SHADERPASS_SHADOWCASTER and testing for the shadowcaster pass

Hi,

In URP 8.2.x, I used SHADERPASS_SHADOWCASTER to change the behavior of some custom nodes in shadergraph during shadowcasting passes:

Code (csharp):

1. #ifdef SHADERPASS_SHADOWCASTER
2. // do something while shadowcasting...
3. #else
4. // do something normally...
5. #endif
6.  

I've upgraded to 2020.2 and URP 10.2.2 and this no longer works. I can't seem to find any reference in the changelog or docs about this functionality. I did see on the (now retired) git that some references were made to 'Fix SHADERPASS inconsistency between pipelines', see eg https://github.com/Unity-Technologies/Graphics/commit/db4dddf00233cbe55aa78414d6985ce292a70b46

This looks like changes were made to the format:

Code (csharp):

1. #if (SHADERPASS == SHADERPASS_SHADOWCASTER)
2. // stuff
3. #endif
4.  

However, I can't seem to get this to work in my shader! Whatever I try the value is always true. What is the 'correct' way to test for the shadowcasting pass in URP 10?

Cheers,
Elliot

 

More information:

I've looked at the ShaderLab code generated by ShaderGraph for each version.

In the URP 8.2 version, the shadowcaster pass looks like the following:

Code (csharp):

1.  
2.         Pass
3.         {
4.             Name "ShadowCaster"
5.             Tags
6.             {
7.                 "LightMode" = "ShadowCaster"
8.             }
9.  
10.             // Render State
11.             Blend One Zero, One Zero
12.             Cull Off
13.             ZTest LEqual
14.             ZWrite On
15.             // ColorMask: <None>
16.  
17.             HLSLPROGRAM
18.             #pragma vertex vert
19.             #pragma fragment frag
20.        
21.             // Debug
22.             // <None>
23.        
24.             // --------------------------------------------------
25.             // Pass
26.        
27.             // Pragmas
28.             #pragma prefer_hlslcc gles
29.             #pragma exclude_renderers d3d11_9x
30.             #pragma target 2.0
31.             #pragma multi_compile_instancing
32.  
33.  ....(a whole forest of keyword permutations, followed by)...
34.  
35.             #if defined(UNITY_SUPPORT_INSTANCING) && defined(INSTANCING_ON)
36.             #define UNITY_DOTS_INSTANCING_ENABLED
37.             #endif
38.             #define SHADERPASS_SHADOWCASTER
39.             //-------------------------------------------------------------------------------------
40.             // Dots Instancing vars
41.             //-------------------------------------------------------------------------------------
42. ....
43.  

Hence, SHADERPASS_SHADOWCASTER is clearly defined in the Shadowcasting pass.

In URP 10.2 the generated shader is different:

Code (csharp):

1.  
2.             Pass
3.             {
4.                 Name "ShadowCaster"
5.                 Tags
6.                 {
7.                     "LightMode" = "ShadowCaster"
8.                 }
9.    
10.                 // Render State
11.                 Cull Off
12.                 Blend One Zero
13.                 ZTest LEqual
14.                 ZWrite On
15.                 ColorMask 0
16.    
17.                 // Debug
18.                 // <None>
19.    
20.                 // --------------------------------------------------
21.                 // Pass
22.    
23.                 HLSLPROGRAM
24.    
25.                 // Pragmas
26.                 #pragma target 4.5
27.                 #pragma exclude_renderers gles gles3 glcore
28.                 #pragma multi_compile_instancing
29.                 #pragma multi_compile _ DOTS_INSTANCING_ON
30.                 #pragma vertex vert
31.                 #pragma fragment frag
32.    
33.                 #if SHADER_TARGET >= 35 && (defined(SHADER_API_D3D11) || defined(SHADER_API_GLES3) || defined(SHADER_API_GLCORE) || defined(SHADER_API_XBOXONE) || defined(SHADER_API_PSSL) || defined(SHADER_API_VULKAN) || defined(SHADER_API_METAL))
34.                     #define UNITY_SUPPORT_INSTANCING
35.                 #endif
36.                 #if defined(UNITY_SUPPORT_INSTANCING) && defined(INSTANCING_ON)
37.                     #define UNITY_HYBRID_V1_INSTANCING_ENABLED
38.                 #endif
39.                 #if defined(UNITY_HYBRID_V1_INSTANCING_ENABLED)
40.                 #define HYBRID_V1_CUSTOM_ADDITIONAL_MATERIAL_VARS \
41.                 UNITY_DEFINE_INSTANCED_PROP(float, _PixelSize_Array)\
42.                 UNITY_DEFINE_INSTANCED_PROP(float4, _PixelGridOrigin_Array)
43.                 #define _PixelSize UNITY_ACCESS_INSTANCED_PROP(unity_Builtins0, _PixelSize_Array)
44.                 #define _PixelGridOrigin UNITY_ACCESS_INSTANCED_PROP(unity_Builtins0, _PixelGridOrigin_Array)
45.                 #endif
46.    
47.                 // Keywords
48.                 // PassKeywords: <None>
49.                 #pragma shader_feature_local _ COLOR_GRADING_ON
50.                 #pragma shader_feature_local _ RECEIVE_SHADOWS_ON
51.                 #pragma shader_feature_local _ USE_OBJECT_POSITION_ON
52.                 #pragma shader_feature_local _ NORMAL_MAP_ON
53.                 #pragma shader_feature_local _ USE_EMISSION_ON
54.                 #pragma shader_feature_local _ USE_ALPHA_ON
55.                
56. ...(a whole forest of keyword permutations, followed by)...
57.    
58.                 #define FEATURES_GRAPH_VERTEX
59.                 /* WARNING: $splice Could not find named fragment 'PassInstancing' */
60.                 #define SHADERPASS SHADERPASS_SHADOWCASTER
61.                 /* WARNING: $splice Could not find named fragment 'DotsInstancingVars' */
62.    
63.                 // Includes
64.                 #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Color.hlsl"
65.                 #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
66.                 #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
67.                 #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/TextureStack.hlsl"
68.                 #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/ShaderGraphFunctions.hlsl"
69.    ...

