void draw() {

  background(0);

  // render background image

  image(reef, 0, 0);

  //directionalLight(20, 20, 200, 0, 1, -1);

  //ambientLight(50, 70, 252);

  physics.update();

  gl = pgl.beginGL();

  gl.glDisable(GL.GL_DEPTH_TEST);

  gl.glEnable(GL.GL_BLEND);

  gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE);

  for (int i = 0; i < NUM_BOIDS; i++) {

    Boid b = (Boid)boids.get(i);

    b.run(boids);

  }

  // this does not llok like is working

  //gl.glDisable(GL.GL_BLEND);

  pgl.endGL();

  saveFrame();

  //println("fps: " + frameRate);

}