[Play animation once]

I have a real simple animation when you scroll the page using ScrollMagic I want to know how do you play the animation only once after you have scrolled the scene into view of the trigger.

 

var controller = new ScrollMagic.Controller();

var tween_1 = TweenMax.to('#obj_1', 0.5, {
    left: '0%', delay: .1
});

var containerScene = new ScrollMagic.Scene({
    triggerElement: '#scene_1',
    offset: -100
})
.setTween(tween_1)
.addIndicators()
.addTo(controller);