gistfile1.txt

PVector[] stars;
float[] phase;

void setup() {
  size(600, 600, P3D);
  stars = new PVector[1000];
  phase = new float[1000];
  
  for(int i = 0 ; i < 1000; ++i) {
    stars[i] = new PVector(random(width), random(height));
    phase[i] = random(TWO_PI);
  }
}

float t =0;
void draw() {
  background(0);
  for(int i = 0 ; i < stars.length; ++i) {
    float r = map(sin(t + phase[i]), -1, 1, 2, 4);
    noStroke();
    fill(255);
    ellipse(stars[i].x, stars[i].y, r, r);
  }
  
  t += 0.1; // if t >= TWO_PI, it will loop 
}