Shader trouble when using TRANSFORM_TEX built-in macro

Question

I'm trying to include a texture's Tiling and Offset values in my shader, and understand that the TRANSFORM_TEX macro must be used for that to work. Following this guide, I wrote a shader.

 Shader "Custom/Displacement Ramp Debug"
 {
     Properties
     {
         _DispTex ("Displacement Texture", 2D) = "gray" {}
     }
  
     SubShader
     {
         Tags { "RenderType"="Opaque" }
         Cull Off
         LOD 300
  
         CGPROGRAM
         #pragma surface surf Lambert vertex:disp nolightmap
         #pragma target 3.0
         #pragma glsl
         #include "UnityCG.cginc"
  
         sampler2D _DispTex;
         uniform float4 _DispTex_ST; // Needed for TRANSFORM_TEX(v.texcoord, _DispTex)
  
         struct Input
         {
             float2 uv_DispTex;
         };
  
         void disp (inout appdata_full v)
         {
             float2 newUV = TRANSFORM_TEX(v.texcoord.xy, _DispTex);
             v.vertex.xyz += newUV.x;
         }
  
         void surf (Input IN, inout SurfaceOutput o)
         {
             half4 c = tex2D(_DispTex, IN.uv_DispTex);
             o.Albedo = c.rgb;
         }
         ENDCG
     }
     FallBack "Diffuse"
 }

When compiling, I get this error on a non-existent line:

 Shader error in 'Custom/Displacement Ramp Debug': declaration of "_DispTex_ST" conflicts with previous declaration at (21) at line 62

But if I try to remove _DispTex_ST, I get this error:

 Shader error in 'Custom/Displacement Ramp Debug': undefined variable "_DispTex_ST" undefined variable "_DispTex_ST" at line 30

Any ideas on why this is happening?

Answer 1

Best Answer

Answer by tanoshimi · Feb 19, 2015 at 06:51 PM

From memory, I had a surface shader problem like this in the past caused by using variables that began with an underscore. Try this instead:

 Shader "Custom/Displacement Ramp Debug"
 {
     Properties
     {
       DispTex ("Displacement Texture", 2D) = "gray" {}
     }
     SubShader
     {
       Tags { "RenderType"="Opaque" }
       Cull Off
       LOD 300
       CGPROGRAM
       #pragma surface surf Lambert vertex:disp nolightmap
       #pragma target 3.0
       #pragma glsl
       #include "UnityCG.cginc"
       sampler2D DispTex;
       uniform float4 DispTex_ST; // Needed for TRANSFORM_TEX(v.texcoord, _DispTex)
       struct Input
       {
         float2 uv_DispTex;
       };
       void disp (inout appdata_full v)
       {
         float2 newUV = TRANSFORM_TEX(v.texcoord.xy, DispTex);
         v.vertex.xyz += newUV.x;
       }
       void surf (Input IN, inout SurfaceOutput o)
       {
         half4 c = tex2D(DispTex, IN.uv_DispTex);
         o.Albedo = c.rgb;
       }
       ENDCG
       }
     FallBack "Diffuse"
 }

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Sprakle · Feb 19, 2015 at 09:26 PM 0

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Unfortunately that doesn't solve the problem because _{TextureName}_ST is a special variable name that Unity uses. The tiling/offset data is put into any variable with that name.

So if I rename it to not use the underscore, I don't get the required data.

tanoshimi · Feb 19, 2015 at 10:30 PM 0

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Did you try my code? Works for me, including the scaling and offset parameters of the texture slot (well, the x- offset and scaling, which is all you use), in 4.6.2

Sprakle · Feb 19, 2015 at 10:59 PM 0

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@tanoshimi Oh sorry, I messed up copy/pasting your code. It works great now, thanks!

Sprakle · Feb 19, 2015 at 11:11 PM 0

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No wait, that breaks uv_DispTex (line 21) because the name no longer matches, so Unity doesn't add the UV data.

And if I rename it to uvDispTex, the original conflict error comes up.

tanoshimi · Feb 20, 2015 at 02:29 PM 1

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Ok, I think you're right - my half-remembering a bug with variables beginning with an underscore is unrelated (something to do with the fact that Unity macros auto-prefix your variables with another underscore, and variables beginning with two underscores are reserved according to the GLSL spec (p13)). But anyway...

Let's try another solution to your problem - from your original shader, in the vertex modifier function try changing:

 float2 newUV = TRANSFOR$$anonymous$$_TEX(v.texcoord.xy, _DispTex);

to:

 float2 newUV = TRANSFOR$$anonymous$$_UV(0);

Does that work?

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