// BY https://bibdectrl.github.io/brain/ not my code

const ALIVE = 1;

const DYING = 10;

const DEAD = 0;

const CELLSIZE = 10;

​

function Grid(width, height){

  this.width = width;

  this.height = height;

  this.paused = false;

  this.pause = function(){

    this.paused = ! this.paused;

  };

  this.reset = function(){

      var new_grid = [];

      for (var x = 0; x < this.width; x++){

        new_grid[x] = [];

        for (var y = 0; y < this.height; y++){

          var c = (Math.random() < 0.25) ? ALIVE : (Math.random() < 75) ? DEAD : DYING;

          new_grid[x][y] = c;

        }

      };

      this._grid = new_grid;

  };

  this._grid = [];

  this.reset();

​

  this.next = function(x, y){

    if (this._grid[x][y] == DEAD){

        var xMp = (x == this.width - 1) ? 0 : x + 1;

        var xMm = (x == 0) ? this.width - 1 : x - 1;

        var yMp = (y == this.height -1) ? 0 : y + 1;

        var yMm = (y == 0) ? this.height - 1 : y - 1;

        var sum = 0;

        if (this._grid[xMp][y] == ALIVE) sum++;

        if (this._grid[xMp][yMp]== ALIVE) sum++;

        if (this._grid[xMp][yMm]== ALIVE) sum++;

        if (this._grid[x][yMp]== ALIVE) sum++;

        if (this._grid[x][yMm]== ALIVE) sum++;

        if (this._grid[xMm][y]== ALIVE) sum++;

        if (this._grid[xMm][yMp]== ALIVE) sum++;

        if (this._grid[xMm][yMm]== ALIVE) sum++;

        if (sum === 2) {

          return ALIVE;

        } else {

          return DEAD;

        }

    } else if (this._grid[x][y] == DYING) {

      return DEAD;

    } else if (this._grid[x][y] == ALIVE) {

      return DYING

    }

  };

  this.update = function(){

    if (! this.paused ){

      var new_grid = [];

      for (var x = 0; x < this.width; x++){

        new_grid[x] = [];

        for (var y = 0; y < this.height; y++){

          new_grid[x][y] = this.next(x, y);

        }

      }

      for (var x = 0; x < this.width; x++){

        for (var y = 0; y < this.height; y++){

          this._grid[x][y] = new_grid[x][y];

        }

      }

​

    } else if ( mouseIsPressed ) {

          var x = Math.floor(mouseX / CELLSIZE);

          var y = Math.floor(mouseY / CELLSIZE);

          if (x < 0 || x > this.width) return;

          if (y < 0 || y > this.height) return;

          if (this._grid[x] == undefined) return;

          this._grid[x][y] = ALIVE;

    }

  };

​

  this.show = function(){

    for (var x = 0; x < this.width; x++){

      for (var y = 0; y < this.height; y++){

        switch( this._grid[x][y] ){

          case DEAD:

            break;

          case ALIVE:

            fill(255, 255, 255);

            rect(x*CELLSIZE, y*CELLSIZE, CELLSIZE, CELLSIZE);

            break;

          case DYING:

            fill(0,  0,  255);

            rect(x*CELLSIZE, y*CELLSIZE, CELLSIZE, CELLSIZE);

            break;

        }

      }

    }

  };

}

​

var grid;

var width;

var height;

var resetButton;

var pauseButton;

​

function setup(){

  width = 800;

  height = 600;

  grid = new Grid(80, 60);

  createCanvas(800,600)

  resetButton = createButton('Reset');

  resetButton.mousePressed(() => { grid.reset(); });

  pauseButton = createButton('Pause');

  pauseButton.mousePressed(() => { grid.pause(); });

}

​

function draw(){

  background(0);

  grid.show();

  grid.update();

}

​