A simple Javascript-based entropy-to-graphic harness.

Try it at https://gavofyork.github.io/entropretty/.

npm install
npm run bundle
npm start

1. Create a new .js file with a unique name, for example mydesign.js.
2. Define a draw function in it which places a unique design onto a canvas for any given 4-byte seed, e.g.:

function draw(ctx, seed) {
  ctx.font = '25px serif';
  seed.forEach((n, i) => ctx.fillText(n, 50, i * 25 + 25, 100));
}

3. Export your new design as schema with a line like:

export const schema = { draw, name: "My Cool Design", artist: "myartistname" };

4. Include your file in the const DESIGNS array of artist.js.

Draw functions take two arguments; the context and the seed. The context is a Javascript canvas 2D drawing context with width and height each 100 px.

It may be assumed to be initialized thus:

ctx.lineWidth = 1;
ctx.lineCap = 'butt';
ctx.lineJoin = 'miter';
ctx.strokeStyle = 'black';
ctx.fillStyle = 'black';
ctx.textAlign = 'center';
ctx.textBaseline = 'bottom';

A seed represents the entropy of a figure and is just an array of four bytes (numbers between 0 and 255 inclusive). The reason for four bytes rather than a single 32-bit integer is Javascript's habit of turning such large integers into negative values whenever it feels like it.

There are several functions provided for operating on seeds:

• bit(seed, n): Get the nth bit from the seed, indexed from 0. Returns either 0 or 1.
• bits(seed, from, to): Get a number built from the bits of seed of the given span from and to.
• bits(seed): Get a number built from all bits of the seed, somewhere between 0 and 2**32 - 1 inclusive.
• split(seed, parts): Return an array of numbers, parts in length, each using approximately the same number of bits from the seed.
• randomGenerator(seed): Return a function which itself takes no arguments and returns a stream of random numbers between 0 and 1. This uses the Prando algorithm. There is also cheapRandomGenerator (using SFC32) and secureRandomGenerator (using SHA-256).