let h = 300;

let size = 3;

let game, nextGen;

let count;

let dispersion = 30;

​

function setup() {

  createCanvas(w, h);

  noStroke();

  //frameRate(5);

  game = new Array(h);

  for (let i=0;i<h;i++) {

    game[i] = new Array(w);

    for (let j=0;j<w;j++)

      game[i][j] = random(100) < dispersion ? 1 : 0;

  }

  background(237, 222, 180);

  /*createLoop({duration: 10,

              startLoop:40,

              gif:true, 

              download: true,

              fileName: 'game-of-sand.gif',

              open: true});//*/

}

​

function draw() {

  fill(237, 222, 180, 2);

  rect(0, 0, w, h);

  fill(212, 119, 6);

  nextGen = new Array(h);

  for (let i=0;i<h;i++) {

    nextGen[i] = new Array(w);

    for (let j=0;j<w;j++) {

      // draw

      if (game[i][j] === 1) rect(i,j, 1, 1);

      // compute next gen

      count = neighbours(game, i, j);

      if (game[i][j] === 0 && (count === 3 || count == 6 || count == 7))

        nextGen[i][j] = 1;

      else if (game[i][j] === 1 && (count === 2 || count === 3))

        nextGen[i][j] = 1;

      else {

        nextGen[i][j] = 0;

      } 

    }

  }

   // hard copy next generation

  for (let i = 0 ; i < h ; i++)

    for (let j = 0 ; j < w ; j++)

      game[i][j] = nextGen[i][j];

}

​

function neighbours(game, x, y) {

  let c = 0;

  for (let i = -1 ; i <= 1 ; i++)

    for (let j = -1 ; j <= 1 ; j++)

      if (!(i==0 && j==0))

        c += game[(x+i+w) % w][(y+j+h) % h];

  return c;

}