var game = new Phaser.Game(800, 600, Phaser.CANVAS, 'phaser-example', { preload: preload, create: create, render: render });

var baseIncSpeed= 0.006;

function preload() {
    game.load.spritesheet('item', 'assets/buttons/number-buttons-90x90.png', 90, 90);
}

function create() {

    // Add some items.
    for (var i = 0; i < 3; i++)
    {
        // Give the items a different alpha increase speed.
        game.add.sprite(290, 98 * (i + 1), 'item', i).alphaIncSpeed = baseIncSpeed * (i + 1);
        game.add.sprite(388, 98 * (i + 1), 'item', i + 3).alphaIncSpeed = baseIncSpeed * (i + 4);
    }

    game.input.onTap.add(resetAlpha,this);

}

function resetAlpha() {

    // Set "alpha" value of all the childs.
    game.world.setAll('alpha', Math.random());

}

function render() {

    game.debug.renderText('Tap or click to set random alpha of all the items.', 240, 480);
    
}