Your browser does not seem to support JavaScript. As a result, your viewing experience will be diminished, and you may not be able to execute some actions.
Please download a browser that supports JavaScript, or enable it if it's disabled (i.e. NoScript).
？如何实现放置拆除
这包含好多知识，先有背包，通过拖动，或者点击加4方控制，和背包丢物品到地面一样的原理
