Reference

Shading theory

Providing vertex data to vertex programs #基础 ##Vertex Shader

可编程管道允许你通过 shader 来控制 顶点和像素的变换. vertex shader 能干什么?

Vertex transformations.
Normal transformations.
Normal normalization (i.e., turn it into a unit vector). 
Handling of per-vertex lighting.
Handling of texture coordinates. 不能干什么?

View volume clipping. 
Homogeneous division. 
Viewport mapping.
Backface culling.
Polygon mode.
Polygon offset.

在 unity 中每个物体都有一个 mesh renderer, 他负责调用 opengl 函数 把 mesh 相关的参数 (顶点坐标,法线,UV)传入流水线,包括:

Vertex: 顶点：顶点的位置
Normal: 法线：顶点的法线
Tangent: 切线：顶点的切线
Texcoord: 主要的UV坐标
Texcoord1: 次要的UV坐标
Color: 颜色：每个顶点颜色

你可以自定义一个结构来传递参数:

struct vertexInput {
     float4 vertex : POSITION;
     float4 tangent : TANGENT;
     float3 normal : NORMAL;
     float4 texcoord : TEXCOORD0;
     float4 texcoord1 : TEXCOORD1;
     fixed4 color : COLOR;
  };

也可以使用内置的,只需要包含头文件 #include "UnityCG.cginc"

       struct appdata_base {
          float4 vertex : POSITION;
          float3 normal : NORMAL;
          float4 texcoord : TEXCOORD0;
       };
       struct appdata_tan {
          float4 vertex : POSITION;
          float4 tangent : TANGENT;
          float3 normal : NORMAL;
          float4 texcoord : TEXCOORD0;
       };
       struct appdata_full {
          float4 vertex : POSITION;
          float4 tangent : TANGENT;
          float3 normal : NORMAL;
          float4 texcoord : TEXCOORD0;
          float4 texcoord1 : TEXCOORD1;
          fixed4 color : COLOR;
          // and additional texture coordinates only on XBOX360)
       };

Fragment Shader

View volume clipping. 
Homogeneous division. 
Viewport mapping.
Backface culling.
Polygon mode.
Polygon offset.  a
 
Blending.
Stencil test.
Depth test.
Scissor test.
Stippling operations.
Raster operations performed as a pixel is being written to the framebuffer.

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