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Trouble with .getFirstExists


YuShaN
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Hi everyone, I made a game with one only state. It's running good but music load slow. So I trying change it to many state(for loading source at a state before start game). But at state game (this state run game). I got at error at line 118 (this.enemy = this.enemyGroup.getFirstExists(false);)

 

Uncaught TypeError: Cannot read property 'getFirstExists' of undefined

but at line 107 (this.playerBullet = this.playerBulletGroup.getFirstExists(false);) that method .getFirstExists run normal ( when i remove function lauchEnemy & line 67 (this.game.time.events.add(2000, this.launchEnemy);) i can move and shoot normal no error). Someone help me :(. Thank you for reading. This is my code 

BasicGame.Game = function (game) {    //	When a State is added to Phaser it automatically has the following properties set on it, even if they already exist:    this.game;		//	a reference to the currently running game    this.add;		//	used to add sprites, text, groups, etc    this.camera;	//	a reference to the game camera    this.cache;		//	the game cache    this.input;		//	the global input manager (you can access this.input.keyboard, this.input.mouse, as well from it)    this.load;		//	for preloading assets    this.math;		//	lots of useful common math operations    this.sound;		//	the sound manager - add a sound, play one, set-up markers, etc    this.stage;		//	the game stage    this.time;		//	the clock    this.tweens;	//	the tween manager    this.world;		//	the game world    this.particles;	//	the particle manager    this.physics;	//	the physics manager    this.rnd;		//	the repeatable random number generator    //  You can use any of these from any function within this State.    //  But do consider them as being 'reserved words', i.e. don't create a property for your own game called "world" or you'll over-write the world reference.    this.background;    this.player;    this.playerBullet;    this.playerBulletGroup;    this.shoot;    this.enemy;    this.enemyGroup;    this.cursors;    this.bulletTimer = 0;    this.enemyTimer;};BasicGame.Game.prototype = {    create: function () {        // Background        background = this.game.add.tileSprite(0, 0, 500, 600, 'background');        // Player        this.player = this.game.add.sprite(300, 300, 'cirno');        this.player.anchor.setTo(0.5, 0.5);        this.game.physics.enable(this.player, Phaser.Physics.ARCADE);        // Player BulletGroup        this.playerBulletGroup = this.game.add.group();        this.playerBulletGroup.enableBody = true;        this.playerBulletGroup.physicsBodyType = Phaser.Physics.ARCADE;        this.playerBulletGroup.createMultiple(200, 'bullet');        this.playerBulletGroup.setAll('anchor.x', 0.5);        this.playerBulletGroup.setAll('anchor.y', 1);        this.playerBulletGroup.setAll('outOfBoundsKill', true);        this.playerBulletGroup.setAll('checkWorldBounds', true);        this.playerBulletGroup.forEach(function(enemy){            enemy.body.setSize(15, 70);        });        //  Enemy        this.enemyGroup = this.game.add.group();        this.enemyGroup.enableBody = true;        this.enemyGroup.physicsBodyType = Phaser.Physics.ARCADE;        this.enemyGroup.createMultiple(10, 'luna');        this.enemyGroup.setAll('anchor.x', 0.5);        this.enemyGroup.setAll('anchor.y', 0.5);        this.enemyGroup.setAll('outOfBoundsKill', true);        this.enemyGroup.setAll('checkWorldBounds', true);        this.enemyGroup.forEach(function(enemy){            enemy.body.setSize(30, 30);        });        // Lauch enemy        this.game.time.events.add(2000, this.launchEnemy);        // Key input        this.cursors = this.game.input.keyboard.createCursorKeys();        this.shoot = this.game.input.keyboard.addKey(Phaser.Keyboard.Z);    },    update: function () {        // scroll bg        background.tilePosition.y += 1;        // Reset velocity & set size        this.player.body.velocity.setTo(0, 0);        this.player.body.setSize(10, 10);        if (this.cursors.left.isDown && !this.cursors.right.isDown) {            if(this.player.x >50){                this.player.body.velocity.x = -300;            }        }        else if (this.cursors.right.isDown && !this.cursors.left.isDown) {            if (this.player.x < 450){                this.player.body.velocity.x = 300;            }        }        if (this.cursors.up.isDown && !this.cursors.down.isDown) {            if(this.player.y >50){                this.player.body.velocity.y = -300;            }        }        else if (this.cursors.down.isDown && !this.cursors.up.isDown) {            if (this.player.y < this.game.height - 50){                this.player.body.velocity.y = 300;            }        }        //  Fire bullet        if (this.player.alive && this.shoot.isDown) {            this.fireBullet();        }    },    fireBullet: function() {        if (this.game.time.now > this.bulletTimer) {            this.playerBullet = this.playerBulletGroup.getFirstExists(false);            if (this.playerBullet) {                  this.playerBullet.alpha = 0.5;                      this.playerBullet.reset(this.player.x, this.player.y);                                this.playerBullet.body.velocity.y = -800;                this.bulletTimer = this.game.time.now + 80;            }                               }    },    launchEnemy: function() {        this.enemy = this.enemyGroup.getFirstExists(false);        if (this.enemy) {            this.enemy.reset(this.game.rnd.integerInRange(0, 480), -10);            this.enemy.body.velocity.x = this.game.rnd.integerInRange(-200, 200);            if (this.enemy.body.velocity.x >0) {                this.enemy.scale.x = -1;            }            else {                this.enemy.scale.x = 1;            }            this.enemy.body.velocity.y = this.game.rnd.integerInRange(10, 50);                   }        //  time creat enemy        this.enemyTimer = this.game.time.events.add(this.game.rnd.integerInRange(1500, 3000), this.launchEnemy);    }}
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The reason why it's failing is because the this variable in launchEnemy() is pointing to the Window element of the page.

 

You will need to set the context argument (3rd argument ) when adding event callbacks to make sure that methods you reference are then called back in the context of the game state, and now the window.

 

For e.g.,

this.game.time.events.add(2000, this.launchEnemy);

should be

this.game.time.events.add(2000, this.launchEnemy, this);

Similarly, this:

this.enemyTimer = this.game.time.events.add(this.game.rnd.integerInRange(1500, 3000), this.launchEnemy);

should be:

this.enemyTimer = this.game.time.events.add(this.game.rnd.integerInRange(1500, 3000), this.launchEnemy, this);

I have a working example of your code (but without your resources) at this jsFiddle: https://jsfiddle.net/chongdashu/79tf3t6n/

 

Hope it helps!

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The reason why it's failing is because the this variable in launchEnemy() is pointing to the Window element of the page.

 

You will need to set the context argument (3rd argument ) when adding event callbacks to make sure that methods you reference are then called back in the context of the game state, and now the window.

 

For e.g.,

this.game.time.events.add(2000, this.launchEnemy);

should be

this.game.time.events.add(2000, this.launchEnemy, this);

Similarly, this:

this.enemyTimer = this.game.time.events.add(this.game.rnd.integerInRange(1500, 3000), this.launchEnemy);

should be:

this.enemyTimer = this.game.time.events.add(this.game.rnd.integerInRange(1500, 3000), this.launchEnemy, this);

I have a working example of your code (but without your resources) at this jsFiddle: https://jsfiddle.net/chongdashu/79tf3t6n/

 

Hope it helps!

Thank you so much. Can I add you. I have many questions need help :(

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