unity urp 17 Bloom效果

ainatipen · 发表于 2022-7-14 12:29

一、思路

Bloom的效果就是再模糊效果的基础上完成的。整体的思路就是设置一个阈值，提取图中高亮区域，对其进行模糊处理，然后再将处理后的图像与原图混合。
具体的过程是：创建一个Shader文件和一个Render Feature文件，Shader文件中有三个Pass（两个一个维高斯模糊的情况下有四个pass）
第一个pass中使用luminance函数获取纹理的亮度，然后根据设置的阈值来获取高亮区域。
第二个pass中则对纹理图像进行高斯模糊计算。
第三个pass讲原始纹理图像与高斯模糊后得到的纹理图像进行混合。
在SimpleBloom.cs文件中，依次使用shader中的三个pass来处理图像。其中高斯模糊计算后的图像可以使用CommandBuffer.SetGlobalTexture()来将buffer中的纹理存储在rendertexture中。
cmd.SetGlobalTexture(&#34;_Bloom&#34;, buffer2);另外，在shader入门精要中提到，在开启抗锯齿并且有多个rendertexture的情况下，要根据平台差异来改变纹理的y轴方向
            output.uv = input.texcoord;
            output.uv2 = input.texcoord;
            #if UNITY_UV_STARTS_AT_TOP
            if(_MainTex_TexelSize.y<0.0)
                  output.uv2.y = 1.0 - output.uv2.y;
            #endif二、代码

Bloom.shader
Shader &#34;Unlit/20_Bloom&#34;
{
Properties
{
      [HideInInspector]_MainTex (&#34;Texture&#34;, 2D) = &#34;white&#34; {}
      _BlurSize(&#34;Blur Size&#34;, Float) = 1.0
      _Threshold(&#34;Threshold&#34;, Float) = 1.0
      _Bloom(&#34;Bloom&#34;,2D) = &#34;Black&#34; {}
      _Intensity(&#34;Intensity&#34;, Float) = 1.0
}
SubShader
{
      Tags
      {
         &#34;RenderPipeline&#34;=&#34;UniversalRenderPipeline&#34;
      }
      Cull Off
      ZWrite Off
      ZTest Always

      HLSLINCLUDE
      #include &#34;Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl&#34;
      CBUFFER_START(UnityPerMaterial)
      float _BlurSize;
      float4 _MainTex_TexelSize;
      float _Threshold;
      float _Intensity;
      CBUFFER_END
      TEXTURE2D(_MainTex);
      SAMPLER(sampler_MainTex);
      TEXTURE2D(_Bloom);
      SAMPLER(sampler_Bloom);
      struct Attributes
      {
         float4 positionOS: POSITION;
         float2 texcoord: TEXCOORD0;
      };
      struct Varyings
      {
         float4 positionCS:SV_POSITION;
         float2 uv:TEXCOORD0;
         float2 uv2: TEXCOORD1;
      };
      ENDHLSL

      //获取较亮部分
      Pass
      {
         HLSLPROGRAM
         #pragma vertex vert
         #pragma fragment frag

         float luminance(float4 color)
         {
            return 0.2125*color.r+0.7154*color.g+0.0721*color.b;
         }

         Varyings vert(Attributes input)
         {
            Varyings output;
            output.positionCS = TransformObjectToHClip(input.positionOS);
            output.uv = input.texcoord;
            return output;
         }

         float4 frag (Varyings input) : SV_Target
         {
            half4 tex = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, input.uv);
            float bloom = clamp(luminance(tex) - _Threshold, 0.0, 1.0);

            return tex*bloom;
         }
         ENDHLSL
      }

      //进行高斯模糊
      Pass
      {
         HLSLPROGRAM
         #pragma vertex vert
         #pragma fragment frag

         Varyings vert(Attributes input)
         {
            Varyings output;
            output.positionCS = TransformObjectToHClip(input.positionOS);
            output.uv = input.texcoord;
            return output;
         }

         float4 frag (Varyings input) : SV_Target
         {
            half4 tex = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, input.uv);
            float2 uv = input.uv;
            half4 col = float4(0,0,0,0);
            col += 0.060 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(-1,-1)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.098 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(0,-1)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.060 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(1,-1)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.098 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(-1,0)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.162 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv);
            col += 0.098 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(1,0)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.060 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(1,-1)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.022 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(1,0)*_MainTex_TexelSize.xy*_BlurSize);
            col += 0.060 * SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, uv + float2(1,1)*_MainTex_TexelSize.xy*_BlurSize);

            return col;
         }
         ENDHLSL
      }

      //混合原图像，高亮区域高斯模糊的后的结果
      Pass
      {
         HLSLPROGRAM
         #pragma vertex vert
         #pragma fragment frag

