Stop an object from being shootable

[GourmetGorilla]

I'm playing around with phasers invaders example game.

When the object is shot, instead of killing it I'm changing the sprite and moving it to the bottom of the screen. However, it can now be shot again. I don't want it to be shootable a 2nd time. I'm thinking that because the gamephysics are on the group 'aliens', there are probably two options.

a) Either I can take the single shot alien out of the group 'aliens' and hope that stops it from being shot a 2nd time.

Or there's some way of saying ' alien just shot = now protected from being shot again' , I tried the following to no avail.

alien.physicsBodyType = null;

This is my collision handler right now  

function collisionHandler (bullet, alien) {// When a bullet hits an alien we kill them bothbullet.kill();alien.loadTexture("cured");// move alien to bottomvar tween2 = game.add.tween(alien).to( { y: 300 }, 1000, Phaser.Easing.Linear.EaseIn, true);tween2.onComplete.add(doNext, this);tween2.start();

So, basically the changed sprite can still be shot at, I need to make it so it cannot be shot at.


Here's the full code:

var game = new Phaser.Game(800, 600, Phaser.AUTO, 'phaser-example', { preload: preload, create: create, update: update, render: render });function preload() {    game.load.image('bullet', 'assets/games/invaders/bullet.png');    game.load.image('enemyBullet', 'assets/games/invaders/enemy-bullet.png');    game.load.spritesheet('invader', 'assets/games/invaders/invader32x32x4.png', 32, 32);    game.load.spritesheet('cured', 'assets/games/invaders/happy32x32x4.png', 32, 32);    game.load.image('ship', 'assets/games/invaders/player.png');    game.load.spritesheet('kaboom', 'assets/games/invaders/explode.png', 128, 128);    game.load.spritesheet('love', 'assets/games/invaders/hearts.png', 128, 128);    game.load.image('starfield', 'assets/games/invaders/starfield.png');}var player;var aliens;var bullets;var bulletTime = 0;var cursors;var fireButton;var explosions;var explosions2;var starfield;var score = 0;var scoreString = '';var scoreText;var lives;var enemyBullet;var firingTimer = 0;var stateText;var livingEnemies = [];function create() {    game.physics.startSystem(Phaser.Physics.ARCADE);    //  The scrolling starfield background    starfield = game.add.tileSprite(0, 0, 800, 600, 'starfield');    //  Our bullet group    bullets = game.add.group();    bullets.enableBody = true;    bullets.physicsBodyType = Phaser.Physics.ARCADE;    bullets.createMultiple(30, 'bullet');    bullets.setAll('anchor.x', 0.5);    bullets.setAll('anchor.y', 1);    bullets.setAll('outOfBoundsKill', true);    bullets.setAll('checkWorldBounds', true);    // The enemy's bullets    enemyBullets = game.add.group();    enemyBullets.enableBody = true;    enemyBullets.physicsBodyType = Phaser.Physics.ARCADE;    enemyBullets.createMultiple(30, 'enemyBullet');    enemyBullets.setAll('anchor.x', 0.5);    enemyBullets.setAll('anchor.y', 1);    enemyBullets.setAll('outOfBoundsKill', true);    enemyBullets.setAll('checkWorldBounds', true);    //  The hero!    player = game.add.sprite(400, 535, 'ship');    player.anchor.setTo(0.5, 0.5);    game.physics.enable(player, Phaser.Physics.ARCADE);    //  The baddies!    aliens = game.add.group();    aliens.enableBody = true;    aliens.physicsBodyType = Phaser.Physics.ARCADE;    createAliens();    //  The score    scoreString = 'Score : ';    scoreText = game.add.text(10, 10, scoreString + score, { font: '34px Arial', fill: '#1C2840' });    //  Lives    lives = game.add.group();    game.add.text(game.world.width - 100, 10, 'Lives ', { font: '34px Arial', fill: '#1C2840' });    //  Text    stateText = game.add.text(game.world.centerX,game.world.centerY,' ', { font: '84px Arial', fill: '#5C85D6' });    stateText.anchor.setTo(0.5, 0.5);    stateText.visible = false;    for (var i = 0; i < 3; i++)     {        var ship = lives.create(game.world.width - 100 + (35 * i), 60, 'ship');        ship.anchor.setTo(0.5, 0.5);        ship.angle = 0;        ship.alpha = 0.5;    }    //  An explosion pool    explosions = game.add.group();    explosions.createMultiple(30, 'love');    explosions.forEach(setupInvader, this);    //  2nd explosion pool    explosions2 = game.add.group();    explosions2.createMultiple(30, 'kaboom');    explosions2.forEach(setupPlayer, this);    //  And some controls to play the game with    cursors = game.input.keyboard.createCursorKeys();    fireButton = game.input.keyboard.addKey(Phaser.Keyboard.SPACEBAR);    }function createAliens () {    for (var y = 0; y < 4; y++)    {        for (var x = 0; x < 10; x++)        {            var alien = aliens.create(x * 48, y * 50, 'invader');            alien.anchor.setTo(0.5, 0.5);            alien.animations.add('fly', [ 0, 1, 2, 3 ], 20, true);            alien.play('fly');            alien.body.moves = false;        }    }    aliens.x = 100;    aliens.y = 200;    //  All this does is basically start the invaders moving. Notice we're moving the Group they belong to, rather than the invaders directly.    