URP 毛玻璃（升级至URP_v14.0.6）

weigogo

注：这篇笔记的目的不在于如何制作玻璃特效（毛玻璃作为实践的素材），目的在于升级任何使用了【cmd.Blit】这个api的URP特效，以撑持Single-Pass Instanced VR
本篇包含内容：
unity版本2021.3.8，URP版本v12.1.7：暂未能撑持Single-Pass Instanced VR；
unity版本2022.2.7，URP版本v14.0.6：可撑持Single-Pass Instanced VR；
(URP在不竭升级，技术更迭…这篇笔记里的东西过不了多久可能也会变成过时的东西，但愿能帮到此刻的你 )
0.一个BRP示例（含毛玻璃shader）

先看一个过时的BRP示例，来自： https://blog.unity.com/technology/extending-unity-5-rendering-pipeline-command-buffers
流程概括：


一个用于做Blur计算的shader(”Hidden/SeparableGlassBlur”)；(下面的shader语法已改为URP)

1. Shader ”Hidden/SeparableGlassBlur” {
2.     Properties {
3.         _MainTex (”Base (RGB)”, 2D) = ”” {}
4.     }
5.     ......//注：我喜欢把代码分块排版，这样看起来斗劲舒服，代码里呈现的【......】意思是这部门内容在长虚线下面
6. }
7. ------------------------------------------------------------------------------------------
8. Subshader {
9.     Tags { ”RenderPipeline”=”UniversalPipeline” }
10.     Pass {
11.         Name ”01”
12.         Tags { ”LightMode”=”UniversalForward” }
13.         ZTest Always
14.         Cull Off
15.         ZWrite Off
16.         Fog { Mode off }
17.         
18.         HLSLPROGRAM
19.         #include ”Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl”
20.         #pragma fragmentoption ARB_precision_hint_fastest
21.         #pragma vertex vert
22.         #pragma fragment frag
23.         ......
24.         ENDHLSL
25.     }
26. }
27. ------------------------------------------------------------------------------------------
28. struct appdata_img {
29.     float4 vertex : POSITION;
30.     half2 uv : TEXCOORD0;
31.     UNITY_VERTEX_INPUT_INSTANCE_ID
32. };
33. struct v2f {
34.     float4 pos : POSITION;
35.     float2 uv : TEXCOORD0;
36.     float4 uv01 : TEXCOORD1;
37.     float4 uv23 : TEXCOORD2;
38.     float4 uv45 : TEXCOORD3;
39. };
40. float4 offsets;
41. sampler2D _MainTex;
42. v2f vert (appdata_img v) {
43.     v2f o;
44.     o.pos = TransformObjectToHClip(v.vertex);
45.     o.uv.xy = v.uv.xy;
46.     o.uv01 =  v.uv.xyxy + offsets.xyxy * float4(1,1, -1,-1);
47.     o.uv23 =  v.uv.xyxy + offsets.xyxy * float4(1,1, -1,-1) * 2.0;
48.     o.uv45 =  v.uv.xyxy + offsets.xyxy * float4(1,1, -1,-1) * 3.0;
49.     return o;
50. }
51. half4 frag (v2f i) : COLOR {
52.     half4 color = float4 (0,0,0,0);
53.     color += 0.40 * tex2D (_MainTex, i.uv);
54.     color += 0.15 * tex2D (_MainTex, i.uv01.xy);
55.     color += 0.15 * tex2D (_MainTex, i.uv01.zw);
56.     color += 0.10 * tex2D (_MainTex, i.uv23.xy);
57.     color += 0.10 * tex2D (_MainTex, i.uv23.zw);
58.     color += 0.05 * tex2D (_MainTex, i.uv45.xy);
59.     color += 0.05 * tex2D (_MainTex, i.uv45.zw);
60.    
61.     return color;
62. }

复制代码

一个用于衬着玻璃的shader(GlassWithoutGrab.shader)；(下面的shader语法已改为URP)

