function setup() {

  createCanvas(600, 600);

  gfx = createGraphics(width, height);

  let mid_h = width/2;

  let max_radius = 100;

  background(0);

  fill(255);

  for (let i = 0; i < 50000; i++) {

    let _x = random(width);

    let _y = random(mid_h,height);

    let _radius = random(5);

    let _col = map(_y,mid_h,height,255,0);

    gfx.fill(color(_col,_col,_col,128));

    gfx.ellipse(_x,_y,_radius,_radius); // grayscale

    gfx.fill(color(0,0,_col,255)); // blue

    gfx.ellipse(_x,height-_y,_radius,_radius);

  }

  gfx.stroke(color(128,128,128,128));

  gfx.strokeWeight(2);

  gfx.line(0,mid_h,width,mid_h);

  for (let i = 0; i < 15; i++) {

    let start_rad = random(max_radius,max_radius-50);

    let min_x = start_rad+2;

    let max_x = width - (start_rad+2);

    let min_y = start_rad+2;

    let max_y = mid_h - (start_rad+2);

​

    let _x = random(min_x,max_x);

    let _y = random(min_y,max_y);

    let _r = start_rad;

    for (let j = 0; j < 10; j++) {

      let _col = map(j,0,9,255,0);

      gfx.fill(color(_col,_col,_col,128));

      gfx.stroke(map(_y,mid_h,height,0,255));

      gfx.ellipse(_x,_y,_r,_r);

      gfx.fill(color(0,0,_col,128));

      gfx.stroke(map(_y,mid_h,height,0,255));

      gfx.ellipse(_x,height-_y,_r,_r);

      _r -= 10;

    }

  }

  image(gfx,0,0);

}

​

function draw() {

  //background(0);

}