Unity3D-UGUI特效之Image的高斯模糊效果

这几天研究了下模糊特效，看了很多文章，其原理就是拿取图片或屏幕数据，然后将周围的元素和目标位置的颜色值进行一个融合计算，然后自己写了一个小小的测试程序。

这个模糊也可以分成两种，一个是自身模糊，一个是从屏幕上取值进行模糊。第一个用于一些小的列表展示，比如未解锁时，是模糊的。第二个是凸显弹框效果的，将背景都模糊掉，自己将这个稍微加强了些可以指定模糊一个位置。

针对移动平台，使用高斯模糊，其实效率不是很高，如果要很好的效果，那么速度卡；如果要速度快，那么效果达不到要求。但是还是在这里记录下，兴许以后能用上。

先说第一个，挂在Image下的模糊特效。

Shader "Custom/FrontBlur" {
Properties
{
[PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
_Color ("Tint", Color) = (1,1,1,1)

[HideInInspector]_StencilComp ("Stencil Comparison", Float) = 8
[HideInInspector]_Stencil ("Stencil ID", Float) = 0
[HideInInspector]_StencilOp ("Stencil Operation", Float) = 0
[HideInInspector]_StencilWriteMask ("Stencil Write Mask", Float) = 255
[HideInInspector]_StencilReadMask ("Stencil Read Mask", Float) = 255

[HideInInspector]_ColorMask ("Color Mask", Float) = 15

[Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0

_Size ("Size", Range(0, 50)) = 5
}

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 "FrontBlurHor"
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma target 2.0

#include "UnityCG.cginc"
#include "UnityUI.cginc"

#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;

v2f vert(appdata_t IN)
{
v2f OUT;
UNITY_SETUP_INSTANCE_ID(IN);
UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
OUT.worldPosition = IN.vertex;
OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);

OUT.texcoord = IN.texcoord;

OUT.color = IN.color * _Color;
return OUT;
}

sampler2D _MainTex;
float4 _MainTex_TexelSize;
float _Size;

half4 GrabPixel(v2f i, float weight, float kernelx){
if (_Size <= 1 || weight == 0){
return tex2D(_MainTex, half2(i.texcoord.x + _MainTex_TexelSize.x*kernelx*_Size, i.texcoord.y)) * weight;
}else{
half4 sum = half4(0,0,0,0);
sum += tex2D(_MainTex, half2(i.texcoord.x + _MainTex_TexelSize.x*kernelx*_Size*0.2, i.texcoord.y))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x + _MainTex_TexelSize.x*kernelx*_Size*0.4, i.texcoord.y))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x + _MainTex_TexelSize.x*kernelx*_Size*0.6, i.texcoord.y))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x + _MainTex_TexelSize.x*kernelx*_Size*0.8, i.texcoord.y))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x + _MainTex_TexelSize.x*kernelx*_Size*1.0, i.texcoord.y))*0.2;
return (sum + _TextureSampleAdd) * weight;
}
}

half4 GrabPixely(v2f i, float weight, float kernely){
if (_Size <= 1 || weight == 0){
return tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size)) * weight;
}else{
half4 sum = half4(0,0,0,0);
sum += tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size*0.2))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size*0.4))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size*0.6))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size*0.8))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size*1.0))*0.2;
return (sum + _TextureSampleAdd) * weight;
}
}

fixed4 frag(v2f IN) : SV_Target
{
half4 sum = half4(0,0,0,0);
// #define GRABPIXEL(weight, kernelx) (tex2D(_MainTex, half2(IN.texcoord.x + _MainTex_TexelSize.x * kernelx*_Size, IN.texcoord.y)) + _TextureSampleAdd) * weight

// sum += GrabPixel(IN, 0.05, -4.0);
// sum += GrabPixel(IN, 0.09, -3.0);
// sum += GrabPixel(IN, 0.12, -2.0);
// sum += GrabPixel(IN, 0.15, -1.0);
// sum += GrabPixel(IN, 0.18,  0.0);
// sum += GrabPixel(IN, 0.15, +1.0);
// sum += GrabPixel(IN, 0.12, +2.0);
// sum += GrabPixel(IN, 0.09, +3.0);
// sum += GrabPixel(IN, 0.05, +4.0);

for(int i=0;i<9;i++){
sum += GrabPixel(IN, 1.0/9, i-4.0);
}

// half4 sumy = half4(0,0,0,0);
// for(int i=0;i<15;i++){
// 	sumy += GrabPixely(IN, 1.0/15, i-7.0);
// }
// half4 sum = (sumx + sumy) * 0.5;

