// Daniel Shiffman

// http://natureofcode.com

​

let w = 8;

let columns, rows;

let board;

​

function setup() {

  createCanvas(640, 240);

  columns = width / w;

  rows = height / w;

  board = create2DArray(columns, rows);

  for (let i = 1; i < columns - 1; i++) {

    for (let j = 1; j < rows - 1; j++) {

      board[i][j] = new Cell(floor(random(2)), i * w, j * w, w);

    }

  }

}

​

function draw() {

  //{!2} Looping but skipping the edge cells

  for (let x = 1; x < columns - 1; x++) {

    for (let y = 1; y < rows - 1; y++) {

      let neighborSum = 0;

      for (let i = -1; i <= 1; i++) {

        for (let j = -1; j <= 1; j++) {

          //{!1 .bold} Use the previous state when counting neighbors

          neighborSum += board[x + i][y + j].previous;

        }

      }

      neighborSum -= board[x][y].previous;

​

      //{!3} Set the cell's new state based on the neighbor count

      if (board[x][y].state == 1 && neighborSum < 2) {

        board[x][y].state = 0;

      } else if (board[x][y].state == 1 && neighborSum > 3) {

        board[x][y].state = 0;

      } else if (board[x][y].state == 0 && neighborSum == 3) {

        board[x][y].state = 1;

      }

      // else do nothing!

    }

  }

​

  for (let i = 0; i < columns; i++) {

    for (let j = 0; j < rows; j++) {

      //{!1} evaluates to 255 when state is 0 and 0 when state is 1

      board[i][j].show();

      //{!1} save the previous state before the next generation!

      board[i][j].previous = board[i][j].state;

    }

  }

}

​

function create2DArray(columns, rows) {

  let arr = new Array(columns);

  for (let i = 0; i < columns; i++) {

    arr[i] = new Array(rows);

    for (let j = 0; j < rows; j++) {

      arr[i][j] = new Cell(0, i * w, j * w, w);

    }

  }

  return arr;

}

​