         Varyings vert(Attributes input)
         {
            Varyings output;
            output.positionCS = TransformObjectToHClip(input.positionOS);
            output.uv = input.texcoord;
            output.uv2 = input.texcoord;
            #if UNITY_UV_STARTS_AT_TOP
            if(_MainTex_TexelSize.y<0.0)
                  output.uv2.y = 1.0 - output.uv2.y;
            #endif
            return output;
         }

         float4 frag (Varyings input) : SV_Target
         {
            half4 tex = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, input.uv);
            half4 bloom = SAMPLE_TEXTURE2D(_Bloom, sampler_Bloom, input.uv2);

            return tex+bloom*_Intensity;
         }
         ENDHLSL
      }
}
}
SimpleBloom.cs
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;

public class SimpleBloom : ScriptableRendererFeature
{
//定义配置类
[System.Serializable]
public class Setting
{
      //默认在透明物体绘制完成后进行处理
      public RenderPassEvent passEvent = RenderPassEvent.AfterRenderingTransparents;
      //后续需要用到的材质
      public Material mat;
      [Range(0, 4)] public int iterations = 3;
      [Range(0.2f, 3.0f)] public float blurSpread = 0.6f;
      [Range(1, 8)] public int downSample = 2;
}

public Setting setting = new Setting();

//*************************************************
//**********    自定义Pass类 **************
//**************************************************
class CustomRenderPass : ScriptableRenderPass
{
      //后处理用到的材质
      public Material passMat = null;
      private RenderTargetIdentifier passSource { get; set; }//源图像，目标图像
      private RenderTargetIdentifier buffer1;
      private RenderTargetIdentifier buffer2;
      private RenderTargetHandle passTempleColorTex;//临时计算的图像
      //标签名，用于在帧调试器中显示缓冲区的名称
      private string passTag;
      public int iterations;
      public float blurSpread;
      public int downSample;
      public FilterMode passFilterMode { get; set; }

      //构造函数
      public CustomRenderPass(RenderPassEvent passEvent, Material material, string tag)
      {
         this.renderPassEvent = passEvent;
         this.passMat = material;
         passTag = tag;
      }

      //设置Pass
      public void SetUp(RenderTargetIdentifier source)
      {
         this.passSource = source;
      }

      public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
      {
         int bufferid1 = Shader.PropertyToID(&#34;bufferblur1&#34;);
         int bufferid2 = Shader.PropertyToID(&#34;bufferblur2&#34;);
         //从命令缓冲区池获取一个带标签的命令缓冲区，该标签名在帧调试器中可以见到
         CommandBuffer cmd = CommandBufferPool.Get(passTag);
         //获取目标相机的描述信息，创建一个结构体，里面有render texture各中信息，比如尺寸，深度图精度等等
         RenderTextureDescriptor opaqueDesc = renderingData.cameraData.cameraTargetDescriptor;
         int width = opaqueDesc.width / downSample;
         int height = opaqueDesc.height / downSample;
         //设置深度缓冲区，0表示不需要深度缓冲区
         opaqueDesc.depthBufferBits = 0;
         //申请临时图像
         cmd.GetTemporaryRT(bufferid1, width, height, 0, FilterMode.Bilinear, RenderTextureFormat.ARGB32);
         cmd.GetTemporaryRT(bufferid2, width, height, 0, FilterMode.Bilinear, RenderTextureFormat.ARGB32);
         buffer1 = new RenderTargetIdentifier(bufferid1);
         buffer2 = new RenderTargetIdentifier(bufferid2);
         //获取index为0个pass，进行处理
         //获取高亮区域
         cmd.Blit(passSource, buffer1,passMat,0);
         for (int i = 0; i < iterations; i++)
         {
            cmd.SetGlobalFloat(&#34;BlurSize&#34;, 1.0f+i*blurSpread);
            //进行高斯模糊
            cmd.Blit(buffer1, buffer2, passMat,1);
            var tmpRT = buffer1;
            buffer1 = buffer2;
            buffer2 = tmpRT;
         }

         //生成名为Bloom的Render Texture
         //passMat.SetTexture(&#34;_Bloom&#34;, bufferid1);
         cmd.SetGlobalTexture(&#34;_Bloom&#34;, buffer2);
         //执行pass：混合高亮区域和原图像
         cmd.Blit(passSource,buffer1, passMat ,2);
         cmd.Blit(buffer1, passSource);
         //执行命令缓冲区
         context.ExecuteCommandBuffer(cmd);
         //释放命令缓存
         CommandBufferPool.Release(cmd);
         cmd.ReleaseTemporaryRT(bufferid1);
         cmd.ReleaseTemporaryRT(bufferid2);
      }
}

private CustomRenderPass pass;
//*************************************************
//**********       初始化    **************
//**************************************************
public override void Create()
{
      pass = new CustomRenderPass(setting.passEvent, setting.mat, name);
      pass.blurSpread = setting.blurSpread;
      pass.downSample = setting.downSample;
      pass.iterations = setting.iterations;
}

//*************************************************
//**********    将pass添加到渲染管线 **************
//**************************************************
public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
{
      //获取当前相机中的图像
      var src = renderer.cameraColorTarget;
      pass.SetUp(src);
      //将该pass添加到渲染管线中
      renderer.EnqueuePass(pass);
}
}
三、结果

法线图像有些模糊，并且bloom效果不太理想。

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unity urp 17 Bloom效果

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