​

let points = [];

let pointIndex = 0;

let hull = [];

​

function setup() {

  createCanvas(windowWidth, windowHeight);

​

  let buffer = 20;

  while (points.length < numOfPoints) {

    let x = randomGaussian(width / 2, width / 5);

    let y = randomGaussian(height / 2, height / 5);

    if (x > buffer && x < width - buffer && y > buffer && y < height - buffer) {

      points.push(createVector(x, y));

    }

  }

​

  // Sort by angle

  let p0 = points.sort((a, b) => ((b.y - a.y) != 0 ? (b.y - a.y) : (a.x - b.x)))[0];

  points = points.sort((a, b) => {

    let getTanAngleToP0 = (p) => ((p.x - p0.x) / (p.y - p0.y));

    let angleA = getTanAngleToP0(a);

    let angleB = getTanAngleToP0(b);

    if (angleA == angleB) return a.sub(p0).mag() - b.sub(p0).mag();

    return angleA - angleB;

  });

}

​

function draw() {

  frameRate(numOfPoints / 4);

  background(0);

​

  strokeWeight(4);

  stroke(100);

  for (let i = 0; i < points.length; i++) {

    if (i > pointIndex) stroke(255);

    point(points[i].x, points[i].y);

  }

​

  strokeWeight(2);

  stroke(255);

  noFill();

  beginShape();

  for (let i = 0; i < hull.length; i++) {

    vertex(hull[i].x, hull[i].y);

  }

  endShape();

​

  // Graham scan

  let p = points[pointIndex];

  if (p) {

    if (hull.length > 1 && ccw(hull[hull.length - 2], hull[hull.length - 1], p)) {

      hull.pop();

    } else {

      hull.push(p);

      pointIndex++;

    }

  } else { // Closing line

    stroke(255);

    line(hull[hull.length - 1].x, hull[hull.length - 1].y, hull[0].x, hull[0].y);

  }

}

​

function ccw(a, b, c) {

  // draw current points

  stroke(255, 0, 0);

  line(a.x, a.y, b.x, b.y);

  line(b.x, b.y, c.x, c.y);

​

  return ((b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x)) > 0;

}