Unity图形学之法线贴图原理

1.正常贴图：RGBA 4通道 每个通道取值范围 0-255 贴图里面取值是 0-1

2.法线贴图：法线怎么存入正常贴图的过程

每个通道里面存储的是一个向量(x,y,z,w) 通常我们会对应xyzw为rgba 存储值的范围也是0-1向量的取值范围是 -1到1法线怎么存入正常贴图的过程：法线中的向量取值范围怎么变换为0-1： (-1,1) *0.5 +0.5 ==(0,1)正常贴图变成法线的过程：(0,1) -0.5 *2 == (-1,1)

3.法线贴图为蓝色：是因为法线经常是朝向Z轴的，法线倾向 Z值 ，Z值映射到贴图里面，对应的是RGBA中的B值，所以呈现蓝色

4.法线贴图从哪里来？

1.美术制作
2.U3D里设置 图片类型为 Normal Map

5.法线贴图的作用？

1.增加明暗对比度，让凸出的地方看起来更凸

法线计算：

Shader "Custom/NormalMap"
{Properties{_Color ("Color", Color) = (1,1,1,1)_MainTex ("Albedo (RGB)", 2D) = "white" {}_NorTex ("NormalMap (RGB)", 2D) = "white" {}}SubShader{Tags { "RenderType"="Opaque" }LOD 200CGPROGRAM// Physically based Standard lighting model, and enable shadows on all  light types#pragma surface surf Lambert// Use shader model 3.0 target, to get nicer looking lighting#pragma target 3.0sampler2D _MainTex;sampler2D _NorTex;struct Input{float2 uv_MainTex;float2 uv_NorTex;};fixed4 _Color;void surf (Input IN, inout SurfaceOutput o){// Albedo comes from a texture tinted by colorfixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;o.Normal = UnpackNormal(tex2D (_NorTex, IN.uv_MainTex));o.Albedo = c.rgb;o.Alpha = c.a;}ENDCG}FallBack "Diffuse"
}