Wordpress Loop posts in Bootstrap 3 grid layout

Question

I am using Bootstrap 3 within Wordpess and have an issue getting my archive posts to display across the page in a grid format. My wordpress loop code is...

<?php if ( have_posts() ) : ?>

<?php
$args=array(
'post_type' => 'artist',
'post_status' => 'publish',
'posts_per_page' => -1,
'caller_get_posts'=> 1
);
$my_query = null;
$my_query = new WP_Query($args);
if( $my_query->have_posts() ) {
echo '';
while ($my_query->have_posts()) : $my_query->the_post(); ?>
<li>
<img src="<?php the_field('artist_photo'); ?>" alt="" class="img-responsive" />
</li>

<?php endwhile;
}
wp_reset_query(); 
?>

<?php while ( have_posts() ) : the_post(); ?>
<?php endwhile; ?>
<?php else : ?>
<?php endif; ?>

This displays a list containing the post's image. Right now, they list one after the other down the page.

How would I get them to use my bootstrap grid showing 4 across the page, then the next 4 in the row beneath, then the next 4 in row beneath that like this...

<div class="row">

<div class="col-md-3">
<li>image 1 goes here</li>
</div>

<div class="col-md-3">
<li>image 2 goes here</li>
</div>

<div class="col-md-3">
<li>image 3 goes here</li>
</div>

<div class="col-md-3">
<li>image 4 goes here</li>
</div>

</div>

etc. Is that possible? Basically i want the Wordpress loop to list ALL of my posts 4 across the page instead of one after the other in a html list down the page.

Answer 1

// Opening container or wrap outside of the loop
<div class="container my-container">
// start the loop
<?php
  $args=array(
     'post_type' => 'post',
     'post_status' => 'publish',
     'posts_per_page' => 18
    );

  $my_query = null;
  $my_query = new WP_Query($args);

  if( $my_query->have_posts() ) {

    $i = 0;
    while ($my_query->have_posts()) : $my_query->the_post();
  // modified to work with 3 columns
  // output an open <div>
  if($i % 3 == 0) { ?> 

  <div class="row">

  <?php
  }
  ?>

    <div class="col-md-4">
      <div class="my-inner">
      // all your content, title, meta fields etc go here.
      </div>
    </div>  
// increment the loop BEFORE we test the variable
      <?php $i++; 
      if($i != 0 && $i % 3 == 0) { ?>
        </div><!--/.row-->
        <div class="clearfix"></div>

      <?php
       } ?>

      <?php  
        endwhile;
        }
        wp_reset_query();
        ?>

</div><!--/.container-->