code: function(c1, c2) {
        return [
          {x: c1[1].x - c1[0].x, y: c1[1].y - c1[0].y},
          {x: c1[1].x - c1[3].x, y: c1[1].y - c1[3].y},
          {x: c2[0].x - c2[2].x, y: c2[0].y - c2[2].y},
          {x: c2[0].x - c2[1].x, y: c2[0].y - c2[1].y}
        ];
      }
docs: Compute the four axis between corners of rectangle A and corners of
  rectangle B. This is needed later to check an eventual collision.
  
  @param  {array} An array of rectangle A's four corners (x, y).
  @param  {array} An array of rectangle B's four corners (x, y).
  @return {array} An array of four axis defined by their coordinates (x,y).