Installation¶

OCP Viewer is the standalone viewer: a local web server whose page is the CAD Viewer, used from any editor or plain Python. All client-side features are available — the show* family, measurement mode, materials — except visual debugging, which is VS Code's.

pip install ocp_viewer

into the environment that also holds your CAD library (build123d or cadquery). Then start it:

ocp-viewer

or, equivalently, as a module of the environment's Python:

python -m ocp_viewer

and open the printed URL in a browser — http://127.0.0.1:3939 by default. Both forms are the same program and take the same flags; ocp-viewer is the console script the package installs next to python, python -m ocp_viewer spells out which interpreter it runs in. Stop the server with Ctrl-C; a page that is still open keeps trying to reconnect until it is closed or the server is back.

From Python, in the same environment:

from build123d import *
from ocp_viewer import *

show(Box(1, 2, 3))

Installing from a checkout¶

For local use straight from a clone — uv add path/to/ocp-viewer, uv pip install path/to/ocp-viewer or pip install path/to/ocp-viewer — run make assets in the checkout first. The page's JavaScript and stylesheet are copied in from npm and are not in git, so a package built from a checkout that never ran it ships without them; a server started from such a package says so and names the files. make dist runs it for you, and a released wheel from PyPI carries them.

Remote use over SSH¶

The server binds to 127.0.0.1, which is unreachable from your local machine when it runs on a remote host. Rather than exposing it to the network with --host, forward the port over SSH:

ssh -L 3939:localhost:3939 user@host

then open http://localhost:3939 in your local browser — the connection is tunnelled, and nothing is exposed beyond your machine.