How you you add a glow effect where two objects are touching

Unity Engine
1

Hi I’m currently making a Hardlight Bridge (from Halo games) shader. Here is a quick clip of the current WIP version

What I would like to add is a glow effect around where objects touch the bridge. I have made a quick mockup in photoshop of what I mean here

913×588 320 KB

Does anyone know how I can achieve this, This is my first time messing with shaders
In case it’s relavent, here is the code for the shader so far

Shader "Custom/Hardlight" {
    Properties{
        _MainTex("Texture", 2D) = "white" {}
        _Alpha("Hardlight Opacity",Range(0,1)) = 0.4
        _Speed("Speed",Range(0,10)) = 2
        _Wobble("Wobble", Range(0,10)) = 2
        _Colour("Colour", Color) = (0,0,0,0)
    }

        SubShader{
        Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" "ForceNoShadowCasting" = "True" }

        CGPROGRAM


    #pragma surface surf NoLighting  noambient alpha

    sampler2D _MainTex;
    float4 _Colour;
    half _Alpha;
    half _Speed;
    half _Wobble;

    struct Input {
        half2 uv_MainTex;
    };

    fixed4 LightingNoLighting(SurfaceOutput s, fixed3 lightDir, fixed atten)
    {
        fixed4 c;
        c.rgb = s.Albedo;
        c.a = s.Alpha;
        return c;
    }

    void surf(Input IN, inout SurfaceOutput o)
    {
        o.Albedo = tex2D(_MainTex, IN.uv_MainTex + float2(0.01*(IN.uv_MainTex.y / 20 + _Time[1] * _Speed*0.5), 0.01*sin(_Speed*0.3 * _Time[1] * _Wobble)) ).r * _Colour * 0.65;
        o.Albedo += tex2D(_MainTex, IN.uv_MainTex + float2(0.01*(IN.uv_MainTex.y / 20 + _Time[1] * _Speed), 0.01*cos(_Speed * _Time[1] * _Wobble))).b * _Colour;


        o.Alpha = tex2D(_MainTex, IN.uv_MainTex + float2(0.01*(IN.uv_MainTex.y / 20 + _Time[1] * _Speed*0.5), 0.01*sin(_Speed*0.3 * _Time[1] * _Wobble))).r;
        o.Alpha += tex2D(_MainTex, IN.uv_MainTex + float2(0.01*(IN.uv_MainTex.y / 20 + _Time[1] * _Speed), 0.01*cos(_Speed * _Time[1] * _Wobble))).b;

        if (o.Alpha <= 0.2) {
            o.Albedo = _Colour*1.8;
            o.Alpha = 0.07;
        }

        o.Alpha *= _Alpha*2.5;
    }
    ENDCG
    }

    Fallback "Diffuse"
}
2

Use decals, that’s how it’s generally done.

3

By decal do you just mean a flat textured plane?
How would that work with a glow for all shapes as opposed to just cubes?