Fog of war

Hello, and first of all sorry if the question seems too easy or was already answered.

I'm a new user of shader forge and I'd like to translate a fog of war shader to shader forge. The shader is this one:

Shader "FogOfWar/FogShader" {
Properties {
     _OldFogTex ("Old Fog Texture", 2D) = "gray" {}
     _FogTex ("Fog Texture", 2D) = "gray" {}
     _Color ("Color", Color) = (0,0,0,0)
}
Subshader {
Tags {"Queue"="Transparent"}
Pass {
ZWrite Off
Blend DstColor Zero
Offset -1, -1

CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma multi_compile_fog
#include "UnityCG.cginc"

struct v2f {
     float4 uvShadow : TEXCOORD0;
     UNITY_FOG_COORDS(2)
     float4 pos : SV_POSITION;
};

float4x4 unity_Projector;
float4x4 unity_ProjectorClip;

v2f vert (float4 vertex : POSITION)
{
     v2f o;
     o.pos = mul (UNITY_MATRIX_MVP, vertex);
     o.uvShadow = mul (unity_Projector, vertex);
     UNITY_TRANSFER_FOG(o,o.pos);
     return o;
}

sampler2D _OldFogTex;
sampler2D _FogTex;
fixed4 _Color;
uniform float _Blend;

fixed4 frag (v2f i) : SV_Target
{
    fixed a1 = tex2Dproj (_OldFogTex, UNITY_PROJ_COORD(i.uvShadow)).a;
     fixed a2 = tex2Dproj (_FogTex, UNITY_PROJ_COORD(i.uvShadow)).a;

     fixed a = lerp(a1, a2, _Blend);
     fixed4 col = lerp(_Color, fixed4(1,1,1,1), a);

     UNITY_APPLY_FOG_COLOR(i.fogCoord, col, fixed4(1,1,1,1));
     return col;
}
ENDCG
}
}
}

I'm having a hard time trying to figure out how can I change the tex2Dproj function for some Shader forge node and the Apply fog color as well. Is it the right approach to try to find a translation directly? Is there any other way I could do it?

Thanks in advance.