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：

说明这是一个外部置入的RenderTexture
红色方块说明存在写入操作
绿色方块指存在读取操作（红绿方块说明读写操作）
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 classDistortTunnelPass_Tunnel : ScriptableRenderPass

{classPassData

    {publicRenderer tunnelObject;publicMaterial 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    }#pragma warning disable 618, 672 //Type or member is obsolete, Member overrides obsolete member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 voidConfigure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescripor)

    {

    }//Unity calls the Execute method in the Compatibility mode
    public override void Execute(ScriptableRenderContext context, refRenderingData 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 voidRecordRenderGraph(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);

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= newMaterialPropertyBlock();

        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：

usingUnityEngine;usingUnityEngine.Rendering.Universal;usingUnityEngine.Rendering;public classMyBlurSceneController : MonoBehaviour

{publicMaterial 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;privateMyBlurPass mMyBlurPass;private voidOnEnable()

    {

        SetupPass();



        RenderPipelineManager.beginCameraRendering+=OnBeginCamera;

    }private voidOnDisable()

    {

        RenderPipelineManager.beginCameraRendering-=OnBeginCamera;

    }public virtual voidSetupPass()

    {

        mMyBlurPass= newMyBlurPass();



        mMyBlurPass.renderPassEvent= injectionPoint +injectionPointOffset;

        mMyBlurPass.material=material;



        mMyBlurPass.ConfigureInput(inputRequirements);

    }public virtual voidOnBeginCamera(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：

usingUnityEngine;usingUnityEngine.Rendering.RenderGraphModule;usingUnityEngine.Rendering;usingUnityEngine.Rendering.Universal;usingUnityEngine.Rendering.RenderGraphModule.Util;public classMyBlurPass : ScriptableRenderPass

{public classPassData

    {publicTextureHandle tempRt1;publicTextureHandle tempRt2;

    }publicMaterial 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 voidRecordRenderGraph(RenderGraph renderGraph, ContextContainer frameData)

    {var resourceData = frameData.Get<UniversalResourceData>();var passData = newPassData();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= newMaterialPropertyBlock();

                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。

Unity6 URP17使用初探