const { XRGLTF, GLTF, Animator, Transform, XRLight, Light, XRMesh, Mesh, XRNode, ARTracker, Vector3, Matrix4, Quaternion, Camera, CameraOrbitControl} = wx.getXrFrameSystem(); ... const obj = scene.createElement(XRMesh, { states: 'cullOn:false', geometry: 'plane', material: "videoTransparentTopByBottom", uniforms: `u_baseColorMap:video-animal`, }); const mesh = obj.getComponent(Transform); const arV4 = Matrix4.lookAt(mesh.position, camera.position, Vector3.Up); let xx = new Vector3(), m4 = new Matrix4(), zz = new Vector3(); const isDeal = arV4.decomposeTransRotMatScale(xx, m4, zz); if(isDeal) { const quat = Quaternion.createFromMatrix4(m4); mesh.quaternion.set(quat); } 需求是需要这个视频始终面向相机 目前，相机移动过程中，arV4一直是不变 请问下lookAt上的使用问题还是decomposeTransRotMatScale上的问题？ 解决思路是对的么

尝试用外层view组件但是回呗xrframe直接覆盖,那么在XR-FRAME中该如何实现相机移动的过程中始终处于相机固定位置 用于制作轮盘,方向键

渲染透明视频可以通过将透明视频通道转换为灰度图的方式，利用uv将透明叠加到视频上。shader处理如下：  vec4 color = texture2D(u_baseColorMap, vec2(vTextureCoord.x*0.5,vTextureCoord.y));  vec4 colora = texture2D(u_baseColorMap, vec2(vTextureCoord.x*0.5 + 0.5,vTextureCoord.y)); vec4 baseColor = vec4(color.xyz,colora.x); gl_FragData[0] = baseColor; 具体代码： const xrFrameSystem = wx.getXrFrameSystem(); function createVideoTsbsEffect(scene) {     return scene.createEffect(         {             "name": "video-tsbs",             "properties": [                 {                     "key": "u_baseColorFactor",                     "type": 3,                     "default": [1, 1, 1, 0]                 }             ],             "images": [{ "key": "u_baseColorMap", "default": "white", "macro": "WX_USE_BASECOLORMAP" }],             "defaultRenderQueue": 3000,             "passes": [                 {                     "renderStates": { "cullOn": true, "blendOn": true, "depthWrite": true, "cullFace": 2 },                     "lightMode": "ForwardBase",                     "useMaterialRenderStates": true,                     "shaders": [0, 1]                 }],             "shaders": [                 `#version 100   precision highp float;   attribute vec3 a_position;   attribute vec2 a_texCoord;   uniform mat4 u_projection;   uniform mat4 u_world;   uniform mat4 u_view;   varying highp vec2 vTextureCoord;      void main()   {     vTextureCoord = a_texCoord;     gl_Position = u_projection * u_view * u_world * vec4(a_position,1.0);   }`,                 `#version 100   precision highp float;   uniform highp vec4 u_baseColorFactor;   #ifdef WX_USE_BASECOLORMAP     uniform sampler2D u_baseColorMap;   #endif   varying highp vec2 vTextureCoord;   void main()   { #ifdef WX_USE_BASECOLORMAP   vec4 color = texture2D(u_baseColorMap, vec2(vTextureCoord.x*0.5,vTextureCoord.y));   vec4 colora = texture2D(u_baseColorMap, vec2(vTextureCoord.x*0.5 + 0.5,vTextureCoord.y));     vec4 baseColor = vec4(color.xyz,colora.x); #else     vec4 baseColor = u_baseColorFactor; #endif   gl_FragData[0] = baseColor;   }       `]         }     ) } xrFrameSystem.registerEffect("video-tsbs", createVideoTsbsEffect); wxml: <xr-scene  bind:ready="handleReady">     <xr-assets>         <xr-asset-load type="texture" asset-id="waifu" src="https://mmbizwxaminiprogram-1258344707.cos.ap-guangzhou.myqcloud.com/xr-frame/demo/waifu.png" />         <xr-asset-load type="video-texture" asset-id="test" src="https://demo.uality.cn/output-lr.mp4" options="autoPlay:true,loop:true" />         <xr-asset-material asset-id="video-tsbs-mat" effect="video-tsbs" uniforms="u_baseColorMap:video-test" />     </xr-assets>     <xr-mesh node-id="cube" geometry="cube" material="video-tsbs-mat" />     <xr-camera clear-color="0.4 0.8 0.6 1" position="0 1 4" target="cube" camera-orbit-control /> </xr-scene> 视频生成： 通过ffmpeg生成将带有透明通道的mov格式视频转换为左（rgb通道信息）右（alpha通道信息）的MP4视频。 ffmpeg -i input.mov -vf "split [a], pad=iw*2:ih [b], [a] alphaextract, [b] overlay=w" -y output-lr.mp4 也可以用百度小程序“AFX透明视频”带的工具制作。（左右的话，直接修改shader的偏移就可以了） 转换出来的视频结果如下图： [图片]