Shader "UI/VerticalGradient"
{
    Properties
    {
        _ColorTop("Top Color", Color) = (0, 0, 0, 0)
        _ColorBottom("Bottom Color", Color) = (0, 0, 0, 1)
    }
        SubShader
    {
        Tags { "Queue" = "Overlay" "RenderType" = "Transparent" }
        Blend SrcAlpha OneMinusSrcAlpha
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

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

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

            fixed4 _ColorTop;
            fixed4 _ColorBottom;

            v2f vert(appdata_t v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                return lerp(_ColorBottom, _ColorTop, i.uv.y);
            }
            ENDCG
        }
    }
}