ScrollTrigger start seems wrong but end is correct? (NextJS / React)

[akalex_x]

Hi, im working on a animation for this website https://alex-wand.vercel.app/  . It looks like ScrollTrigger sets the markers in the correct place ( start when the top of the section hits the center of the screen, and end when the center of the section reaches the center of the screen. ) However it looks like the animation itself starts late but then does end correctly at the center.

 

 

const tl = gsap.timeline({
  ease: "none",
  scrollTrigger: {
    trigger: $section.current,
    start: "top center",
    end: "center center",
    scrub: true,
    markers: true,
    toggleActions: 'play none reverse none',
  }
});

tl.to($children[0],{
  top: '5%',
  left: '10%',
},1);

tl.to($children[1],{
  top: '0%',
  left: '60%',
},1);

tl.to($children[3],{
  top: '57.5%',
  left: '5%',
},1);

tl.to($children[4],{
  top: '80%',
  left: '40%',
},1);

tl.to($children[5],{
  top: '56%',
  left: '82.5%',
},1);

[GSAP Helper]

It's pretty tough to troubleshoot without a minimal demo - the issue could be caused by CSS, markup, a third party library, your browser, an external script that's totally unrelated to GSAP, etc. Would you please provide a very simple CodePen or CodeSandbox that demonstrates the issue? 

 

Please don't include your whole project. Just some colored <div> elements and the GSAP code is best (avoid frameworks if possible). See if you can recreate the issue with as few dependancies as possible. If not, incrementally add code bit by bit until it breaks. Usually people solve their own issues during this process! If not, then at least we have a reduced test case which greatly increases your chances of getting a relevant answer.

 

Here's a starter CodePen that loads all the plugins. Just click "fork" at the bottom right and make your minimal demo: 

See the Pen aYYOdN by GreenSock (@GreenSock) on CodePen

 

If you're using something like React/Next/Vue/Nuxt or some other framework, you may find StackBlitz easier to use. We have a series of collections with different templates for you to get started on these different frameworks: React/Next/Vue/Nuxt.

 

Once we see an isolated demo, we'll do our best to jump in and help with your GSAP-specific questions. 

[akalex_x]

@GSAP Helper here is a link to a minimal demo of it.

https://stackblitz.com/edit/nextjs-kvs972?file=styles%2Fglobals.css,pages%2F_app.js,pages%2Findex.js,components%2Fgallery.js

[Rodrigo]

Hi,

 

I think the issue relates to the position parameter you're using on each instance in the timeline:

tl.to(
  $children[0],
  {
    top: '5%',
    left: '10%',
  },
  1 // <- THIS NUMBER
);

Basically that tells GSAP: "Put this instance at 1 second". GSAP does that exactly, so all the instances start at 1 second. Since you're using the default duration (0.5 seconds) the timeline lasts 1.5 seconds and there is 1 second where nothing happens, so the perception is that 66.7% of the time nothing happens, but that is exactly what should happening with that number you're passing.

 

You should remove that from all the instances and the animations will start when you expect:

tl.to(
  $children[0],
  {
    top: '5%',
    left: '10%',
  }
);

Hopefully this clear things up. Let us know if you have more questions.

Happy Tweening!

[akalex_x]

Thanks @Rodrigo I thought that last parameter was just to group elements to animate together, didnt know it would affect timing. I wanted them all to move at the same time so I just passed a string instead and its working as expected now.