​

let board = [

  ['', '', ''],

  ['', '', ''],

  ['', '', ''],

];

​

let players = ['X', 'O'];

​

let currentPlayer;

let available = [];

​

let w;

let h;

​

function setup() {

  createCanvas(400, 400);

  engine = Engine.create();

  world = engine.world;

  w = width / 3;

  h = height / 3;

  frameRate(3);

  currentPlayer = floor(random(players.length));

  for (let j = 0; j < 3; j++) {

    for (let i = 0; i < 3; i++) {

      available.push([i, j]);

    }

  }

}

​

function equals3(a, b, c) {

  return (a == b && b == c && a != '');

}

​

function checkWinner() {

  let winner = null;

  stroke(0, 250, 0);

  // horizontal

  for (let i = 0; i < 3; i++) {

    if (equals3(board[i][0], board[i][1], board[i][2])) {

      winner = board[i][0];

      line((i * w) + (w / 2), 0, (i * w) + (w / 2), height);

    }

  }

​

  // Vertical

  for (let i = 0; i < 3; i++) {

    if (equals3(board[0][i], board[1][i], board[2][i])) {

      winner = board[0][i];

      line(0, (i * w) + (w / 2), width, (i * w) + (w / 2));

    }

  }

​

  // Diagonal

  if (equals3(board[0][0], board[1][1], board[2][2])) {

    winner = board[0][0];

    line(0, 0, width, height);

  }

  if (equals3(board[2][0], board[1][1], board[0][2])) {

    winner = board[2][0];

    line(0, height, width, 0);

  }

​

  if (winner == null && available.length == 0) {

    return 'tie';

  } else {

    return winner;

  }

​

}

​

function nextTurn() {

  let index = floor(random(available.length));

  let spot = available.splice(index, 1)[0];

  let i = spot[0];

  let j = spot[1];

  board[i][j] = players[currentPlayer];

  currentPlayer = (currentPlayer + 1) % players.length;

}

​

// function mousePressed() {

//   nextTurn(); 

// }

​

function draw() {

  background(255);

  stroke(0);

  strokeWeight(4);

​

  line(w, 0, w, height);

  line(w * 2, 0, w * 2, height);

  line(0, h, width, h);

  line(0, h * 2, width, h * 2);

​

  for (let j = 0; j < 3; j++) {

    for (let i = 0; i < 3; i++) {

      let x = w * i + w / 2;

      let y = h * j + h / 2;

      let spot = board[i][j];

      if (spot == players[1]) {

        noFill();

        ellipse(x, y, w / 2);

      } else if (spot == players[0]) {

        let xr = w / 4;

        line(x - xr, y - xr, x + xr, y + xr);

        line(x + xr, y - xr, x - xr, y + xr);

      }

    }

  }

​

  let result = checkWinner();

  if (result != null) {

    noLoop();

    let resultP = createP('');

    resultP.style('font-size', '32pt');

    if (result == 'tie') {

      resultP.html("Tie!")

    } else {

      resultP.html(`${result} wins!`);

    }

  } else if (currentPlayer == players[1]) {

    nextTurn();

  }

}