Penplotting.js

Penplotting.js is a JavaScript framework for making generative art in SVG format for penplotters. This project is a personal project, and as such, it is a work-in-progress. New features and breaking changes are expected in future updates. Use at your own discretion, feel free to contribute and raise issues.

Features

• Shapes and geometry classes: Vector, Point, Line, Path, Circle, AABB, Matrix
• Seedable PRNG implementations with useful methods
• Quadtree for optimised nearest-neighbour search
• Paper sizes

Installation

npm i @jakebeamish/penplotting

Usage

To start a new plot, run

npx new-plot

This command runs a shell script that will create boilerplate index.html, style.css and plot.js files in the current working directory.

Inside plot.js, adjust the options for initializing the plot. A full list of options can be found in the Plot constructor docs.

const plot = new Plot({
  units: "mm",
  title: "My amazing plot",
  size: Paper.A5,
  strokeWidth: 0.05,
});

The image is defined in a plot.generate() function in which Vectors and other shape objects can be created, manipulated, and added to the SVG document with plot.add(shapes), where shapes is a shape or an array of shapes.

For a complete overview, see the API Documentation.

import {
  Plot,
  Vector,
  Triangle,
  Line,
  AABB,
  Circle,
  Path,
  PAPER,
  PRNG,
} from "@jakebeamish/penplotting";

// Setup a new plot with configuration options
let plot = new Plot({
  size: PAPER.A6.landscape(),
  backgroundColor: "white",
  strokeWidth: 0.3,
});

// Create the work inside the plot.generate() function
plot.generate = () => {
  // Initialise PRNG
  const prng = new PRNG({ seed: plot.seed.decimal });

  // Destructure the plot size for easy access to width and height
  const { width, height } = plot.size;

  // The Vector constructor takes up to three parameters x, y, and z
  // If an argument is not given for a coordinate, the default value is 0
  const centre = new Vector(width / 2, height / 2);

  // Lines can be created using the constructor, or the fromArray static method
  // which requires an array in the format [x1, y1, x2, y2]
  const line = Line.fromArray([30, centre.y - 10, 30, centre.y + 10]);

  // Shapes are added to the SVG using plot.add()
  plot.add(line);

  // Circles can be created in a similar way. It requires a position (either as
  // a Vector or as individual coordinates), and a radius
  const circle = Circle.fromVector(new Vector(50, centre.y), 10);

  plot.add(circle);

  const square = new AABB(80, centre.y, 10, 10);

  const triangle = new Triangle(
    new Vector(100, centre.y + 10),
    new Vector(110, centre.y - 10),
    new Vector(120, centre.y + 10)
  );

  // AABBs and Triangles can't be added to a plot directly - the lines() method
  // can be used to return an array of lines that compose the shape
  // plot.add() can be given an (optionally nested) array to add multiple shapes
  plot.add([square.lines(), triangle.lines()]);

  let randomPoints = [];

  for (let i = 0; i < 30; i++) {
    randomPoints.push(
      Vector.lerp(new Vector(30, 20), new Vector(width - 20, 20), i / 30).add(
        new Vector(0, prng.randomBipolarFloat() * 5)
      )
    );
  }

  let randomPath = new Path(randomPoints);

  let sinPoints = [];

  for (let i = 0; i < 100; i++) {
    sinPoints.push(
      Vector.lerp(
        new Vector(30, height - 20),
        new Vector(width - 20, height - 20),
        i / 100
      ).add(new Vector(0, Math.sin((i / 100) * Math.PI * 10) * 3))
    );
  }

  let sinPath = new Path(sinPoints);

  plot.add([randomPath, sinPath]);
};

plot.draw();

Calling plot.draw() at the end of the file generates an SVG element and UI inside index.html, which can be viewed in a browser.

The above code results in the following output:

Keyboard shortcuts

| Action | Key | | --------------------------- | --- | | Download an SVG file | d | | Regenerate with random seed | r |

Plotting the SVG files

The SVG file can be downloaded and optionally processed further. Personally, I use vpype to optimise the file, and then the axidraw Inkscape plugin to control the plotter.

Contributing

Contributions are welcome. Issues, comments and Pull Requests can be made at https://github.com/jakebeamish/penplot-svg-tool/issues.

The project is tested using jest. Documentation is generated using JSDoc.

License

This project is licensed under the MIT License. See the LICENSE.md file for details.

Acknowledgements

This project incorporates code from:

• CodingTrain/Quadtree - Licensed under the MIT License.