​

function make2DArray(cols, rows) {

  let arr = new Array(cols);

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

    arr[i] = new Array(rows);

  }

  return arr;

}

​

let grid, next;

let cols;

let rows;

let resolution = 3; // lower resolution for more cells;

​

function setup() {

  // createCanvas(windowWidth, windowHeight);

  createCanvas(600, 600);

  cols = floor(width / resolution);

  rows = floor(height / resolution);

​

  grid = make2DArray(cols, rows);

  for (let i = 0; i < cols; i++) {

    for (let j = 0; j < rows; j++) {

      grid[i][j] = floor(random(2));

    }

  }

  next = 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(0,60);

  noStroke();

  for (let i = 0; i < cols; i++) {

    for (let j = 0; j < rows; j++) {

      let x = i * resolution;

      let y = j * resolution;

      if (grid[i][j] == 1) {

        fill(90,255,90);

        // stroke(0);

        rect(x, y, resolution-1, resolution-1);

      }

    }

  }

​

  // Compute next based on grid

  for (let i = 0; i < cols; i++) {

    for (let j = 0; j < rows; j++) {

      let state = grid[i][j];

      // Count live neighbors!

      let neighbors = countNeighbors(grid, i, j);

      if (state == 0 && neighbors == 3) {

        next[i][j] = 1;

      } else if (state == 1 && (neighbors < 2 || neighbors > 3)) {

        next[i][j] = 0;

      } else {

        next[i][j] = state;

      }

​

    }

  }

​

  [grid, next] = [next, grid];

}

​

function countNeighbors(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];

    }

  }

  // remove self value from sum

  sum -= grid[x][y];

  return sum;

}