List Products via function fn.catalog.php

How we can get a list of products for a specific category_id using a function from fn.catalog.php?



At the moment the system lists all products when i use the fn.catalog function



// list first-level categories
// if a cateogory has products, list them!
$my_params = array (
'category_id' => 0,
'visible' => false,
// Only current level
'simple' => true,
// product_count (?)
'plain' => false
// array von 0 fortlaufend ohne Baumstruktur
);
$func1 = fn_get_categories($my_params);

foreach($func1[0] as $count => $val)
{
if ($val['subcategories']) { // check if has products
echo $val['category']."
";
}else{
echo "".$val['category'].""."
";
echo "

";


// WHICH FUNCTION TO USE FOR LIST PRODUCT NAMES ???

echo "
";
}
}




Thank u for help