🎈 前言

"Avatar换装"

随着元宇宙概念的火热，数字人换装捏脸的实现方案逐渐受到更多关注，本篇内容主要介绍如何在Unity中实现数字人的换装系统，涉及的所有美术资源均来源于RPM（Ready Player Me），地址：Ready Player Me主页。

实现该系统涉及到的无非是老生常谈的几项内容：

Skinned Mesh Renderer - 蒙皮网格
Material - 材质球
Avatar Bone - 骨架

重要点，也是核心点，就是基于Avatar数字人的同一套骨架，也就是讲当数字人进行换装时，切换的是Skinned Mesh Renderer中的Mesh网格及Material材质球，骨架是不会去改变的。

🎈 如何将RPM中编辑的Avatar导入到Unity

本专栏的第一篇内容中有介绍RPM的使用以及将Avatar导入Unity的过程，下面简要说明。

首先要下载其SDK，地址：Ready Player Me - Unity SDK，将下载的.unitypackage包导入到Unity中，可以看到菜单栏中有了Ready Player Me的选项，Avatar Loader可以将我们自定义的Avatar模型导入到Unity中：

Avatar Loader

在RPM的Avatar Hub中，选择我们想要导入到Unity中的Avatar，通过Copy .glb URL复制链接。

Copy .glb URL
回到Unity中，将复制的链接粘贴到Avatar URL or Short Code中，点击Load Avatar

Load Avatar
下载完成后，在Resources文件夹下可以看到下载的.glb模型文件：

glb 模型
Unity中常用的模型文件格式为.fbx类型，可以通过Blender软件将.glb格式文件转换为.fbx格式文件，需要注意在导出选项里，将路径模式改为复制，并选中后面的内嵌纹理，否则导入到Unity中只是一个白模，并没有材质、贴图。

导出fbx

🎈 如何提取模型中的Mesh网格、Material材质、及Texture贴图

Mesh网格和Material材质的提取可以直接在Skinned Mesh Renderer组件中获取并通过实例化并调用AssetDatabase类中的CreateAsset来创建和保存资产：

// 摘要:
//     Creates a new asset at path.
//
// 参数:
//   asset:
//     Object to use in creating the asset.
//
//   path:
//     Filesystem path for the new asset.
[MethodImpl(MethodImplOptions.InternalCall)]
[NativeThrows]
[PreventExecutionInState(AssetDatabasePreventExecution.kGatheringDependenciesFromSourceFile, PreventExecutionSeverity.PreventExecution_ManagedException, "Assets may not be created during gathering of import dependencies")]
public static extern void CreateAsset([NotNull("ArgumentNullException")] UnityEngine.Object asset, string path);

asset：第一个参数为要进行保存/创建的资产；
path：第二个参数为该资产生成的文件夹路径。

而Texture贴图资源可以通过调用AssetDatabase类中的GetDependencies方法获取材质球的依赖项文件路径：

// 摘要:
//     Returns an array of all the assets that are dependencies of the asset at the
//     specified pathName. Note: GetDependencies() gets the Assets that are referenced
//     by other Assets. For example, a Scene could contain many GameObjects with a Material
//     attached to them. In this case, GetDependencies() will return the path to the
//     Material Assets, but not the GameObjects as those are not Assets on your disk.
//
// 参数:
//   pathName:
//     The path to the asset for which dependencies are required.
//
//   recursive:
//     Controls whether this method recursively checks and returns all dependencies
//     including indirect dependencies (when set to true), or whether it only returns
//     direct dependencies (when set to false).
//
// 返回结果:
//     The paths of all assets that the input depends on.
public static string[] GetDependencies(string pathName)
{return GetDependencies(pathName, recursive: true);
}

