Unity3D UGUI特效之Image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：

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。