Unity3D Lights

   

  光照的两种方式：

  一、基于顶点的。

  二、基于像素的。

   第一种开销小，但是功能少。第二少开销大，功能多，效果好。

  Lights can be rendered using either of two methods:

Vertex lighting calculates the illumination only at the vertices of meshes and interpolates the vertex values over the rest of the surface. Some lighting effects are
not supported by vertex lighting but it is the cheaper of the two methods in terms of processing overhead. Also, this may be the only method available on older graphics cards.

Pixel lighting is calculated separately at every screen pixel. While slower to render, pixel lighting does allow some effects that are not possible with vertex lighting.
Normal-mapping, light cookies and realtime shadows are only rendered for pixel lights. Additionally, spotlight shapes and point light highlights look much better when rendered in pixel mode.

 
因为pixel lights比 vertex lights.Unity 只将最亮的 光用pixel 方式渲染。   pixel lights的个数可以在quality setting里面设置。

 Since
pixel lights have a much higher rendering overhead than vertex lights, Unity will only render the brightest lights at per-pixel quality and render the rest as vertex lights. The maximum number of pixel lights can be set in theQuality
Settings for webplayer and standalone build targets.

关于影子：
 Soft 影子比hard
影子消耗更大，但只是针对于GPU上的消耗。
Soft shadows
have a greater rendering overhead than hard shadows but this only affects the GPU and does not cause much extra CPU work.