Unity Shader 屏幕后效果——高斯模糊

 1 using UnityEngine;
 2 
 3 public class GaussianBlurCtrl : ScreenEffectBase
 4 {
 5     private const string _BlurSize = "_BlurSize";//只有模糊范围需要在GPU中计算
 6 
 7     [Range(0, 4)]
 8     public int iterations = 3;//迭代次数
 9     [Range(0.2f, 3)]
10     public float blurSize = 0.6f;//模糊范围
11     [Range(1, 8)]
12     public int downSample = 2;//降采样系数
13 
14     private void OnRenderImage(RenderTexture source, RenderTexture destination)
15     {
16         if (Material != null)
17         {
18             //得到屏幕的渲染纹理后直接除以降采样系数以成倍减少计算量，但过大时模糊效果不佳
19             int rtw = source.width/downSample;
20             int rth = source.height/downSample;
21 
22             RenderTexture buffer0 = RenderTexture.GetTemporary(rtw, rth, 0);
23             buffer0.filterMode = FilterMode.Bilinear;
24 
25             Graphics.Blit(source, buffer0);
26 
27             //利用迭代次数对模糊范围加以控制，用到了类似于双缓冲的方式对纹理进行处理
28             for (int i = 0; i < iterations; i++)
29             {
30                 //设置采样范围，根据迭代次数范围增加，之后会与纹理坐标进行乘积操作，固基础值为1
31                 Material.SetFloat(_BlurSize, blurSize*i+1);
32 
33                 RenderTexture buffer1 = RenderTexture.GetTemporary(rtw, rth, 0);
34                 Graphics.Blit(buffer0, buffer1, Material, 0);
35                 //每次处理完立即释放相应缓存，因为Unity内部已经对此做了相应的优化
36                 RenderTexture.ReleaseTemporary(buffer0);
37                 buffer0 = RenderTexture.GetTemporary(rtw, rth, 0);
38                 Graphics.Blit(buffer1, buffer0,Material, 1);
39                 RenderTexture.ReleaseTemporary(buffer1);
40             }
41             Graphics.Blit(buffer0, destination);
42             RenderTexture.ReleaseTemporary(buffer0);
43         }
44         else
45             Graphics.Blit(source, destination);
46     }
47 }

  1 Shader "MyUnlit/GaussianBlur"
  2 {
  3     Properties
  4     {
  5         _MainTex ("Texture", 2D) = "white" {}
  6     }
  7     SubShader
  8     {
  9         Tags { "RenderType"="Opaque" }
 10 
 11         //CGINCLUDE中的代码可被其他Pass重复调用，用于简化不必要的重复代码
 12         CGINCLUDE
 13 
 14         #pragma multi_compile_fog
 15         #include "UnityCG.cginc"
 16 
 17         struct appdata
 18         {
 19             float4 vertex : POSITION;
 20             float2 uv : TEXCOORD0;
 21         };
 22 
 23         struct v2f
 24         {
 25             half2 uv[5] : TEXCOORD0;
 26             UNITY_FOG_COORDS(1)
 27             float4 pos : SV_POSITION;
 28         };
 29 
 30         sampler2D _MainTex;
 31         float4 _MainTex_TexelSize;
 32         float _BlurSize;
 33 
 34         //用于计算纵向模糊的纹理坐标元素
 35         v2f vert_v(appdata v)
 36         {
 37             v2f o;
 38             o.pos = UnityObjectToClipPos(v.vertex);
 39             half2 uv = v.uv;
 40 
 41             //以扩散的方式对数组进行排序，只偏移y轴，其中1和2,3和4分别位于原始点0的上下，且距离1个单位和2个像素单位
 42             //得到的最终偏移与模糊范围的控制参数进行乘积
 43             o.uv[0] = uv;
 44             o.uv[1] = uv + float2(0.0, _MainTex_TexelSize.y*1.0)*_BlurSize;
 45             o.uv[2] = uv - float2(0.0, _MainTex_TexelSize.y*1.0)*_BlurSize;
 46             o.uv[3] = uv + float2(0.0, _MainTex_TexelSize.y*2.0)*_BlurSize;
 47             o.uv[4] = uv - float2(0.0, _MainTex_TexelSize.y*2.0)*_BlurSize;
 48 
 49             UNITY_TRANSFER_FOG(o, o.vertex);
 50             return o;
 51         }        
 52         
 53         //用于计算横向模糊的纹理坐标元素
 54         v2f vert_h(appdata v)
 55         {
 56             v2f o;
 57             o.pos = UnityObjectToClipPos(v.vertex);
 58             half2 uv = v.uv;
 59 
 60             //与上面同理，只不过是x轴向的模糊偏移
 61             o.uv[0] = uv;
 62             o.uv[1] = uv + float2( _MainTex_TexelSize.x*1.0,0.0)*_BlurSize;
 63             o.uv[2] = uv - float2( _MainTex_TexelSize.x*1.0,0.0)*_BlurSize;
 64             o.uv[3] = uv + float2( _MainTex_TexelSize.x*2.0,0.0)*_BlurSize;
 65             o.uv[4] = uv - float2( _MainTex_TexelSize.x*2.0,0.0)*_BlurSize;
 66 
 67             UNITY_TRANSFER_FOG(o, o.vertex);
 68             return o;
 69         }
 70 
 71         //在片元着色器中进行最终的模糊计算，此过程在每个Pass中都会进行一次计算，但计算方式是统一的
 72         fixed4 frag(v2f i) : SV_Target
 73         {
 74             float weights[3] = {0.4026,0.2442,0.0545};
 75 
 76             fixed4 col = tex2D(_MainTex, i.uv[0]);
 77 
 78             fixed3 sum = col.rgb*weights[0];
 79 
 80             //对采样结果进行对应纹理偏移坐标的权重计算，以得到模糊的效果
 81             for (int it = 1; it < 3; it++) 
 82             {
 83                 sum += tex2D(_MainTex, i.uv[2 * it - 1]).rgb*weights[it];//对应1和3，也就是原始像素的上方两像素
 84                 sum += tex2D(_MainTex, i.uv[2 * it]).rgb*weights[it];//对应2和4，下方两像素
 85             }
 86             fixed4 color = fixed4(sum, 1.0);
 87             UNITY_APPLY_FOG(i.fogCoord, color);
 88             return color;
 89         }
 90 
 91         ENDCG
 92 
 93         ZTest Always
 94         Cull Off
 95         ZWrite Off
 96 
 97         //纵向模糊Pass，直接用指令调用上面的函数
 98         Pass
 99         {
100             NAME "GAUSSIANBLUR_V"
101             CGPROGRAM
102             #pragma vertex vert_v
103             #pragma fragment frag
104 
105             ENDCG
106         }
107 
108         //横向模糊Pass
109         Pass
110         {
111             NAME "GAUSSIANBLUR_H"
112             CGPROGRAM
113             #pragma vertex vert_h
114             #pragma fragment frag
115 
116             ENDCG
117         }
118     }
119     Fallback Off
120 }