two col layout bootstrap 4 with one fixed col and fade in effect on image

I've created a layout for my single post that have a fixed column and another that contains images that has the vertical scroll. I'm using viewportchecker to check if the images are inside the viewport to add a fade in effect using animate.css library. The problem is that it will work only for the first image. Can anyone suggest me a solution?Here is the code:

?php get_header(); ?

div class="container-fluid" id="post-content"
  div class="row"
?php if( have_posts() ): while( have_posts() ): the_post();
  $attached_images = get_post_gallery_images($post-ID);
?
  div class="col-sm-12 col-md-6 col-lg-4 shadow" id="single-post-text"
    h2 class=""?php the_title(); ?/h2
?php
  add_filter('the_content', 'remove_shortcode_from');
  the_content();
  remove_filter('the_content', 'remove_shortcode_from');
?
  /div
?php if($attached_images): ?
  div class="col-sm-12 col-md-6 col-lg-6" id="single-post-img"
?php foreach($attached_images as $image): ?
    img class="img-fluid w-100 show" src="?php echo $image; ?" alt="" title="" id="post-image" /
?php endforeach; ?
  /div
?php endif; ?

?php endwhile; ?
?php endif; wp_reset_postdata(); ?
  /div
/div

?php get_footer(); ?

JS

$(window).scroll(function(e){
     var scroll = $(window).scrollTop();
       $('#post-image').viewportChecker({
         classToAdd: 'animated fadeInUp show',
         classToRemove: 'hide',
         offset: 50,
       });
     });

CSS

.hide{
  opacity: 0;
}
.show{
  opacity: 1;
}
#single-post-text{
  position: fixed;
  top: 25%;
  left: 2%;
  background-color: white;
}
#single-post-img{
  position: relative;
  top: 0;
  left: 50%;
  right: 0;
}

Another question, how I can obtain the images attached to a gallery of a page?