public static boolean checkPlacement(
    Fixture fixtures[], World world
  ) {
    Box2D limits = null ;
    for (Fixture f : fixtures) {
      if (limits == null) f.area(limits = new Box2D()) ;
      else limits.include(f.area()) ;
    }
    if (! checkAreaClear(
      world.tileAt(limits.xpos() + 0.5f, limits.ypos() + 0.5f),
      (int) limits.xdim(),
      (int) limits.ydim(),
      fixtures[0].owningType()
    )) return false ;
    
    for (Fixture f : fixtures) if (! f.canPlace()) return false ;
    return true ;
  }