Adding second texture to Vertex Fragment Shader

I have the following shader which supports a single texture plus lighting. I've been trying to get it working with a second texture (2 sided quad)without luck. In previous tests I was able to determine which side was facing the camera by using the VFACE Semantic in the pixel shader constructor.

ie

Code (csharp):

1. float4 frag(vertexOutput i, float facing : VFACE) : COLOR

and then simply checking if facing was greater than or < zero. But doesn't seem to work for me here. Any shader gurus that can possibly help?

Code (csharp):

1.  
2. Shader "custom/one sided plus lighting"{
3.    Properties {
4.      _Color ("Color Tint", Color) = (1.0,1.0,1.0,1.0)
5.      _MainTex ("Diffuse Texture", 2D) = "white" {}
6.      _SpecColor ("Specular Color", Color) = (1.0,1.0,1.0,1.0)
7.      _Shininess ("Shininess", Float) = 10
8.  
9.    }
10.    SubShader {
11.      Pass {
12.        Tags {"LightMode" = "ForwardBase"}
13.        CGPROGRAM
14.        #pragma vertex vert
15.        #pragma fragment frag
16.      
17.        //user defined variables
18.        uniform sampler2D _MainTex;
19.        uniform float4 _MainTex_ST;
20.        uniform float4 _Color;
21.        uniform float4 _SpecColor;
22.        uniform float _Shininess;
23.      
24.        //unity defined variables
25.        uniform float4 _LightColor0;
26.      
27.        //base input structs
28.        struct vertexInput{
29.          float4 vertex : POSITION;
30.          float3 normal : NORMAL;
31.          float4 texcoord : TEXCOORD0;
32.        };
33.        struct vertexOutput{
34.          float4 pos : SV_POSITION;
35.          float4 tex : TEXCOORD0;
36.          float4 posWorld : TEXCOORD1;
37.          float3 normalDir : TEXCOORD2;
38.        };
39.      
40.        //vertex Function
41.      
42.        vertexOutput vert(vertexInput v){
43.          vertexOutput o;
44.        
45.          o.posWorld = mul(_Object2World, v.vertex);
46.          o.normalDir = normalize( mul( float4( v.normal, 0.0 ), _World2Object ).xyz );
47.          o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
48.          o.tex = v.texcoord;
49.        
50.          return o;
51.        }
52.      
53.        //fragment function
54.      
55.        float4 frag(vertexOutput i) : COLOR
56.        {
57.          float3 normalDirection = i.normalDir;
58.          float3 viewDirection = normalize( _WorldSpaceCameraPos.xyz - i.posWorld.xyz );
59.          float3 lightDirection;
60.          float atten;
61.        
62.          if(_WorldSpaceLightPos0.w == 0.0){ //directional light
63.            atten = 1.0;
64.            lightDirection = normalize(_WorldSpaceLightPos0.xyz);
65.          }
66.          else{
67.            float3 fragmentToLightSource = _WorldSpaceLightPos0.xyz - i.posWorld.xyz;
68.            float distance = length(fragmentToLightSource);
69.            atten = 1.0/distance;
70.            lightDirection = normalize(fragmentToLightSource);
71.          }
72.        
73.          //Lighting
74.          float3 diffuseReflection = atten * _LightColor0.xyz * saturate(dot(normalDirection, lightDirection));
75.          float3 specularReflection = diffuseReflection * _SpecColor.xyz * pow(saturate(dot(reflect(-lightDirection, normalDirection), viewDirection)) , _Shininess);
76.        
77.    
78.        
79.          float3 lightFinal = UNITY_LIGHTMODEL_AMBIENT.xyz + diffuseReflection + specularReflection;// + rimLighting;
80.        
81.          //Texture Maps
82.          float4 tex = tex2D(_MainTex, i.tex.xy * _MainTex_ST.xy + _MainTex_ST.zw);
83.        
84.          return float4(tex.xyz * lightFinal * _Color.xyz, 1.0);
85.        }
86.      
87.        ENDCG
88.      
89.      }
90.    
91.    
92.    }
93.    //Fallback "Specular"
94. }
95.  

 

I think you should just do it in 2 pass, one pass cull back with the first texture and another pass cull front with the other texture.

 

Thanks, what would the tags be in the second pass?

 

I think you can do something like:

Code (CSharp):

1.  
2. Tags {"LightMode" = "ForwardBase"}
3. Cull Back
4. Pass {
5. ...
6. }
7.  
8. Cull Front
9. Pass{
10. ...
11. }

 

yes thanks thats more or less it
FINALLY working after reading some of the examples
https://en.wikibooks.org/wiki/Cg_Programming/Unity/Two-Sided_Surfaces

In stead of using VFACE semantic which works well for textures without lighting, need to use a 2nd pass, one for front, one for back.