//clang-format off
Shader "Unlit/PassthroughShadow"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Alpha("Alpha", Float) = 0.5
    }
    SubShader
    {
        Tags { "RenderType"="Transparent" }
        LOD 100

        Pass
        {
            ZTest Always
            ZWrite Off
            Blend SrcAlpha OneMinusSrcAlpha, One One
            BlendOp Add, Max
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

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

            struct v2f
            {
                float2 uv : TEXCOORD0;
                UNITY_FOG_COORDS(1)
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;
            float _Alpha;

            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
            {
                // sample the texture
                fixed4 col = 1.0 - tex2D(_MainTex, i.uv);
                return float4(0, 0, 0, (1.0f - col.x * col.x * col.x * col.x) * _Alpha);
            }
            ENDCG
        }
    }
}