基于Z_Pass算法的体积阴影，代码简单明了，是学习这个算法的极好例子，不过尚不完美，单核心部分都做出来了，这可费了我很大的功夫啊-Volume shadow based on Z_Pass algorithms, the code is simple, is an excellent example of learning algorithm, but not perfect, single-core parts to do it, it can cost me a lot of effort