本文档主要是对Unity官方手册的个人理解与总结（其实以翻译记录为主：>）
仅作为个人学习使用，不得作为商业用途，欢迎转载，并请注明出处。
文章中涉及到的操作都是基于Unity2018.1版本
参考链接：https://docs.unity3d.com/Manual/GIIntro.html
Global Illumination (GI) is a system that models how light is bounced off of surfaces onto other surfaces (indirect light) rather than being limited to just the light that hits a surface directly from a light source (direct light). Modelling indirect lighting allows for effects that make the virtual world seem more realistic and connected, since objects affect each other’s appearance. One classic example is ‘color bleeding’ where, for example, sunlight hitting a red sofa will cause red light to be bounced onto the wall behind it. Another is when sunlight hits the floor at the opening of a cave and bounces around inside so the inner parts of the cave are illuminated too.
全局光照（GI）是一个模拟光照从一表面反弹到另一表面（间接光），而不是仅仅局限于直接从光源（直接光）照射到表面的光照系统。模拟间接照明可以使虚拟世界看起来更真实、更有联系，因为物体会影响彼此的着色。一个经典的例子是“渗色”，例如，阳光照射在红色的沙发上，会导致红色的光线反弹到后面的墙上。另一种是当阳光照射到洞穴的底部，并在洞穴里面反弹，这样洞穴的内部也被照亮。
Global illumination in the Scene View. Note the subtle effect of indirect lighting.
场景视图中的全局照明。注意间
