Add Smoothness value to a Shader

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This is the Unity Standard Terrain Shader source code, I'm trying to add a smoothness value so I can change the entire terrain smoothness via script, this to make the terrain look's wet, I try this but it give me an error. What can be? Thanks.

 Shader "Nature/Terrain" {
     Properties {
         [HideInInspector] _Control ("Control (RGBA)", 2D) = "red" {}
         [HideInInspector] _Splat3 ("Layer 3 (A)", 2D) = "white" {}
         [HideInInspector] _Splat2 ("Layer 2 (B)", 2D) = "white" {}
         [HideInInspector] _Splat1 ("Layer 1 (G)", 2D) = "white" {}
         [HideInInspector] _Splat0 ("Layer 0 (R)", 2D) = "white" {}
         [HideInInspector] _Normal3 ("Normal 3 (A)", 2D) = "bump" {}
         [HideInInspector] _Normal2 ("Normal 2 (B)", 2D) = "bump" {}
         [HideInInspector] _Normal1 ("Normal 1 (G)", 2D) = "bump" {}
         [HideInInspector] _Normal0 ("Normal 0 (R)", 2D) = "bump" {}
         // used in fallback on old cards & base map
         [HideInInspector] _MainTex ("BaseMap (RGB)", 2D) = "white" {}
         [HideInInspector] _Color ("Main Color", Color) = (1,1,1,1)


         _Glossiness ("Smoothness", Range(0,1)) = 0.5 // NEW LINE
     }
 
     CGINCLUDE
         #pragma surface surf Lambert vertex:SplatmapVert finalcolor:SplatmapFinalColor finalprepass:SplatmapFinalPrepass finalgbuffer:SplatmapFinalGBuffer noinstancing
         #pragma multi_compile_fog
         #include "TerrainSplatmapCommon.cginc"
 
         void surf(Input IN, inout SurfaceOutput o)
         {
             half4 splat_control;
             half weight;


             half _Glossiness; // NEW LINE


             fixed4 mixedDiffuse;
             SplatmapMix(IN, splat_control, weight, mixedDiffuse, o.Normal);
             o.Albedo = mixedDiffuse.rgb;
             o.Alpha = weight;



             o.Smoothness = _Glossiness; // NEW LINE
         }
     ENDCG
 
     Category {
         Tags {
             "Queue" = "Geometry-99"
             "RenderType" = "Opaque"
         }
 
         // TODO: Seems like "#pragma target 3.0 _TERRAIN_NORMAL_MAP" can't fallback correctly on less capable devices?
         // Use two sub-shaders to simulate different features for different targets and still fallback correctly.
         SubShader { // for sm3.0+ targets
             CGPROGRAM
                 #pragma target 3.0
                 #pragma multi_compile __ _TERRAIN_NORMAL_MAP
             ENDCG
         }
         SubShader { // for sm2.0 targets
             CGPROGRAM
             ENDCG
         }
     }
 
     Dependency "AddPassShader" = "Hidden/TerrainEngine/Splatmap/Diffuse-AddPass"
     Dependency "BaseMapShader" = "Diffuse"
     Dependency "Details0"      = "Hidden/TerrainEngine/Details/Vertexlit"
     Dependency "Details1"      = "Hidden/TerrainEngine/Details/WavingDoublePass"
     Dependency "Details2"      = "Hidden/TerrainEngine/Details/BillboardWavingDoublePass"
     Dependency "Tree0"         = "Hidden/TerrainEngine/BillboardTree"
 
     Fallback "Diffuse"
 }

Answer 1

Answer by Namey5 · Jul 21, 2021 at 12:18 AM

You need to define the shader property as a uniform outside of the surface function itself;

 #include "TerrainSplatmapCommon.cginc"
 
 half _Glossiness; // NEW LINE
  
 void surf(Input IN, inout SurfaceOutput o)
 {
     half4 splat_control;
     half weight;
     fixed4 mixedDiffuse;
     SplatmapMix(IN, splat_control, weight, mixedDiffuse, o.Normal);
     o.Albedo = mixedDiffuse.rgb;
     o.Alpha = weight;
     o.Smoothness = _Glossiness; // NEW LINE
 }

This may not work the way you expect though - in order for terrains to support the number of textures they do, the shader itself is split into multiple passes; each additional pass will use the "AddPassShader" listed at the bottom.

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arth9130 · Jul 21, 2021 at 01:42 AM 0

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I already know that i need to define the property as uniform to modify it but that's it's not my problem i'm asking if is there a way to add a glossiness value to the unity standard terrain shader. I marked the new properties that give me an error with //NEW LINE Thanks.

Namey5 arth9130 · Jul 21, 2021 at 03:18 AM 1

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If you look closer at my answer you'll notice the definition of the _Glossiness variable has moved. You had originally defined it as a local variable within the surface function, meaning not only will it not register with the material property as it isn't a uniform but it will also throw errors as you are using the local variable without initialising it.

arth9130 Namey5 · Jul 21, 2021 at 12:42 PM 0

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Yes thanks but the problem is not on the variable, it's in the SurfaceOutput that dosen't have a property called Smoothness.

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Add Smoothness value to a Shader

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