Unity中的基础光照（漫反射）

漫反射光照

详情参见&＃xff1a;https://github.com/mrxandlingsa
&＃xff08;冯乐乐&＃xff09;
兰伯特光照模型&＃xff08;Lambert&＃xff09;
应用&＃xff1a;Lambert 模型较好地表现了粗糙表面上的光照现象&＃xff0c;如石灰粉刷的墙壁、纸张等
公式&＃xff1a;C(diffuse)&＃61;(C(light)*m(diffuse))*max(0,n,l)
C&＃xff08;light&＃xff09;:入射光线的颜色和强度
m(diffuse):材质的反射系数发v
n:表面法线
l:光源方向
CG中saturate(x)函数可代替上述公式

1&＃xff09;Lambert光照的逐顶点光照实现

Shader "Unlit/Lambert"
{
Properties {_Diffuse ("Diffuse", Color) &＃61; (1, 1, 1, 1)//材质的漫反射颜色}SubShader {Pass { Tags { "LightMode"&＃61;"ForwardBase" }CGPROGRAM#pragma vertex vert#pragma fragment frag#include "Lighting.cginc"fixed4 _Diffuse;struct a2v {float4 vertex : POSITION;float3 normal : NORMAL;};struct v2f {float4 pos : SV_POSITION;fixed3 color : COLOR;};v2f vert(a2v v) {v2f o;// Transform the vertex from object space to projection space//顶点位置的坐标转化到剪裁空间o.pos &＃61; UnityObjectToClipPos(v.vertex);// Get ambient term环境光fixed3 ambient &＃61; UNITY_LIGHTMODEL_AMBIENT.xyz;//公式应用是都在世界空间下进行// Transform the normal from object space to world space//世界坐标下法线向量并归一化fixed3 worldNormal &＃61; normalize(mul(v.normal, (float3x3)unity_WorldToObject));// Get the light direction in world space//世界坐标下的光源方向&＃xff08;单一光源&＃xff09;fixed3 worldLight &＃61; normalize(_WorldSpaceLightPos0.xyz);// Compute diffuse term//Lambert公式的应用&＃xff08;dot为2个向量的点积&＃xff09;fixed3 diffuse &＃61; _LightColor0.rgb * _Diffuse.rgb * saturate(dot(worldNormal, worldLight));o.color &＃61; ambient &＃43; diffuse;return o;}fixed4 frag(v2f i) : SV_Target {return fixed4(i.color, 1.0);}ENDCG}}FallBack "Diffuse"
}

&＃96;&＃96;效果如上
2&＃xff09;逐像素的Lambert光照实现
之需要将世界空间下的法线传递给片元着色器
实现如下&＃xff1a;

在这里插入代码片
struct
{float4 pos:SV_POSITION;float3 worldNormal:TEXCOORD0;
}
v2f vert(a2v v) {v2f o;// Transform the vertex from object space to projection space//顶点位置的坐标转化到剪裁空间o.pos &＃61; UnityObjectToClipPos(v.vertex);o.worldNormal&＃61;mul(v.normal,(float3x3)unity_WorldToObject);return o;}fixed4 frag(v2f i) : SV_Target {fixed3 ambient &＃61; UNITY_LIGHTMODEL_AMBIENT.xyz;fixed worldNormal&＃61;normalize(i.worldNormal);fixed3 worldLight&＃61;normalize(_WorldSpaceLightPos0.xyz);fixed3 diffuse &＃61; _LightColor0.rgb * _Diffuse.rgb * saturate(dot(worldNormal, worldLight));fixed3 color &＃61; ambient &＃43; diffuse;return fixed4(color, 1.0);}


效果如下

3&＃xff09;半兰伯特模型
公式&＃xff1a;
C(diffuse)&＃61;(C(light)*m(diffuse))&＃xff08;0.5&＃xff08;n,l&＃xff09;&＃43;0.5&＃xff09;
原理&＃xff1a;将n·l的结果范围从[-1,1]映射到[0,1]的范围内。
只需要更改片元着色器的代码即可

fixed4 frag(v2f i) : SV_Target {// Get ambient termfixed3 ambient &＃61; UNITY_LIGHTMODEL_AMBIENT.xyz;// Get the normal in world spacefixed3 worldNormal &＃61; normalize(i.worldNormal);// Get the light direction in world spacefixed3 worldLightDir &＃61; normalize(_WorldSpaceLightPos0.xyz);// Compute diffuse termfixed halfLambert &＃61; dot(worldNormal, worldLightDir) * 0.5 &＃43; 0.5;fixed3 diffuse &＃61; _LightColor0.rgb * _Diffuse.rgb * halfLambert;fixed3 color &＃61; ambient &＃43; diffuse;return fixed4(color, 1.0);}


不知道关于漫反射还有其他模型么&＃xff1f;