| """ |
| Render Experiment 1: The Indistinguishable Pair |
| Two visually identical cubes pushed with the same force — wildly different outcomes. |
| """ |
| import mujoco |
| import numpy as np |
| import imageio |
|
|
| |
| WIDTH, HEIGHT = 1280, 720 |
| FPS = 60 |
| OUTPUT_DIR = "." |
|
|
| |
| XML = """ |
| <mujoco model="indistinguishable_pair"> |
| <option timestep="0.002" gravity="0 0 -9.81"/> |
| |
| <visual> |
| <global offwidth="{w}" offheight="{h}"/> |
| <quality shadowsize="4096"/> |
| <headlight ambient="0.3 0.3 0.3" diffuse="0.6 0.6 0.6"/> |
| </visual> |
| |
| <asset> |
| <texture name="grid" type="2d" builtin="checker" rgb1="0.35 0.35 0.38" rgb2="0.30 0.30 0.33" |
| width="256" height="256"/> |
| <material name="grid_mat" texture="grid" texrepeat="8 8" reflectance="0.1"/> |
| <texture name="wood" type="2d" builtin="flat" rgb1="0.45 0.35 0.25" width="1" height="1"/> |
| <material name="wood_mat" texture="wood" specular="0.1"/> |
| <material name="red_mat" rgba="0.85 0.18 0.18 1" specular="0.4" shininess="0.6"/> |
| <material name="pusher_mat" rgba="0.3 0.35 0.7 0.8" specular="0.3"/> |
| </asset> |
| |
| <worldbody> |
| <light pos="0 -0.5 1.5" dir="0 0.3 -1" castshadow="true" diffuse="0.8 0.8 0.8"/> |
| <light pos="0.5 0.5 1.2" dir="-0.3 -0.3 -1" castshadow="false" diffuse="0.3 0.3 0.35"/> |
| |
| <geom name="floor" type="plane" size="2 2 0.1" material="grid_mat"/> |
| |
| <!-- Table --> |
| <body name="table" pos="0 0 0.38"> |
| <geom type="box" size="0.45 0.25 0.02" material="wood_mat"/> |
| <!-- Legs --> |
| <geom type="cylinder" size="0.015 0.18" pos="-0.40 -0.20 -0.2" rgba="0.4 0.3 0.2 1"/> |
| <geom type="cylinder" size="0.015 0.18" pos=" 0.40 -0.20 -0.2" rgba="0.4 0.3 0.2 1"/> |
| <geom type="cylinder" size="0.015 0.18" pos="-0.40 0.20 -0.2" rgba="0.4 0.3 0.2 1"/> |
| <geom type="cylinder" size="0.015 0.18" pos=" 0.40 0.20 -0.2" rgba="0.4 0.3 0.2 1"/> |
| </body> |
| |
| <!-- Label markers on table surface --> |
| <body name="label_heavy" pos="-0.15 0.15 0.405"> |
| <geom type="box" size="0.06 0.008 0.001" rgba="0.2 0.3 0.7 0.6"/> |
| </body> |
| <body name="label_light" pos="0.15 0.15 0.405"> |
| <geom type="box" size="0.06 0.008 0.001" rgba="0.7 0.3 0.1 0.6"/> |
| </body> |
| |
| <!-- Heavy cube: steel, 2kg --> |
| <body name="cube_heavy" pos="-0.15 0 0.435"> |
| <joint type="free"/> |
| <geom type="box" size="0.03 0.03 0.03" mass="2.0" material="red_mat" |
| friction="0.5 0.005 0.0001"/> |
| </body> |
| |
| <!-- Light cube: foam, 0.05kg — VISUALLY IDENTICAL --> |
| <body name="cube_light" pos="0.15 0 0.435"> |
| <joint type="free"/> |
| <geom type="box" size="0.03 0.03 0.03" mass="0.05" material="red_mat" |
| friction="0.3 0.005 0.0001"/> |
| </body> |
| |
| <!-- Camera --> |
| <camera name="main" pos="0 -0.65 0.75" xyaxes="1 0 0 0 0.55 0.84" fovy="50"/> |
| <camera name="top" pos="0 0 1.3" xyaxes="1 0 0 0 1 0" fovy="50"/> |
| <camera name="side" pos="0.8 0 0.55" xyaxes="0 1 0 -0.5 0 0.87" fovy="50"/> |
| </worldbody> |
| </mujoco> |
| """.format(w=WIDTH, h=HEIGHT) |
|
|
|
|
| def render_push(force_magnitude, filename, camera="main", duration_sec=3.0): |
| """Render a push experiment to video.""" |
| model = mujoco.MjModel.from_xml_string(XML) |
| data = mujoco.MjData(model) |
| renderer = mujoco.Renderer(model, height=HEIGHT, width=WIDTH) |
| |
| heavy_id = mujoco.mj_name2id(model, mujoco.mjtObj.mjOBJ_BODY, "cube_heavy") |
| light_id = mujoco.mj_name2id(model, mujoco.mjtObj.mjOBJ_BODY, "cube_light") |
| cam_id = mujoco.mj_name2id(model, mujoco.mjtObj.mjOBJ_CAMERA, camera) |
| |
| mujoco.mj_forward(model, data) |
| |
| |
| for _ in range(300): |
| mujoco.mj_step(model, data) |
| |
| total_steps = int(duration_sec / model.opt.timestep) |
