function get_dist(obj1, obj2)
    local gg = game_graph()
    local ob1_gv = gg:vertex(obj1.m_game_vertex_id)
    local ob2_gv = gg:vertex(obj2.m_game_vertex_id)
    if ob1_gv:level_id() == ob2_gv:level_id() then
        return obj1.position:distance_to_sqr(obj2.position)
    end
    return ob1_gv:game_point():distance_to_sqr(ob2_gv:game_point())
end