1. Shader ”FX/Glass/Stained BumpDistort (no grab)” {
2.     Properties {
3.         _BumpAmt  (”Distortion”, range (0,64)) = 10
4.         _TintAmt (”Tint Amount”, Range(0,1)) = 0.1
5.         _MainTex (”Tint Color (RGB)”, 2D) = ”white” {}
6.         _BumpMap (”Normalmap”, 2D) = ”bump” {}
7.     }
8.     ......
9. }
10. ------------------------------------------------------------------------------------------
11. SubShader{
12.     // We must be transparent, so other objects are drawn before this one.
13.     Tags { ”RenderPipeline”=”UniversalPipeline” ”Queue”=”Transparent” ”RenderType”=”Opaque” }
14.     Pass {
15.         Name ”BASE”
16.         Tags { ”LightMode”=”UniversalForward” }
17.             
18.         HLSLPROGRAM
19.         #pragma vertex vert
20.         #pragma fragment frag
21.         #pragma multi_compile_fog
22.         #include ”Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl”
23.         ......
24.         ENDHLSL
25.     }
26. }
27. ------------------------------------------------------------------------------------------
28. struct appdata_t {
29.     float4 vertex : POSITION;
30.     float2 uv: TEXCOORD0;
31. };
32. struct v2f {
33.     float4 vertex : POSITION;
34.     float4 uvgrab : TEXCOORD0;
35.     float2 uvbump : TEXCOORD1;
36.     float2 uvmain : TEXCOORD2;
37.     // UNITY_FOG_COORDS(3)
38.     float fogFactor : TEXCOORD3;
39. };
40. float _BumpAmt;
41. half _TintAmt;
42. float4 _BumpMap_ST;
43. float4 _MainTex_ST;
44. v2f vert (appdata_t v)
45. {
46.     v2f o;
47.     o.vertex = TransformObjectToHClip(v.vertex);
48.     #if UNITY_UV_STARTS_AT_TOP
49.     float scale = -1.0;
50.     #else
51.     float scale = 1.0;
52.     #endif
53.     o.uvgrab.xy = (float2(o.vertex.x, o.vertex.y*scale) + o.vertex.w) * 0.5;
54.     o.uvgrab.zw = o.vertex.zw;
55.     o.uvbump = TRANSFORM_TEX( v.uv, _BumpMap );
56.     o.uvmain = TRANSFORM_TEX( v.uv, _MainTex );
57.     o.fogFactor = ComputeFogFactor(o.vertex.z);
58.     return o;
59. }
60. sampler2D _GrabBlurTexture;
61. float4 _GrabBlurTexture_TexelSize;
62. sampler2D _BumpMap;
63. sampler2D _MainTex;
64. half4 frag (v2f i) : SV_Target
65. {
66.     // calculate perturbed coordinates
67.     // we could optimize this by just reading the x & y without reconstructing the Z
68.     half2 bump = UnpackNormal(tex2D( _BumpMap, i.uvbump )).rg;
69.     float2 offset = bump * _BumpAmt * _GrabBlurTexture_TexelSize.xy;
70.     i.uvgrab.xy = offset * i.uvgrab.z + i.uvgrab.xy;
71.    
72.     half4 col = tex2Dproj (_GrabBlurTexture, i.uvgrab/i.uvgrab.w);
73.     half4 tint = tex2D(_MainTex, i.uvmain);
74.     col = lerp (col, tint, _TintAmt);
75.     col.rgb = MixFog(col.rgb, i.fogFactor);
76.     return col;
77. }

复制代码

一个担任自Monobehaviour的脚本(CommandBufferBlurRefraction.cs)，没有用到RendererFeature；
把 scene color 传输给 RT_screenCopyID；

1. CommandBufferBlurRefraction.cs脚本：
2. OnWillRenderObject()：
3. // copy screen into temporary RT
4. int screenCopyID = Shader.PropertyToID(”_ScreenCopyTexture”);
5. cmd.GetTemporaryRT (screenCopyID, -1, -1, 0, FilterMode.Bilinear);
6. cmd.Blit (BuiltinRenderTextureType.CurrentActive, screenCopyID);
7. // 但我实在不能理解，即使我把上面的cmd.Blit替换为下面这句，毛玻璃效果也正常显示？？？
8. // 但如果注释掉cmd.Blit，毛玻璃效果就会消掉，合着意思是只要有cmd.Blit，不管他source给了啥，都传 scene color 给 destination？？？
9. cmd.Blit (Shader.PropertyToID(”_ttttttt”), screenCopyID);

复制代码

新建2张RT，长宽是全屏的一半，记为 RT_blurredID 和 RT_blurredID2；把 RT_screenCopyID 传输给 RT_blurredID；

1. // get two smaller RTs
2. int blurredID = Shader.PropertyToID(”_Temp1”);
3. int blurredID2 = Shader.PropertyToID(”_Temp2”);
4. cmd.GetTemporaryRT (blurredID, -2, -2, 0, FilterMode.Bilinear);
5. cmd.GetTemporaryRT (blurredID2, -2, -2, 0, FilterMode.Bilinear);
7. // downsample screen copy into smaller RT, release screen RT
8. cmd.Blit (screenCopyID, blurredID);

复制代码

• 开始倒腾：
  
  
  
