createCanvas(600, 600);

  noFill();

  noCursor();  

  //noLoop();

  frameRate(10);

}

​

function draw() {

  background(250);

  stroke(100);

  strokeWeight(0.25);

  translate(width/2, height/2);

​

  for (var i = 0; i < 100000; i++) {

    var r1 = 250 * sqrt(random());

    var θ1 = random(0, 360);

    var r2 = 250 * sqrt(random());

    var θ2 = random(0, 360);

    var pointDistance = distance(r1 * cos(θ1), r1 * sin(θ1),

                                 r2 * cos(θ2), r2 * sin(θ2));

    var maxDistance = map(mouseX, 0, width, 50, 100);

    if (pointDistance < maxDistance) {

      line(r1 * cos(θ1), r1 * sin(θ1),

           r2 * cos(θ2), r2 * sin(θ2));

    }

  }

}

​

function distance(x1, y1, x2, y2) {

  return sqrt(sq(x2 - x1) + sq(y2 - y1));

}