How to write emission to lightmap in vert/frag shader?

I can output emission value to baked lightmap with a surface shader. But how can i do it in vert/fragment shader.

 

You need a "meta" pass. Look and the generated code from a surface shader to see what that looks like, or look at the standard shader.

 

I try to add a meta pass like this. Suppose to get red emission on the light map but nothing. Or did i miss something.

Code (CSharp):

1.     // ------------------------------------------------------------------
2.     // Extracts information for lightmapping, GI (emission, albedo, ...)
3.     // This pass it not used during regular rendering.
4.         Pass
5.         {
6.             Name "META"
7.             Tags {"LightMode"="Meta"}
8.             Cull Off
9.             CGPROGRAM
10.             #include"UnityStandardMeta.cginc"
11.             float4 frag_meta2 (v2f_meta i): SV_Target
12.             {
13.                 // we're interested in diffuse & specular colors,
14.                 // and surface roughness to produce final albedo.
15.              
16.                 FragmentCommonData data = UNITY_SETUP_BRDF_INPUT (i.uv);
17.                 UnityMetaInput o;
18.                 UNITY_INITIALIZE_OUTPUT(UnityMetaInput, o);
19.                 o.Albedo = fixed3(1,0,0);
20.                 o.Emission = fixed3(1,0,0);
21.                 return UnityMetaFragment(o);
22.             }
23.          
24.             #pragma vertex vert_meta
25.             #pragma fragment frag_meta2
26.             #pragma shader_feature _EMISSION
27.             #pragma shader_feature _METALLICGLOSSMAP
28.             #pragma shader_feature ___ _DETAIL_MULX2
29.             ENDCG
30.         }

 

Try posting in the shader and / or global illumination forums. I don't have a ton of experience with the meta pass unfortunately.

 

Thanks. Will try that.

 

I have working out the code. For those whose interesting to add a emission to their shader, here is the minimal setup.

Code (CSharp):

1.  
2. Pass
3. {
4.     Name "META"
5.     Tags {"LightMode"="Meta"}
6.     Cull Off
7.     CGPROGRAM
8.                
9.     #include "UnityStandardMeta.cginc"
10.     #pragma vertex vert_meta
11.     #pragma fragment frag_meta_custom
12.  
13.     fixed4 frag_meta_custom (v2f i) : SV_Target
14.     {
15.         // Colors                
16.         fixed4 col = fixed(1,0,0); // The emission color
17.  
18.         // Calculate emission
19.         UnityMetaInput metaIN;
20.           UNITY_INITIALIZE_OUTPUT(UnityMetaInput, metaIN);
21.           metaIN.Albedo = col.rgb;
22.           metaIN.Emission = col.rgb;
23.           return UnityMetaFragment(metaIN);
24.  
25.         return col;
26.     }
27.  
28.     ENDCG
29. }
30.  

 

Thank

 

Hi there, just wanna know how do you actually output emission value to baked lightmap with surface shader? As shown here, the image which shows the environment lighted up is done by the standard shader, attaching the circuitry texture to the emission section of the standard shader. Where as what I have now, I'm able to attached the similar circuitry texture and adjust the brightness of the texture, however, it is not emitting light to the surrounding like what the standard shader does. Please advise.

 

https://forum.unity.com/threads/emmisive.492609/#post-3206559

 

Thanks for the example code, but I notice there are two return statements in that fragment shader (I guess the second one is unnecessary). Anyway for me it doesn't work at all.