Wordpress show only subcategories from current parentrent

//************************ BEGIN CAT FUNCTION

function get_mymenu($curcat = 0, $depth = 1)
{
    $current_cat ="";
    $breadcats = my_get_breadcats($curcat);
    $my_cats = my_get_all_categories();
    if($depth == 0){$listlevel = "parentlist";}
    else{$listlevel = "childlists";}

    $html = "$parentid<ul class=\"".$listlevel."\">";
    $categories = $my_cats[$breadcats[$depth]];
    if(isset($categories))
    {
        foreach ($categories as $cat)
        {
            $parent ="";
            $parentid = $cat->category_parent;
            $catid = $cat->cat_ID;

            if($depth == 1){$level = "levelone";}
            elseif($depth == 0){$level = "levelzero";}
            elseif($depth == 2){$level = "leveltwo";}
            elseif($depth == 3){$level = "levelthree";}
            else{$level = "";}

            if($curcat == $cat->cat_ID){$current_subcat = "current_subcat";}
            else{$current_subcat = "";}

            $anc = get_ancestors($curcat,'category');
            foreach($anc as $ancestor){
                if($ancestor == $catid) {
                    $parent = "current-cat-parent";
                }
            }

            $html.= "<li class=\"cat-item ".$current_subcat." ".$level." ".$parent."\"><a href=\"". get_category_link( $cat->cat_ID ) ."\">". $cat->cat_name ."</a></li>";
            if ($cat->cat_ID == $breadcats[$depth+1] && $depth<count($breadcats))
            {
                $html.= get_mymenu($curcat, $depth+1);
            }
            $html.= "</li>\n";
        }

    }
    $html.= "</ul>\n";
    return $html;
}


function my_get_all_categories()
{
    static $my_cats = array();
    if (count($my_cats)==0)
    {
        $categories = get_categories('child_of=0', 'orderby=name');
        foreach ($categories as $cat)
        {
            $my_cats[$cat->category_parent][$cat->cat_ID] = $cat;
        }
    }
    return $my_cats;
}

function my_get_breadcats($curcat = 0)
{
    global $post;
    static $breadcats = array();
    if (count($breadcats)==0)
    {
        $curcat = intval($curcat);
        $breadcats[] = $curcat;
        while($curcat!=0)
        {
            $curcategory = get_category($curcat);
            $curcat = intval($curcategory->category_parent);
            $breadcats[] = $curcat;
        }
        $breadcats = array_reverse($breadcats);
    }
    return $breadcats;
}

//************************ END CAT FUNCTION