// sum += GrabPixel(IN, 0.01, -9.0);
// sum += GrabPixel(IN, 0.02, -8.0);
// sum += GrabPixel(IN, 0.03, -7.0);
// sum += GrabPixel(IN, 0.04, -6.0);
// sum += GrabPixel(IN, 0.05, -5.0);
// sum += GrabPixel(IN, 0.06, -4.0);
// sum += GrabPixel(IN, 0.07, -3.0);
// sum += GrabPixel(IN, 0.08, -2.0);
// sum += GrabPixel(IN, 0.09, -1.0);
// sum += GrabPixel(IN, 0.10,  0.0);
// sum += GrabPixel(IN, 0.09, +1.0);
// sum += GrabPixel(IN, 0.08, +2.0);
// sum += GrabPixel(IN, 0.07, +3.0);
// sum += GrabPixel(IN, 0.06, +4.0);
// sum += GrabPixel(IN, 0.05, +5.0);
// sum += GrabPixel(IN, 0.04, +6.0);
// sum += GrabPixel(IN, 0.03, +7.0);
// sum += GrabPixel(IN, 0.02, +8.0);
// sum += GrabPixel(IN, 0.01, +9.0);

sum = sum * IN.color;
sum.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
#ifdef UNITY_UI_ALPHACLIP
clip (sum.a - 0.001);
#endif
return sum;

// float distance = _Distance;

// fixed4 color = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;

// color += (tex2D(_MainTex, half2(IN.texcoord.x + distance, IN.texcoord.y + distance)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x + distance, IN.texcoord.y)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x + distance, IN.texcoord.y - distance)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x, IN.texcoord.y - distance)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x - distance, IN.texcoord.y - distance)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x - distance, IN.texcoord.y)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x - distance, IN.texcoord.y + distance)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x, IN.texcoord.y + distance)) + _TextureSampleAdd) * IN.color;
// color /= 9;

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

// #ifdef UNITY_UI_ALPHACLIP
// clip (color.a - 0.001);
// #endif

// return color;
}
ENDCG
}
Pass
{
Name "FrontBlurVer"
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma target 2.0

#include "UnityCG.cginc"
#include "UnityUI.cginc"

#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;

v2f vert(appdata_t IN)
{
v2f OUT;
UNITY_SETUP_INSTANCE_ID(IN);
UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
OUT.worldPosition = IN.vertex;
OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);

OUT.texcoord = IN.texcoord;

OUT.color = IN.color * _Color;
return OUT;
}

sampler2D _MainTex;
float4 _MainTex_TexelSize;
float _Size;

half4 GrabPixel(v2f i, float weight, float kernely){
if (_Size <= 1 || weight == 0){
return tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size)) * weight;
}else{
half4 sum = half4(0,0,0,0);
sum += tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size*0.2))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size*0.4))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size*0.6))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size*0.8))*0.2;
sum += tex2D(_MainTex, half2(i.texcoord.x, i.texcoord.y + _MainTex_TexelSize.y*kernely*_Size*1.0))*0.2;
return (sum + _TextureSampleAdd) * weight;
}
}

fixed4 frag(v2f IN) : SV_Target
{
half4 sum = half4(0,0,0,0);
// #define GRABPIXEL(weight, kernely) (tex2D(_MainTex, half2(IN.texcoord.x, IN.texcoord.y + _MainTex_TexelSize.y * kernely*_Size)) + _TextureSampleAdd) * weight

