Shader "Custom/Baiye"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)
        _Color2 ("Secondary Color", Color) = (1,1,1,1)
        _Direction ("Gradient Direction", Vector) = (0,1,0,0)
    }

    SubShader
    {
        Tags
        {
            "Queue"="Transparent"
            "IgnoreProjector"="True"
            "RenderType"="Transparent"
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True"
        }

        Cull Off
        Lighting Off
        ZWrite Off
        ZTest [unity_GUIZTestMode]
        Blend SrcAlpha OneMinusSrcAlpha

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

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

            struct v2f
            {
                float4 vertex   : SV_POSITION;
                fixed4 color    : COLOR;
                float2 texcoord  : TEXCOORD0;
                float4 worldPosition : TEXCOORD1;
            };

            sampler2D _MainTex;
            fixed4 _Color;
            fixed4 _Color2;
            float4 _Direction;
            float4 _ClipRect;

            v2f vert(appdata_t IN)
            {
                v2f OUT;
                OUT.worldPosition = IN.vertex;
                OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);
                OUT.texcoord = IN.texcoord;
                OUT.color = IN.color * _Color;
                return OUT;
            }

            fixed4 frag(v2f IN) : SV_Target
            {
                half4 color = tex2D(_MainTex, IN.texcoord) * IN.color;
                float gradient = dot(IN.texcoord - 0.5, _Direction) + 0.5;
                color.rgb = lerp(_Color.rgb, _Color2.rgb, gradient) * color.a;
                
                color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
                return color;
            }
            ENDCG
        }
    }
}