Global Illumination

【Global Illumination】

　　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).

　　GI用于模拟反射光照。

　　Baked GI (also known as Baked Lightmaps) vs Precomputed Realtime GI.

　　Both Baked GI and Precomputed Realtime GI have the limitation that only static objects can be included in the bake/precomputation - so moving objects cannot bounce light onto other objects and vice versa. 

　　在  Window > Lighting > Settings > Scene > Auto Generate 中可以生成 lightmap

　　NOTE: When using Auto Generate mode, Unity stores your lighting data in a temporary cache with a limited size.Uncheck Auto Generate, and generate the lighting data manually for all your Scenes. Unity then saves your lighting data as Asset files in your project folder, which means you have the data saved as part of your project and included in your build.

　　自动生成会放置到GI Cache目录下。必须手动点Build，才会生成到Asset目录下。