Shader "yum_food/fourier_water_display"
{
    Properties
    {
        _MainTex ("FFT output", 2D) = "black" {}
        [IntRange] _Stage("Stage", Range(-1, 30)) = 0
        [IntRange] _Num_Stages("Num stages", Range(1, 30)) = 0
        [IntRange] _Direction("Direction", Range(0, 1)) = 0
    }
    SubShader
    {
        Tags { "RenderType" = "Opaque" }
        Cull Off

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

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

            sampler2D _MainTex;
            float4 _MainTex_TexelSize;
            int _Num_Stages;
            int _Stage;
            int _Direction;

            v2f vert(appdata_img v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.uv = v.texcoord;
                return o;
            }

            float4 frag(v2f i) : SV_Target
            {
                float4 c = tex2D(_MainTex, frac(i.uv + 0.5));
                float total_stage = ((float) _Stage + _Direction * _Num_Stages) / (_Num_Stages * 2);
                c *= lerp(_MainTex_TexelSize.z, 1, total_stage);
                return float4(c.xyz, 1);
            }
            ENDCG
        }
    }
}