Unity6 URP17使用初探

1.简介

随着Unity6的发布，URP17也已经可以上手使用，相对旧的版本改动较大的是加入了

RenderGraph、STP、Foveated rendering、GPU Resident Drawer等功能，部分功能只需要开关参数即可使用，

而GRD更像是Gpu driven管线下的SRP Batches升级，RenderGraph相较于HDRP之前使用的版本换了一套API。

最大的不同是，使用URP17编写Feature时，必须依赖于RenderGraph进行编写，接下来就来介绍一下。

 

1.1 相关Demo

目前URP17比较容易找到的学习Demo如下：

• URP17 Package内自带的Samples
• Fantasy Kingdom (https://assetstore.unity.com/packages/essentials/tutorial-projects/fantasy-kingdom-in-unity-6-urp-298128)
• 在Unity Hub可以直接下载的Universal 3D sample（包含3个场景）

2.RenderGraph

打开任意URP的示例场景查看，RenderGraphView上各图标含义如下：

1. 说明这是一个外部置入的RenderTexture
2. 红色方块说明存在写入操作
3. 绿色方块指存在读取操作（红绿方块说明读写操作）
4. 该图标说明标记了全局RenderTexture

 而顶部表明当前渲染一帧的各个Pass，左侧是各类RT。

 

URP17同时保留了旧的Feature逻辑与RenderGraph逻辑(打开任意pass文件为例)：

public class DistortTunnelPass_Tunnel : ScriptableRenderPass
{class PassData{public Renderer tunnelObject;public Material tunnelMaterial;}#pragma warning disable 618, 672 // Type or member is obsolete, Member overrides obsolete member// Unity calls the Configure method in the Compatibility mode (non-RenderGraph path)public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescripor){}// Unity calls the Execute method in the Compatibility modepublic override void Execute(ScriptableRenderContext context, ref RenderingData renderingData){}#pragma warning restore 618, 672// Unity calls the RecordRenderGraph method to add and configure one or more render passes in the render graph system.public override void RecordRenderGraph(RenderGraph renderGraph, ContextContainer frameData){}
}

参考时忽略掉Configure和Execute的逻辑，执行逻辑关注RecordRenderGraph函数。

 

2.1 操作方式的改变

在RenderGraph中，之前的RTHandle由于不在该系统中托管，进入RenderGraph的材质都需要调用API进行转换，

转换为RendeGraph的RT后，无需考虑释放操作：

RenderTextureDescriptor textureProperties = new RenderTextureDescriptor(Screen.width, Screen.height, RenderTextureFormat.Default, 0);
TextureHandle textureHandle = UniversalRenderer.CreateRenderGraphTexture(renderGraph, textureProperties, "My texture", false);

相关文档：

https://docs.unity3d.com/Manual/urp/render-graph-create-a-texture.html

 

此外RenderGraph对于空调用的pass，也会剔除进行优化，使用者需要手动标记以防止被剔除。

 

2.1 RecordRenderGraph

在该函数内可组织渲染逻辑，pass相关的逻辑需放在对应的代码块中，例如：

using (var builder = renderGraph.AddRasterRenderPass<PassData>(passName, out _))
{builder.UseTexture(rt1);builder.SetRenderAttachment(resourceData.activeColorTexture, 0);builder.SetRenderFunc<PassData>((data, context) =>{MaterialPropertyBlock materialPropertyBlock = new MaterialPropertyBlock();materialPropertyBlock.SetTexture("_BlitTexture", rt1);materialPropertyBlock.SetVector("_BlitScaleBias", new Vector4(1, 1, 0, 0));context.cmd.DrawProcedural(Matrix4x4.identity, material, 0, MeshTopology.Triangles, 3, 1, materialPropertyBlock);});
}

URP提供了多种RenderPass，例如处理光栅化相关逻辑使用RasterRenderPass组织相关逻辑。

在RenderPass的代码块中可使用builder对象配置RenderTarget、标记材质的读写等

而具体的pass绘制逻辑则在SetRenderFunc代码块中。

 

RecordRenderGraph内可以调用多次AddRenderPass，但URP并没有整理旧API的代码和相关工具类，

以至于容易使用旧的API导致报错，这点需要注意。

 

3.编写Feature

3.1 Blit与SetTarget

从前有句俗话“切RT的性能消耗相当于半个pass”，Unity SRP在几个版本的升级都在逐渐强调不切RenderTarget直接绘制，

如Cockpit Demo的屏幕空间描边。

 

3.2 屏幕模糊Demo

下面通过屏幕模糊Demo案例，演示URP17下pass的编写。

 

