var phi = 60;

var counter1 = 0;

var counter2 = 0;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  angleMode(DEGREES);

  strokeWeight(8);

}

​

function draw() {

  background(31);

  translate(width / 4, height * 0.75);

  stroke(255);

  line(0, 0, r, 0);

  let x = r * cos(counter1);

  let y = r * -sin(counter1);

  line(0, 0, x, y);

  counter1 = constrain(counter1 + 0.5, 0, phi);

  if (counter1 == phi) {

    stroke(255,0,105);

    let aim = createVector(r - x, -y).setMag(counter2);

    line(x, y, x + aim.x, y + aim.y);

    counter2 = constrain(counter2 + 1, 0, 250)

  }

}