Tinted Shader + Alpha = reversed normals?

I have a version of my regular weapon material with an added blue glow custom shader (mostly cut and pasted, im a shader troglodyte). I use it for the weapon pickups, as opposed to the weapon in the players hand.

I have a new weapon now that relies on the alpha channel for a transparent/cutout/specular bumped material. When I try and add an alpha channel to my custom glow shader the normals are reversed!!

Ive read about an issue involving mirrored symetrical UVs on meshes imported via fbx from maya also. Not sure if this is my problem or its my custom shader. All meshes and materials/normals looked kosher. just the addition of the alpha channel on my shader that reversed the normals.

Code (CSharp):

1.  
2. Shader "Custom/ItemGlow" {
3.     Properties {
4.         _ColorTint("Colour Tint",Color) = (1,1,1,1)
5.         _MainTex ("Base (RGB) Alpha(A)", 2D) = "white" {}
6.         _BumpMap ("Normal Map" ,2D)="bump"{}
7.         _RimColor("Rim Color",Color)=(1,1,1,1)
8.         //_RimPower("Rim Power",Range(0.1,6.0))=3.0
9.      
10.     }
11.     SubShader {
12.         Tags { "Queue"="Transparent" "RenderType"="Transparent" }
13.         ZWrite Off
14.          Blend SrcAlpha OneMinusSrcAlpha
15.      
16.         CGPROGRAM
17.         #pragma surface surf Lambert alpha
18.  
19.      
20.  
21.         struct Input
22.         {
23.             float4 color : Color;
24.             float2 uv_MainTex;
25.             float2 uv_BumpMap;
26.             float3 viewDir;
27.         };
28.         float4 _ColorTint;
29.         sampler2D _MainTex;
30.         sampler2D _BumpMap;
31.         float4 _RimColor;
32.         float _RimPower;
33.      
34.         void surf (Input IN, inout SurfaceOutput o)
35.         {
36.      
37.             IN.color = _ColorTint;
38.          
39.             o.Albedo = tex2D (_MainTex,IN.uv_MainTex).rgb * IN.color;
40.             o.Alpha = tex2D (_MainTex, IN.uv_MainTex).a;
41.             o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));
42.             //o.Normal.y *= sign(unity_Scale.y);
43.             half rim = 1.0 - saturate(dot(normalize(IN.viewDir),o.Normal));
44.          
45.             o.Emission = _RimColor.rgb * pow(rim,0.7);//<---_RimPower goes there,
46.          
47.         }
48.         ENDCG
49.     }
50.     FallBack "Diffuse"
51. }
52.  
53.  

this was my glow shader that had correct normals before i needed the alpha channel

Code (CSharp):

1.  
2. Shader "Custom/ItemGlow" {
3.     Properties {
4.         _ColorTint("Colour Tint",Color) = (1,1,1,1)
5.         _MainTex ("Base (RGB)", 2D) = "white" {}
6.         _BumpMap ("Normal Map",2D)="bump"{}
7.         _RimColor("Rim Color",Color)=(1,1,1,1)
8.         //_RimPower("Rim Power",Range(0.1,6.0))=3.0
9.      
10.     }
11.     SubShader {
12.         Tags { "RenderType"="Opaque" }
13.      
14.      
15.         CGPROGRAM
16.         #pragma surface surf Lambert
17.  
18.      
19.  
20.         struct Input
21.         {
22.             float4 color : Color;
23.             float2 uv_MainTex;
24.             float2 uv_BumpMap;
25.             float3 viewDir;
26.         };
27.         float4 _ColorTint;
28.         sampler2D _MainTex;
29.         sampler2D _BumpMap;
30.         float4 _RimColor;
31.         float _RimPower;
32.      
33.         void surf (Input IN, inout SurfaceOutput o)
34.         {
35.      
36.             IN.color = _ColorTint;
37.             o.Albedo = tex2D (_MainTex,IN.uv_MainTex).rgb * IN.color;
38.             o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));
39.             half rim = 1.0 - saturate(dot(normalize(IN.viewDir),o.Normal));
40.             o.Emission = _RimColor.rgb * pow(rim,0.7);//<---_RimPower goes there,
41.          
42.         }
43.         ENDCG
44.     }
45.     FallBack "Diffuse"
46. }
47.  

Thanks for any help fellow game creators

 

A screenshot could help to identify the problem. When using alpha blending with complex objects, depth sorting is what causes headache usually. Tim described the problem and a solution in the Transparent Depth Shader (good for ghosts!) thread, is this what you mean with reversed normals?

 

Not sure that depth sorting is the problem. The top image is before I added the alpha channel, bottom afterwards.

 

It is. With z writing disabled, you're rendering the inside parts over the outside parts. Normals are fine.

 

hmmmm, I commented out the ZWrite line, still looks the same. Appreciate the feedback though, thanks.