game-of-life-p5js

Run Conway's Game of Life (and its B/S relatives like HighLife) on a p5.js canvas. The grid wraps around its edges, so gliders fly off one side and reappear on the other.

The drawing helper takes a p5 instance as its first argument, so the package works in instance mode (and global mode too). The grid model and the step rule are pure and decoupled from p5, so the whole simulation can be used and tested without a canvas.

Installation

npm install game-of-life-p5js

p5 is a peer dependency (^1.0.0); install it alongside if you haven't already:

npm install p5

Usage (instance mode)

const p5 = require('p5');
const { randomGrid, step, drawGrid } = require('game-of-life-p5js');

new p5((p) => {
    const cell = 8;
    let grid;

    p.setup = () => {
        p.createCanvas(640, 480);
        p.frameRate(12);
        grid = randomGrid(p.width / cell, p.height / cell, 0.3, () => p.random());
    };

    p.draw = () => {
        p.background(10);
        p.fill(0, 255, 140);
        drawGrid(p, grid, cell);
        grid = step(grid); // advance one generation
    };
});

Run a variant by passing a different B/S rule:

const { step, parseRule } = require('game-of-life-p5js');

grid = step(grid, parseRule('B36/S23')); // HighLife (self-replicating patterns)

API

randomGrid(cols, rows, density = 0.3, randomFn = Math.random)

Builds a rows × cols grid seeded randomly. randomFn returns [0, 1); pass () => p.random() to share p5's RNG.

step(grid, rule = { birth: [3], survival: [2, 3] })

Advances the grid one generation and returns a fresh grid (the input is never mutated). The default rule is Conway's Life (B3/S23).

parseRule(rulestring)

Parses a rulestring like "B3/S23" or "B36/S23" into { birth, survival } arrays.

drawGrid(p, grid, cellSize = 10)

Draws the live cells as filled squares. The background and fill colour are left to the caller, so fades and trails are possible.

Pure helpers (no p5 needed)

• createGrid(cols, rows, fill = 0) — an empty rows × cols grid.
• countNeighbors(grid, x, y) — live neighbours in the wrapped 8-neighbourhood.

const { createGrid, step } = require('game-of-life-p5js');

let grid = createGrid(5, 5);
grid[2][1] = grid[2][2] = grid[2][3] = 1; // a blinker
grid = step(grid); // now vertical

License

MIT © Damian Sire