与上篇逐顶点光照很像,只是改为在片元着色器中计算光照,下为逐像素光照shader

Shader "study/Chapter6/PixelShader"{
Properties{
_Diffuse ("Diffuse", Color) = (1, 1, 1, 1)
}
SubShader{
Pass{
Tags{"LightMode"="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;
float3 worldNormal : TEXCOORD0;
}; v2f vert(a2v v) {
v2f o;
// Transform the vertex from object space to projection space
o.pos = UnityObjectToClipPos(v.vertex); // Transform the normal from object space to world space
o.worldNormal = mul(v.normal, (float3x3)unity_WorldToObject); return o;
} fixed4 frag(v2f i) : SV_Target {
// Get ambient term
fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz; // Get the normal in world space
fixed3 worldNormal = normalize(i.worldNormal);
// Get the light direction in world space
fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz); // Compute diffuse term
fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * saturate(dot(worldNormal, worldLightDir)); fixed3 color = ambient + diffuse; return fixed4(color, 1.0);
}
ENDCG
}
}
FallBack "Diffuse"
}

下为半兰伯特光照模型

广义的半兰伯特光照模型公式如下:

漫反射(C)=((C) * (M))(α(n*I)+β)

半兰伯特模型没有使用max防止表面法线和光照方向的点成为负值,而是进行了α倍的缩放和一个β倍的偏移,大多情况下α和β均为0.5

Shader "study/Chapter6/Half Lambert" {
Properties {
_Diffuse ("Diffuse", Color) = (1, 1, 1, 1)
}
SubShader {
Pass {
Tags { "LightMode"="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;
float3 worldNormal : TEXCOORD0;
}; v2f vert(a2v v) {
v2f o;
// Transform the vertex from object space to projection space
o.pos = UnityObjectToClipPos(v.vertex); // Transform the normal from object space to world space
o.worldNormal = mul(v.normal, (float3x3)unity_WorldToObject); return o;
} fixed4 frag(v2f i) : SV_Target {
// Get ambient term
fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz; // Get the normal in world space
fixed3 worldNormal = normalize(i.worldNormal);
// Get the light direction in world space
fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz); // Compute diffuse term
fixed halfLambert = dot(worldNormal, worldLightDir) * 0.5 + 0.5;
fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * halfLambert; fixed3 color = ambient + diffuse; return fixed4(color, 1.0);
} ENDCG
}
}
FallBack "Diffuse"
}

  

05-11 22:19