phaser/labs/code/004 maggot batch.js

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

function preload() {

    game.load.image('maggot', 'assets/sprites/maggot.png');

}

var batch;
var dudeBoundsPadding = 100;
var dudeBounds = new Phaser.Rectangle(-dudeBoundsPadding, -dudeBoundsPadding, 800 + dudeBoundsPadding * 2, 600 + dudeBoundsPadding * 2);
var tick = 0;

function create() {

	batch = game.add.spriteBatch();

	var total = (game.renderType === Phaser.WEBGL) ? 5000 : 100;

	for (var i = 0; i < total; i++)
	{
		var dude = batch.create(game.world.randomX, game.world.randomY, 'maggot');

		dude.anchor.set(0.5);
		dude.scale.set(0.8 + Math.random() * 0.3);
		dude.direction = Math.random() * Math.PI * 2;
		dude.turningSpeed = Math.random() - 0.8;
		dude.speed = (2 + Math.random() * 2) * 0.2;	
		dude.offset = Math.random() * 100;
	}

}

function update() {

	batch.forEach(updateMaggot, this, false);

	tick += 0.1;

}

function updateMaggot(dude) {

	dude.scale.y = 0.95 + Math.sin(tick + dude.offset) * 0.05
	dude.direction += dude.turningSpeed * 0.01;
	dude.position.x += Math.sin(dude.direction) * (dude.speed * dude.scale.y);
	dude.position.y += Math.cos(dude.direction) * (dude.speed * dude.scale.y);
	dude.rotation = -dude.direction + Math.PI;

	// wrap the dudes by testing their bounds..
	if (dude.position.x < dudeBounds.x)
		dude.position.x += dudeBounds.width;
	else if (dude.position.x > dudeBounds.x + dudeBounds.width)
		dude.position.x -= dudeBounds.width;

	if (dude.position.y < dudeBounds.y)
		dude.position.y += dudeBounds.height;
	else if (dude.position.y > dudeBounds.y + dudeBounds.height)
		dude.position.y -= dudeBounds.height;

}