// sum += GrabPixel(IN, 0.05, -4.0);
// sum += GrabPixel(IN, 0.09, -3.0);
// sum += GrabPixel(IN, 0.12, -2.0);
// sum += GrabPixel(IN, 0.15, -1.0);
// sum += GrabPixel(IN, 0.18,  0.0);
// sum += GrabPixel(IN, 0.15, +1.0);
// sum += GrabPixel(IN, 0.12, +2.0);
// sum += GrabPixel(IN, 0.09, +3.0);
// sum += GrabPixel(IN, 0.05, +4.0);

for(int i=0;i<9;i++){
sum += GrabPixel(IN, 1.0/9, i-4.0);
}

// sum += GrabPixel(IN, 0.01, -9.0);
// sum += GrabPixel(IN, 0.02, -8.0);
// sum += GrabPixel(IN, 0.03, -7.0);
// sum += GrabPixel(IN, 0.04, -6.0);
// sum += GrabPixel(IN, 0.05, -5.0);
// sum += GrabPixel(IN, 0.06, -4.0);
// sum += GrabPixel(IN, 0.07, -3.0);
// sum += GrabPixel(IN, 0.08, -2.0);
// sum += GrabPixel(IN, 0.09, -1.0);
// sum += GrabPixel(IN, 0.10,  0.0);
// sum += GrabPixel(IN, 0.09, +1.0);
// sum += GrabPixel(IN, 0.08, +2.0);
// sum += GrabPixel(IN, 0.07, +3.0);
// sum += GrabPixel(IN, 0.06, +4.0);
// sum += GrabPixel(IN, 0.05, +5.0);
// sum += GrabPixel(IN, 0.04, +6.0);
// sum += GrabPixel(IN, 0.03, +7.0);
// sum += GrabPixel(IN, 0.02, +8.0);
// sum += GrabPixel(IN, 0.01, +9.0);

sum = sum * IN.color;
sum.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
#ifdef UNITY_UI_ALPHACLIP
clip (sum.a - 0.001);
#endif
return sum;

// float distance = _Distance;

// fixed4 color = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;

// color += (tex2D(_MainTex, half2(IN.texcoord.x + distance, IN.texcoord.y + distance)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x + distance, IN.texcoord.y)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x + distance, IN.texcoord.y - distance)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x, IN.texcoord.y - distance)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x - distance, IN.texcoord.y - distance)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x - distance, IN.texcoord.y)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x - distance, IN.texcoord.y + distance)) + _TextureSampleAdd) * IN.color;
// color += (tex2D(_MainTex, half2(IN.texcoord.x, IN.texcoord.y + distance)) + _TextureSampleAdd) * IN.color;
// color /= 9;

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

// #ifdef UNITY_UI_ALPHACLIP
// clip (color.a - 0.001);
// #endif

// return color;
}
ENDCG
}
}
}

里面分了两个Pass来计算，这样算出的效果会好很多，然后里面试了跟多的计算，越多的分层，那么得到的效果也越高，也意味着更加的不流畅。将shader放到一个新建的材质球上，然后把材质拖到Image组件的Material属性栏上就可以了。



看看效果：





然后说第二个方式，它是将背景都给模糊的效果。

Shader "Custom/BackBlur"
{
Properties
{
[PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
_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;

// static float GaussianKernel[9] = {
//     0.05, 0.09, 0.12,
//     0.15, 0.18, 0.15,
//     0.12, 0.09, 0.05
// };

// static float GaussianKernel[19] = {
//     0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09,
//     0.1,
//     0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01,
// };
// static float GaussianKernelD[19] = {
//     -9.0, -8.0, -7.0, -6.0, -5.0, -4.0, -3.0, -2.0, -1.0,
//     0.0,
//     +1.0, +2.0, +3.0, +4.0, +5.0, +6.0, +7.0, +8.0, +9.0,
// };

half4 GrabPixel(v2f i, float weight, float kernelx){
if (i.uvgrab.x == 0 && i.uvgrab.y == 0){
kernelx = 0;
}
return tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(float4(i.uvgrab.x + _GrabTexture_TexelSize.x*kernelx*_Size, i.uvgrab.y, i.uvgrab.z, i.uvgrab.w))) * weight;
}
half4 frag( v2f i ) : COLOR {
half4 sum = half4(0,0,0,0);
// #define GRABPIXEL(weight, kernelx) tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(float4(i.uvgrab.x + _GrabTexture_TexelSize.x * kernelx*_Size, i.uvgrab.y, i.uvgrab.z, i.uvgrab.w))) * weight