  • 把 RT_blurredID 经SeparableGlassBlur.shader计算(偏移”2”在x标的目的加权平均)后传输给 RT_blurredID2；
    
  • 把 RT_blurredID2 经SeparableGlassBlur.shader计算(偏移”2”在y标的目的加权平均)后传输给 RT_blurredID；
    
  • 把 RT_blurredID 经SeparableGlassBlur.shader计算(偏移”4”在x标的目的加权平均)后传输给 RT_blurredID2；
    
  • 把 RT_blurredID2 经SeparableGlassBlur.shader计算(偏移”4”在y标的目的加权平均)后传输给 RT_blurredID；
    
  
  

把 RT_blurredID 传输给 ”_GrabBlurTexture”，传给用于衬着玻璃的shader(GlassWithoutGrab.shader)使用；

1. cmd.SetGlobalTexture(”_GrabBlurTexture”, blurredID);

复制代码

1. 改用RendererFeature实现

把OnWillRenderObject这个函数里的CommandBuffer改用RendererFeature实现
下面，我们试着把它的脚本(CommandBufferBlurRefraction.cs)改为RendererFeature
参考： https://zhuanlan.zhihu.com/p/248903320
大体照搬上面链接里的脚本，就是记得把 RT_blurredID 传给 ”_GrabBlurTexture”


unity版本2021.3.8，URP版本v12.1.7
代码在[f01_v12_1_7]这个文件夹里：FrostedGlassRenderFeature.cs

1. public class FrostedGlassRenderFeature : ScriptableRendererFeature{
2.     //在RendererFeature类里写一个class Settings，并实例化它
3.     [System.Serializable]
4.     public class Settings{
5.         public RenderPassEvent renderEvent = RenderPassEvent.AfterRenderingSkybox;
6.         public Material blurMat;
7.     }
8.     public Settings settings = new Settings();
9.     //----------------------------------------------------------------
10.     public class FrostedGlassRenderPass : ScriptableRenderPass{......}
11.     FrostedGlassRenderPass m_ScriptablePass;
12.     //----------------------------------------------------------------
13.     //在ScriptableRendererFeature的Create方式里实例化ScriptableRenderPass类
14.     public override void Create(){
15.         m_ScriptablePass = new FrostedGlassRenderPass(settings);
16.     }
17.     //----------------------------------------------------------------
18.     //在AddRenderPasses方式里设置ScriptableRenderPass的source
19.     public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData){
20.         var src = renderer.cameraColorTarget;
21.         m_ScriptablePass.Setup(src);
22.         //----------------------
23.         renderer.EnqueuePass(m_ScriptablePass);
24.     }
25. }
26. ------------------------------------------------------------------------------------------
27. ......的部门：
29. public class FrostedGlassRenderPass : ScriptableRenderPass{
30.     CommandBuffer cmd;
31.     string m_ProfilerTag;//cmd name
32.     Material m_blurMat;
33.     RenderTargetHandle blurredID01;
34.     RenderTargetHandle blurredID02;
36.     RenderTargetIdentifier source;
37.     RenderTargetHandle m_tempColorTex;
39.     //首先写这个ScriptableRenderPass的构造函数
40.     public FrostedGlassRenderPass(FrostedGlassRenderFeature.Settings param){
41.         m_ProfilerTag = ”FrostedGalss”;
42.         this.renderPassEvent = param.renderEvent;
43.         m_blurMat = param.blurMat;
44.         blurredID01.Init(”_Blur01”);
45.         blurredID02.Init(”_Blur02”);
46.     }
47.     //----------------------------------------------------------------
48.     public void Setup(RenderTargetIdentifier src){
49.         this.source = src;//传入renderer.cameraColorTarget
50.     }
51.     //----------------------------------------------------------------
52.     //在Execute方式里执行CommandBuffer
53.     public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData){
54.         if ((renderingData.cameraData.camera.cullingMask & 1<<LayerMask.NameToLayer(”UI”))>0) {
55.             //Debug.Log(”camera的cullingMask包含UI层，返回”);//并设置Camera>CullingMask不包罗UI层
56.             return;
57.         }
59.         CommandBuffer cmd = CommandBufferPool.Get(m_ProfilerTag);
60.         Vector2[] sizes = {
61.             new Vector2(Screen.width, Screen.height),
62.             new Vector2(Screen.width / 2, Screen.height / 2),
63.             new Vector2(Screen.width / 4, Screen.height / 4),
64.             new Vector2(Screen.width / 8, Screen.height / 8),
65.         };
66.         int numIterations = 3;
67.         RenderTextureDescriptor opaqueDesc = renderingData.cameraData.cameraTargetDescriptor;
68.         opaqueDesc.depthBufferBits = 0;
69.         // The precision of the render texture&#39;s depth buffer in bits (0, 16, 24 and 32 are supported).// 为什么加这句？
70.         cmd.GetTemporaryRT(m_tempColorTex.id, opaqueDesc, FilterMode.Bilinear);
71.         cmd.Blit(source, m_tempColorTex.Identifier());
72.         for (int i = 0; i < numIterations; ++i){
73.             cmd.GetTemporaryRT(blurredID01.id, opaqueDesc, FilterMode.Bilinear);
74.             cmd.GetTemporaryRT(blurredID02.id, opaqueDesc, FilterMode.Bilinear);
75.             cmd.Blit(m_tempColorTex.Identifier(), blurredID01.Identifier());
76.             cmd.SetGlobalVector(”offsets”, new Vector4(2.0f / sizes[i].x, 0, 0, 0));
77.             cmd.Blit(blurredID01.Identifier(), blurredID02.Identifier(), m_blurMat);
78.             cmd.SetGlobalVector(”offsets”, new Vector4(0, 2.0f / sizes[i].y, 0, 0));
79.             cmd.Blit(blurredID02.Identifier(), blurredID01.Identifier(), m_blurMat);
80.             cmd.Blit(blurredID01.Identifier(), m_tempColorTex.Identifier());
81.         }
82.         //把最终的内容传给 ”_GrabBlurTexture”
83.         cmd.SetGlobalTexture(”_GrabBlurTexture”, blurredID01.Identifier());
84.         //-----------
85.         context.ExecuteCommandBuffer(cmd);
86.         CommandBufferPool.Release(cmd);
87.     }
88.     //----------------------------------------------------------------
89.     // 释放临时资源
90.     public override void FrameCleanup(CommandBuffer cmd){
91.         cmd.ReleaseTemporaryRT(m_tempColorTex.id);
92.         cmd.ReleaseTemporaryRT(blurredID01.id);
93.         cmd.ReleaseTemporaryRT(blurredID02.id);
94.     }
95. }

