minor tweaks to simulator

sim/scripts/simulate_mjcf.py

@@ -2,7 +2,7 @@
 """Defines a simple demo script for simulating a MJCF to observe the physics.
 
 Run with mjpython:
-    mjpython mjpython sim/scripts/simulate_mjcf.py
+    mjpython sim/scripts/simulate_mjcf.py --record
 """
 
 import time
@@ -11,37 +11,42 @@
 import mediapy as media
 import argparse
 
+from sim.env import stompy_mjcf_path
+
 
 def simulate(model_path, duration, framerate, record_video):
     frames = []
     model = mujoco.MjModel.from_xml_path(model_path)
     data = mujoco.MjData(model)
     renderer = mujoco.Renderer(model)
 
-    while data.time < duration:
-        step_start = time.time()
-        mujoco.mj_step(model, data)
-
-        time_until_next_step = model.opt.timestep - (time.time() - step_start)
-        if time_until_next_step > 0:
-            time.sleep(time_until_next_step)
+    with mujoco.viewer.launch_passive(model, data) as viewer:
+        while data.time < duration:
+            step_start = time.time()
+            mujoco.mj_step(model, data)
+            viewer.sync()
+            time_until_next_step = model.opt.timestep - (time.time() - step_start)
+            if time_until_next_step > 0:
+                time.sleep(time_until_next_step)
 
-        if record_video and len(frames) < data.time * framerate:
-            renderer.update_scene(data)
-            pixels = renderer.render()
-            frames.append(pixels)
+            if record_video and len(frames) < data.time * framerate:
+                renderer.update_scene(data)
+                pixels = renderer.render()
+                frames.append(pixels)
 
-    if record_video:
-        video_path = "mjcf_simulation.mp4"
-        media.write_video(video_path, frames, fps=framerate)
-        print(f"Video saved to {video_path}")
+        if record_video:
+            video_path = "mjcf_simulation.mp4"
+            media.write_video(video_path, frames, fps=framerate)
+            print(f"Video saved to {video_path}")
 
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(description="MuJoCo Simulation")
-    parser.add_argument("--model_path", type=str, required=True, help="Path to the MuJoCo XML model file")
+    parser.add_argument(
+        "--model_path", type=str, default=str(stompy_mjcf_path()), help="Path to the MuJoCo XML model file"
+    )
     parser.add_argument("--duration", type=int, default=3, help="Duration of the simulation in seconds")
-    parser.add_argument("--framerate", type=int, default=60, help="Frame rate for video recording")
+    parser.add_argument("--framerate", type=int, default=30, help="Frame rate for video recording")
     parser.add_argument("--record", action="store_true", help="Flag to record video")
 
     args = parser.parse_args()