Shader "BF/UI/UITutorial"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)

        _StencilComp ("Stencil Comparison", Float) = 8
        _Stencil ("Stencil ID", Float) = 0
        _StencilOp ("Stencil Operation", Float) = 0
        _StencilWriteMask ("Stencil Write Mask", Float) = 255
        _StencilReadMask ("Stencil Read Mask", Float) = 255

        _ColorMask ("Color Mask", Float) = 15

        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0

        //-------------------add----------------------
        _Center ("Center", vector) = (0, 0, 0, 0)
        // _Blur ("Blur", Range(1,100)) = 25 // 边缘虚化
        // _Radius ("Silder", Range(0,1000)) = 100 // 圆形半径
        _Ellipse("_Ellipse", Range(0,100)) = 10 // 椭圆系数
        _Rect_X ("Rect_X", Range(0,1500)) = 1500
        _Rect_Y ("Rect_Y", Range(0,1500)) = 1500
        //-------------------add----------------------
    }

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

        Stencil
        {
            Ref [_Stencil]
            Comp [_StencilComp]
            Pass [_StencilOp]
            ReadMask [_StencilReadMask]
            WriteMask [_StencilWriteMask]
        }

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

        Pass
        {
            Name "Default"
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 2.0

            #include "UnityCG.cginc"
            #include "UnityUI.cginc"

            #pragma multi_compile __ UNITY_UI_ALPHACLIP

            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;
                float2 grey     : TEXCOORD2;
            };

            sampler2D _MainTex;
            fixed4 _Color;
            fixed4 _TextureSampleAdd;
            float4 _ClipRect;
            float4 _MainTex_ST;

            //-------------------add----------------------
            // float _Blur;
            // float _Radius;
            float2 _Center;
            float _Ellipse;
            float _Rect_X;
            float _Rect_Y;
            //-------------------add----------------------

            v2f vert(appdata_t v)
            {
                v2f OUT;
                OUT.worldPosition = v.vertex;
                OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);
                OUT.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
                OUT.color = _Color * v.color;
                int g_greyFactor = step(v.color.g, 0.001);
                int rb_greyFactor = step(1.999, v.color.r + v.color.b);
                int greyFactor = g_greyFactor * rb_greyFactor;
                OUT.grey = float2(greyFactor , 1 - greyFactor);
                return OUT;
            }

            fixed4 frag(v2f IN) : SV_Target
            {
                half4 texColor = tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd;
                half4 color = texColor * IN.color;
                float grey = dot(texColor.rgb, float3(0.299, 0.587, 0.114));
                color.rgb = float3(grey * IN.grey.x + color.r * IN.grey.y, grey * IN.grey.x + color.g * IN.grey.y, grey * IN.grey.x + color.b * IN.grey.y);
                color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
                #ifdef UNITY_UI_ALPHACLIP
                clip (color.a - 0.001);
                #endif

                //-------------------add----------------------
                // float circle_dis = distance(IN.worldPosition.xy, _Center.xy);
                // fixed circle_tmp = step(circle_dis, _Radius);
                // float circle_blur = (clamp(circle_dis, _Radius - _Blur, _Radius) - (_Radius - _Blur)) / _Blur;
                // color.a *= (1 - circle_tmp) + circle_tmp * circle_blur;

                float rect_x_dis = abs(IN.worldPosition.x - _Center.x);
                float rect_y_dis = abs(IN.worldPosition.y - _Center.y);
                fixed rect_factor = clamp(pow(abs(rect_x_dis / _Rect_X), _Ellipse) + pow(abs(rect_y_dis / _Rect_Y), _Ellipse), 0.0, 1.0);
                fixed rect_tmp = step(rect_factor, 1.0f);
                color.a *= (1 - rect_tmp) + rect_tmp * rect_factor;

               	color.rgb *= color.a;
               	//-------------------add----------------------

                return color;
            }
        ENDCG
        }
    }
}