复制代码

附：一个可以开关RendererFeature的脚本，来自<link>
错误谬误：
①是用cmd.Blit实现的传输，不撑持Single-Pass Instanced VR 且URP不建议使用这个过时的API；
②没有使用RTHandle，v13.1.9之后的URP版本需要使用 RTHandle 替代 RenderTargetIdentifier、RenderTargetHandle；
③玻璃后的半透明物体不成见；
④玻璃前的opaque物体也会被衬着到玻璃上，但是不太明显(大部门被玻璃前的opaque物体自身盖住了，只是边缘有点颜色溢出）
下面升级unity版本，可以撑持Single-Pass Instanced VR；

那如果不想升级版本的话，怎么撑持Single-Pass Instanced VR？
呃……我试了一个下午……好吧我不会……
URP v13.1.9之后才有【RenderingUtils.ReAllocateIfNeeded()】方式——用不了RTHandle的话，就用RenderTargetIdentifier；用不了Blitter封装好的方式，那就搬它的源码；可单是源码的话还不够啊，不知道差了什么设置才能撑持Single-Pass Instanced VR；而且不知道为什么在URP版本v12.1.7里，每用1次Blitter源码，画面就会变亮一个等级，为什么会变亮啊……

2. 迁移至URP v14.0.6

迁移至unity版本2022.2.7，URP版本v14.0.6
报错：You can only call cameraColorTarget inside the scope of a ScriptableRenderPass. Otherwise the pipeline camera target texture might have not been created or might have already been disposed.
解决方式1：参考<github/UniversalRenderingExamples/RenderPasses>在 RenderPass 的 OnCameraSetup(CommandBuffer cmd, ref RenderingData renderingData)方式里获取cameraColorTarget
解决方式2：参考<Perform a full screen blit in URP(V14.0.6)>或者参考< Upgrading to version 2022.1 of URP > 在 RenderFeature 里重写SetupRenderPasses()方式，在SetupRenderPasses()方式里你可以访谒renderer.cameraColorTargetHandle
3.升级至 RTHandle & Blitter

