SOURCE

let angle = 0.10;
let r = 600;
function setup() {
    createCanvas(600, 600);
    background(110);
}
function draw() {
    stroke(255 - angle);
    let x = width / 4 + cos(angle) * (r - angle);
    let y = height / 2 + sin(angle) * (r - angle);
    line(width / 3, height / 2, x, y);
    angle += 0.1;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.1.9/p5.min.js"></script>