How can I get tangent on a surface shader ?

I have this test shader(below), no errors, except some d3d11 warnings
(Shader warning in 'Surface Vertex Test': Program 'frag_surf', 'surf': output parameter 'o' not completely initialized (compiling for d3d11) at line 51)

How can I get rid of the warnings ?

Code (csharp):

1.  
2. Shader "Surface Vertex Test"
3. {
4.     Properties
5.     {
6.          _MainTex ("Diffuse (RGB) Alpha (A)", 2D) = "white" {}
7.     }
8.    
9.     SubShader
10.     {  
11.         CGPROGRAM
12.         #pragma surface surf Custom vertex:vert
13.                                                        
14.             struct Input             
15.             {
16.                 float2 uv_MainTex;
17.                
18.                 half3 tangent_input;
19.                 half3 binormal_input;                        
20.             };
21.  
22.             struct SurfaceOutputCustom
23.             {
24.                 fixed3 Albedo;
25.                 fixed3 Normal;
26.                 fixed3 Emission;
27.                 half Specular;
28.                 fixed Gloss;
29.                 fixed Alpha;
30.                
31.                 half3 tangent_input;
32.                 half3 binormal_input;
33.             };
34.            
35.             void vert(inout appdata_full i, out Input o)
36.             {      
37.                 half4 p_normal = mul(float4(i.normal,0.0f),_World2Object);
38.                 half4 p_tangent = mul(_Object2World,i.tangent);
39.                                            
40.                 half3 normal_input = normalize(p_normal.xyz);
41.                 half3 tangent_input = normalize(p_tangent.xyz);
42.                 half3 binormal_input = cross(p_normal.xyz,tangent_input.xyz) * i.tangent.w;
43.                
44.                 o.tangent_input = tangent_input ;
45.                 o.binormal_input = binormal_input ;
46.             }
47.                        
48.             sampler2D _MainTex;
49.            
50.             void surf (Input IN, inout SurfaceOutputCustom o)
51.             {            
52.                 fixed4 albedo = tex2D(_MainTex, IN.uv_MainTex);
53.                 o.Albedo = albedo.rgb;
54.                 o.Alpha = albedo.a;
55.                
56.                 o.tangent_input = IN.tangent_input;
57.                 o.binormal_input = IN.binormal_input ;
58.             }
59.            
60.             inline fixed4 LightingCustom (SurfaceOutputCustom s, fixed3 lightDir, fixed3 viewDir, fixed atten)
61.             {
62.                 fixed4 c;
63.                 c.rgb = s.tangent_input;
64.                 c.a = 1.0;
65.                 return c;
66.             }
67.            
68.         ENDCG
69.     }
70.     FallBack "Transparent/Cutout/VertexLit"
71. }
72.  

 

I believe this is a bug. I have experienced similar problems with custom input structures and DX11. I've reported the bug and they've reproduced it, but I've not heard that it's been resolved yet. As a (terrible) work around, you could disassemble the shader using #pragma debug and see where unity is failing to put your tangents into the struct and put them in yourself, but it's a really bad hack.

 

Compiler for DX11 is picky about variable initialization. You have to initialize all the outputs, otherwise it doesn't compile correctly. UNITY_INITIALIZE_OUTPUT makes it easier.
Also it threats errors as warnings most of the time, which is a bug IMO.

Code (csharp):

1. void vert(inout appdata_full i, out Input o)
2. {      
3.     UNITY_INITIALIZE_OUTPUT(Input, o);
4.  
5.     half4 p_normal = mul(float4(i.normal,0.0f),_World2Object);
6.     half4 p_tangent = mul(_Object2World,i.tangent);
7.                                            
8.     half3 normal_input = normalize(p_normal.xyz);
9.     half3 tangent_input = normalize(p_tangent.xyz);
10.     half3 binormal_input = cross(p_normal.xyz,tangent_input.xyz) * i.tangent.w;
11.                
12.     o.tangent_input = tangent_input ;
13.     o.binormal_input = binormal_input ;
14. }

 

awesome, thanks cician, UNITY_INITIALIZE_OUTPUT(Input, o); worked great = ]