Picking up and dropping a gun sprite, issues with child/parent positioning

[piotr]

Hi all, 

I have a player sprite that collides with a gun sprite and picks it up. Clicking a button makes the gun drop again on the ground. The code works fine except that the player has always to move some pixels from where the overlap happened otherwise the gun will not drop (the gun sprite is not showing, the function is triggered). I guess my issue is with the positioning code, but I can't figure out what's wrong:

this.weapon.x += this.player.x + 50;
this.weapon.y += this.player.y - 20;

Full code is here

Playstate

var playState = {
	
create: function() {
	
	game.physics.arcade.gravity.y = 1200;
	this.player = null;

	this.game.input.keyboard.addKeyCapture([
    //working code, omitting for brevity
	]);

	this.cursors = this.game.input.keyboard.createCursorKeys();
	this.createWorld();
	this.createPlayer();
	this.createWeaponCollectible();
	game.add.button(game.width - 95, game.height - 20, 'button', this.dropWeapon, this, 2, 1, 0);
},

update: function() {
	game.physics.arcade.collide(this.player, this.layerDirt); 
	game.physics.arcade.collide(this.weapon, this.layerDirt); 
	game.physics.arcade.overlap(this.player, this.weapon, this.collectWeapon, null, this); 
},

createPlayer: function() {
	this.player = new Player(this.game,'player');
	this.game.add.existing(this.player);
},


createWeaponCollectible: function() {
	this.weapon = new WeaponCollectible(this.game);
	this.game.add.existing(this.weapon);
	this.weapon.reset(200,30);
},

collectWeapon: function (player, weapon) { //arguments are needed to remove children from group
	
    if(!this.player.hasWeapon) {
		weapon.x = 0;
		weapon.y = 0;
		player.addChild(weapon);
		player.setHasWeapon(true);	
		weapon.visible = false;

	}
},

dropWeapon: function () {

	if(this.player.hasWeapon) {
		console.log("it dropped!"); //check if function is triggered
	    this.game.world.add(this.weapon);
		this.weapon.x += this.player.x + 50;
		this.weapon.y += this.player.y - 20;
		this.player.setHasWeapon(false);
		this.weapon.visible = true;
	}
},

createWorld: function(){
	//working code, omitting for brevity
},

};

Create weapon

var WeaponCollectible = function (game,powerup) {
	this.powerup = powerup;

	Phaser.Sprite.call(this, game, 0,0,'weapon01');
	game.physics.enable(this, Phaser.Physics.ARCADE);
	this.anchor.setTo(0.5, 0.5);
	this.scale.setTo(1);

};

WeaponCollectible.prototype = Object.create(Phaser.Sprite.prototype);
WeaponCollectible.prototype.constructor = WeaponCollectible;

 

[piotr]

Ping

[samme]

Is it possible that the item still overlaps the player at the time it's dropped?

 

[piotr]

Yes, that's very possible. It's just not clear to me, why the formula works only after I move the player, that means why the weapon overlaps the player around the spot where the collision happened and doesn't some pixels after.