Unity自定义半透明surface材质shader

Shader "Custom/StencilStandardTransparentCull"
{
    Properties
    {
        _Color ("Color", Color) = (1,1,1,1)
        _MainTex ("Albedo (RGB)", 2D) = "white" {}
        _NormalMap("NormalMap", 2D) = "bump" {}
        _BumpScale("Bump Scale", Float) = 1.0
        _AlphaScale("Alpha Scale", Float) = 1.0
        _Glossiness ("Smoothness", Range(0,1)) = 0.5
        _Metallic ("Metallic", Range(0,1)) = 0.0
        _Cutoff("Alpha Culloff", Range(0, 1)) = 0.5

        [IntRange] _StencilRef("Stencil Reference Value", Range(0,255)) = 0
    }
    SubShader
    {
        Tags { "Queue" = "Transparent" "IgnoreProjector" = "True" "RenderType" = "Transparent" }

        Stencil{
            Ref[_StencilRef]
            Comp Equal
        }

         CGPROGRAM
            #pragma surface surf Standard fullforwardshadows alpha:fade    // 半透明， 无反射， 可融合，边缘平滑
            //#pragma surface surf Standard fullforwardshadows alphatest:_Cutoff   // 硬边，多用于植被，开销小，不能融合
            //#pragma surface surf Standard fullforwardshadows alpha:premul  // 半透明，有反射，适用于玻璃

            // Use shader model 3.0 target, to get nicer looking lighting
            #pragma target 3.0

            sampler2D _MainTex;
            sampler2D _NormalMap;

            struct Input
            {
                float2 uv_MainTex;
                float2 uv_NormalMap;
            };

            half _Glossiness;
            half _Metallic;
            fixed4 _Color;
            float _BumpScale;
            float _AlphaScale;

            UNITY_INSTANCING_BUFFER_START(Props)
                // put more per-instance properties here
            UNITY_INSTANCING_BUFFER_END(Props)

            void surf (Input IN, inout SurfaceOutputStandard o)
            {
                // Albedo comes from a texture tinted by color
                fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
                float3 normal = UnpackNormal(tex2D(_NormalMap, IN.uv_NormalMap)) * _BumpScale;
                o.Albedo = c.rgb;
                // Metallic and smoothness come from slider variables
                o.Metallic = _Metallic;
                o.Smoothness = _Glossiness;
                o.Alpha = c.a * _AlphaScale;
                o.Normal = normal;
            }
            ENDCG
        }
    FallBack "Transparent/Cutout/VertexLit"
}