为什么要升级？——URP官网说了：cmd.Blit是已过时的API，且不撑持 Single-Pass Instanced VR；在URP项目中，请避免使用CommandBuffer.Blit及其它依赖于它的API(比如RenderingUtils.Blit)；详见：URP Blit 入门（这篇笔记还没发）
◆ 用 Blitter 替换cmd.Blit，是否就可以撑持 Single-Pass Instanced VR？是的！shader也要记得升级，见下一章节
◆ 用 RTHandle 替代 RenderTargetHandle(这个obsolete了必定要被替换的)、RenderTargetIdentifier(这个还是可以用的那要替换吗)——在试图用 Blitter 替换 cmd.Blit 的过程中，我找到的解决方式是“不要用RenderTargetIdentifier，全用RTHandle”
◆ 参与了Blit过程的材质球(shader)也需要改削：增加[_BlitTexture]变量用于绑定Blitter函数的 input texture；
详细的踩坑记录见：URP Blit 入门 -03 Class Blitter（这篇笔记还没发）
代码在[f02_v14_0_6]这个文件夹里：FrostedGlassRenderFeature.cs
（下面这个就是本篇笔记的真心实意了 真是踩了好多坑啊）

1. public class FrostedGlassRenderFeature : ScriptableRendererFeature{
2.     //在ScriptableRendererFeature类里写一个class Settings，并实例化它
3.     [System.Serializable]
4.     public class Settings{
5.         public RenderPassEvent renderEvent = RenderPassEvent.BeforeRenderingTransparents;
6.         public Material blurMat;
7.     }
8.     public Settings settings = new Settings();
9.     //----------------------------------------------------------------
10.     public class FrostedGlassRenderPass : ScriptableRenderPass{......}
11.     //----------------------------------------------------------------
12.     FrostedGlassRenderPass m_ScriptablePass;
13.     public override void Create(){  //在Create方式里实例化ScriptableRenderPass类
14.         m_ScriptablePass = new FrostedGlassRenderPass(settings);//实例化包含了renderPassEvent的设置
15.     }
16.     public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData){
17.         //m_ScriptablePass.Setup(renderer.cameraColorTargetHandle);
18.         //上面这行放在AddRenderPasses()方式里会报错：
19.         //可以放到RenderPass的OnCameraSetup()里；也可以放到RendererFeature的SetupRenderPasses()里；
20.         m_ScriptablePass.ConfigureInput(ScriptableRenderPassInput.Color);
21.         if (renderingData.cameraData.cameraType == CameraType.Game){
22.             renderer.EnqueuePass(m_ScriptablePass);
23.         }
24.     }
25. }
26. ------------------------------------------------------------------------------------------
27. ......
29. public class FrostedGlassRenderPass : ScriptableRenderPass{
30.     CommandBuffer cmd;
31.     string m_ProfilerTag;//cmd name
32.     Material m_blurMat;
33.     RTHandle source;
34.     RTHandle rth_tempTex;
35.     RTHandle rth_Blur01;
36.     RTHandle rth_Blur02;
37.     //首先写这个ScriptableRenderPass的构造函数
38.     public FrostedGlassRenderPass(FrostedGlassRenderFeature.Settings param){
39.         m_ProfilerTag = ”FrostedGalss”;
40.         this.renderPassEvent = param.renderEvent;
41.         m_blurMat = param.blurMat;
42.     }
43.     //----------------------------------------------------------------
44.     // This method is called before executing the render pass.
45.     // It can be used to configure render targets and their clear state. Also to create temporary render target textures.
46.     // When empty this render pass will render to the active camera render target.
47.     public override void OnCameraSetup(CommandBuffer cmd, ref RenderingData renderingData) {
48.         var renderer = renderingData.cameraData.renderer;
49.         this.source = renderer.cameraColorTargetHandle;
50.         RenderTextureDescriptor opaqueDesc = renderingData.cameraData.cameraTargetDescriptor;
