Shader "Custom/HolePrepare" {
    Properties{
    }

    SubShader{
        Tags { "RenderType" = "Opaque" "Queue" = "Geometry+1"}
        ColorMask 0
        ZWrite off
        Stencil {
            Ref 1
            Comp always
            Pass replace
        }

        CGINCLUDE
            struct appdata {
                float4 vertex : POSITION;
            };
            struct v2f {
                float4 pos : SV_POSITION;
            };
            v2f vert(appdata v) {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                return o;
            }
            half4 frag(v2f i) : SV_Target {
                return half4(1,1,0,1);
            }
        ENDCG

        Pass {
            Cull Front
            ZTest Less

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            ENDCG
        }
        Pass {
            Cull Back
            ZTest Greater

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            ENDCG
        }
    }
}

Shader "Custom/Hole" {
    Properties{
    }
    SubShader{
        Tags{ "Queue" = "Geometry+10" }

        ColorMask RGB
        ZWrite On

        Stencil {
            Ref 1
            Comp notequal
            Pass Zero
        }

        Pass{}
    }
}