Question Liquid Shader based on Quake

Hi. I don't know how to write a shader myself, but I need liquid emulation for the game.
In this topic https://forum.unity.com/threads/quake-1-liquid-shader.873616/ I found the easiest solution to my problem. But I'm stuck on the error invalid subscript 'uv' at line 39 (on d3d11)

Shader

Code (CSharp):

1. Shader "Custom/Water"
2. {
3.     //Based on bgolus QuakeLiquid shader;
4.     Properties
5.     {
6.         _MainTex ("Albedo (RGB)", 2D) = "white" {}
7.         _Color("Color", Color) = (1,1,1,1)
8.         _Amplitude("Amplitude", Float) = 0.12
9.         _Scale("Scale", Float) = 0.7
10.         _Frequency("Frequency", Float) = 0.2
11.     }
12.     SubShader
13.     {
14.         Tags { "RenderType"="Opaque" }
15.         LOD 200
16.  
17.         CGPROGRAM
18.         #pragma surface surf Lambert
19.         #pragma vertex vert
20.  
21.         sampler2D _MainTex;
22.  
23.         struct Input
24.         {
25.             float2 uv_MainTex;
26.             float4 vertex : POSITION;
27.             float2 uv : TEXCOORD0;
28.         };
29.  
30.         fixed4 _Color;
31.         float _Amplitude;
32.         float _Scale;
33.         float _Frequency;
34.  
35.         void vert(inout appdata_full v, out Input o)
36.         {
37.             UNITY_INITIALIZE_OUTPUT(Input, o);
38.             o.vertex = UnityObjectToClipPos(v.vertex);
39.             o.uv = TRANSFORM_TEX(v.uv, _MainTex);
40.         }
41.  
42.         void surf (Input IN, inout SurfaceOutput o)
43.         {
44.             // Albedo comes from a texture tinted by color
45.             float2 DeltaTime = (IN.uv.yx * _Scale + _Time.y * _Frequency) * UNITY_PI;
46.             float2 uv = IN.uv + float2(sin(DeltaTime.x), sin(DeltaTime.y)) * _Amplitude;
47.             fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
48.             o.Albedo = c.rgb;
49.         }
50.         ENDCG
51.     }
52.     FallBack "Diffuse"
53. }

Please tell me where I might have made a mistake and how it can be resolved.

 

The appdata_full struct uses "texcoord" as a subscript for the texture coordinates not "uv" like you used in your Input struct.

 

That’s technically the error the compiler is complaining about, but that’s not actually the issue in the shader.

The issue is you don’t need a

vert

function in a surface shader to pass the UV along, and thus you shouldn’t be using the

.uv

in the

surf

function. With surface shaders the UV is automatically handled with the

.uv_MainTex

variable passed to the

surf

function. All that math being done to

.uv

in the surf function should be applied to the

.uv_MainTex

instead.

 

Thank you so much for the information!