unity之模糊背景（带你欣赏女人的朦胧美）

最近项目用到了模糊背景效果。实现方法为：shader。代码来自百度。接下来给大家介绍一下模糊背景的实现过程。首先你需要一个先人已经写好的shader（当然，如果你有能力，也可以自己实现！）
没有的可以通过以下链接下载材质球和对应的shader。
模糊背景shader
模糊背景材质球
shader如下：

Shader "FT/Blur/Back"{	Properties	{		_Color ("Main Color", Color) = (1,1,1,1)        _Size ("Size", Range(0, 20)) = 1	}	Category {            // We must be transparent, so other objects are drawn before this one.         Tags { 			"Queue"="Transparent" 			"IgnoreProjector"="True" 			"RenderType"="Transparent"			"PreviewType" = "Plane"			"CanUseSpriteAtlas" = "True"		}              SubShader {                // Horizontal blur             GrabPass 			{                                      Tags { "LightMode" = "Always" }              }              Pass {                Tags { "LightMode" = "Always" }                  Name "BackBlurHor"                CGPROGRAM                  #pragma vertex vert                  #pragma fragment frag                  #pragma fragmentoption ARB_precision_hint_fastest                  #include "UnityCG.cginc"                    struct appdata_t {                      float4 vertex : POSITION;                      float2 texcoord : TEXCOORD0;					float4 color    : COLOR;                };                    struct v2f {                      float4 vertex : POSITION;                      float4 uvgrab : TEXCOORD0;					float4 color    : COLOR;                };                  v2f vert (appdata_t v) {                      v2f o;                     o.vertex = UnityObjectToClipPos(v.vertex);                      #if UNITY_UV_STARTS_AT_TOP                      float scale = -1.0;                      #else                      float scale = 1.0;                      #endif                      o.uvgrab.xy = (float2(o.vertex.x, o.vertex.y*scale) + o.vertex.w) * 0.5;                      o.uvgrab.zw = o.vertex.zw;  					o.color = v.color;                    return o;                  }                    sampler2D _GrabTexture;                  float4 _GrabTexture_TexelSize;			    float4 _MainTex_TexelSize;                float _Size;                uniform float4 _Color;                half4 GrabPixel(v2f i, float weight, float kernel){                    kernel = sign(sign(abs(i.uvgrab.x)) + sign(abs(i.uvgrab.y))) * kernel;					return tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(float4(i.uvgrab.x + _GrabTexture_TexelSize.x * kernel * _Size, i.uvgrab.y, i.uvgrab.z, i.uvgrab.w))) * weight;                }                half4 frag( v2f i ) : COLOR {                   	half4 sum = half4(0,0,0,0);                    sum += GrabPixel(i, 0.05, -4.0);                    sum += GrabPixel(i, 0.09, -3.0);                    sum += GrabPixel(i, 0.12, -2.0);                    sum += GrabPixel(i, 0.15, -1.0);                    sum += GrabPixel(i, 0.18,  0.0);                    sum += GrabPixel(i, 0.15, +1.0);                    sum += GrabPixel(i, 0.12, +2.0);                    sum += GrabPixel(i, 0.09, +3.0);                    sum += GrabPixel(i, 0.05, +4.0);                    float4 col5 = tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(i.uvgrab));					fixed decayFactor = sign(sign(abs(i.uvgrab.x)) + sign(abs(i.uvgrab.y)));					sum = lerp(col5, sum, decayFactor) * i.color * _Color;                      return sum;                  }                  ENDCG              }  			            // Vertical blur             GrabPass {                                          Tags { "LightMode" = "Always" }              }              Pass {                  Tags { "LightMode" = "Always" }                Name "BackBlurVer"                CGPROGRAM                  #pragma vertex vert                  #pragma fragment frag                  #pragma fragmentoption ARB_precision_hint_fastest                  #include "UnityCG.cginc"                    struct appdata_t {                      float4 vertex : POSITION;                      float2 texcoord: TEXCOORD0;  					float4 color    : COLOR;                };                    struct v2f {                      float4 vertex : POSITION;                      float4 uvgrab : TEXCOORD0;  					float4 color    : COLOR;                };                    v2f vert (appdata_t v) {                      v2f o;                      o.vertex = UnityObjectToClipPos(v.vertex);                      #if UNITY_UV_STARTS_AT_TOP                      float scale = -1.0;                      #else                      float scale = 1.0;                      #endif                      o.uvgrab.xy = (float2(o.vertex.x, o.vertex.y*scale) + o.vertex.w) * 0.5;                      o.uvgrab.zw = o.vertex.zw;  					o.color = v.color;                    return o;                  }                    sampler2D _GrabTexture;                  float4 _GrabTexture_TexelSize;                  float _Size;                uniform float4 _Color;                half4 GrabPixel(v2f i, float weight, float kernel){					kernel = sign(sign(abs(i.uvgrab.x)) + sign(abs(i.uvgrab.y))) * kernel;                    return tex2Dproj( _GrabTexture, UNITY_PROJ_COORD(float4(i.uvgrab.x, i.uvgrab.y + _GrabTexture_TexelSize.y * kernel * _Size, i.uvgrab.z, i.uvgrab.w))) * weight;                }                  half4 frag( v2f i ) : COLOR				{                    half4 sum = half4(0,0,0,0);                      sum += GrabPixel(i, 0.05, -4.0);                    sum += GrabPixel(i, 0.09, -3.0);                    sum += GrabPixel(i, 0.12, -2.0);                    sum += GrabPixel(i, 0.15, -1.0);                    sum += GrabPixel(i, 0.18,  0.0);                    sum += GrabPixel(i, 0.15, +1.0);                    sum += GrabPixel(i, 0.12, +2.0);                    sum += GrabPixel(i, 0.09, +3.0);                    sum += GrabPixel(i, 0.05, +4.0);					float4 col5 = tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(i.uvgrab));					fixed decayFactor = sign(sign(abs(i.uvgrab.x)) + sign(abs(i.uvgrab.y)));					sum = lerp(col5, sum, decayFactor) * i.color * _Color;                      return sum;                  }                  ENDCG              }        }	}}

unity中使用方法：
为工程导入下载的材质球和shader
通常我们新建Material文件夹存放材质球

创建Shader文件夹存放shader代码

新建背景Image，命名为bg，并为其赋上指定的图片资源，如下：

新建模糊材质背景Image，命名为mask，SourceImage指定任意值即可；Material指定下载的材质球

效果如下：

调节材质球的Size可以调节模糊程度。值越大，效果越模糊。
在这里插入图片描述

将size值拉到5效果如下：