Transparent Vertex Boolean Shader

I am working on boolean shader for WebGL, Where one object's particular part should be hide/transparent when it comes in range of another transparent object, In my code first object's particular part is getting visible when its coming with the range of second object, i want reverse of this function where second object's part should be invisible on contacted part.
Please see attached ScreenShot.
AlphaEffect is applied on first object (Textured in image)
StandardShader is applied on second object (Red colour object in image)
===========================Code=====================

Shader "AlphaEffect" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {}
_RimColor ("Rim Color", Color) = (1,1,1,1)
}

SubShader {
Pass {
ZTest Always Cull Off ZWrite off
Fog { Mode off }

CGPROGRAM
#pragma vertex vert_img
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
float4 _RimColor;
#include "UnityCG.cginc"

uniform sampler2D _MainTex;
uniform float _TexWidth;
uniform float _TexHeight;

fixed4 frag (v2f_img i) : COLOR
{

fixed4 original = tex2D(_MainTex, i.uv);

return original;
}
ENDCG

}
}

Fallback Off

}

 

Hello Thank you for reply,
As you can see common area of both cube are visible so that common area should be invisible/hide. Texture of second cube is showing on red cube, i want that area should be invisible