Mobile shader fresnel

Hi,
I'm trying to create for a VR game a mobile shader (as they are optimized). The challenge is to take the built-in BumpSpecular one and and tweak it to multiply the reflection by a "fresnel" ramp.
I don't know what's wrong, I'm not a shader developer but I need it to process on a Single Pass VR.

The commented lines are which break the shader.
Anyone can help me? Thanks on advance,

Code (CSharp):

1. Shader "Reflect-BumpSpec" {
2. Properties {
3.     _Color ("Main Color", Color) = (1,1,1,1)
4.     _SpecColor ("Specular Color", Color) = (0.5,0.5,0.5,1)
5.     _Shininess ("Shininess", Range (0.01, 1)) = 0.078125
6.     _ReflectColor ("Reflection Color", Color) = (1,1,1,0.5)
7.     _Fresnel ("Fresnel", Range(0.0,8.0)) = 2.0
8.     _MainTex ("Base (RGB) RefStrGloss (A)", 2D) = "white" {}
9.     _Cube ("Reflection Cubemap", Cube) = "" {}
10.     _BumpMap ("Normalmap", 2D) = "bump" {}
11. }
12.  
13. SubShader {
14.     Tags { "RenderType"="Opaque" }
15.     LOD 400
16. CGPROGRAM
17. #pragma surface surf BlinnPhong
18. #pragma target 3.0
19.  
20. sampler2D _MainTex;
21. sampler2D _BumpMap;
22. samplerCUBE _Cube;
23.  
24. fixed4 _Color;
25. fixed4 _ReflectColor;
26. half _Shininess;
27.  
28. struct Input {
29.     float2 uv_MainTex;
30.     float2 uv_BumpMap;
31.     float3 worldRefl;
32.     float3 viewDir;
33.     INTERNAL_DATA
34. };
35.  
36. void surf (Input IN, inout SurfaceOutput o) {
37.     fixed4 tex = tex2D(_MainTex, IN.uv_MainTex);
38.     fixed4 c = tex * _Color;
39.     o.Albedo = c.rgb;
40.  
41.     o.Gloss = tex.a;
42.     o.Specular = _Shininess;
43.  
44.     o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));
45.  
46.     half rim = 1-saturate(dot(normalize(IN.viewDir), o.Normal));
47.  
48.     float3 worldRefl = WorldReflectionVector (IN, o.Normal);
49.     fixed4 reflcol = texCUBE (_Cube, worldRefl);
50.     half refl_lum = _ReflectColor.r * 0.3 + _ReflectColor.g * 0.59 + _ReflectColor.b * 0.11;
51.  
52.     //reflcol *= (_Fresnel * pow(rim,refl_lum));
53.     //reflcol *= _RimPower;
54.     reflcol *= tex.a;
55.    
56.     o.Emission = reflcol.rgb * _ReflectColor.rgb;
57.     o.Alpha = reflcol.a * _ReflectColor.a;
58. }
59. ENDCG
60. }
61.  
62. FallBack "Legacy Shaders/Reflective/Bumped Diffuse"
63. }
64.  
65.  

 

You haven't declared your variables. line 27 add:

Code (csharp):

1. float _Fresnel;
2. float _RimPower;
3.  

You also don't have _RimPower declared in your properties block so you won't get any input options in the inspector.