php class scope when calling a non-method function not accessing all class members

So I'm using a stand alone function from within a class that that uses the class it's being called from. Here's the function

function catalogProductLink($product_id,$product_name,$categories=true) {
    //This is the class that the function is called from
    global $STATE;
if ($categories) {
    //The $STATE->category_id is the property I want to access, which I can't
    if (is_array($STATE->category_id)) {
        foreach($STATE->category_id as $cat_id) {
            if ($cat_id == 0) continu开发者_JS百科e;
            $str .= "c$cat_id/";
        }
    }
}
$str .= catalogUrlKeywords($product_name).'-p'.$product_id.'.html';
return $str;
}

And here's the function call, which is being made from within the $STATE class.

$redirect = catalogProductLink($this->product_id, $tempProd->product_name, true, false);

The object that I need access to is the $STATE object that has been declared global. Prior to this function call there are lots of public properties populated, but when I look at the $STATE object within the function scope it loses all the properties but one, product_id. The property that matters for this function is the category_id property, which is an array of category id's.

I'm wondering why I don't have access to all the public properties of the $STATE object and how I can get access to them.

What is catalogUrlKeywords() doing? I bet it is modifiying the $STATE This sounds like a horrible design BTW. If global is an integral part of a framework, RUN!

Edit

Or you could just add an optional parameter to take category_id and be done with it. Maybe instead of having $categories=true, make $categories take an array of category_id's or zero.

function catalogProductLink($product_id,$product_name,$category_ids=0) {