Shader: Add one image's alpha to the other while keeping it unlit

Questions & Answers
1

I’m trying to get the top texture to blend onto the gold bar and make it shine, but I cannot figure out the right combination of blendmode and SetTexture.

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I have tried to read up on SubShader but I cannot get it to work. The code:

Shader "Unlit/AlphaWithHighlight"
{
	Properties
	{
		_Color ("Main Color", Color) = (1,1,1,1)
		_MainTex ("Base (RGB)", 2D) = "white" {}
		_DecalTex ("Base (RGB) Trans (A)", 2D) = "white" {}
	}

	SubShader
	{
	    Tags 
	    {
	    	"Queue"="Transparent"
	     	"IgnoreProjector"="True"
	      	"RenderType"="Transparent"
      	}
	    LOD 200
	   
	    //ZWrite On
		Blend SrcAlpha OneMinusSrcAlpha // Alpha blending

		Pass
		{
			SetTexture[_MainTex]
			{
				combine texture
			}

			SetTexture[_DecalTex]
			{
				combine previous * texture alpha
			}

			// Add color in the end
		}
	}

	Fallback "Diffuse"
}
2

This Fragment Shader should work.

Shader "Custom/Shine" {
    Properties {
        
        _Color("Color",Color) = (1,1,1,1)
        _MainTex ("Base (RGB)", 2D) = "white" {}
        _Detail("Detail(RGB)",2D) = "white" {}
        _Speed("speed", Float) = 1
      
    
    }
    SubShader {
        Tags { "Queue"="Transparent" "IgnoreProjector"="True"  }
        Blend SrcAlpha OneMinusSrcAlpha
        
        //Cull Off 
        //ZWrite Off
        
        Pass
        {
            
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma fragmentoption ARB_precision_hint_fastest        
            
            #include "UnityCG.cginc"

             sampler2D _MainTex;
             
             Float _Speed;
            sampler2D _Detail;
         	fixed4 _Color;
                struct v2f
                {

                    float4 pos : SV_POSITION;

                     float2 uv: TEXCOORD0;
                    
                };
            
                v2f vert(appdata_full v)
                {
                    v2f o;
                    o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                    float2 uv = v.texcoord.xy;
                     
                     o.uv = uv;
               
                    return o;

                }
            
            
            fixed4 frag(v2f i) : COLOR {
            
                float2 uv = i.uv;
                    // scrolls shine texture in x direction
                uv.x += _Time.x * _Speed;
                    // scrolls shine texture in y direction
                    //uv.y += _Time.x * _Speed;
                fixed4 t1 =  (tex2D(_MainTex,i.uv)) * _Color;
                    t1 = (t1 +tex2D(_Detail,uv))*t1.a;
                return t1;
                
                
            }

            ENDCG
        }
    } 
    FallBack "Unlit/Transparent"
}