渐变纹理Shader

来自于 shader 入门精要代码：

Shader "MyShaders/RampTexture"
{
    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;
            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"
}