// Daniel Shiffman

// http://natureofcode.com

​

var walker;

var graphics;

​

function setup() {

  createCanvas(400, 400);

  graphics = createGraphics(400, 400);

  walker = new Walker();

  //graphics.background(127,0,200);

  graphics.clear();

}

​

function draw() {

  background(127);

  walker.step();

  walker.render();

  fill(0,255,0);

  ellipse(mouseX, mouseY, 24, 24);

  image(graphics,0,0);

}

​

function Walker() {

  this.x = width / 2;

  this.y = height / 2;

​

  this.render = function() {

    graphics.stroke(0);

    graphics.point(this.x, this.y);

  };

​

  this.step = function() {

    var choice = floor(random(4));

    if (choice === 0) {

      this.x++;

    } else if (choice == 1) {

      this.x--;

    } else if (choice == 2) {

      this.y++;

    } else {

      this.y--;

    }

    this.x = constrain(this.x, 0, width - 1);

    this.y = constrain(this.y, 0, height - 1);

  };

}