使用渐变纹理控制漫反射光照

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// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'
// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

Shader "Unity Shaders Book/Chapter 7/Ramp Texture" {
Properties {
_Color ("Color Tint", Color) = (1, 1, 1, 1)
_RampTex ("Ramp Tex", 2D) = "white" {}
_Specular ("Specular", Color) = (1, 1, 1, 1)
_Gloss ("Gloss", Range(8.0, 256)) = 20
}
SubShader {
Pass {
Tags { "LightMode"="ForwardBase" }

CGPROGRAM

#pragma vertex vert
#pragma fragment frag

#include "Lighting.cginc"

fixed4 _Color;
sampler2D _RampTex;
float4 _RampTex_ST;
fixed4 _Specular;
float _Gloss;

struct a2v {
float4 vertex : POSITION;
float3 normal : NORMAL;
float4 texcoord : TEXCOORD0;
};

struct v2f {
float4 pos : SV_POSITION;
float3 worldNormal : TEXCOORD0;
float3 worldPos : TEXCOORD1;
float2 uv : TEXCOORD2;
};

v2f vert(a2v v) {
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);

o.worldNormal = UnityObjectToWorldNormal(v.normal);

o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;

o.uv = TRANSFORM_TEX(v.texcoord, _RampTex);

return o;
}

fixed4 frag(v2f i) : SV_Target {
fixed3 worldNormal = normalize(i.worldNormal);
fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));

fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;

// Use the texture to sample the diffuse color
fixed halfLambert = 0.5 * dot(worldNormal, worldLightDir) + 0.5;
//斜线采样
fixed3 diffuseColor = tex2D(_RampTex, fixed2(halfLambert, halfLambert)).rgb * _Color.rgb;

fixed3 diffuse = _LightColor0.rgb * diffuseColor;

fixed3 viewDir = normalize(UnityWorldSpaceViewDir(i.worldPos));
fixed3 halfDir = normalize(worldLightDir + viewDir);
fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(max(0, dot(worldNormal, halfDir)), _Gloss);

return fixed4(ambient + diffuse + specular, 1.0);
}

ENDCG
}
}
FallBack "Specular"
}

对一个渐变纹理采样即可。