Fixes issue where the indices were not created correctly. (#1660)

# Description

This PR fixes an issue in articulation object from omni.isaac.lab. The
functions `write_root_com_pose_to_sim` and `write_root_link_to_sim` both
result in an error where a variable is called before being assigned. I
checked and there is a test for this, but I'm not sure why they don't
catch it...

The two functions have been changed to match the behaviors of
`write_root_link_pose_to_sim` and `write_root_com_velocity_to_sim`.



Fixes #1659 

## Type of change

- Bug fix (non-breaking change which fixes an issue)

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [ ] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

---------
Co-authored-by: Kelly Guo <kellyg@nvidia.com>

source/extensions/omni.isaac.lab/omni/isaac/lab/assets/articulation/articulation.py

@@ -385,11 +385,13 @@ class Articulation(AssetBase):
             env_ids: Environment indices. If None, then all indices are used.
         """
         # resolve all indices
+        physx_env_ids = env_ids
         if env_ids is None:
-            local_env_ids = slice(None)
+            env_ids = slice(None)
+            physx_env_ids = self._ALL_INDICES
 
-        com_pos = self.data.com_pos_b[local_env_ids, 0, :]
-        com_quat = self.data.com_quat_b[local_env_ids, 0, :]
+        com_pos = self.data.com_pos_b[env_ids, 0, :]
+        com_quat = self.data.com_quat_b[env_ids, 0, :]
 
         root_link_pos, root_link_quat = math_utils.combine_frame_transforms(
             root_pose[..., :3],
@@ -399,7 +401,7 @@ class Articulation(AssetBase):
         )
 
         root_link_pose = torch.cat((root_link_pos, root_link_quat), dim=-1)
-        self.write_root_link_pose_to_sim(root_pose=root_link_pose, env_ids=env_ids)
+        self.write_root_link_pose_to_sim(root_pose=root_link_pose, env_ids=physx_env_ids)
 
     def write_root_velocity_to_sim(self, root_velocity: torch.Tensor, env_ids: Sequence[int] | None = None):
         """Set the root center of mass velocity over selected environment indices into the simulation.
@@ -458,18 +460,20 @@ class Articulation(AssetBase):
             env_ids: Environment indices. If None, then all indices are used.
         """
         # resolve all indices
+        physx_env_ids = env_ids
         if env_ids is None:
-            local_env_ids = slice(None)
+            env_ids = slice(None)
+            physx_env_ids = self._ALL_INDICES
 
         root_com_velocity = root_velocity.clone()
-        quat = self.data.root_link_state_w[local_env_ids, 3:7]
-        com_pos_b = self.data.com_pos_b[local_env_ids, 0, :]
+        quat = self.data.root_link_state_w[env_ids, 3:7]
+        com_pos_b = self.data.com_pos_b[env_ids, 0, :]
         # transform given velocity to center of mass
         root_com_velocity[:, :3] += torch.linalg.cross(
             root_com_velocity[:, 3:], math_utils.quat_rotate(quat, com_pos_b), dim=-1
         )
         # write center of mass velocity to sim
-        self.write_root_com_velocity_to_sim(root_velocity=root_com_velocity, env_ids=env_ids)
+        self.write_root_com_velocity_to_sim(root_velocity=root_com_velocity, env_ids=physx_env_ids)
 
     def write_joint_state_to_sim(
         self,

source/extensions/omni.isaac.lab/test/assets/test_articulation.py

@@ -1088,6 +1088,7 @@ class TestArticulation(unittest.TestCase):
                                 # make quaternion a unit vector
                                 rand_state[..., 3:7] = torch.nn.functional.normalize(rand_state[..., 3:7], dim=-1)
 
+                                env_idx = env_idx.to(device)
                                 for i in range(10):
 
                                     # perform step
@@ -1096,9 +1097,15 @@ class TestArticulation(unittest.TestCase):
                                     articulation.update(sim.cfg.dt)
 
                                     if state_location == "com":
+                                        if i % 2 == 0:
                                             articulation.write_root_com_state_to_sim(rand_state)
+                                        else:
+                                            articulation.write_root_com_state_to_sim(rand_state, env_ids=env_idx)
                                     elif state_location == "link":
+                                        if i % 2 == 0:
                                             articulation.write_root_link_state_to_sim(rand_state)
+                                        else:
+                                            articulation.write_root_link_state_to_sim(rand_state, env_ids=env_idx)
 
                                     if state_location == "com":
                                         torch.testing.assert_close(rand_state, articulation.data.root_com_state_w)