plotline 0.1.0.dev0

Turn images into drawings for pen plotters.

Open it in your browser  ·  Command line  ·  Design brief

plotline converts raster images into vector line art, such as stippling, single continuous lines, dashes and sketched strokes. It comes with a live preview that shows the algorithm at work, so you can see what a setting does before you commit ink to paper.

The image	grid: dots on a regular grid	hatch: crossing parallel lines
waves: rippling lines, one stroke each	spiral: one rippling spiral	ink: line art, here the logo

_{plotline drew every picture above with a 0.3 mm pen, from images it renders in code.}

Features

• Eighteen styles, from dots on a grid to one continuous spiral. The table below describes each one.
• Live preview. The browser GUI shows the drawing being built. It runs the engine inside the page as WebAssembly, so your image is never uploaded.
• Suggestions. The engine measures a new image and suggests changes: line art, levels, invert, noise, page orientation and colour. You apply each one with a click. The tone stage's Levels can also be Auto, which sets black and white from the image.
• Short pen travel. Every run orders its paths to keep the pen's travel short, and the line styles lift the pen far less often than grid.
• Plotter-ready output. An SVG in millimetres holds one layer per pen that draws, each labelled with the name of its pen. A run can also write the paths as JSON, and a PNG preview that draws each mark at its real pen width. For a pen-fitted 3D printer, the GUI writes one G-code file per pen.
• Several pens. Pen use shares a drawing between your pens: light to dark in list order, or each pen by its colour, so cyan, magenta, yellow and black pens can draw a colour image. By default the first pen draws alone.
• Real pens. A bank of common fineliners, technical pens, gel pens, ballpoints and markers gives each pen its maker's line width, and a list of common inks gives it a colour.
• Presets. A small JSON file holds the style, page, pens, settings and machine of a run, so you can keep a look and share it.
• One engine. The engine is written in Rust and compiled twice: to a native extension for the Python package, and to WebAssembly for the browser. The Python package and the command line are thin layers over it.

stipple, line, dashes, tree, mesh and cells share one placement of points, so switching between them at their default settings reuses the points. A style switch resets the settings to the new style's defaults.

In the browser

Open jonathanrjoyner.github.io/plotline. There is nothing to install.

1. Drop or paste a PNG, JPEG or WebP image, or click Sample image.
2. Pick a style, change its settings and click Run to watch it draw.
3. Set up your pens in the Pens dialog, and choose how they share the drawing under Pen use. The page remembers your setup between visits.
4. Click Export SVG in the toolbar, ready for a pen plotter's own software.

For a new image the Suggestions panel, at the top of the right column, lists what would suit it, each with an Apply button. Nothing changes until you click.

For G-code, enter your machine in the Settings dialog: the drawable area, pen heights, feeds, and start and end G-code. The export panel then writes one G-code file per pen. The preset carries the machine, so save a preset to keep it. A short tour of the page opens on your first visit, and Tour in the toolbar opens it again.

Command line

There is no release yet, so work from a clone of this repository. Building the Python extension needs a Rust toolchain: install one with rustup. With uv installed as well, run this in the clone, where uv sync builds the extension and installs the package:

uv sync
uv run plotline --help

Then draw an image of your own:

uv run plotline run grid your-photo.jpg --out drawing.svg --preview preview.png

This writes drawing.svg and preview.png, and prints a one-line summary with the path count and an estimated plot time.

plotline gui serves the browser GUI from your machine. Building it needs Node, wasm-pack and the wasm32-unknown-unknown Rust target: run npm run wasm, npm ci and npm run build in web/.

With an AI assistant

plotline mcp serves plotline to an AI assistant over the Model Context Protocol, on stdio. From a clone, uv sync installs the MCP extra; once there is a release, pip install "plotline[mcp]" will. Give an MCP client the server as {"command": "plotline", "args": ["mcp"]}, where command is the plotline on the client's PATH or the full path to it (for a clone, the one in its .venv). The assistant can load an image, ask analyse_image what would suit it, run styles, look at previews, also zoomed in on a part of the page, and export the result.

Roadmap

plotline is early software. The goals, architecture, decisions and everything still planned are in the design brief.

License

MIT