Update function

[YuShaN]

Hi everyone. I have a trouble with funtion update. This is my code.

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, this);    }}

Now i want my enemy can shoot bullet. I wrote a group bullet for enemy in funtion creat

 

this.enemyBullets = this.game.add.group();

        this.enemyBullets .enableBody = true;

        this.enemyBullets .physicsBodyType = Phaser.Physics.ARCADE;

        this.enemyBullets .createMultiple(300, 'lunaBullet');

        this.enemyBullets .setAll('alpha', 0.9);

        this.enemyBullets .setAll('anchor.x', 0.5);

        this.enemyBullets .setAll('anchor.y', 0.5);

        this.enemyBullets .setAll('outOfBoundsKill', true);

        this.enemyBullets .setAll('checkWorldBounds', true);

        this.enemyBullets .forEach(function(enemy){

            enemy.body.setSize(15, 15);

        });

Now i wrote a function update for my enemy

    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);              this.enemy.update = function() {                this.enemyBullet = this.enemyBullets.getFirstExists(false);                if (this.enemyBullet && this.alive && this.y > 0 && this.game.time.now > 2000 + this.lastShot){                    this.lastShot = this.game.time.now;                    this.enemyBullet.reset(this.enemy.x, this.enemy.y + this.enemy.height / 2);                    this.enemyBullet.damageAmount = 20;                    this.angle = this.game.physics.arcade.moveToObject(this.lunaBullet, this.player, 150);                    this.enemyBullet.angle = this.game.math.radToDeg(this.angle);                    this.enemyBullet.update = function() {                        if (this.x > (this.game.width-320)) {                            this.kill();                        }                    }                }            }                 }        //  time creat enemy        this.enemyTimer = this.game.time.events.add(this.game.rnd.integerInRange(1500, 3000), this.launchEnemy);    }}

I don't know how to call enemyBulets. I can't write this.this.enemyBullets. Someone help me. Thank you!

[chongdashu]

Hi, I think it's the same issue from your previous thread.

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

You are again not setting the context for the callback. Hence, the "this" in this.enemyBullets will be referring to the Window and not the state object itself.

[YuShaN]

Hi, I think it's the same issue from your previous thread.

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

You are again not setting the context for the callback. Hence, the "this" in this.enemyBullets will be referring to the Window and not the state object itself.

 

Yes. I know but how to call  enemybullets to state object

[chongdashu]

As mentioned, you need to make sure you pass in this as the third parameter to the events.add() method in order to to use this.enemyBullets. 

 

When launchEnemy gets called in your current version of the code, the "this" will refer to the Window, which doesn't have the enemyBullets group. If you change your code to pass in "this" as the third param, it will ensure that the context of "this" in enemyBullets refers to the state object, and not the window. 

[YuShaN]

As mentioned, you need to make sure you pass in this as the third parameter to the events.add() method in order to to use this.enemyBullets. 

 

When launchEnemy gets called in your current version of the code, the "this" will refer to the Window, which doesn't have the enemyBullets group. If you change your code to pass in "this" as the third param, it will ensure that the context of "this" in enemyBullets refers to the state object, and not the window. 

launchEnemy: function() {        this.enemy = this.enemyGroup.getFirstExists(false);        this.enemyBullet = this.enemyBullets.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);              this.enemy.update = function() {                if (this.enemyBullet && this.alive && this.y > 0 && this.game.time.now > 2000 + this.lastShot){                    this.lastShot = this.game.time.now;                    this.enemyBullet.reset(this.enemy.x, this.enemy.y + this.enemy.height / 2);                    this.enemyBullet.damageAmount = 20;                    this.angle = this.game.physics.arcade.moveToObject(this.lunaBullet, this.player, 150);                    this.enemyBullet.angle = this.game.math.radToDeg(this.angle);                    this.enemyBullet.update = function() {                        if (this.x > (this.game.width-320)) {                            this.kill();                        }                    }                }            }                 }        //  time creat enemy        this.enemyTimer = this.game.time.events.add(this.game.rnd.integerInRange(1500, 3000), this.launchEnemy, this);    }}

I changed like it. Enemy appear but they don't shoot. My brain hurt

[chongdashu]

Hi, I'm not sure what was changed -- but what's being suggested is still not being addressed.

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);

Take a look at the documentation of Phaser.Timer's add() method here: http://phaser.io/docs/2.4.4/Phaser.Timer.html#add

 

It states that it takes three compulsory arguments: delay, callback, and context. In your code, you are never setting the context. If you do not set the context parameter to "this" when you call it, it will never know to use the State object as opposed to the Window object.

