code: function(bb, v)
  {
      var ix = Math.abs(bb.r - bb.l);
      var modx = (v.x - bb.l) % ix;
      var x = (modx > 0) ? modx : modx + ix;
      
      var iy = Math.abs(bb.t - bb.b);
      var mody = (v.y - bb.b) % iy;
      var y = (mody > 0) ? mody : mody + iy;
      
      return new Vect(x + bb.l, y + bb.b);
  }
docs: TODO edge case issue / Wrap a vector to a bounding box.