Shader "Custom/PostProcessing"
{
    Properties
    {
        _MainTex ("MainTexture", 2D) = "white" {}
        _ScreenSize ("ScreenSize", Vector) = (0,0,0,0)
        _Wave1 ("Wave1", Vector) = (0,0,0,0)
    }
    SubShader
    {
        Tags { "RenderType"="Opaque"}
        ZWrite Off
        Cull Off

        Pass {
            Blend SrcAlpha OneMinusSrcAlpha

            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag
            
            #include "UnityCG.cginc"

            #define PI 3.1415926

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

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

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float4 _ScreenSize;
            float4 _Wave1;
            
            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                return o;
            }
            
            fixed4 frag (v2f i) : SV_Target
            {
                fixed4 basic = tex2D(_MainTex, i.uv);
                fixed2 screen_pos = i.uv * _ScreenSize.xy;
                fixed2 wave_dir = (0,0);
                fixed dist1 = length(screen_pos - _Wave1.xy);
                if(dist1<_Wave1.z){
                    if(abs(dist1/_Wave1.z-_Wave1.w*2)<0.25){
                        fixed wave = cos(PI*4*abs(dist1/_Wave1.z-_Wave1.w*2))*8;
                        wave_dir = wave_dir + normalize(screen_pos-_Wave1.xy)*wave;
                        // if(wave>3.99){
                            //     return(1,0,0,1);
                        // }

                    }
                }
                wave_dir = wave_dir / _ScreenSize.xy;
                return tex2D(_MainTex, i.uv+wave_dir);
            }
            ENDCG

        }

    }
    FallBack "Diffuse"
}