gsap scrollTrigger is not being pinned during the animation

I'm really new to GSAP and my way of doing might be wrong.

I've created a code pen : https://codepen.io/Emma-miu/pen/dyBYKYe

GSAP settings:

gsap.to(".before", {
            scrollTrigger: {
                trigger: ".flex",
                start: "top top",
                end: () => "+=" + document.querySelector(".before").offsetWidth,
                scrub: "true",
                pin: "true",
                toggleAction: "play none none reverse"
            },
            x: '-100%',
            duration: 2
});

gsap.to(".after", {
            scrollTrigger: {
                trigger: ".flex",
                start: "top top",
                end: () => "+=" + document.querySelector(".after").offsetWidth,
                scrub: "true",
                pin: "true",
                toggleAction: "play none none reverse"
            },
            x: '100%',
            duration: 2
});

In my example, i have gsap-container div, going from white to showing the background image. I would like to 'pin' the container for the duration of the animation.

So i will only see the white to background div until the background is fully showing then I will be able to continue scrolling down.

I thought "pin: true" settings will achieve that but i can still scroll down to red box

Can somebody tell me what i'm doing wrong here ?

Solution

You don't need pin two ScrollTriggers for that...

You need to tweak a little bit end value and synchronized transition, create value statically. Also, keep in mind that you pinned the same container twice.

gsap.registerPlugin(ScrollTrigger);

gsap.to(".before", {
  scrollTrigger: {
    trigger: ".gsap-container",
    start: "top top",
    end: "+=100%",
    scrub: true,
    pin: true,
    toggleActions: "play none none reverse"
  },
  x: '-100%',
  duration: 2
});

gsap.to(".after", {
  scrollTrigger: {
    trigger: ".gsap-container",
    start: "top top",
    end: "+=100%",
    scrub: true,
    pin: false, // No needing
    toggleActions: "play none none reverse"
  },
  x: '100%',
  duration: 2
});

.big-space {
  width: 100%;
  height: 100vh;
  background-color: red;
  text-align: center;
  font-size: 30px;
}

.blue {
  background-color: teal;
}

.flex {
  display: flex;
  width: 100%;
  height: 100vh;
  background-image: url("https://picsum.photos/200");
  background-position: center;
  background-size: cover;
}

.gsap-container {
  position: relative;
  height: 100vh;
}

.text-container {
  position: absolute;
  top: 50%;
  left: 50%;
  text-align: center;
}

h2, p {
  color: white;
  mix-blend-mode: difference;
}

.before {
  width: 50%;
  height: 100vh;
  background-color: white;
}

.after {
  width: 50%;
  height: 100vh;
  background-color: white;
}

<script src="https://cdn.jsdelivr.net/npm/gsap@3.12.5/dist/gsap.min.js"></script>

<script src="https://cdn.jsdelivr.net/npm/gsap@3.12.5/dist/ScrollTrigger.min.js"></script>

<div class="big-space">scroll down</div>
<div class="gsap-container">
  <div class="flex">
    <div class="before"></div>
    <div class="after"></div>
  </div>
  <div class="text-container">
    <h2>Hello</h2>
    <p>this is some text</p>
  </div>
</div>
<div class="big-space"></div>
<div class="big-space blue"></div>