【Unity Shader】透明度物体的阴影

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

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'

Shader "Custom/AlphaTestWithShadow"
{
    Properties{
        _Color("Color Tint", Color) = (1,1,1,1)
        _MainTex("Main Tex", 2D) = "white"{}
        _Cutoff("Alpha Cutoff", Range(0, 1)) = 0.5
    }


    SubShader{
        Tags{"Queue" = "AlphaTest" "IgnoreProjector" = "True" "RenderType" = "TransparentCutout"}

        pass{
            Tags{"LightMode" = "ForwardBase"}

            Cull off
            CGPROGRAM

            #pragma multi_compile_fwdbase

            #pragma vertex vert
            #pragma fragment frag

            #include "Lighting.cginc"
            #include "AutoLight.cginc"

            fixed4 _Color;
            sampler2D _MainTex;
            float4 _MainTex_ST;
            fixed _Cutoff;

            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;
                SHADOW_COORDS(3)
            };

            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, _MainTex);
                TRANSFER_SHADOW(o);
                return o;
            }

            fixed4 frag(v2f i) : SV_Target{
                fixed3 worldNormal = normalize(i.worldNormal);
                fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));
                fixed4 texColor = tex2D(_MainTex, i.uv);

                clip(texColor.a - _Cutoff);     //透明度裁剪（Alpha测试）
                fixed3 albedo = texColor.rgb * _Color.rgb;

                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
                fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(worldNormal, worldLightDir));
                //计算阴影和光照衰减
                UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);
                return fixed4(ambient + diffuse * atten, 1.0);
            }
            ENDCG
        }
    }
    Fallback "Transparent/Cutout/VertexLit"
}