UGUI 背景虚化Shader

Shader "Custom/Blur"
{
	Properties
	{
		_Blur("Blur", float) = 10
	}
		SubShader
		{
			Tags{ "Queue" = "Transparent"
				}

			GrabPass
			{}

			Pass
			{
				CGPROGRAM

				#pragma vertex vert
				#pragma fragment frag
				#include "UnityCG.cginc"

				struct appdata
				{
					float4 vertex : POSITION;
					float2 uv : TEXCOORD0;
					fixed4 color : COLOR;
				};

				struct v2f
				{
					float4 grabPos : TEXCOORD0;
					float4 pos : SV_POSITION;
					float4 vertColor : COLOR;
				};

				v2f vert(appdata v)
				{
					v2f o;
					o.pos = UnityObjectToClipPos(v.vertex);
					o.grabPos = ComputeGrabScreenPos(o.pos);
					o.vertColor = v.color;
					return o;
				}

				sampler2D _GrabTexture;
				fixed4 _GrabTexture_TexelSize;

				float _Blur;

				half4 frag(v2f i) : SV_Target
				{
					float blur = _Blur;
					blur = max(1, blur);

					fixed4 col = (0, 0, 0, 0);
					float weight_total = 0;

					[loop]
					for (float x = -blur; x <= blur; x += 1)
					{
						float distance_normalized = abs(x / blur);
						float weight = exp(-0.5 * pow(distance_normalized, 2) * 5.0);
						weight_total += weight;
						col += tex2Dproj(_GrabTexture, i.grabPos + float4(x * _GrabTexture_TexelSize.x, 0, 0, 0)) * weight;
					}

					col /= weight_total;
					return col;
				}
				ENDCG
			}
			GrabPass
			{}

			Pass
			{
				CGPROGRAM

				#pragma vertex vert
				#pragma fragment frag
				#include "UnityCG.cginc"

				struct appdata
				{
					float4 vertex : POSITION;
					float2 uv : TEXCOORD0;
					fixed4 color : COLOR;
				};

				struct v2f
				{
					float4 grabPos : TEXCOORD0;
					float4 pos : SV_POSITION;
					float4 vertColor : COLOR;
				};

				v2f vert(appdata v)
				{
					v2f o;
					o.pos = UnityObjectToClipPos(v.vertex);
					o.grabPos = ComputeGrabScreenPos(o.pos);
					o.vertColor = v.color;
					return o;
				}

				sampler2D _GrabTexture;
				fixed4 _GrabTexture_TexelSize;

				float _Blur;

				half4 frag(v2f i) : SV_Target
				{
					float blur = _Blur;
					blur = max(1, blur);

					fixed4 col = (0, 0, 0, 0);
					float weight_total = 0;

					[loop]
					for (float y = -blur; y <= blur; y += 1)
					{
						float distance_normalized = abs(y / blur);
						float weight = exp(-0.5 * pow(distance_normalized, 2) * 5.0);
						weight_total += weight;
						col += tex2Dproj(_GrabTexture, i.grabPos + float4(0, y * _GrabTexture_TexelSize.y, 0, 0)) * weight;
					}

					col /= weight_total;
					return col;
				}
				ENDCG
			}

		}
}

此效果可以模糊图片遮挡区域