wordpress – get forum list in a dropdown in bbpress

I am using bbpress plugin in WordPress for forum. I need to display the forum list in a dropdown and on click of ‘apply’ button it will show topic results according to the selected forum.

Below is a reference site, similar to which I want to do in my project.

http://manhattanbeachpageant.com/forum/active?forum=All

Also I need to know what arguments to pass in the below function to get the results ?

<?php if ( bbp_has_topics( $bbp_loop_args ) ) : ?>
    <?php while ( bbp_topics() ) : bbp_the_topic(); ?>

        <?php bbp_get_template_part( 'loop', 'single-topic' ); ?>

    <?php endwhile; ?>
<?php endif;?>

where

$bbp_loop_args = array();

So how I will display the forum list in a dropdown & what arguments I need to pass in the above array ?