function drawVector(v, loc, scale){
  push();
  let arrowsize = 4;
  translate(loc.x, loc.y);
  stroke(255);
  rotate(v.heading());

  let len = v.mag() * scale;
  line(0, 0, len,0);
  line(len, 0, len-arrowsize, +arrowsize / 2);
  line(len, 0, len-arrowsize, -arrowsize / 2);
  pop();
}
This function draws an arrow showing the direction our "wind" is blowing.