要让2DUI跟随3D物件，比如说敌人头上有血条。请问要怎么做?

麥

所有的3D场景还有人物都是从Unity导入Laya里面的，如果我要让2DUI跟随3D物件，比如说，敌人头上有血条。请问要怎么做?
(已经尝试过Unity做好血条再导出到Laya是看不见的)

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let out = window.app.fcUtil.worldToViewportPoint(this.owner.transform.position, window.GameMag.Camera1);
this.hpNode.x = out.x - this.hpNode.width / 2
this.hpNode.y = out.y + this.hpNode.height *3.5
//this.owner.transform 3d的物体
//this.hpNode 2d的ui

//3d坐标转2d屏幕坐标

    /**
     * 
     * @param {*} point 3d世界坐标
     * @param {*} camera 摄像机
     */
    worldToViewportPoint(point, camera) {
        let pos = new Laya.Vector3(point.x, point.y, point.z);;
        let out = new Laya.Vector4(0, 0, 0, 0);
        camera.worldToViewportPoint(pos, out);
        return out;
    }