如何解决Babylon.js中AudioContext was not allowed to start异常问题

当在BabylonJS中使用音频引擎时，可能会遇到以下错误：

audioEngine.ts:172 The AudioContext was not allowed to start. It must be resumed (or created) after a user gesture on the page. https://goo.gl/7K7WLu

这个错误是因为浏览器的安全策略要求音频上下文必须在用户事件（例如单击、键盘按键等）中启用。这意味着，如果您尝试在没有用户事件的情况下自动播放音乐，则会抛出此错误。

为了解决这个问题，我们需要启用音频上下文。在BabylonJS中，可以通过AudioEngine()类来创建音频上下文。您可以使用以下代码在用户事件触发后启用音频上下文：

let audioContext = new AudioEngine().audioContext;
audioContext.resume();

在以上示例中，我们创建了一个AudioEngine实例，并从中获取了音频上下文。接下来，我们调用resume()方法启用音频上下文。请注意，在启用之前，必须先检查音频上下文是否存在。如果不存在，则需要将其创建。

这样就可以成功地启用音频上下文，然后您可以在BabylonJS中播放音频文件而不会遇到错误。

示例源码(修改前)：

playingSoundSprites = (scene: Scene, canvas: HTMLCanvasElement) => {
        var freeCamera = new FreeCamera("freeCamera", new Vector3(0, 0, 0), scene);
        var theSound = new Sound("allSounds", "https://playground.babylonjs.com/sounds/6sounds.mp3", scene, null, {autoplay: false});
        var isPlaying = 0;
        let audioContext = new AudioEngine().audioContext;
        var soundArray = [
            [0.0, 5.000],
            [5.100, 6.600],
            [12.000, 1.600],
	        [14.000, 9.200],
	        [23.000, 7.900],
	        [31.000, 2.800],
        ];
        theSound.onended = function() {
            isPlaying = 0;
            console.log("not playing");
        };

        var advanceTexture = AdvancedDynamicTexture.CreateFullscreenUI("UI");
        var uiPanel = new StackPanel();
        uiPanel.width = "220px";
        uiPanel.fontSize = "14px";
        uiPanel.horizontalAlignment = Control.HORIZONTAL_ALIGNMENT_CENTER;
        uiPanel.verticalAlignment = Control.VERTICAL_ALIGNMENT_CENTER;
        advanceTexture.addControl(uiPanel);

        var button = Button.CreateSimpleButton("but", "Play All Sounds");
        button.paddingTop = "10px";
        button.width = "150px";
        button.height = "50px";
        button.color = "white";
        button.background = "green";
        button.onPointerDownObservable.add(function() {
            if (isPlaying === 0) {
                isPlaying = 1;
                theSound.play();
                console.log("playing");
            }
        });
        uiPanel.addControl(button);

        var button1 = Button.CreateSimpleButton("but1", "Play Random Sound");
        button1.paddingTop = "10px";
        button1.width = "150px";
        button1.height = "50px";
        button1.color = "white";
        button1.background = "green";
        button1.onPointerDownObservable.add(function() {
            if (isPlaying === 0) {
                isPlaying = 1;
                var randomSound = Math.floor(Math.random() * 6);
                theSound.play(0, soundArray[randomSound][0], soundArray[randomSound][1]);
                console.log("playing");
            }
        });
        uiPanel.addControl(button1);

        return scene;
    }

运行结果如下：

不能播放声音，在浏览器控制台，查看日志如下：

The AudioContext was not allowed to start. It must be resumed (or created) after a user gesture on the page. https://goo.gl/7K7WLu

示例源码（修改后）：

playingSoundSprites = (scene: Scene, canvas: HTMLCanvasElement) => {
        var freeCamera = new FreeCamera("freeCamera", new Vector3(0, 0, 0), scene);
        var theSound = new Sound("allSounds", "https://playground.babylonjs.com/sounds/6sounds.mp3", scene, null, {autoplay: false});
        var isPlaying = 0;
        var soundArray = [
            [0.0, 5.000],
            [5.100, 6.600],
            [12.000, 1.600],
	        [14.000, 9.200],
	        [23.000, 7.900],
	        [31.000, 2.800],
        ];
        theSound.onended = function() {
            isPlaying = 0;
            console.log("not playing");
        };

        var advanceTexture = AdvancedDynamicTexture.CreateFullscreenUI("UI");
        var uiPanel = new StackPanel();
        uiPanel.width = "220px";
        uiPanel.fontSize = "14px";
        uiPanel.horizontalAlignment = Control.HORIZONTAL_ALIGNMENT_CENTER;
        uiPanel.verticalAlignment = Control.VERTICAL_ALIGNMENT_CENTER;
        advanceTexture.addControl(uiPanel);

        var button = Button.CreateSimpleButton("but", "Play All Sounds");
        button.paddingTop = "10px";
        button.width = "150px";
        button.height = "50px";
        button.color = "white";
        button.background = "green";
        button.onPointerDownObservable.add(function() {
            let audioContext = new AudioEngine().audioContext;
            audioContext!.resume().then(() => {
                if (isPlaying === 0) {
                    isPlaying = 1;
                    theSound.play();
                    console.log("playing");
                }
            });
            
        });
        uiPanel.addControl(button);

        var button1 = Button.CreateSimpleButton("but1", "Play Random Sound");
        button1.paddingTop = "10px";
        button1.width = "150px";
        button1.height = "50px";
        button1.color = "white";
        button1.background = "green";
        button1.onPointerDownObservable.add(function() {
            let audioContext = new AudioEngine().audioContext;
            audioContext!.resume().then(() => {
                if (isPlaying === 0) {
                    isPlaying = 1;
                    var randomSound = Math.floor(Math.random() * 6);
                    theSound.play(0, soundArray[randomSound][0], soundArray[randomSound][1]);
                    console.log("playing");
                }
            });
        });
        uiPanel.addControl(button1);

        return scene;
    }