贴图阴影shader(模糊渐变)

// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'
Shader "Custom/Sprites/DefaultShadowIndistinct"
{ 
	Properties
	{
		  [HideInInspector]_MainTex("Main Tex", 2D) = "white" {}
		  _RadiusX("_RadiusX", Range(0, 2)) = 1
		  _RadiusY("_RadiusY", Range(0, 2)) = 1

		  _AlphaX("_AlphaX", Range(0, 1)) = 0.5
		  _AlphaY("_AlphaY", Range(0, 1)) = 0.5

		  _ScaleY("_ScaleY", Range(0, 1)) = 0.5

		  _Offset("Offset", vector) = (0, 0, 0, 0)

	}

	CGINCLUDE
	#include "UnityCG.cginc"
	sampler2D _MainTex;

	float _AlphaX;
	float _AlphaY;

	float _RadiusX;
	float _RadiusY;

	float _ScaleY;

	float4 _Offset;
	float4 _MainTex_ST;

	struct v2f 
	{
		float4 pos : POSITION;
		float2 uv : TEXCOORD0;
		float3 worldPos : TEXCOORD1;
	};

	v2f vert_normal(appdata_base v) 
	{
		v2f o;
		o.pos = UnityObjectToClipPos(v.vertex);
		o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
		return o;
	}

	v2f vert_offset(appdata_base v) 
	{
		v2f o;
		float4 pos = mul(unity_ObjectToWorld, v.vertex);
		o.pos = mul(UNITY_MATRIX_VP, pos + _Offset);
		o.pos.y = o.pos.y * _ScaleY;//贴图压扁
		o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
		//o.uv.y = o.uv.y * _ScaleY;
		return o;
	}

	float4 frag_normal(v2f i) : COLOR 
	{
		float4 texcol = tex2D(_MainTex, i.uv);
		return texcol;
	}

	float4 frag_color(v2f i) : COLOR
	{
		float4 color = tex2D(_MainTex, i.uv);
	
		//y渐变
		//float y = i.uv.y + _Alpha + _UVY;
		//color *= float4(0, 0, 0, y);
		
		//圆心渐变
		//float radius = ((i.uv.x - 0.5) * (i.uv.x - 0.5) + (i.uv.y - 0.5) * (i.uv.y - 0.5)) * _Radius;
		//color *= float4(0, 0, 0, radius + _Alpha);
		
		//x，y渐变
		float x2 = (i.uv.x - 0.5) * (i.uv.x - 0.5) * _RadiusX * _AlphaX;
		float y2 = (i.uv.y - 0.5) * (i.uv.y - 0.5) * _RadiusY * _AlphaY;
		float alpha = (1 - (x2 + y2));

		color *= float4(0, 0, 0, alpha);

		return color;
	}
	ENDCG

	SubShader 
	{
		Tags{ "Queue" = "Transparent" }
		Pass
		{
			ZWrite Off
			Blend SrcAlpha OneMinusSrcAlpha
			CGPROGRAM
			#pragma vertex vert_offset
			#pragma fragment frag_color
			ENDCG
		}
		Pass
		{
			ZWrite Off
			Blend SrcAlpha OneMinusSrcAlpha
			CGPROGRAM
			#pragma vertex vert_normal
			#pragma fragment frag_normal
			ENDCG
		}
	}
	FallBack "Diffuse"
}