MeshCat

Warnings

• deprecated The `zmq.eventloop.ioloop` module used internally by older `meshcat` versions is deprecated in `pyzmq` 17+. While `meshcat` typically handles this gracefully, direct usage or older environments might show warnings.
  Fix: Upgrade `meshcat` and `pyzmq` if available; otherwise, be aware of the warning. The `meshcat-python` project mentions this issue but has not released a new version since `0.3.2`.
• gotcha MeshCat has known limitations with DAE (Collada) files, particularly regarding scaling and display. They may not appear or scale correctly in the viewer.
  Fix: Consider converting DAE files to other supported formats like STL, or manually adjusting `meshScale` if using a wrapper like `pinocchio.visualize.MeshcatVisualizer`.
• gotcha When integrating with simulation environments (e.g., Drake), the default visualization update frequency of MeshCat might cause initial conditions or very fast state changes to be visually missed or incorrectly displayed. The visualization might lag behind the simulation's true initial state.
  Fix: Increase the `frames_per_second` parameter when initializing or recording the MeshCat visualization if your integration allows.
• gotcha Converting MeshCat animations to video files requires `ffmpeg` to be installed on your system. If `ffmpeg` is not found, the video conversion functions will fail silently or with an error about `ffmpeg` not being callable.
  Fix: Ensure `ffmpeg` is installed and accessible in your system's PATH. For Linux, `sudo apt install ffmpeg` or similar. For macOS, `brew install ffmpeg`.

Install

• pip install meshcat Install stable version

Imports

• Visualizer

  import meshcat
  vis = meshcat.Visualizer()

• geometry

  import meshcat.geometry as g

• transformations

  import meshcat.transformations as tf

Quickstart

Initializes a MeshCat visualizer, opens it in a web browser, and displays a red box and a blue sphere. The example demonstrates setting objects at the root and at a sub-path, and applying transformations.

import meshcat
import meshcat.geometry as g
import meshcat.transformations as tf

# Create a new visualizer. This will launch a local server
# and typically open a browser window with the visualization.
vis = meshcat.Visualizer().open()

# You can also get the URL to open it manually:
# print(f"MeshCat URL: {vis.url()}")

# Set a red box at the root of the scene
vis.set_object(g.Box([0.2, 0.2, 0.2]), g.MeshPhongMaterial(color=0xff0000))

# Move the box slightly along the x-axis
vis.set_transform(tf.translation_matrix([0.5, 0, 0]))

# Add a blue sphere at a sub-path within the scene tree
vis["sphere"].set_object(g.Sphere(0.1), g.MeshPhongMaterial(color=0x0000ff))
vis["sphere"].set_transform(tf.translation_matrix([0, 0.5, 0]))

print("Visualization created. Check your browser window or the URL printed above.")