javascript - Phaser.js，javascript，未捕获的类型错误 : Cannot read property 'forEach' of undefined

Question

我是 Phaser.js 和 Javascript 的初学者。我正在制作一款游戏，但遇到了一个错误，我不知道如何修复它。 我想我可以解释为什么会发生这种情况:当我调试 phisics 组 SpritesPlatform 时显示它不是未定义的..我不知道为什么..

这是我遇到错误的文件(我无法将整个应用程序放在这里，因为有很多文件，但问题仅涉及此文件，并且 Sprite 被加载到另一个文件中)。

文件 game.js (main.js)

MyGame.Game = function (game) {
    this.game;      //  a reference to the currently running game (Phaser.Game)
    this.add;       //  used to add sprites, text, groups, etc (Phaser.GameObjectFactory)
    this.load;      //  for preloading assets (Phaser.Loader)
    this.stage;     //  the game stage (Phaser.Stage)
    this.state;     //  the state manager (Phaser.StateManager)
    this.world;     //  the game world (Phaser.World)
    this.physics;   //  the physics manager (Phaser.Physics)
};

MyGame.Game.prototype = {

    init: function () {

            this.game.renderer.renderSession.roundPixels = true;
            this.physics.startSystem(Phaser.Physics.ARCADE);
            this.physics.arcade.gravity.y = 800;

    },

    create: function () {

        // background color bleu
        this.stage.backgroundColor = 0x479cde;

        //add sprites into physics group
        SpritesPlatform = this.game.add.physicsGroup();
        a = SpritesPlatform.create(0, 150, 'sprite');
        a.scale.setTo(0.2, 0.2);
        b = SpritesPlatform.create(79, 187, 'sprite2');
        b.scale.setTo(0.2, 0.2);
        c = SpritesPlatform.create(300, 100, 'sprite3');
        c.scale.setTo(0.4, 0.4);

        SpritesPlatform.setAll('body.allowGravity', false);
        SpritesPlatform.setAll('body.immovable', true);
        SpritesPlatform.setAll('body.velocity.x', 150);

        //test to see if the group contains the sprites
        /*var i = 0;
        for (var i = 0, len = SpritesPlatform.children.length; i < len; i++) {
            console.log(SpritesPlatform.children[i]);
        }*/

        //debug
        console.log(this.game.SpritesPlatform); // prints undefined .. why???


  },

    // repeat the mouvement of the sprites when it crosses the screen
    wrapSprites: function (SpritesPlatform) {

           if (SpritesPlatform.body.velocity.x < 0 && SpritesPlatform.x <= -160)
            {
                SpritesPlatform.x = 800;
            }

        },


    update: function () {

        console.log(this.game.SpritesPlatform); // prints undefined  also of course... ?? why??
        //the error is here ... if i put this in comment the code will display the board and the sprite ...
        //this.game.SpritesPlatform.forEach(this.game.wrapSprites, this.game);
    },
};

问题出在更新函数中://this.game.SpritesPlatform.forEach(this.game.wrapSprites, this.game);

看起来 SpritesPlatform 未定义，我不明白为什么以及我缺少什么。

感谢您的帮助。

Answer 1

当你第一次创建组时，你必须这样声明它:

this.SpritesPlatform = this.game.add.physicsGroup();

无论何时您想引用该组，都可以使用 console.log(this.SpritesPlatform)

编辑:

你实际上不必做那样的事情

MyGame.Game = function (game) {
  this.game;      //  a reference to the currently running game (Phaser.Game)
  this.add;       //  used to add sprites, text, groups, etc (Phaser.GameObjectFactory)
  this.load;      //  for preloading assets (Phaser.Loader)
  this.stage;     //  the game stage (Phaser.Stage)
  this.state;     //  the state manager (Phaser.StateManager)
  this.world;     //  the game world (Phaser.World)
  this.physics;   //  the physics manager (Phaser.Physics)
};

所有这些属性都很容易访问，因此您可以在状态内的任何地方使用它们。这应该可以正常工作:

MyGame.Game = function () {
};