var tween = game.add.tween(aliens).to( { x: 200 }, 2000, Phaser.Easing.Linear.None, true, 0, 1000, true);    //  When the tween loops it calls descend    tween.onLoop.add(descend, this);}function setupInvader (invader) {    invader.anchor.x = 0.5;    invader.anchor.y = 0.5;    invader.animations.add('love');}function setupPlayer (ship) {    ship.anchor.x = 0.5;    ship.anchor.y = 0.5;    ship.animations.add('kaboom');}function descend() {    aliens.y -= 10;}function update() {    //  Scroll the background  //  starfield.tilePosition.y += 2;    if (player.alive)    {        //  Reset the player, then check for movement keys        player.body.velocity.setTo(0, 0);        if (cursors.left.isDown)        {            player.body.velocity.x = -200;        }        else if (cursors.right.isDown)        {            player.body.velocity.x = 200;        }        //  Firing?        if (fireButton.isDown)        {            fireBullet();        }        if (game.time.now > firingTimer)        {            enemyFires();        }        //  Run collision        game.physics.arcade.overlap(bullets, aliens, collisionHandler, null, this);        game.physics.arcade.overlap(enemyBullets, player, enemyHitsPlayer, null, this);    }}function render() {    // for (var i = 0; i < aliens.length; i++)    // {    //     game.debug.body(aliens.children[i]);    // }}function collisionHandler (bullet, alien) {    //  When a bullet hits an alien we kill them both    bullet.kill();//    alien.physicsBodyType = null;    alien.loadTexture("cured");    // move alien to bottom     var tween2 = game.add.tween(alien).to( { y: 300 }, 1000, Phaser.Easing.Linear.EaseIn, true);tween2.onComplete.add(doNext, this);        tween2.start();function doNext (happy){        alien.kill();};        //  Increase the score    score += 20;    scoreText.text = scoreString + score;    //  And create an explosion     var explosion = explosions.getFirstExists(false);    explosion.reset(alien.body.x, alien.body.y);    explosion.play('love', 30, false, true);    if (aliens.countLiving() == 0)    {        score += 1000;        scoreText.text = scoreString + score;        enemyBullets.callAll('kill',this);        stateText.text = " You Won, \n Click to restart";        stateText.visible = true;        //the "click to restart" handler        game.input.onTap.addOnce(restart,this);    }}function enemyHitsPlayer (player,bullet) {        bullet.kill();    live = lives.getFirstAlive();    if (live)    {        live.kill();    }    //  And create an explosion     var explosion2 = explosions2.getFirstExists(false);    explosion2.reset(player.body.x, player.body.y);    explosion2.play('kaboom', 30, false, true);    // When the player dies    if (lives.countLiving() < 1)    {        player.kill();        enemyBullets.callAll('kill');        stateText.text=" GAME OVER \n Click to restart";        stateText.visible = true;        //the "click to restart" handler        game.input.onTap.addOnce(restart,this);    }}function enemyFires () {    //  Grab the first bullet we can from the pool    enemyBullet = enemyBullets.getFirstExists(false);    livingEnemies.length=0;    aliens.forEachAlive(function(alien){        // put every living enemy in an array        livingEnemies.push(alien);    });    if (enemyBullet && livingEnemies.length > 0)    {                var random=game.rnd.integerInRange(0,livingEnemies.length-1);        // randomly select one of them        var shooter=livingEnemies[random];        // And fire the bullet from this enemy        enemyBullet.reset(shooter.body.x, shooter.body.y);        game.physics.arcade.moveToObject(enemyBullet,player,120);        firingTimer = game.time.now + 2000;    }}function fireBullet () {    //  To avoid them being allowed to fire too fast we set a time limit    if (game.time.now > bulletTime)    {        //  Grab the first bullet we can from the pool        bullet = bullets.getFirstExists(false);        if (bullet)        {            //  And fire it            bullet.reset(player.x, player.y + 8);            bullet.body.velocity.y = -400;            bulletTime = game.time.now + 200;        }    }}function resetBullet (bullet) {    //  Called if the bullet goes out of the screen    bullet.kill();}function restart () {    //  A new level starts        //resets the life count    lives.callAll('revive');    //  And brings the aliens back from the dead     aliens.removeAll();    createAliens();    //revives the player    player.revive();    //hides the text    stateText.visible = false;}

