let cols;

let rows;

let res = 5;

let offset;

​

function setup() {

  createCanvas(500, 500);

  offset = random(100);

  cols = width / res;

  rows = height / res;

  grid = make2DArray(cols, rows);

  for (let i = 0; i < cols; i++) {

    for (let j = 0; j < rows; j++) {

      grid[i][j] = floor(random(2));

    }

  }

}

​

function draw() {

  background(50);

  for (let i = 0; i < cols; i++) {

    for (let j = 0; j < rows; j++) {

      let x = i * res;

      let y = j * res;

      for (let m = 0; m < cols / 10; m++){

        grid[m][j] = 0;

      }

     for (let m = 0; m < rows / 10; m++){

       grid[i][m] = 0;

     }

     for (let m = cols * 0.9; m < cols; m++){

        grid[m][j] = 0;

     }

     for (let m = rows * 0.9; m < rows; m++){

       grid[i][m] = 0;

     }

      if (grid[i][j] == 1) {

        fill(offset, 255, offset);

        noStroke();

        rect(x, y, res, res);

      } else {

​

        fill(50, 50, 255);

        noStroke();

        rect(x, y, res, res);

      }

    }

  }

  let next = make2DArray(cols, rows);

  for (let i = 0; i < cols; i++) {

    for (let j = 0; j < rows; j++) {

      let neighbours = count(grid, i, j);

      let state = grid[i][j];

      if (neighbours > 4) {

        next[i][j] = 1;

      } else if (neighbours < 4) {

        next[i][j] = 0;

      } else {

        next[i][j] = grid[i][j]

      }

    }

  }

  grid = next;

}

​

​

function make2DArray(cols, rows) {

  let arr = new Array(cols);

  for (let i = 0; i < arr.length; i++){

    arr[i] = new Array(rows);

  }

  return arr;

}

​

function count(grid, x, y) {

  let sum = 0;

  for (let i = -1; i < 2; i++) {

    for (let j = -1; j < 2; j++) {

       let col = (x + i + cols) % cols;

       let row = (y + j + rows) % rows;

       sum += grid[col][row];

    } 

  }

  sum -= grid[x][y];

  return sum;

}