​

var rotor;

​

function setup() {

  createCanvas(400, 400);

  background(0);

  noFill();

  stroke(255, 255, 255, 15);

  var vs = random(2, 6);

  rotor = {

    x: random(0, width),

    y: random(0, height),

    vx: random(vs),

    vy: random(vs),

    length: random(8, 32),

    angle: random(TWO_PI),

    speed: (random(1) < 0.5 ? -1 : 1) * random(TWO_PI / 360, TWO_PI / 45)

  };

}

​

function draw() {

  //background(220);

  rotor.x += rotor.vx;

  rotor.y += rotor.vy;

  rotor.angle += rotor.speed;

  //rotor.x += rotor.vx;

  //rotor.y += rotor.vy;

  rotor.angle += rotor.speed;

​

  if(rotor.x < 0 || rotor.x > width)

    rotor.vx = -rotor.vx;

  if(rotor.y < 0 || rotor.y > height)

    rotor.vy = -rotor.vy;

  var x1 = rotor.x + rotor.length * cos(rotor.angle);

  var y1 = rotor.y + rotor.length * sin(rotor.angle);

  var x2 = rotor.x - rotor.length * cos(rotor.angle);

  var y2 = rotor.y - rotor.length * sin(rotor.angle);

  line(x1, y1, x2, y2);

}