本人这边项目里有个需求，就是人脸检测后，将指定的模型附加到使用者的脸上，随后有一个拍摄照片功能，将附加模型后的用户的画面截取出来，并存储到手机本地中，现在人脸识别，以及相关模型也附加到人脸上，但是在拍摄上出现问题，总是保存失败，wxml文件： <xr-scene ar-system="modes:Face;camera:Front" bind:ready="handleReady" bind:tick="handleTick">   <xr-assets bind:loaded="handleAssetsLoaded">     <xr-asset-load type="gltf" asset-id="mask" src="{{ObjectPath}}" />   </xr-assets>   <xr-env env-data="xr-frame-team-workspace-day" />   <xr-light type="ambient" color="1 1 1" intensity="1" />   <xr-light type="directional" rotation="40 70 0" color="1 1 1" intensity="3" />   <xr-ar-tracker mode="Face" auto-sync="43">     <xr-gltf id="mask" model="mask" rotation="0 180 0" scale="0.5 0.5 0.5" />   </xr-ar-tracker>   <xr-camera id="camera" clear-color="0.4 0.8 0.6 1" background="ar" is-ar-camera /> </xr-scene> ts 文件： import { MarkerPath, SceneState } from "../../utils/data"; // components/user-xr-start/index.ts Component({   /**    * 组件的属性列表    */   properties: {     modelPath:{       type:String,       value:""     }   },   /**    * 组件的初始数据    */   data: {     loaded:false,     hasFrontCamera: false,     cameraPermissionGranted: false,     ObjectPath:MarkerPath.object,     tempImagePath:"",     currentState:SceneState.Init,   },   // 添加生命周期函数   lifetimes: {     attached: function() {       // 初始化实例属性       this.scene = null;       this.camera = null;       this.mask = null;       this.tmpV3 = null;              // 组件加载时检查相机状态       this.checkCameraStatus();     },          detached: function() {       // 清理引用       this.scene = null;       this.camera = null;       this.mask = null;       this.tmpV3 = null;     }   },     scene: null,     mask: null,   /**    * 组件的方法列表    */   methods: {     // 检查相机状态     checkCameraStatus: function() {       const that = this;              // 1. 检查是否有前置相机       wx.getSystemInfo({         success: function(res) {           // 大多数现代手机都有前置相机，但可以进一步确认           that.setData({             hasFrontCamera: true // 假设有前置相机           });                      // 2. 检查相机权限           that.checkCameraPermission();         },         fail: function(err) {           console.error('获取系统信息失败:', err);           that.showCameraWarning('无法检测相机硬件状态');         }       });     },       // 检查相机权限     checkCameraPermission: function() {       const that = this;              wx.getSetting({         success: (res) => {           if (res.authSetting['scope.camera']) {             // 已授权相机权限             that.setData({               cameraPermissionGranted: true             });           } else {             // 未授权相机权限             that.setData({               cameraPermissionGranted: false             });             that.requestCameraPermission();           }         },         fail: (err) => {           console.error('获取设置失败:', err);           that.showCameraWarning('无法检测相机权限状态');         }       });     },     // 请求相机权限     requestCameraPermission: function() {       const that = this;              wx.authorize({         scope: 'scope.camera',         success: () => {           // 用户同意授权           that.setData({             cameraPermissionGranted: true           });         },         fail: (err) => {           console.error('相机权限授权失败:', err);           that.showCameraWarning('请允许使用相机以体验AR功能');         }       });     },     // 显示相机警告     showCameraWarning: function(message) {       wx.showModal({         title: '相机提示',         content: message,         showCancel: false,         confirmText: '确定',         success: (res) => {           if (res.confirm) {             // 用户点击确定后的操作             console.log('用户确认相机提示');           }         }       });     },           handleReady: function ({detail}) {       // if (!this.data.cameraPermissionGranted || !this.data.hasFrontCamera) {       //   this.showCameraWarning('无法启动前置相机，请检查设备是否支持和权限设置');       //   return;       // }       console.log("user-xr handleReady");       console.log(detail.value);       console.log("scene 对象方法:", Object.getOwnPropertyNames(detail.value));       console.log("scene 对象原型方法:", Object.getOwnPropertyNames(Object.getPrototypeOf(detail.value)));       if(this.data.ObjectPath === ""){         this.setData({           ObjectPath:MarkerPath.object,         });       }       this.scene = detail.value;       const xrFrameSystem = wx.getXrFrameSystem();       this.camera = this.scene.getElementById('camera').getComponent(xrFrameSystem.Camera);       // this.mask = {el: this.scene.getElementById('mask'), color: 'rgba(44, 44, 44, 0.5)'};       const maskElement = this.scene.getElementById('mask');       if (maskElement) {         this.mask = {el: maskElement, color: 'rgba(44, 44, 44, 0.5)'};         console.log('Mask element found:', maskElement);       } else {         this.mask = null;         console.warn('Mask element not found in scene');       }       this.tmpV3 = new (xrFrameSystem.Vector3)();       console.log("user-xr handleReady:", {         scene: this.scene,         maskElementExists: !!maskElement,         sceneHasExportImage: typeof this.scene.exportImage === 'function',         sceneHasGetContainer: typeof this.scene.getContainer === 'function'       });       this.triggerEvent('ready', detail.value);     },     handleAssetsLoaded: function (detail) {       console.log('资源加载完成', detail.value);       if(!this.scene){         this.scene = detail.value;         const xrFrameSystem = wx.getXrFrameSystem();         this.camera = this.scene.getElementById('camera').getComponent(xrFrameSystem.Camera);                const maskElement = this.scene.getElementById('mask');         if (maskElement) {           this.mask = {el: maskElement, color: 'rgba(44, 44, 44, 0.5)'};           console.log('Mask element found after asset load:', maskElement);         }       }       console.log("user: "+ this.data.ObjectPath);       this.triggerEvent('assetsLoaded', detail.value);     },     handleTick: function({detail}) {       // this.mask && this.triggerEvent('syncPositions', [       //   this.getScreenPosition(this.mask)       // ]);       if (this.mask && this.mask.el) {         this.triggerEvent('syncPositions', [           this.getScreenPosition(this.mask)         ]);       } else {         // 可选：触发一个空的位置事件或者不触发         console.log('Mask element not ready yet');       }     },     handleTouchModel: function ({detail}) {       const {target} = detail.value;       this[target.id].color = `rgba(${Math.random()*255}, ${Math.random()*255}, ${Math.random()*255}, 0.5)`;     },     getScreenPosition: function(value) {       const {el, color} = value;       const xrFrameSystem = wx.getXrFrameSystem();       // console.log("getScreenPosition" + xrFrameSystem);       if (!el || typeof el.getComponent !== 'function') {         console.error('Invalid element:', el);         return [0, 0, color, ''];       }       const transformComponent = el.getComponent(xrFrameSystem.Transform);       if (!transformComponent) {         console.error('Transform component not found on element:', el);         return [0, 0, color, ''];       }       this.tmpV3.set(transformComponent.worldPosition);       // this.tmpV3.set(el.getComponent(xrFrameSystem.Transform).worldPosition);       const clipPos = this.camera.convertWorldPositionToClip(this.tmpV3);       const {frameWidth, frameHeight} = this.scene;       return [((clipPos.x + 1) / 2) * frameWidth, (1 - (clipPos.y + 1) / 2) * frameHeight, color, el.id];     },     takephoto:function(){       console.log("user-xr takephoto ");       console.log("调试信息:", {         scene: this.scene,         sceneType: typeof this.scene,         sceneIsNull: this.scene === null,         sceneIsUndefined: this.scene === undefined,       });       if (!this.scene) {         console.error('场景未初始化，请确保 handleReady 已被调用');         wx.showToast({           title: '场景未准备好',           icon: 'none'         });         return;       }         // 确保场景已经准备就绪       if (!this.camera) {         wx.showToast({           title: '相机未准备就绪',           icon: 'none'         });         return;       }       console.log("user-xr takephoto 2");       const that = this;       try {         // 方法1: 通过相机组件截图         if (this.camera && this.camera.el) {           console.log("使用相机组件截图");                      // 获取相机元素的渲染目标           const cameraEl = this.camera.el;           if (cameraEl && typeof cameraEl.exportImage === 'function') {             cameraEl.exportImage({               success: function(res) {                 console.log("相机截图成功:", res);                 that.handlePhotoSuccess(res.tempFilePath);               },               fail: function(err) {                 console.error('相机截图失败:', err);                 that.tryAlternativeCapture();               }             });           } else {             // 方法2: 尝试通过场景的 canvas 截图             console.log("尝试通过场景 canvas 截图");             this.trySceneCanvasCapture();           }         } else {           console.log("尝试通过场景 canvas 截图");           this.trySceneCanvasCapture();         }       } catch (error) {         console.error('截图过程出错:', error);         this.tryAlternativeCapture();       }        },     tryAlternativeCapture: function() {       const that = this;              // 尝试通过 xr-camera 组件截图       if (this.camera && this.camera.el) {         console.log("尝试通过 camera 元素截图");         // 这里可以添加通过相机元素截图的逻辑                  wx.showToast({           title: '截图功能暂不可用',           icon: 'none'         });                  // 触发失败事件         this.triggerEvent('phototaken', {           success: false,           error: '截图功能不可用'         });       }     },     handlePhotoSuccess: function(filePath) {       const that = this;              this.setData({         tempImagePath: filePath       });       console.log("user-xr takephoto success: " + filePath);       this.saveImage();       // 触发事件将结果返回给父组件       this.triggerEvent('phototaken', {         success: true,         filePath: filePath       });     },     takephotoFromPage: function() {       // 这个方法需要从页面调用，通过 selectComponent 获取 XR 组件       // 然后调用组件的截图方法       try {         // 如果您的页面中有对组件的引用         if (this.scene && typeof this.scene.exportImage === 'function') {           this.scene.exportImage({             success: (res) => {               this.handlePhotoSuccess(res.tempFilePath);             },             fail: (err) => {               console.error('截图失败:', err);               this.triggerEvent('phototaken', {                 success: false,                 error: err               });             }           });         }       } catch (e) {         console.error('截图异常:', e);       }     },     saveImage:function(){       const that = this;       wx.getSetting({         success: (res) => {           if (!res.authSetting['scope.writePhotosAlbum']) {             // 没有权限，请求权限             wx.authorize({               scope: 'scope.writePhotosAlbum',               success: () => {                 // 授权成功，保存图片                 that.saveImageToPhotosAlbum();               },               fail: (err) => {                 console.error('相册授权失败', err);                 // 引导用户打开授权设置                 that.showAuthGuide();               }             });           } else {             // 已有权限，直接保存             that.saveImageToPhotosAlbum();           }         }       });     },          saveImageToPhotosAlbum:function(){       wx.saveImageToPhotosAlbum({         filePath: this.data.tempImagePath,         success: () => {           wx.showToast({             title: '保存成功',             icon: 'success',             duration: 2000           });         },         fail: (err) => {           console.error('保存失败', err);           // 处理保存失败的特定情况           if (err.errMsg.includes('auth deny')) {             this.showAuthGuide();           } else {             wx.showToast({               title: '保存失败',               icon: 'none',               duration: 2000             });           }         }       });     },     showAuthGuide:function(){       wx.showModal({         title:'提示',         content:'需要您授权保存到相册权限',         confirmText: '去设置',         success: (res) => {           if (res.confirm) {             // 打开设置页面             wx.openSetting({               success: (settingRes) => {                 if (settingRes.authSetting['scope.writePhotosAlbum']) {                   wx.showToast({                     title: '授权成功',                     icon: 'success'                   });                 }               }             });           }         }       })     },   },   observers:{     'cameraPosition': function(eve) {       console.log('用户:', eve);     },     "currentState":function(state){       console.log('当前状态:', state);       if(this.data.currentState !== state){         this.setData({           currentState:state,         },()=>{             console.log("user-xr currentState:" + this.data.currentState);             if(state === SceneState.TakePhoto){                 this.takephoto();             }         });       };     }   } })请问哪里不对？

https://developers.weixin.qq.com/miniprogram/dev/framework/xr-frame/ 你们的案例demo在什么位置，你们的开发文档之说查看demo，但是文档里根本没有 demo的地址，