根据路径调用LoadAssetAtPath方法加载贴图资源：

// 摘要:
//     Returns the first asset object of type type at given path assetPath.
//
// 参数:
//   assetPath:
//     Path of the asset to load.
//
//   type:
//     Data type of the asset.
//
// 返回结果:
//     The asset matching the parameters.
[MethodImpl(MethodImplOptions.InternalCall)]
[PreventExecutionInState(AssetDatabasePreventExecution.kGatheringDependenciesFromSourceFile, PreventExecutionSeverity.PreventExecution_ManagedException, "Assets may not be loaded while dependencies are being gathered, as these assets may not have been imported yet.")]
[PreventExecutionInState(AssetDatabasePreventExecution.kDomainBackup, PreventExecutionSeverity.PreventExecution_ManagedException, "Assets may not be loaded while domain backup is running, as this will change the underlying state.")]
[NativeThrows]
[TypeInferenceRule(TypeInferenceRules.TypeReferencedBySecondArgument)]
public static extern UnityEngine.Object LoadAssetAtPath(string assetPath, Type type);public static T LoadAssetAtPath<T>(string assetPath) where T : UnityEngine.Object;

本篇内容中提取Avatar数字人相关资产的工作流如下：

fbx导入到Unity后，在Import Settings导入设置中将Material Location类型改为Use External Materials（Legacy），应用后编辑器会在该fbx文件所在目录下生成相应的材质和贴图资源文件夹：

Materials Location

将所有法线贴图的Texture Type改为Normal map，并检查法线贴图是否用在相应材质球上：
调用自定义的编辑器方法，提取资产：

提取资产
该方法可以提取Avatar的头部、身体、上衣、裤子及鞋子的相关资产，代码如下：

using UnityEngine;
using UnityEditor;namespace Metaverse
{/// <summary>/// 用于提取ReadyPlayerMe的Avatar服装资源/// </summary>public class RPMAvatarClothingCollecter {[MenuItem("Metaverse/Ready Player Me/Avatar Clothing Collect")]public static void Execute(){//如果未选中任何物体if (Selection.activeGameObject == null) return;//弹出窗口 选择资源提取的路径string collectPath = EditorUtility.OpenFolderPanel("选择路径", Application.dataPath, null);//如果路径为空或无效 返回if (string.IsNullOrEmpty(collectPath)) return;//AssetDatabase路径collectPath = collectPath.Replace(Application.dataPath, "Assets");if (!AssetDatabase.IsValidFolder(collectPath)) return;//头部Transform head = Selection.activeGameObject.transform.Find("Wolf3D_Head");if (head != null) Collect(collectPath, head.GetComponent<SkinnedMeshRenderer>(), "head");//身体Transform body = Selection.activeGameObject.transform.Find("Wolf3D_Body");if (head != null) Collect(collectPath, body.GetComponent<SkinnedMeshRenderer>(), "body");//上衣Transform top = Selection.activeGameObject.transform.Find("Wolf3D_Outfit_Top");if (top != null) Collect(collectPath, top.GetComponent<SkinnedMeshRenderer>(), "top");//裤子Transform bottom = Selection.activeGameObject.transform.Find("Wolf3D_Outfit_Bottom");if (bottom != null) Collect(collectPath, bottom.GetComponent<SkinnedMeshRenderer>(), "bottom");//鞋子Transform footwear = Selection.activeGameObject.transform.Find("Wolf3D_Outfit_Footwear");if (footwear != null) Collect(collectPath, footwear.GetComponent<SkinnedMeshRenderer>(), "footwear");//刷新AssetDatabase.Refresh();}public static void Collect(string path, SkinnedMeshRenderer smr, string suffix){//创建Mesh网格资产AssetDatabase.CreateAsset(Object.Instantiate(smr.sharedMesh), string.Format("{0}/mesh_{1}.asset", path, suffix));//创建Material材质球资产Material material = Object.Instantiate(smr.sharedMaterial);AssetDatabase.CreateAsset(material, string.Format("{0}/mat_{1}.asset", path, suffix));//获取材质球的依赖项路径string[] paths = AssetDatabase.GetDependencies(AssetDatabase.GetAssetPath(material));//遍历依赖项路径for (int i = 0;i < paths.Length; i++){//AssetDatabase路径string p = paths[i].Replace(Application.dataPath, "Assets");//根据路径加载Texture贴图资源Texture tex = AssetDatabase.LoadAssetAtPath<Texture>(p);if (tex == null) continue;TextureImporter textureImporter = AssetImporter.GetAtPath(p) as TextureImporter;//主贴图if (textureImporter.textureType == TextureImporterType.Default){AssetDatabase.MoveAsset(p, string.Format("{0}/tex_{1}_d.jpg", path, suffix));}//法线贴图if (textureImporter.textureType == TextureImporterType.NormalMap){AssetDatabase.MoveAsset(p, string.Format("{0}/tex_{1}_n.jpg", path, suffix));}}}}
}

