Shader "Custom/GlassBlur"
{
    Properties
    {
        _MainTex ("Base (RGB)", 2D) = "white" {}
        _Distortion ("Distortion", Range(0.0,1.0)) = 0.5
        _BlurSize ("Blur Size", Range(0.0,1.0)) = 0.2
    }
    SubShader
    {
        Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
        LOD 200

        Blend SrcAlpha OneMinusSrcAlpha
        ZWrite Off
        AlphaTest Greater 0.5
        Cull Off

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

            struct appdata_t
            {
                float4 vertex : POSITION;
                float2 texcoord : TEXCOORD0;
            };

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

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float _Distortion;
            float _BlurSize;

            v2f vert (appdata_t v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                float2 uv = i.uv;
                float2 offset = float2(_Distortion, _Distortion) * _BlurSize;

                float4 col = tex2D(_MainTex, uv);
                col += tex2D(_MainTex, uv + float2(offset.x, offset.y));
                col += tex2D(_MainTex, uv + float2(-offset.x, offset.y));
                col += tex2D(_MainTex, uv + float2(offset.x, -offset.y));
                col += tex2D(_MainTex, uv + float2(-offset.x, -offset.y));

                col /= 5.0;

                return col;
            }
            ENDCG
        }
    }
    FallBack "Diffuse"
}