• 🎈 前言
• 🎈 如何将RPM中编辑的Avatar导入到Unity
• 🎈 如何提取模型中的Mesh网格、Material材质、及Texture贴图
• 🎈 如何提取RPM网页中的图片资源
• 🎈 资源配置

🎈 前言

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：

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。

回到Unity中，将复制的链接粘贴到Avatar URL or Short Code中，点击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：

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。

🎈 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：

• 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：

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

选中想要下载的图片资源并开始下载：

🎈 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];
    }
}

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;
    }
}