| frames_per_step = max(1, int(1.0 / (FPS * model.opt.timestep))) |
| force_steps = 40 |
| |
| frames = [] |
| |
| |
| calm_steps = int(0.5 / model.opt.timestep) |
| for step in range(calm_steps): |
| mujoco.mj_step(model, data) |
| if step % frames_per_step == 0: |
| renderer.update_scene(data, camera=cam_id) |
| frame = renderer.render() |
| frames.append(frame.copy()) |
| |
| |
| for step in range(total_steps): |
| if step < force_steps: |
| data.xfrc_applied[heavy_id, :3] = [force_magnitude, 0, 0] |
| data.xfrc_applied[light_id, :3] = [force_magnitude, 0, 0] |
| else: |
| data.xfrc_applied[heavy_id, :3] = [0, 0, 0] |
| data.xfrc_applied[light_id, :3] = [0, 0, 0] |
| |
| mujoco.mj_step(model, data) |
| |
| if step % frames_per_step == 0: |
| renderer.update_scene(data, camera=cam_id) |
| frame = renderer.render() |
| frames.append(frame.copy()) |
| |
| |
| output_path = f"{OUTPUT_DIR}/{filename}" |
| writer = imageio.get_writer(output_path, fps=FPS, codec='libx264', |
| output_params=['-crf', '20', '-preset', 'medium']) |
| for frame in frames: |
| writer.append_data(frame) |
| writer.close() |
| print(f"Saved: {output_path} ({len(frames)} frames, {len(frames)/FPS:.1f}s)") |
| |
| renderer.close() |
| return frames |
|
|
|
|
| def render_force_sweep(filename, forces=[0.5, 1.0, 2.0, 3.0, 5.0]): |
| """Render multiple forces sequentially in one video with title cards.""" |
| model = mujoco.MjModel.from_xml_string(XML) |
| renderer = mujoco.Renderer(model, height=HEIGHT, width=WIDTH) |
| |
| all_frames = [] |
| |
| for force in forces: |
| data = mujoco.MjData(model) |
| mujoco.mj_forward(model, data) |
| |
| heavy_id = mujoco.mj_name2id(model, mujoco.mjtObj.mjOBJ_BODY, "cube_heavy") |
| light_id = mujoco.mj_name2id(model, mujoco.mjtObj.mjOBJ_BODY, "cube_light") |
| cam_id = mujoco.mj_name2id(model, mujoco.mjtObj.mjOBJ_CAMERA, "main") |
| |
| |
| for _ in range(300): |
| mujoco.mj_step(model, data) |
| |
| frames_per_step = max(1, int(1.0 / (FPS * model.opt.timestep))) |
| force_steps = 40 |
| total_steps = int(2.5 / model.opt.timestep) |
| |
| |
| for _ in range(int(0.3 * FPS)): |
| renderer.update_scene(data, camera=cam_id) |
| frame = renderer.render() |
| all_frames.append(frame.copy()) |
| |
| |
| for step in range(total_steps): |
| if step < force_steps: |
| data.xfrc_applied[heavy_id, :3] = [force, 0, 0] |
| data.xfrc_applied[light_id, :3] = [force, 0, 0] |
| else: |
| data.xfrc_applied[heavy_id, :3] = [0, 0, 0] |
| data.xfrc_applied[light_id, :3] = [0, 0, 0] |
| |
| mujoco.mj_step(model, data) |
| |
| if step % frames_per_step == 0: |
| renderer.update_scene(data, camera=cam_id) |
| frame = renderer.render() |
| all_frames.append(frame.copy()) |
| |
| print(f" Force {force}N: {len(all_frames)} total frames so far") |
| |
| output_path = f"{OUTPUT_DIR}/{filename}" |
| writer = imageio.get_writer(output_path, fps=FPS, codec='libx264', |
| output_params=['-crf', '20', '-preset', 'medium']) |
| for frame in all_frames: |
| writer.append_data(frame) |
| writer.close() |
| print(f"Saved: {output_path} ({len(all_frames)} frames, {len(all_frames)/FPS:.1f}s)") |
| |
| renderer.close() |
|
|
|
|
| if __name__ == "__main__": |
| print("=== Rendering Experiment 1: The Indistinguishable Pair ===\n") |
| |
| print("--- Single push at 2N ---") |
| render_push(2.0, "exp1_push_2N.mp4", camera="main") |
| |
| print("\n--- Single push at 5N ---") |
| render_push(5.0, "exp1_push_5N.mp4", camera="main") |
| |
| print("\n--- Top-down view at 5N ---") |
| render_push(5.0, "exp1_push_5N_top.mp4", camera="top") |
| |
| print("\n--- Force sweep ---") |
| render_force_sweep("exp1_force_sweep.mp4") |
| |
| print("\nDone!") |
|
|
