let grid;

​

function setup() {

  createCanvas(600, 600);

  grid = new Grid(width / resolution, height / resolution, resolution);

  grid.initialize();

}

​

function draw() {

  background(0);

  grid.display();

  grid.update();

​

  if (mouseIsPressed) {

    grid.addLiveCell(mouseX, mouseY);

  }

}

​

class Cell {

  constructor(x, y, resolution) {

    this.x = x;

    this.y = y;

    this.resolution = resolution;

    this.state = floor(random(2));

    this.nextState = this.state;

    this.color =  color('lime');

  }

​

  calculateNextState(grid) {

    let neighbors = this.countNeighbors(grid);

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

      this.nextState = 1;

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

      this.nextState = 0;

    } else {

      this.nextState = this.state;

    }

  }

​

  updateState() {

    this.state = this.nextState;

  }

​

  display() {

    if (this.state == 1) {

      fill(this.color);

      stroke(0);

      rect(this.x * this.resolution, this.y * this.resolution, this.resolution, this.resolution);

    }

  }

​

  countNeighbors(grid) {

    let sum = 0;

    let cols = grid.cols;

    let rows = grid.rows;

    for (let i = -1; i < 2; i++) {

      for (let j = -1; j < 2; j++) {

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

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

        sum += grid.cells[col][row].state;

      }

    }

    sum -= grid.cells[this.x][this.y].state;

    return sum;

  }

}

​

class Grid {

  constructor(cols, rows, resolution) {

    this.cols = cols;

    this.rows = rows;

    this.resolution = resolution;

    this.cells = this.create2DArray();

  }

​

  create2DArray() {

    let arr = new Array(this.cols);

    for (let i = 0; i < this.cols; i++) {

      arr[i] = new Array(this.rows);

      for (let j = 0; j < this.rows; j++) {

        arr[i][j] = new Cell(i, j, this.resolution);

      }

    }

    return arr;

  }

​

  initialize() {

    for (let i = 0; i < this.cols; i++) {

      for (let j = 0; j < this.rows; j++) {

        this.cells[i][j] = new Cell(i, j, this.resolution);

      }

    }

  }

​

  display() {

    for (let i = 0; i < this.cols; i++) {

      for (let j = 0; j < this.rows; j++) {

        this.cells[i][j].display();

      }

    }

  }

​

  update() {

    for (let i = 0; i < this.cols; i++) {

      for (let j = 0; j < this.rows; j++) {

        this.cells[i][j].calculateNextState(this);

      }

    }

    for (let i = 0; i < this.cols; i++) {

      for (let j = 0; j < this.rows; j++) {

        this.cells[i][j].updateState();

      }

    }

  }

​

  addLiveCell(x, y) {

    let col = floor(x / this.resolution);

    let row = floor(y / this.resolution);

    if (col >= 0 && col < this.cols && row >= 0 && row < this.rows) {

      this.cells[col][row].state = 1;

      this.cells[col][row].color = color('lime');

    }

  }

}

​