int unit = 40;
  int num;
  Module[] mods;
  
  void setup() 
  {
    size(200, 200);
    background(176);
    noStroke();
    
    num = width/unit * width/unit;
    mods = new Module[num];
    
    for (int i = 0; i < height/unit; i++) {
      for (int j = 0; j < height/unit; j++) {
        int index = (i * height/unit) + j;
        mods[index] = new Module(j*unit, i*unit, unit/2, unit/2, random(0.05, 0.8));  
      }
    }
  }
  
  void draw() 
  {
    for (int i = 0; i < num; i++) {
      mods[i].update();
      mods[i].draw();
    }
  }
  
  class Module {
    float mx, my;
    int size = unit;
    float x, y = 0;
    int xdir = 1;
    int ydir = 1;
    float speed; 
    
    // Contructor (required)
    Module(float imx, float imy, float ix, float iy, float ispeed) {
      mx = imy;
      my = imx;
      x = int(ix);
      y = int(iy);
      speed = ispeed;
    }
    
    // Custom method for updating the variables
    void update() {
      x = x + (speed * xdir);
      if (x >= size || x <= 0) {
        xdir *= -1;
        x = x + (1 * xdir);
        y = y + (1 * ydir);
      }
      if (y >= size || y <= 0) {
        ydir *= -1;
        y = y + (1 * ydir);
      }
    }
    
    // Custom method for drawing the object
    void draw() {
      stroke(second()*4);
      point(mx+x-1, my+y-1);
    }
  }