Extracts success term and add check in Robomimic play script (#358)

# Description

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This change extracts the success term from the env and uses it to check
for policy success in the Robomimic play script.

Fixes # (issue)

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Previously the script used the termination condition as a check for
success. However, if other termination terms are added to an env that
reset the env without a success occuring, then that would cause false
positives. The script now explicitly uses the "success" termination
event to fix this.

## Type of change

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applicable. -->

- 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
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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scripts/imitation_learning/robomimic/play.py

@@ -72,7 +72,7 @@ if args_cli.enable_pinocchio:
 from isaaclab_tasks.utils import parse_env_cfg
 
 
-def rollout(policy, env, horizon, device):
+def rollout(policy, env, success_term, horizon, device):
     """Perform a single rollout of the policy in the environment.
 
     Args:
@@ -128,9 +128,10 @@ def rollout(policy, env, horizon, device):
         traj["actions"].append(actions.tolist())
         traj["next_obs"].append(obs)
 
-        if terminated:
+        # Check if rollout was successful
+        if bool(success_term.func(env, **success_term.params)[0]):
             return True, traj
-        elif truncated:
+        elif terminated or truncated:
             return False, traj
 
     return False, traj
@@ -150,6 +151,10 @@ def main():
     # Disable recorder
     env_cfg.recorders = None
 
+    # Extract success checking function
+    success_term = env_cfg.terminations.success
+    env_cfg.terminations.success = None
+
     # Create environment
     env = gym.make(args_cli.task, cfg=env_cfg).unwrapped
 
@@ -167,7 +172,7 @@ def main():
     results = []
     for trial in range(args_cli.num_rollouts):
         print(f"[INFO] Starting trial {trial}")
-        terminated, traj = rollout(policy, env, args_cli.horizon, device)
+        terminated, traj = rollout(policy, env, success_term, args_cli.horizon, device)
         results.append(terminated)
         print(f"[INFO] Trial {trial}: {terminated}\n")