Shrug ¯\_(ツ)_/¯

What article is that ?
 
Similar has been inquired about previously on the GSAP forum. For instance this previous topic along with this one discussed a similar effect. The examples found in those threads should help you accomplish your goals, all the best with your project.
 
PS: MorphSVGPlugin for the win, worth every penny. 😉

👆Indeed. That site appears to be using Matter.js for the collision detection logic / effects.
 
As Rodrigo pointed out in his post, you can benefit greatly from understanding the general logic of basic collisions yourself before using a complex library like Matter.js to go further.

It sounds like you instead want the stack of images to fade through as you scroll? If so then you can remove the pin, try scrub: true, adjust the start &/or end values and play around with the next var (stagger) and fade var . Just play around until you get everything to your liking (if you want to stick with that example). 
 
 
The ScrollTrigger Docs have detailed information on those things along with links too many ScrollTrigger examples and demos. I sugggest you take time to get familar with the usage.
 
 

Congrats regarding your learning of GSAP, etc.,
 
You can just use standard Javascript matchMedia with GSAP. There are many older examples and other things regarding resize events, etc., that can be found throughout forum.  Though looking at those horizontal buttons you may not be able to just size such a configuration for mobile. Instead you will probably need to come up with a different configuration for mobile if you hope to keep the same look and feel. Like a stacked two across approach for usability on mobile.

I would suggest creating modular functions to pass through your target(s) and desired parameter(s) for whatever logic you hope to accomplish. Then anytime you need just call the reusable function. It’s really just a matter of building out the general logic to be reusable for what you want to do.
 
Here are three articles that touch on that aspect:
https://css-tricks.com/writing-smarter-animation-code/#use-functions-to-create-and-return-timelines https://css-tricks.com/tips-for-writing-animation-code-efficiently/#tip-8-modularize-your-animations https://greensock.com/mistakes/#create-before

Hi @AliAwan, welcome to the Greensock Forums.
 
Maybe you mean GLTF ?
 
If so then below are a few examples that you can look over. The ScrollTrigger & GSAP portions are rather minimal and your knowledge of Three.js, etc., is going to be important. But thats a broad topic which is outside the scope of this forum, if you have GSAP related questions then someone will try to help you with those.
 

See the Pen wvWJmGX by kdbkapsere (@kdbkapsere) on CodePen
 

See the Pen gOrBNzq by akeyz (@akeyz) on CodePen
 
Hopefully something will help your efforts.

More specifically the ScrollTrigger.scrollerProxy() feature.