首次加载游戏未定义变量时出现相位器错误 [英] Phaser error on first load of game undefined variables

问题描述

当我在Google Chrome和Firefox中运行游戏时，游戏屏幕为黑色，刷新后即可正常运行.

When I run my game in Google Chrome and Firefox, the game screen is black, once I refresh it, it runs as it should.

当屏幕为黑色时，我在控制台中看到的错误是:

The error I see in the console when the screen is black is:

TypeError:桨未定义(Firefox)

TypeError: paddle is undefined (Firefox)

未捕获的TypeError:无法读取未定义(Chrome)的属性"x"

Uncaught TypeError: Cannot read property 'x' of undefined (Chrome)

我也有一个警告:

Phaser.Loader-取消/重置活动加载(Firefox和Chrome)

Phaser.Loader - active loading canceled / reset (Firefox & Chrome)

我的代码的相关部分是:

The relevant part of my code is:

var game = new Phaser.Game(800, 560, Phaser.AUTO, 'phaser-canvas', { preload: preload, create: create, update: update });

function setUpLevel(i) {
    $.getJSON("levels.json", function(json) {
            paddle.x = json.levels[i].paddle_startX;
    });
}

function processPaddle() {
    var paddle_loc = paddle.x + 80
}

function preload() {    
    //>Game assets
    game.load.image('paddle', 'assets/img/Paddle.png');

    // Load JSON file describing the level
    game.load.json('levels', 'levels.json');
}

//Paddle
var paddle;
var paddle_vel;

var json;

// The function below will be automatically invoked by Phaser when
// the assets in the preload() function finished loading

function create() {
    game.load.reset(true);

    var json = game.cache.getJSON('levels');

    // Enque the load of the background images found inside the level file

    for (var i = 0; i < json.levels.length; i++) {
        game.load.image('background' + i.toString(), json.levels[i].background);
    }

    // Specify loadComplete() as a callback to be called when all assets finished loading

    game.load.onLoadComplete.add(loadComplete, this);

    // Load the newly enqued assets

    game.load.start();
}

// The function below will be automatically invoked by Phaser when
// the assets in the create() function finished loading

function loadComplete() {
    json = game.cache.getJSON('levels');

    game.physics.startSystem(Phaser.Physics.ARCADE);

    paddle = mid_layer.create(100, 400, 'paddle');
    game.physics.enable(paddle, Phaser.Physics.ARCADE);

    paddle.scale.setTo(0.7, 0.7);
    paddle.body.immovable = true;
    paddle.body.collideWorldBounds = true;

    setUpLevel(current_level);    
}

 function update() {
        processPaddle();
 }

我猜错误是因为loadComplete()函数尚未完成，并且update()函数已经启动，它使用了paddle变量，但尚未分配值-但是我没有当然.

I guess the error is because the loadComplete() function hasn't finished yet, and the update() function has started, which uses the paddle variable, which hasn't been assigned a value yet - But I'm not sure.

推荐答案

update函数将在create完成后立即开始触发，但是在您这种情况下，桨叶不存在，因此会出现错误开始被抛出.我建议您将游戏分解为多个状态，启动"状态可以加载json +预加载器资产，然后可以切换到预加载器"状态，以提取所需的所有资产(从json读取) .完成后，您可以进入游戏状态或类似状态.这样也可以使您的东西(逻辑上)保持清洁.

The update function will start firing as soon as create completes, but in your case the paddle doesn't exist by that point, so errors will start being thrown. I would suggest you break your game down into States, a 'Boot' state could load your json + preloader assets, and then you can swap to a 'Preloader' state which pulls in all the assets you need (as read from the json). Upon completion you can move to a Game state or similar. It would help keep things cleaner (logically) for you as well.

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