Car follow path + boost

carfollow.js

var config = {
    type: Phaser.AUTO,
    width: 800,
    height: 600,
    backgroundColor: '#2d2d2d',
    parent: 'phaser-example',
    scene: {
        preload: preload,
        create: create,
        update: update
    }
};

var game = new Phaser.Game(config);

var car;
var path;
var speed = 0.002;
var pathDelta = 0;
var prevPos = new Phaser.Math.Vector2();

function preload ()
{
    this.load.image('car', 'assets/sprites/car-yellow.png');
}

function create ()
{
    var points = [];

    points.push(new Phaser.Math.Vector2(50, 200));
    points.push(new Phaser.Math.Vector2(200, 100));
    points.push(new Phaser.Math.Vector2(500, 50));
    points.push(new Phaser.Math.Vector2(700, 300));
    points.push(new Phaser.Math.Vector2(500, 500));
    points.push(new Phaser.Math.Vector2(300, 400));
    points.push(new Phaser.Math.Vector2(100, 300));
    points.push(new Phaser.Math.Vector2(50, 200));

    path = new Phaser.Curves.Spline(points);

    var graphics = this.add.graphics();

    graphics.lineStyle(1, 0xffffff, 1);

    path.draw(graphics, 64);

    graphics.fillStyle(0x00ff00, 1);

    for (var i = 0; i < points.length; i++)
    {
        graphics.fillCircle(points[i].x, points[i].y, 4);
    }

    var start = path.getStartPoint();

    car = this.add.sprite(start.x, start.y, 'car');

    var boost = false;

    this.input.on('pointerdown', function ()
    {
        if (!boost)
        {
            console.log('turbo boost');

            boost = true;

            var maxSpeed = 0.006;

            this.tweens.addCounter({
                from: speed,
                to: maxSpeed,
                ease: 'Sine.inOut',
                duration: 1000,
                hold: 1000,
                yoyo: true,
                onUpdate: function (tween)
                {
                    speed = tween.getValue()
                },
                onComplete: function ()
                {
                    console.log('boost off');
                    boost = false;
                }
            });
        }
    }, this);
}

function update ()
{
    prevPos.set(car.x, car.y);

    var pos = path.getPoint(pathDelta);

    var speedX = pos.x - prevPos.x;
    var speedY = pos.y - prevPos.y;

    car.setPosition(pos.x, pos.y);

    car.rotation = Math.atan2(speedY, speedX);

    pathDelta = Phaser.Math.Wrap(pathDelta + speed, 0, 1);
}