Shader程式碼如下：

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

Shader "Custom/Forground" {
    Properties {
        _MainTex ("Base (RGB)", 2D) = "white" {}
        _Forground("Ridof (RGB)",Color)=(0,0,0,1)
    } 
    SubShader {
        Tags { "RenderType"="Opaque" }
        Blend SrcAlpha OneMinusSrcAlpha
        pass 
        { 
            CGPROGRAM

            #pragma vertex vertext_convert
            #pragma fragment fragment_convert
            #include "UnityCG.cginc"

            sampler2D  _MainTex;
            float4  _Forground;
            struct Inputvrite
            {
                float4 vertex : POSITION;
                float4 texcoord : TEXCOORD0;
            };
            struct Inputfragment
            {
                float4 pos : SV_POSITION;
                float4 uv : TEXCOORD0;
            };

            float ColorLerp(float3 tmp_nowcolor,float3 tmp_Forground)
            { 
                float3 dis = float3(abs(tmp_nowcolor.x - tmp_Forground.x),abs(tmp_nowcolor.y - tmp_Forground.y),abs(tmp_nowcolor.z - tmp_Forground.z)); 
                float dis0 =sqrt(pow(dis.x,2)+pow(dis.y,2)+pow(dis.z,2));
                float maxdis = sqrt(3);
                float dis1 = lerp(0,maxdis,dis0);
                return dis1;
            }

            Inputfragment vertext_convert(Inputvrite i)
            {
                Inputfragment o;
                o.pos = UnityObjectToClipPos(i.vertex);
                o.uv = float4(i.texcoord.xy,1,1);
                return o;
            }

            float4 fragment_convert(Inputfragment o) : COLOR
            {
                float4 c = tex2D(_MainTex,o.uv);
                c.a *=ColorLerp(c.rgb,_Forground.rgb);
                return c;
            }
        ENDCG
        }
    }
    FallBack "Diffuse"
}