🎈 如何提取RPM网页中的图片资源

提取网页中的图片资源可以使用ImageAssistant图片助手，一款Chrome浏览器中用于嗅探、分析网页图片、图片筛选、下载等功能的扩展程序，当然也可以在Edge浏览器中去使用，地址：Image Assistant

图片助手

选中想要下载的图片资源并开始下载：

下载图片

🎈 资源配置

正常开发工作中，建议构建出不同服装资源的AB（AssetsBundle）包，通过加载AB包来实现各种服装的切换，本篇内容中通过Scriptable Object配置各种服装资源来实现Demo，首先编写外观数据类：

using System;
using UnityEngine;namespace Metaverse
{/// <summary>/// Avatar外观数据/// </summary>[Serializable]    public class AvatarOutlookData{/// <summary>/// 头部网格/// </summary>public Mesh headMesh;/// <summary>/// 头部材质/// </summary>public Material headMaterial;/// <summary>/// 身体网格/// </summary>public Mesh bodyMesh;/// <summary>/// 身体材质/// </summary>public Material bodyMaterial;/// <summary>/// 上衣网格/// </summary>public Mesh topMesh;/// <summary>/// 上衣材质/// </summary>public Material topMaterial;/// <summary>/// 裤子网格/// </summary>public Mesh bottomMesh;/// <summary>/// 裤子材质/// </summary>public Material bottomMaterial;/// <summary>/// 鞋子网格/// </summary>public Mesh footwearMesh;/// <summary>/// 鞋子材质/// </summary>public Material footwearMaterial;/// <summary>/// 缩略图/// </summary>public Sprite thumb;}
}

编写配置类如下，实现后创建一个新的配置表并配置数据：

using UnityEngine;namespace Metaverse
{/// <summary>/// Avatar服装配置/// </summary>[CreateAssetMenu(menuName = "Metaverse/Avatar Clothing Config")]public class AvatarClothingConfig : ScriptableObject{public AvatarOutlookData[] data = new AvatarOutlookData[0];}
}

数据配置

测试脚本如下：

using UnityEngine;public class Example : MonoBehaviour
{[SerializeField] private SkinnedMeshRenderer head;[SerializeField] private SkinnedMeshRenderer body;[SerializeField] private SkinnedMeshRenderer top;[SerializeField] private SkinnedMeshRenderer bottom;[SerializeField] private SkinnedMeshRenderer footwear;[SerializeField] private Metaverse.AvatarOutlookConfig config;private void OnGUI(){if (GUILayout.Button("服装一", GUILayout.Width(200f), GUILayout.Height(50f))) Apply(0);if (GUILayout.Button("服装二", GUILayout.Width(200f), GUILayout.Height(50f))) Apply(1);if (GUILayout.Button("服装三", GUILayout.Width(200f), GUILayout.Height(50f))) Apply(2);}private void Apply(int index){head.sharedMesh = config.data[index].headMesh;head.sharedMaterial = config.data[index].headMaterial;body.sharedMesh = config.data[index].bodyMesh;body.sharedMaterial = config.data[index].bodyMaterial;top.sharedMesh = config.data[index].topMesh;top.sharedMaterial = config.data[index].topMaterial;bottom.sharedMesh = config.data[index].bottomMesh;bottom.sharedMaterial = config.data[index].bottomMaterial;footwear.sharedMesh = config.data[index].footwearMesh;footwear.sharedMaterial = config.data[index].footwearMaterial;}
}