So the #define SHADERPASS_SHADOWCASTER has been swapped for #define SHADERPASS SHADERPASS_SHADOWCASTER, and I would expect the if statement in the first post to now work:

Code (csharp):

1. #if (SHADERPASS == SHADERPASS_SHADOWCASTER)

But it still doesn't! The SHADERPASS_SHADOWCASTER statement is defined in Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/ShaderPass.hlsl. If I put the following into a ShaderGraph Custom Node...

Code (csharp):

1. #ifndef UNIVERSAL_SHADERPASS_INCLUDED
2. #error "Universal ShaderPass not included."
3. #endif

...then I receive the error 'Universal ShaderPass not included' (the same works if I test whether SHADERPASS_SHADOWCASTER is defined).

The 10.2 generated ShadowCaster Pass hlsl ends with:

Code (csharp):

1.                 // --------------------------------------------------
2.                 // Main
3.    
4.                 #include "Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/ShaderPass.hlsl"
5.                 #include "Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/Varyings.hlsl"
6.                 #include "Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/ShadowCasterPass.hlsl"
7.    
8.                 ENDHLSL
9.             }
10.  

...which does include the ShaderPass.hlsl file.

No answers yet, but I'll keep digging.

 

Ok, so I can get this to work if I manually include the ShaderPass.hlsl file at the start of my custom function

Full Solution in 10.2:


Shadows.hlsl:

Code (csharp):

1. #include "Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/ShaderPass.hlsl"
2.  
3. inline void shadowcaster_float(out float _out) {
4. #if ( SHADERPASS == SHADERPASS_SHADOWCASTER )
5.     _out = 1.0;
6. #else
7.     _out = 0.0;
8. #endif
9. }
10.  

This will produce an object which is transparent yet still casts a shadow:


If you do not include the ShaderPass.hlsl file in the custom function, it does not work! So it seems to me that this is a bug, and that the ShaderPass include statement should occur higher up in the generated ShaderGraph file. (Perhaps this should be moved to the ShaderGraph forum?)

 

Note that if you want backwards compatibility with previous render pipeline versions, you will need to switch based on the SRP version. There is also a bug there, so you will need to include Version.hlsl otherwise the VERSION_GREATER_EQUAL macro will not be defined in URP 10.2.

Code (csharp):

1. #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Version.hlsl"
2. #if VERSION_GREATER_EQUAL(10, 0)
3. #include "Packages/com.unity.render-pipelines.universal/Editor/ShaderGraph/Includes/ShaderPass.hlsl"
4. #endif
5.  
6. ... then in your function
7.  
8. #if VERSION_GREATER_EQUAL(10,0)
9. #define SHADOWTEST ( SHADERPASS == SHADERPASS_SHADOWCASTER )
10. #else
11. #define SHADOWTEST defined(SHADERPASS_SHADOWCASTER)
12. #endif
13.  
14. #if SHADOWTEST
15.     //do something in shadowcaster pass
16. #else
17.     //do something in normal pass
18. #endif
19.