Intersection Shader intersects with Intersection Shader!

Hi everyone,

I would like to write a shader which can be applied to two objects. Where the two objects intersect, an unlit red area should be drawn. How can I do this please?

I already have the shader below, but it doesn't seem to work if you have two objects with the same shader applied:

 //Highlights intersections with other objects
  
 Shader "Custom/IntersectionHighlights"
 {
     Properties
     {
         _RegularColor("Main Color", Color) = (1, 1, 1, .5) //Color when not intersecting
         _HighlightColor("Highlight Color", Color) = (1, 1, 1, .5) //Color when intersecting
         _HighlightThresholdMax("Highlight Threshold Max", Float) = 1 //Max difference for intersections
     }
     SubShader
     {
         Tags { "Queue" = "Transparent" "RenderType"="Transparent"  }
  
         Pass
         {
             Blend SrcAlpha OneMinusSrcAlpha
             ZWrite Off
             Cull Off
  
             CGPROGRAM
             #pragma target 3.0
             #pragma vertex vert
             #pragma fragment frag
             #include "UnityCG.cginc"
  
             uniform sampler2D _CameraDepthTexture; //Depth Texture
             uniform float4 _RegularColor;
             uniform float4 _HighlightColor;
             uniform float _HighlightThresholdMax;
  
             struct v2f
             {
                 float4 pos : SV_POSITION;
                 float4 projPos : TEXCOORD1; //Screen position of pos
             };
  
             v2f vert(appdata_base v)
             {
                 v2f o;
                 o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                 o.projPos = ComputeScreenPos(o.pos);
  
                 return o;
             }
  
             half4 frag(v2f i) : COLOR
             {
                 float4 finalColor = _RegularColor;
  
                 //Get the distance to the camera from the depth buffer for this point
                 float sceneZ = LinearEyeDepth (tex2Dproj(_CameraDepthTexture,
                                                          UNITY_PROJ_COORD(i.projPos)).r);
  
                 //Actual distance to the camera
                 float partZ = i.projPos.z;
  
                 //If the two are similar, then there is an object intersecting with our object
                 float diff = (abs(sceneZ - partZ)) /
                     _HighlightThresholdMax;
  
                 if(diff <= 1)
                 {
                     finalColor = lerp(_HighlightColor,
                                       _RegularColor,
                                       float4(diff, diff, diff, diff));
                 }
  
                 half4 c;
                 c.r = finalColor.r;
                 c.g = finalColor.g;
                 c.b = finalColor.b;
                 c.a = finalColor.a;
  
                 return c;
             }
  
             ENDCG
         }
     }
     FallBack "VertexLit"
 }