尝试将界面HUD绘制到单独的Canvas（实际代码用PIXI.js创建Canvas), 然后将该Canvas作为纹理绘制到THREE.js 3D的Mesh中，

模拟器和iOS能正常显示纹理，Android显示为黑色，如果将getContext('webgl')改为getContext('2d')然后fillRect, 几种平台都能正常显示。

猜测，在Android下只能获取一个webgl Canvas

var canvas = wx.createCanvas();

     ...

    var gl = this.canvas.getContext('webgl', {});

    gl.clearColor(1.0, 0.0, 0.0, 1.0);

    gl.clear(gl.COLOR_BUFFER_BIT|gl.DEPTH_BUFFER_BIT);

...

    var texture = new THREE.CanvasTexture(canvas);

    texture.minFilter = THREE.LinearFilter;

    var material = new THREE.MeshBasicMaterial({ map: texture, transparent: true });

   var geometry = new THREE.PlaneGeometry(canvas.width / window.devicePixelRatio / PIXELS_PER_UNIT,

                                                                          canvas.height / window.devicePixelRatio / PIXELS_PER_UNIT);

    var sprite3D = new THREE.Mesh(geometry, material);

   ...

    scene3D.add(sprite3D);

测试问题机： 小米8，小米MIX