code: private static int getOffsetX(Collision collision, Mirror mirror)
      {
          if (mirror == Mirror.HORIZONTAL)
          {
              return -collision.getOffsetX();
          }
          return collision.getOffsetX();
      }
docs: Get the horizontal offset.
  
  @param collision The collision reference.
  @param mirror The mirror used.
  @return The offset value depending of mirror.