51.         opaqueDesc.depthBufferBits = 0; //为什么加这句？// Color and depth cannot be combined in RTHandles
52.         /*下面这个错误的……就当是记录下黑历史……
53.         // int id_tempTex = Shader.PropertyToID(”_TempTex”);
54.         // cmd.GetTemporaryRT(id_tempTex, opaqueDesc, FilterMode.Bilinear);
55.         // rti_tempTex = new RenderTargetIdentifier(id_tempTex);
56.         // rth_tempTex = RTHandles.Alloc(rti_tempTex);
57.         */
58.         RenderingUtils.ReAllocateIfNeeded(ref rth_tempTex, opaqueDesc, FilterMode.Bilinear, TextureWrapMode.Clamp, name: ”_TempTex”);
59.         RenderingUtils.ReAllocateIfNeeded(ref rth_Blur01, opaqueDesc, FilterMode.Bilinear, TextureWrapMode.Clamp, name: ”_Blur01”);
60.         RenderingUtils.ReAllocateIfNeeded(ref rth_Blur02, opaqueDesc, FilterMode.Bilinear, TextureWrapMode.Clamp, name: ”_Blur02”);
61.         // rth_tempTex = RTHandles.Alloc(in opaqueDesc,FilterMode.Bilinear,TextureWrapMode.Clamp,name: ”_TempTex”);
62.         // 上面这个也可以正确运行，但是记得要在OnCameraCleanup()里执行Release
63.     }
64.     //----------------------------------------------------------------
65.     // Here you can implement the rendering logic. 在Execute方式里执行CommandBuffer
66.     public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData){
67.         CommandBuffer cmd = CommandBufferPool.Get();
68.         using(new ProfilingScope(cmd, new ProfilingSampler(m_ProfilerTag))){
69.             Vector2[] sizes = {
70.                 new Vector2(Screen.width, Screen.height),
71.                 new Vector2(Screen.width / 2, Screen.height / 2),
72.                 new Vector2(Screen.width / 4, Screen.height / 4),
73.                 new Vector2(Screen.width / 8, Screen.height / 8),
74.             };
75.             int numIterations = 2;//3
76.             Blitter.BlitCameraTexture(cmd,source,rth_tempTex);//表格里的类型|C|
77.             for (int i = 0; i < numIterations; ++i){
78.                 Blitter.BlitCameraTexture(cmd,rth_tempTex,rth_Blur01);//表格里的类型|C|
80.                 cmd.SetGlobalVector(”_Offset”, new Vector4(2.0f / sizes[i].x, 0, 0, 0));
81.                 Blitter.BlitCameraTexture(cmd, rth_Blur01, rth_Blur02, m_blurMat, 0);//表格里的类型|A|
83.                 cmd.SetGlobalVector(”_Offset”, new Vector4(0, 2.0f / sizes[i].y, 0, 0));
84.                 Blitter.BlitCameraTexture(cmd, rth_Blur02, rth_Blur01, m_blurMat, 0);//表格里的类型|A|
86.                 Blitter.BlitCameraTexture(cmd, rth_Blur01, rth_tempTex);//表格里的类型|C|
87.             }
88.             //把最终内容Blit到一个RenderTexture上。
89.             cmd.SetGlobalTexture(”_GrabBlurTexture”, (RenderTargetIdentifier)rth_Blur01);
90.         }
91.         //---------------------------------------------
92.         context.ExecuteCommandBuffer(cmd);// Use ScriptableRenderContext to issue drawing commands or execute command buffers
93.         cmd.Clear();
94.         CommandBufferPool.Release(cmd);
95.     }
96.     //----------------------------------------------------------------
97.     // Cleanup any allocated resources that were created during the execution of this render pass.
98.     public override void OnCameraCleanup(CommandBuffer cmd){}
99.     public override void FrameCleanup(CommandBuffer cmd){}
100.     public void Dispose(){
101.         rth_tempTex?.Release();
102.         rth_Blur01?.Release();
103.         rth_Blur02?.Release();
104.     }
105. }

