// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)

Shader "UI/UICircular"

{

	Properties

	{

		_R("圆的半径R", Range(0,1)) = 0.5

		_Blur("边缘虚化的范围", Range(0,100)) = 100

		[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

	}

		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_CLIP_RECT

				#pragma multi_compile __ UNITY_UI_ALPHACLIP

				struct appdata_t

				{

					float4 vertex   : POSITION;

					float4 color    : COLOR;

					float2 texcoord : TEXCOORD0;

					UNITY_VERTEX_INPUT_INSTANCE_ID

				};

				struct v2f

				{

					float4 vertex   : SV_POSITION;

					fixed4 color : COLOR;

					float2 texcoord  : TEXCOORD0;

					float4 worldPosition : TEXCOORD1;

					UNITY_VERTEX_OUTPUT_STEREO

				};

				fixed4 _Color;

				fixed4 _TextureSampleAdd;

				float4 _ClipRect;

				float _R;

				float _X;

				float _Y;

				float _Blur;

				v2f vert(appdata_t v)

				{

					v2f OUT;

					UNITY_SETUP_INSTANCE_ID(v);

					UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);

					OUT.worldPosition = v.vertex;

					OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);

					OUT.texcoord = v.texcoord;

					OUT.color = v.color * _Color;

					return OUT;

				}

				sampler2D _MainTex;

				fixed4 frag(v2f IN) : SV_Target

				{

					half4 color = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;

					#ifdef UNITY_UI_CLIP_RECT

					color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);

					#endif

					#ifdef UNITY_UI_ALPHACLIP

					clip(color.a - 0.001);

					#endif

					//圆形

					float x = IN.texcoord.x-0.5f;

					float y = IN.texcoord.y-0.5f;

					float lerp = (1 - _Blur * (_R*_R - (x * x + y * y)))*color.a;//如果不加这句代码，图片边缘会有明显的锯齿

					color.a = (color.a - lerp)*step(x*x + y * y, _R*_R);//如果 _R*_R<(x*x + y * y)，返回 0；否则，返回 1。

					return color;

				}

			ENDCG

			}

		}

}