Shader "Hide/FullBlur"
{
	Properties
	{
		_MainTex("Texture", 2D) = "white" {}
	}
	SubShader
	{
		Tags
        {
            "RenderType"="Opaque"
            "RenderPipeline" = "UniversalPipeline"
        }
		
		LOD 100
		
		HLSLINCLUDE
		#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
		sampler2D _MainTex;
		half4 _MainTex_TexelSize;
		float _BlurSizeX;
		float _BlurSizeY;

		//URP下没有appdata_img结构 要自定义
		struct a2v
		{
			float4 vertex : POSITION;
			float2 texcoord : TEXCOORD0;
		};

		struct v2f
		{
			float4 pos : SV_POSITION;
			half2 uv[5] : TEXCOORD0;
		};

		//我们只需要appdata_img内置结构的数据传入即可（有顶点、纹理坐标）
		v2f vertBlurVertical(a2v v) {
			v2f o;

			//o.pos = UnityObjectToClipPos(v.vertex); //CG
			VertexPositionInputs vertexInputs = GetVertexPositionInputs(v.vertex.xyz);
			o.pos = vertexInputs.positionCS;
			half2 uv = v.texcoord;

			//纵向的5个像素点纹理坐标
			o.uv[0] = uv;
			o.uv[1] = uv + float2(0.0, _MainTex_TexelSize.y * 1.0) * _BlurSizeY;
			o.uv[2] = uv - float2(0.0, _MainTex_TexelSize.y * 1.0) * _BlurSizeY;
			o.uv[3] = uv + float2(0.0, _MainTex_TexelSize.y * 2.0) * _BlurSizeY;
			o.uv[4] = uv - float2(0.0, _MainTex_TexelSize.y * 2.0) * _BlurSizeY;
			return o;
		}

		v2f vertBlurHorizontal(a2v v) {
			v2f o;
			//o.pos = UnityObjectToClipPos(v.vertex); //CG
			VertexPositionInputs vertexInputs = GetVertexPositionInputs(v.vertex.xyz);
			o.pos = vertexInputs.positionCS;
			half2 uv = v.texcoord;

			//横向的5个像素点纹理坐标
			o.uv[0] = uv;
			o.uv[1] = uv + float2(_MainTex_TexelSize.x * 1.0, 0.0) * _BlurSizeX;
			o.uv[2] = uv - float2(_MainTex_TexelSize.x * 1.0, 0.0) * _BlurSizeX;
			o.uv[3] = uv + float2(_MainTex_TexelSize.x * 2.0, 0.0) * _BlurSizeX;
			o.uv[4] = uv - float2(_MainTex_TexelSize.x * 2.0, 0.0) * _BlurSizeX;
			return o;
		}

		//无论是纵向还是横向，它们都会使用这个片元着色器，处理手法一样
		half4 fragBlur(v2f i) : SV_Target{
			float weight[3] = {0.4026, 0.2442, 0.0545};
			//采样RGB然后进行乘以对应的权重累加到sum
			half3 sum = tex2D(_MainTex, i.uv[0]).rgb * weight[0];
			for (int it = 1; it < 3; it++) {
				sum += tex2D(_MainTex, i.uv[it * 2 - 1]).rgb * weight[it];
				sum += tex2D(_MainTex, i.uv[it * 2]).rgb * weight[it];
			}
			//是的这样就完成了，模糊。。。。
			return half4(sum, 1.0);
		}
		ENDHLSL

		//上面都是INCLUDE内容即下面Pass都可使用的内容
		//标配写法
		ZTest Always Cull Off ZWrite Off
		//第一个PASS,纵向模糊处理
		Pass
		{
			NAME "GAUSSIAN_BLUR_VERTICAL"

			//CGPROGRAM //CG
			HLSLPROGRAM

			//纵向的顶点着色器
			#pragma vertex vertBlurVertical
			//片元着色器
			#pragma fragment fragBlur

			//ENDCG //CG
			ENDHLSL
		}
		//第二个Pass 横向模糊处理
		Pass
		{
			NAME "GAUSSIAN_BLUR_HORIZONTAL"

			//CGPROGRAM
			HLSLPROGRAM

			//横向的顶点着色器
			#pragma vertex vertBlurHorizontal
			//片元着色器
			#pragma fragment fragBlur

			//ENDCG
			ENDHLSL
		}
	}//完成SubShader
	Fallback Off
}