let v1, v2;

function setup() {
  createCanvas(800, 300);
  v1 = createVector(50, 250);
  v2 = createVector(750, 250);
  background(0);
  stroke(255);
  koch(v1, v2, 6);
}

function koch(p1, p2, i) {
  if (i === 1) connect(p1, p2);
  else {
    const {a, b, c, d, e} = generateEdges(p1, p2)
    
    koch(a, b, i-1)
    koch(b, c, i-1)
    koch(c, d, i-1)
    koch(d, e, i-1)
  }
}

function connect(p1, p2) {
  line(p1.x, p1.y, p2.x, p2.y);
}

function generateEdges(p1, p2) {
  let v = p5.Vector.sub(p2, p1);
  v.div(3);

  let a = p1.copy();

  let b = p5.Vector.add(p1, v);
  
  let d = p5.Vector.sub(p2, v);
  
  v.rotate(-PI/3);
  let c = p5.Vector.add(b, v);

  e = p2.copy();

  return {a, b, c, d, e}
}