = value.time
	self.data.qpos[:] = np.copy(value.qpos)
	self.data.qvel[:] = np.copy(value.qvel)

This way of saving and loading MoJoCo data ignores the mocap body information. Thus, I made some changes to set_state, get_state, and from_flattened to contain mocap body information. These changes are sufficient and I have verified them with my code.

If I am right and the repo is open to contributions, I'll pull a request for you to check.

Thanks.

[zhuyifengzju]

Hi, thanks for bringing up this issue to our attention. Our repo is open to the community contribution, but we need to discuss and decide how to incorporate this new change. To make the codebase compatible with default behaviors in existing versions, can you make sure you have an additional flag that opt in / out the mocap body saving? Thanks!

@amandlek What do you think of this new feature?

[zichunxx]

To make the codebase compatible with default behaviors in existing versions, can you make sure you have an additional flag that opt in / out the mocap body saving? Thanks!

Actually, I added a default mocap=False label for get_state and set_state_from_flattened functions and created another MjSimStateMocap class referring to MjSimState to save mocap information. Maybe it's not elegant.

[amandlek]

Thanks for this contribution! Why don't we start by having you open a PR so we can review the changes?

[zichunxx]

I have pulled a request for you to check. Thanks.

[Steven-xzr]

Hi @zichunxx! I'm also trying to add mocap bodies to the robosuite codebase these days. Maybe we could have a more detailed discussion on it if it's possible? You can contact me via email [email protected]. Thanks.