复制代码

Shader改削：用于做Blur计算的shader(”Hidden/SeparableGlassBlur”)
使用[_BlitTexture]接受Blitter函数输入的source，不需要手动定义[_BlitTexture]，可直接 include Blit.hlsl；

1. #include ”Packages/com.unity.render-pipelines.core/Runtime/Utilities/Blit.hlsl”

复制代码

Blit.hlsl可以提供 vertex shader (Vert), input structure (Attributes) and output strucutre (Varyings)
（不贴shader了，直接放下一章节里）
4.如何撑持 Single-Pass Instanced VR？

文档： https://docs.unity3d.com/2022.2/Documentation/Manual/SinglePassInstancing.html
我们已经用 Blitter 替换全部的cmd.Blit了，此刻只需要让shader撑持Single-Pass Instanced VR就大功告成啦
用于做Blur计算的shader：

1. Shader ”Hidden/SeparableGlassBlur_v2” {
2.     // Properties {}
3.     Subshader {
4.         Tags { ”RenderType”=”Opaque” ”RenderPipeline”=”UniversalPipeline” }
5.         Pass {
6.             Name ”SeparableGlassBlur”
7.             ZTest Always
8.             Cull Off
9.             ZWrite Off
10.             HLSLPROGRAM
11.             #include ”Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl”
12.             // Blit.hlsl 提供 vertex shader (Vert), input structure (Attributes) and output strucutre (Varyings)
13.             #include ”Packages/com.unity.render-pipelines.core/Runtime/Utilities/Blit.hlsl”
14.             #pragma vertex myVert
15.             #pragma fragment myFrag
16.             // 由Blit.hlsl来定义Attributes
17.             // struct Attributes {
18.             //  float4 posOS : POSITION;
19.             //  half2 uv : TEXCOORD0;
20.             //  UNITY_VERTEX_INPUT_INSTANCE_ID //Insert to support Single-Pass Instanced VR
21.             // };
22.             struct v2f {
23.                 float4 posCS : SV_POSITION;//POSITION;
24.                 float2 uv : TEXCOORD0;
25.                 float4 uv01 : TEXCOORD1;
26.                 float4 uv23 : TEXCOORD2;
27.                 float4 uv45 : TEXCOORD3;
28.                 UNITY_VERTEX_OUTPUT_STEREO //Insert to support Single-Pass Instanced VR
29.             };
30.             float4 _Offset;
31.             v2f myVert (Attributes input) {
32.                 v2f o;
33.                 UNITY_SETUP_INSTANCE_ID(input);//Insert to support Single-Pass Instanced VR
34.                 UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);//Insert to support Single-Pass Instanced VR
35.                 #if SHADER_API_GLES //拷贝自Blit.hlsl
36.                     float4 pos = input.positionOS;
37.                     float2 uv  = input.uv;
38.                 #else
39.                     float4 pos = GetFullScreenTriangleVertexPosition(input.vertexID);
40.                     float2 uv  = GetFullScreenTriangleTexCoord(input.vertexID);
41.                 #endif
42.                 o.posCS = pos;
43.                 o.uv = uv * _BlitScaleBias.xy + _BlitScaleBias.zw;
44.                 o.uv01 =  o.uv.xyxy + _Offset.xyxy * float4(1,1, -1,-1);
45.                 o.uv23 =  o.uv.xyxy + _Offset.xyxy * float4(1,1, -1,-1) * 2.0;
46.                 o.uv45 =  o.uv.xyxy + _Offset.xyxy * float4(1,1, -1,-1) * 3.0;
47.                 return o;
48.             }
49.             half4 myFrag (v2f i) : SV_Target {//COLOR
50.                 UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(i);//Insert to support Single-Pass Instanced VR
51.                 half4 color = float4 (0,0,0,0);
52.                 color += 0.40 * SAMPLE_TEXTURE2D_X(_BlitTexture, sampler_PointClamp, i.uv);
53.                 color += 0.15 * SAMPLE_TEXTURE2D_X(_BlitTexture, sampler_PointClamp, i.uv01.xy);
54.                 color += 0.15 * SAMPLE_TEXTURE2D_X(_BlitTexture, sampler_PointClamp, i.uv01.zw);
55.                 color += 0.10 * SAMPLE_TEXTURE2D_X(_BlitTexture, sampler_PointClamp, i.uv23.xy);
56.                 color += 0.10 * SAMPLE_TEXTURE2D_X(_BlitTexture, sampler_PointClamp, i.uv23.zw);
57.                 color += 0.05 * SAMPLE_TEXTURE2D_X(_BlitTexture, sampler_PointClamp, i.uv45.xy);
58.                 color += 0.05 * SAMPLE_TEXTURE2D_X(_BlitTexture, sampler_PointClamp, i.uv45.zw);
59.                 return color;
60.             }
61.             ENDHLSL
62.         }
63.     }
64. }