[jonoco]

This should be as simple as turning off the alien's body, which would prevent any more collisions being detected.

function collisionHandler (bullet, alien) {  // When a bullet hits an alien we kill them both  bullet.kill();  alien.loadTexture("cured");  alien.body = null;

You can read more about the sprite's body property here if you're curious: http://phaser.io/docs/2.3.0/Phaser.Sprite.html#body

[GourmetGorilla]

Thanks jonoco, nice suggestion, but throws the error: alien.body is null @ invaders.js:243  - basically alien is used later in that function. 

 

here's my new code:

   // change alien sprite    alien.loadTexture("cured");     alien.body = null;    // move alien to bottom of screen    var tween2 = game.add.tween(alien).to( { y: 300 }, 1000, Phaser.Easing.Linear.EaseIn, true);    tween2.onComplete.add(doNext, this);    tween2.start();    //for now, kill alien    function doNext (alien){        alien.kill();    };  

The entire function collisionHandler is as follows.

function collisionHandler (bullet, alien) {    //  When a bullet hits an alien we kill them both    bullet.kill();    // change alien sprite    alien.loadTexture("cured");     alien.body = null;    // move alien to bottom of screen    var tween2 = game.add.tween(alien).to( { y: 300 }, 1000, Phaser.Easing.Linear.EaseIn, true);    tween2.onComplete.add(doNext, this);    tween2.start();    //for now, kill alien    function doNext (alien){        alien.kill();    };        //  Increase the score    score += 20;    scoreText.text = scoreString + score;    //  And create an explosion     var explosion = explosions.getFirstExists(false);    explosion.reset(alien.body.x, alien.body.y);    explosion.play('love', 30, false, true);    // add count    if (aliens.countLiving() == 0)    {        score += 1000;        scoreText.text = scoreString + score;        enemyBullets.callAll('kill',this);        stateText.text = " You Won, \n Click to restart";        stateText.visible = true;        //the "click to restart" handler        game.input.onTap.addOnce(restart,this);    }}

 

If I move that code block to below the last alien reference, as per the below, I get a weird intermittent error: shooter.body is null @ invaders.js:310 

function collisionHandler (bullet, alien) {    //  When a bullet hits an alien we kill them both    bullet.kill();    //  Increase the score    score += 20;    scoreText.text = scoreString + score;    //  And create an explosion     var explosion = explosions.getFirstExists(false);    explosion.reset(alien.body.x, alien.body.y);    explosion.play('love', 30, false, true);    // change alien sprite    alien.loadTexture("cured");     alien.body = null;    // move alien to bottom of screen    var tween2 = game.add.tween(alien).to( { y: 300 }, 1000, Phaser.Easing.Linear.EaseIn, true);    tween2.onComplete.add(doNext, this);    tween2.start();    //for now, kill alien    function doNext (alien){        alien.kill();    };        // add count    if (aliens.countLiving() == 0)    {        score += 1000;        scoreText.text = scoreString + score;        enemyBullets.callAll('kill',this);        stateText.text = " You Won, \n Click to restart";        stateText.visible = true;        //the "click to restart" handler        game.input.onTap.addOnce(restart,this);    }}

Any ideas?

[drhayes]

I think taking the alien out of the aliens group is a great way to stop it from getting shot. Make another group called deadAliens or something? Since you're only checking bullets and aliens you'd be good.

[GourmetGorilla]

Yes I tried that, but for some reason it moves the position of the alien, and also it can still be shot at - strange o.O. 

Here was my group add code (I'm learning  ): 

deadAliens.add(alien);

And I created the group above that:

  deadAliens = game.add.group();

Why can I still shoot these dead aliens when they've been taken out of the group?  poor aliens, being shot dead twice.
 

[ladybenko]

Probably not the most efficient way, but you can always add a flag to the aliens that are not shootable anymore. Then you pass an additional filter to the overlap method. Assuming that flag is called immune, you could have:

game.physics.arcade.overlap(bullets, aliens, collisionHandler, function (bullet, alien) {  return !alien.immune;}, this);

[drhayes]

Adding it to a different group probably moves it because the different group has a new position. See this?

aliens.x = 100;aliens.y = 200;

That's assigning the x/y position of the aliens group. If your new group, deadAliens, has the same x/y position then the aliens won't jump when you switch them from one group to another.

 

And "deadAliens.add(alien);" looks good to me. It'll handle removing the alien from the old group.