Fix: fetch mujoco_menagerie for directly-built envs (snow gait crashed on a fresh container)

app.py

@@ -170,8 +170,13 @@ def build_envs():
     if ENVS:
         return ENVS["env"], ENVS["eval_env"], ENVS["randomization_fn"]
     from mujoco_playground import registry
+    from mujoco_playground._src import mjx_env
 
     STATE["status"] = "building env"
+    # registry.load() clones mujoco_menagerie on demand; the snow-gait and get-up
+    # envs are constructed directly, which skips that, so a fresh container fails
+    # with "Error opening file ... left_hip_pitch_link.STL".
+    mjx_env.ensure_menagerie_exists()
     if TASK == "getup":
         import g1_getup
         log("task: getup (fall recovery) -- flat ground, full-collision G1")

g1_getup.py

@@ -102,6 +102,7 @@ class G1Getup(g1_base.G1Env):
     ) -> None:
         # G1Env.__init__ compiles from an XML path; this task needs the generated
         # full-collision model instead, so set the model up here and skip it.
+        mjx_env.ensure_menagerie_exists()   # registry.load() would do this for us
         mjx_env.MjxEnv.__init__(self, config, config_overrides)
         scene, assets = build_scene()
         self._model_assets = assets

render_worker.py

@@ -15,13 +15,25 @@ def main(mjb, qpos_path, out, fps, width, height, camera):
     model = mujoco.MjModel.from_binary_path(mjb)
     data = mujoco.MjData(model)
     qpos = np.load(qpos_path)
-    cam = camera if mujoco.mj_name2id(model, mujoco.mjtObj.mjOBJ_CAMERA, camera) >= 0 else -1
+
+    # "follow" is a free camera kept above and behind the robot. The scene's own
+    # "track" camera sits 0.35 m above the centre of mass, which ends up inside
+    # the hillside on sloped terrain and renders the ground black.
+    follow = camera == "follow"
+    if follow:
+        cam = mujoco.MjvCamera()
+        cam.azimuth, cam.elevation, cam.distance = 140.0, -15.0, 6.0
+    else:
+        cam = camera if mujoco.mj_name2id(model, mujoco.mjtObj.mjOBJ_CAMERA, camera) >= 0 else -1
+
     with mujoco.Renderer(model, height=int(height), width=int(width)) as r, \
             imageio.get_writer(out, fps=float(fps), codec="libx264", quality=7,
                                macro_block_size=None) as w:
         for q in qpos:
             data.qpos[:] = q
             mujoco.mj_forward(model, data)
+            if follow:
+                cam.lookat[:] = data.qpos[:3]
             r.update_scene(data, camera=cam)
             w.append_data(r.render())
 

snow_gait.py

@@ -34,6 +34,7 @@ import jax.numpy as jp
 from ml_collections import config_dict
 from mujoco import mjx
 
+from mujoco_playground._src import mjx_env
 from mujoco_playground._src.locomotion.g1 import joystick as g1_joystick
 
 # Defaults, all overridable from the Space (see app.py).
@@ -73,6 +74,10 @@ class G1SnowGait(g1_joystick.Joystick):
         config: Optional[config_dict.ConfigDict] = None,
         config_overrides: Optional[Dict[str, Union[str, int, list[Any]]]] = None,
     ) -> None:
+        # Playground clones mujoco_menagerie inside registry.load(); this class is
+        # built directly, so fetch the meshes here or the model compiler fails on
+        # a machine that has not downloaded them yet.
+        mjx_env.ensure_menagerie_exists()
         super().__init__(task=task, config=config or snow_gait_config(),
                          config_overrides=config_overrides)
         self._pelvis_body_id = self._mj_model.body("pelvis").id