int millisoff;

void setup () {
  size(128, 128, P3D);
  ellipseMode(CENTER);
  
  // this little bit lets us synchronize the milliseconds to the current second
  // this way, (millis() - millisoff) % 1000 will always be 0 on a new second
  int s = second();
  while(s == second());
  millisoff = millis();
}

void draw () {
  // get hour, minute, second distances around the clock
  // second is found by adding the current millisecond % 1000 / 1000 to it, so we get a smooth transition.
  // hour and minute each take from the previous one so that they move smoothly as well.
  float s = (second() + ((millis()- millisoff) % 1000) / 1000.0) / 60.0, m = (minute() + s) / 60.0, h = (hour() + m) / 12.0;
  
  background(255);
  translate(64, 64); rotate(-HALF_PI);
  
  stroke(0);
  ellipse(0, 0, 112, 112);
  line(0, 0, cos(h * TWO_PI) * 32, sin(h * TWO_PI) * 32);
  line(0, 0, cos(m * TWO_PI) * 48, sin(m * TWO_PI) * 48);
  
  stroke(255, 0, 0);
  line(0, 0, cos(s * TWO_PI) * 48, sin(s * TWO_PI) * 48);
}