复制代码

用于衬着玻璃的shader：

1. Shader ”FX/Glass/Stained BumpDistort (no grab) v2” {
2.     Properties {
3.         _BumpAmt  (”Distortion”, Range (0,256)) = 125
4.         _TintAmt (”Tint Amount”, Range(0,1)) = 0.1
5.         _MainTex (”Tint Color (RGB)”, 2D) = ”white” {}
6.         _BumpMap (”Normalmap”, 2D) = ”bump” {}
7.     }
8.     SubShader{
9.         Tags {  ”RenderPipeline”=”UniversalPipeline” ”Queue”=”Transparent” ”RenderType”=”Opaque” }
10.         Pass {
11.             Name ”BASE”
12.             Tags { ”LightMode”=”UniversalForward” }
13.             HLSLPROGRAM
14.             #pragma vertex vert
15.             #pragma fragment frag
16.             #pragma multi_compile_fog
17.             #include ”Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl”
18.             struct appdata_t {
19.                 float4 vertex : POSITION;
20.                 float2 texcoord: TEXCOORD0;
21.                 UNITY_VERTEX_INPUT_INSTANCE_ID //Insert to support Single-Pass Instanced VR
22.             };
23.             struct v2f {
24.                 float4 vertex : POSITION;
25.                 float4 uvgrab : TEXCOORD0;
26.                 float2 uvbump : TEXCOORD1;
27.                 float2 uvmain : TEXCOORD2;
28.                 float fogFactor : TEXCOORD3;
29.                 UNITY_VERTEX_OUTPUT_STEREO //Insert to support Single-Pass Instanced VR
30.             };
31.             float _BumpAmt;
32.             half _TintAmt;
33.             float4 _BumpMap_ST;
34.             float4 _MainTex_ST;
35.             v2f vert (appdata_t v){
36.                 v2f o;
37.                 UNITY_SETUP_INSTANCE_ID(v); //Insert to support Single-Pass Instanced VR
38.                 UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o); //Insert to support Single-Pass Instanced VR
39.                 o.vertex = TransformObjectToHClip(v.vertex);
40.                 #if UNITY_UV_STARTS_AT_TOP
41.                     float scale = -1.0;
42.                 #else
43.                     float scale = 1.0;
44.                 #endif
45.                 o.uvgrab.xy = (float2(o.vertex.x, o.vertex.y*scale) + o.vertex.w) * 0.5;
46.                 o.uvgrab.zw = o.vertex.zw;
47.                 o.uvbump = TRANSFORM_TEX( v.texcoord, _BumpMap );
48.                 o.uvmain = TRANSFORM_TEX( v.texcoord, _MainTex );
49.                 o.fogFactor = ComputeFogFactor(o.vertex.z);
50.                 return o;
51.             }
52.             sampler2D _BumpMap;
53.             sampler2D _MainTex;
54.             float4 _GrabBlurTexture_TexelSize;
55.             TEXTURE2D_X(_GrabBlurTexture);// sampler2D _GrabBlurTexture; //Insert to support Single-Pass Instanced VR
56.             SAMPLER(sampler_GrabBlurTexture);//Insert to support Single-Pass Instanced VR
57.             half4 frag (v2f i) : SV_Target{
58.                 UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(i);//Insert to support Single-Pass Instanced VR
59.                 // calculate perturbed coordinates
60.                 // we could optimize this by just reading the x & y without reconstructing the Z
61.                 half2 bump = UnpackNormal(tex2D( _BumpMap, i.uvbump )).rg;
62.                 float2 offset = bump * _BumpAmt * _GrabBlurTexture_TexelSize.xy;
63.                 i.uvgrab.xy = offset * i.uvgrab.z + i.uvgrab.xy;
64.                 // half4 col = tex2Dproj (_GrabBlurTexture, i.uvgrab/i.uvgrab.w);
65.                 half4 col = SAMPLE_TEXTURE2D_X (_GrabBlurTexture, sampler_GrabBlurTexture, i.uvgrab.xy/i.uvgrab.w);
66.                 half4 tint = tex2D(_MainTex, i.uvmain);
67.                 col = lerp (col, tint, _TintAmt);
68.                 col.rgb = MixFog(col.rgb, i.fogFactor);
69.                 return col;
70.             }
71.             ENDHLSL
72.         }
73.     }
74. }

复制代码

完~✿

阿谁……“③玻璃后的半透明物体不成见”啊啊啊啊不想再折腾啦，下次再研究！

5. 完善的毛玻璃效果

Lit+Refraction+Frosted

• Lit：偷懒，用ShaderGraph实现了
  
• Refraction：折射是玻璃效果的本质啊！教程参考 Screen Space Refraction for Glass and Water using Shader Graph 来自 < https://www.youtube.com/watch?v=VMsOPUUj0JA>
  
• Frosted：在 shader graph 里 SceneColor节点 是可以撑持single-pass instanced VR的，但如果使用我们自定义的 GrabBlurTexture 就不能撑持single-pass instanced VR了；……才发现我对single-pass instanced VR这个技术其实一点没搞懂
  

我的解决方式是用 Custom Function 节点，新建一个 hlsl 文件：

1. //UNITY_SHADER_NO_UPGRADE
2. #ifndef MYHLSLINCLUDE_INCLUDED
3. #define MYHLSLINCLUDE_INCLUDED
4. TEXTURE2D_X(_GrabBlurTexture);// sampler2D _GrabBlurTexture; //Insert to support Single-Pass Instanced VR
5. SAMPLER(sampler_GrabBlurTexture);//Insert to support Single-Pass Instanced VR
6. float4 _GrabBlurTexture_TexelSize;
7. void SampleTextureX_float(float2 uv, out half4 col){
8.     col = SAMPLE_TEXTURE2D_X(_GrabBlurTexture, sampler_GrabBlurTexture, uv);
9. }
10. #endif //MYHLSLINCLUDE_INCLUDED

复制代码

唉……


https://www.zhihu.com/video/1670856985879900160