How to use Blend Zero One based on texture color

Graphics Shaders & Materials
1

Hello Guys,

I am trying to make an invisible sphere that masks what’s inside it, but through a criteria (perhabs a texture color) I want to disable the invisibility effect
You can think of it as an invisible house that you can’t look at what’s inside except for through it’s windows

This is what I have achieved so far

Shader "Custom/InvisibleMask" {
   Properties{
     _MainTex("Color (RGB) Alpha (A)", 2D) = "white" {}
   }
   SubShader{
     // draw after all opaque objects (queue = 2001):
     Tags{ "Queue" = "Geometry+1" }

     Pass{
       Blend Zero One

     }

     CGPROGRAM
     #pragma surface surf Standard alpha:fade

     sampler2D _MainTex;

     struct Input {
       float2 uv_MainTex;
     };


     void surf(Input IN, inout SurfaceOutputStandard o)
     {
       fixed4 targetColor = tex2D(_MainTex, IN.uv_MainTex);

       clip(targetColor.r>0.5);
       o.Albedo = float3(0,0,0);
       o.Alpha = 0.25;
     }
     ENDCG
   }
}
2

That seems pretty close. Skipping pixels using clip seems the way to go. Clip discards a pixel if the input value is below zero, so it should be:

clip(0.5 - targetColor.r);

This skips pixels if the red component of targetColor is above 0.5.