Show related images in single image view

sunshine-related-images.php

// Add this to your theme's functions.php file
// Or use this plugin https://wordpress.org/plugins/my-custom-functions/
add_action( 'sunshine_after_content', 'sunshine_related_images' );
function sunshine_related_images() {
	global $sunshine;
  	if ( !empty( SunshineFrontend::$current_image ) ) {
		$args = array(
		    'post_type' => 'attachment',
			'orderby' => 'rand',
			'post_parent' => SunshineFrontend::$current_gallery->ID,
			'exclude' => SunshineFrontend::$current_image->ID,
			'posts_per_page' => $sunshine->options['columns']
		);
		$images = get_posts( $args );
		if ( $images ) {
			echo '<div id="sunshine-image-list">';
			echo '<h2>Related Images</h2>';
			echo '<ul class="sunshine-col-'.$sunshine->options['columns'].'">';
			foreach ($images as $image) {
				$thumb = wp_get_attachment_image_src( $image->ID, 'sunshine-thumbnail');
				$image_html = '<a href="' . get_permalink( $image->ID ) . '"><img src="' . $thumb[0] . '" alt="" /></a>';
				$image_html = apply_filters( 'sunshine_gallery_image_html', $image_html, $image->ID, $thumb );
				?>
				<li id="sunshine-image-<?php echo $image->ID; ?>" class="<?php sunshine_image_class($image->ID, array('sunshine-image-thumbnail')); ?>">
					<?php do_action( 'sunshine_before_loop_image_item' ); ?>
					<?php echo $image_html; ?>
					<?php if ( !empty( $sunshine->options['show_image_data'] ) ) { ?>
						<div class="sunshine-image-name"><?php echo apply_filters('sunshine_image_name', $image->post_title, $image); ?></div>
					<?php } ?>
					<div class="sunshine-image-menu-container">
						<?php sunshine_image_menu($image); ?>
					</div>
					<?php do_action( 'sunshine_image_thumbnail', $image ); ?>
					<?php do_action( 'sunshine_before_loop_image_item' ); ?>
				</li>
				<?php
			}
			echo '</ul>';
			echo '</div>';
		}
  	}
}