 

In the suggested fix, it adds "this" as the context for the callback. This means when you do this.enemyBullets, the this will be in the context of the State object (because you passed it in as the third parameter)

[YuShaN]

Hi, I'm not sure what was changed -- but what's being suggested is still not being addressed.

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);

Take a look at the documentation of Phaser.Timer's add() method here: http://phaser.io/docs/2.4.4/Phaser.Timer.html#add

 

It states that it takes three compulsory arguments: delay, callback, and context. In your code, you are never setting the context. If you do not set the context parameter to "this" when you call it, it will never know to use the State object as opposed to the Window object.

 

In the suggested fix, it adds "this" as the context for the callback. This means when you do this.enemyBullets, the this will be in the context of the State object (because you passed it in as the third parameter)

If don't use this how to call bulletEnemy to use for update function of enemy? I really don't understand.

[chongdashu]

Let me set up a fiddle and see if i can replicate it.

[YuShaN]

I can't upload my project to forum so this is link download it. Please check it for me. Thank you

http://www.mediafire.com/download/87j9kwq4hv3gflw/demo.rar

[chongdashu]

Hi, sorry about my mistake. I realized that you did indeed make the change as I suggested - I just didn't realize it. Sorry about that.
 
However, I spotted where your error is - please take a look:

var state = this;this.enemy.update = function () {    // Note:    // You are now within an inner function of a Phaser.Sprite of the enemy    // Thus, if you use "this" here, it will be referring to the Phaser.Sprite, not the GameState.    // You need to use "state" here, which was created above before entering the function.    this.enemyBullet = state.enemyBullets.getFirstExists(false, true, this.x, this.y, "bullet");    if (!this.lastShot) {        this.lastShot = 0;    }    if (this.enemyBullet && this.alive && this.y > 0 && state.game.time.now > 2000 + this.lastShot) {        this.lastShot = state.game.time.now;        //this.enemyBullet.reset(this.x, this.y + this.height / 2);        this.enemyBullet.damageAmount = 20;        this.angle = state.game.physics.arcade.moveToObject(this.enemyBullet, state.player, 150);        this.enemyBullet.angle = state.game.math.radToDeg(this.angle);        this.enemyBullet.update = function () {            // Note:            // You are now within a Phaser.Sprite of an enemy bullet.            // So you can not use "this" here to refer to the state.            // (e.g., state.game is needed, *not* this.game             if (this.x > (state.game.width - 320)) {                this.kill();            }        }    }}

I've got a (semi) working example here: https://jsfiddle.net/chongdashu/yt9rLfuf/

[YuShaN]

Hi, sorry about my mistake. I realized that you did indeed make the change as I suggested - I just didn't realize it. Sorry about that.

 

However, I spotted where your error is - please take a look:

var state = this;this.enemy.update = function () {    // Note:    // You are now within an inner function of a Phaser.Sprite of the enemy    // Thus, if you use "this" here, it will be referring to the Phaser.Sprite, not the GameState.    // You need to use "state" here, which was created above before entering the function.    this.enemyBullet = state.enemyBullets.getFirstExists(false, true, this.x, this.y, "bullet");    if (!this.lastShot) {        this.lastShot = 0;    }    if (this.enemyBullet && this.alive && this.y > 0 && state.game.time.now > 2000 + this.lastShot) {        this.lastShot = state.game.time.now;        //this.enemyBullet.reset(this.x, this.y + this.height / 2);        this.enemyBullet.damageAmount = 20;        this.angle = state.game.physics.arcade.moveToObject(this.enemyBullet, state.player, 150);        this.enemyBullet.angle = state.game.math.radToDeg(this.angle);        this.enemyBullet.update = function () {            // Note:            // You are now within a Phaser.Sprite of an enemy bullet.            // So you can not use "this" here to refer to the state.            // (e.g., state.game is needed, *not* this.game             if (this.x > (state.game.width - 320)) {                this.kill();            }        }    }}

I've got a (semi) working example here: https://jsfiddle.net/chongdashu/yt9rLfuf/

Yeah! var state = this. Then use it. Why i don't think about it. I feel so stupid (

Thank you so much.

[chongdashu]

No, it was my fault for not checking your code earlier.

 

Anyway, I updated the jsFiddle: https://jsfiddle.net/chongdashu/yt9rLfuf/

 

It has better logic to handle the shooting of bullets and some graphics. It's not well commented though. But hope it helps!

Good work!