UnityShaderBook/Assets/Shaders/Extra/ImageEffect/ImageDistort.shader

Shader "Hidden/ImageDistort"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_DistortTex ("Distort Texture", 2D) = "white" {}
		_DistortScale ("Distort Scale",Range(0,1)) = 1.0 
	}
	SubShader
	{
		// No culling or depth
		Cull Off ZWrite Off ZTest Always
		Tags { }

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "UnityCG.cginc"

			sampler2D _MainTex;
			sampler2D _DistortTex;
			float _DistortScale;

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = v.uv;
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				//i.uv = abs(0.5-i.uv);
				fixed4 noise = tex2D(_DistortTex,i.uv);
				i.uv = i.uv + (0.5-noise.r) * _DistortScale*0.1;
				fixed4 col = tex2D(_MainTex, i.uv);
				// just invert the colors
				//col.rgb = 1 - col.rgb;
				return col;
			}
			ENDCG
		}
	}
}