Shader trouble when using TRANSFORM_TEX built-in macro

Questions & Answers
1

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?

2

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"
}