通过外部EnqueuePass的方式，在场景中通过控制器脚本添加该Pass，

MyBlurSceneController.cs：

using UnityEngine;
using UnityEngine.Rendering.Universal;
using UnityEngine.Rendering;public class MyBlurSceneController : MonoBehaviour
{public Material material;[Range(2, 15)] public int blurPasses = 3;[Range(0, 4)] public int downSample = 0;[Range(0.0f, 10f)] public float offset = 0.2f;public RenderPassEvent injectionPoint = RenderPassEvent.BeforeRenderingPostProcessing;public int injectionPointOffset = 0;public ScriptableRenderPassInput inputRequirements = ScriptableRenderPassInput.Color;public CameraType cameraType = CameraType.Game;private MyBlurPass mMyBlurPass;private void OnEnable(){SetupPass();RenderPipelineManager.beginCameraRendering += OnBeginCamera;}private void OnDisable(){RenderPipelineManager.beginCameraRendering -= OnBeginCamera;}public virtual void SetupPass(){mMyBlurPass = new MyBlurPass();mMyBlurPass.renderPassEvent = injectionPoint + injectionPointOffset;mMyBlurPass.material = material;mMyBlurPass.ConfigureInput(inputRequirements);}public virtual void OnBeginCamera(ScriptableRenderContext ctx, Camera cam){if (mMyBlurPass == null || material == null)return;if ((cam.cameraType & cameraType) == 0) return;mMyBlurPass.blurPasses = blurPasses;mMyBlurPass.downSample = downSample;mMyBlurPass.offset = offset;cam.GetUniversalAdditionalCameraData().scriptableRenderer.EnqueuePass(mMyBlurPass);}
}

 

MyBlurPass.cs：

using UnityEngine;
using UnityEngine.Rendering.RenderGraphModule;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;
using UnityEngine.Rendering.RenderGraphModule.Util;public class MyBlurPass : ScriptableRenderPass
{public class PassData{public TextureHandle tempRt1;public TextureHandle tempRt2;}public Material material;[Range(2, 15)] public int blurPasses = 3;[Range(1, 4)] public int downSample = 1;[Range(0.0f, 10f)] public float offset = 0.2f;public override void RecordRenderGraph(RenderGraph renderGraph, ContextContainer frameData){var resourceData = frameData.Get<UniversalResourceData>();var passData = new PassData();var w = Screen.width >> downSample;var h = Screen.height >> downSample;RenderTextureDescriptor textureProperties = new RenderTextureDescriptor(w, h, RenderTextureFormat.Default, 0);passData.tempRt1 = UniversalRenderer.CreateRenderGraphTexture(renderGraph, textureProperties, "MyBlurPassTempRt1", false);textureProperties = new RenderTextureDescriptor(w, h, RenderTextureFormat.Default, 0);passData.tempRt2 = UniversalRenderer.CreateRenderGraphTexture(renderGraph, textureProperties, "MyBlurPassTempRt2", false);var rt1 = passData.tempRt1;var rt2 = passData.tempRt2;//将屏幕RT Blit到rt1上var para = new RenderGraphUtils.BlitMaterialParameters(resourceData.activeColorTexture, rt1, material, 0);renderGraph.AddBlitPass(para, "MyBlurPassBlitFirst");material.SetFloat("_SampleOffset", offset);//模糊迭代for (int i = 0; i < blurPasses - 1; ++i){para = new RenderGraphUtils.BlitMaterialParameters(rt1, rt2, material, 0);renderGraph.AddBlitPass(para, $"MyBlurPassBlit_{i}");var tmp = rt1;rt1 = rt2;rt2 = tmp;}//通过直接绘制的方式，将模糊RT绘制到屏幕上using (var builder = renderGraph.AddRasterRenderPass<PassData>(passName, out _)){builder.UseTexture(rt1);builder.SetRenderAttachment(resourceData.activeColorTexture, 0);builder.SetRenderFunc<PassData>((data, context) =>{MaterialPropertyBlock materialPropertyBlock = new MaterialPropertyBlock();materialPropertyBlock.SetTexture("_BlitTexture", rt1);materialPropertyBlock.SetVector("_BlitScaleBias", new Vector4(1, 1, 0, 0));context.cmd.DrawProcedural(Matrix4x4.identity, material, 0, MeshTopology.Triangles, 3, 1, materialPropertyBlock);});}}
}

 

接着在ShaderGraph中连出模糊的逻辑，注意Blit对应的参数_BlitTexture、_BlitScaleBias：

 

最后在场景中挂载控制器以及材质球，即可使用该模糊Pass。