grid

int div = 10, unit, cx, cy, rx, ry;
float theta;
float[] off = new float[div*div];
boolean[] rec = new boolean[div*div];

void setup() {
  size(400, 400);
  unit = width/div;
  noStroke();
  rectMode(CENTER);
  for (int i=0; i<rec.length; i++) {
    off[i]= random(TWO_PI);
    if (random(1)>0.3) rec[i]= true;
  }
}

void draw() {
  background(20);
  for (int i=0; i<div; i++) {
    for (int j=0; j<div; j++) {
      cx = (i*unit+unit/2);
      cy = (j*unit+unit/2);
      float sz = unit*.9;
      fill(255);
      ellipse(cx, cy, sz, sz);
    }
  }
  for (int i=1; i<div; i++) {
    for (int j=1; j<div; j++) {
      if (rec[j*div+i]) {
        rx = (i*unit);
        ry = (j*unit);
        float offSet = off[j*div+i] ;
        float sz = map(sin(theta+offSet), -1, 1, 0, unit*1.0);
        fill(20);
        rect(rx, ry, sz, sz);
      }
    }
  }
  theta += 0.0523/2;

  //if (frameCount%2==0 && frameCount<241) saveFrame("image-###.gif");

}