Unlit Shader, find out if r/g/b of texture exist

Hi to all,

I have created an Unlit shader for UI usage, with 2 x Texture2DArrays, 2 x Index for each array and 3 InputColors. Indexes and InputColors are setted from scipt.

Shader is responsible to replace r,g,b colors with the input Colors that are setted outside editor.

But I have an issue that I cant figure out how to solve. In my shader I want to have a float Propertie that is changed within the shader, to represents which of R,G,B are available on the texture. For example if texture has red ,float = 1, if has r,g float = 2 etc. In this way I will have a variable that I can access from another script and know for each case which channels are available on texture (r,g,b)

Is it possible or I am missing the point?How should I edit below shader to make it work?

Properties

Code (CSharp):

1. Properties
2.     {
3.         _MainTex ("Texture", 2D) = "white" {}          
4.      
5.         //Colors
6.         _Color("BlueColor", Color) = (1,1,1,1)
7.         _ColorOverlay("GreenColor", Color) = (1,1,1,1)
8.         _ColorOverlay2("RedColor", Color) = (1,1,1,1)
9.  
10.         //Floats example
11.             _isToggledB("HasBlue", float) = 1.0    
12.             _isToggledG("HasGreen", float) = 1.0    
13.             _isToggledR("HasRed", float) = 1.0
14.  
15.           //Texture2DArray v1
16.         _MainTex0("Textures_Floors", 2DArray) = "" {}
17.         _TextureIndex2("Index_Floors", float) = 0
18.  
19.           //Texture2DArray v2
20.         _MainTex2("Textures_Walls", 2DArray) = "" {}
21.         _TextureIndex("Index_Walls", float) = 0
22.  
23.  
24.         _ChooseTexture("IsWall:1", Int) = 0
25.  
26.     }

Shader code (part of it) :

Code (CSharp):

1. fixed4 frag (v2f i) : SV_Target
2.             {
3.                 // sample the texture
4.                 fixed4 c = tex2D(_MainTex, i.uv);
5.          
6.                 if (UNITY_ACCESS_INSTANCED_PROP(Props, _ChooseTexture) > 0)
7.                 {
8.                     c = UNITY_SAMPLE_TEX2DARRAY(_MainTex2, float3(i.uv, UNITY_ACCESS_INSTANCED_PROP(Props, _TextureIndex)));
9.  
10.                 }
11.                 else
12.                 {
13.                     c = UNITY_SAMPLE_TEX2DARRAY(_MainTex0, float3(i.uv, UNITY_ACCESS_INSTANCED_PROP(Props, _TextureIndex2)));
14.                 }
15.                 //Change Colors
16.                 float4 tempBlue = lerp(float4(0, 0, 0, 0), c.b, UNITY_ACCESS_INSTANCED_PROP(Props, _Color));        
17.                 float4 tempGreen = lerp(float4(0, 0, 0, 0), UNITY_ACCESS_INSTANCED_PROP(Props, _ColorOverlay), c.g);
18.                 float4 tempRed = lerp(float4(0, 0, 0, 0), c.r, UNITY_ACCESS_INSTANCED_PROP(Props, _ColorOverlay2));
19.  
20.                 float4 templerp = lerp(tempRed, float4(1, 1, 1, 0), tempGreen);          
21.                 float4 finalLerp = lerp(tempBlue, float4(1, 1, 1, 1), templerp);
22.  
23.                 c = finalLerp;
24.                 // apply fog
25.                 UNITY_APPLY_FOG(i.fogCoord, c);
26.                 return c;
27.             }