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);

// sum += GrabPixel(i, 0.01, -9.0);
// sum += GrabPixel(i, 0.02, -8.0);
// sum += GrabPixel(i, 0.03, -7.0);
// sum += GrabPixel(i, 0.04, -6.0);
// sum += GrabPixel(i, 0.05, -5.0);
// sum += GrabPixel(i, 0.06, -4.0);
// sum += GrabPixel(i, 0.07, -3.0);
// sum += GrabPixel(i, 0.08, -2.0);
// sum += GrabPixel(i, 0.09, -1.0);
// sum += GrabPixel(i, 0.10,  0.0);
// sum += GrabPixel(i, 0.09, +1.0);
// sum += GrabPixel(i, 0.08, +2.0);
// sum += GrabPixel(i, 0.07, +3.0);
// sum += GrabPixel(i, 0.06, +4.0);
// sum += GrabPixel(i, 0.05, +5.0);
// sum += GrabPixel(i, 0.04, +6.0);
// sum += GrabPixel(i, 0.03, +7.0);
// sum += GrabPixel(i, 0.02, +8.0);
// sum += GrabPixel(i, 0.01, +9.0);

float4 col5 = tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(i.uvgrab));
float decayFactor = 1.0f;
if (i.uvgrab.x == 0 && i.uvgrab.y == 0){
decayFactor = 0;
}
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 kernely){
if (i.uvgrab.x == 0 && i.uvgrab.y == 0){
kernely = 0;
}
return tex2Dproj( _GrabTexture, UNITY_PROJ_COORD(float4(i.uvgrab.x, i.uvgrab.y + _GrabTexture_TexelSize.y*kernely*_Size, i.uvgrab.z, i.uvgrab.w))) * weight;
}

half4 frag( v2f i ) : COLOR {
half4 sum = half4(0,0,0,0);
// #define GRABPIXEL(weight,kernely) tex2Dproj( _GrabTexture, UNITY_PROJ_COORD(float4(i.uvgrab.x, i.uvgrab.y + _GrabTexture_TexelSize.y * kernely*_Size, i.uvgrab.z, i.uvgrab.w))) * weight

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);

// sum += GrabPixel(i, 0.01, -9.0);
// sum += GrabPixel(i, 0.02, -8.0);
// sum += GrabPixel(i, 0.03, -7.0);
// sum += GrabPixel(i, 0.04, -6.0);
// sum += GrabPixel(i, 0.05, -5.0);
// sum += GrabPixel(i, 0.06, -4.0);
// sum += GrabPixel(i, 0.07, -3.0);
// sum += GrabPixel(i, 0.08, -2.0);
// sum += GrabPixel(i, 0.09, -1.0);
// sum += GrabPixel(i, 0.10,  0.0);
// sum += GrabPixel(i, 0.09, +1.0);
// sum += GrabPixel(i, 0.08, +2.0);
// sum += GrabPixel(i, 0.07, +3.0);
// sum += GrabPixel(i, 0.06, +4.0);
// sum += GrabPixel(i, 0.05, +5.0);
// sum += GrabPixel(i, 0.04, +6.0);
// sum += GrabPixel(i, 0.03, +7.0);
// sum += GrabPixel(i, 0.02, +8.0);
// sum += GrabPixel(i, 0.01, +9.0);

float4 col5 = tex2Dproj(_GrabTexture, UNITY_PROJ_COORD(i.uvgrab));
float decayFactor = 1.0f;
if (i.uvgrab.x == 0 && i.uvgrab.y == 0){
decayFactor = 0;
}
sum = lerp(col5, sum, decayFactor) * i.color * _Color;

return sum;
}
ENDCG
}
}
}
}

计算是一样的，不过这个相对来说要慢，毕竟是将整个屏幕那来计算的，肯定会慢很多。用法也一样，shader放到一个新建的材质球上，然后将材质球拖到一个Image组件的Material属性栏中即可，这里你可以调整Image的宽高，这样可以指定模糊那一块区域了。

看效果：



然后我移动和调整宽高之后：



当然也可以调成整屏模糊：