Shaders

【Shaders】

1、Vertex-Lit，顶点光照着色器。

　　Vertex-Lit is one of the simplest shaders. All lights shining on it are rendered in a single pass and calculated at vertices only. Because it is vertex-lit, it won't display any pixel-based rendering effects, such as light cookies, normal mapping, or shadows. This shader is also much more sensitive to tesselation of the models. 

　　 If you put a point light very close to a cube using this shader, the light will only be calculated at the corners. Pixel-lit shaders are much more effective at creating a nice round highlight, independent of tesselation. If that's an effect you want, you may consider using a pixel-lit shader or increase tesselation of the objects instead.

2、Shader的性能。

　　Performance of a shader mostly depends on two things: shader itself and which Rendering Path is used by the project or specific camera.　

　　1）Rendering Paths and shader performance

　　Deferred Lighting and Vertex Lit paths have the most predictable performance. In Deferred lighting, each object is generally drawn twice, no matter what lights are affecting it. Similarly, in Vertex Lit each object is generally drawn once. So then, the performance differences in shaders mostly depend on how many textures they use and what calculations they do.

　　2）Shader Performance in Forward rendering path