Get variables in scope at each PHP backtrace level?

Question

Is there a way to view the variables set in each stack frame in a backtrace? I can come pretty close with a combination of debug_backtrace(true) to get the objects, get_object_vars on each object to get $this vars, the args key in each backtrace frame, and get_defined_vars to get globals, but any temporary variables set within a function I can't find a way to retrieve.

Here's an example situation:

function method1($foo) {
    $temp = method2($foo + 1);
    foreach ($temp as $t) {
        method2($t);
    }
}

function method2($bar) {
    $temp2 = $bar->value + $_GET['val'];
    debug();
}

function debug() {
    // to be created
    $global_scope = get_defined_vars();
    $bt = debug_backtrace(true);
}

I can get $foo and $bar via the args key in the backtrace, the object variables of $bar through get_object_vars, and the globals through get_defined_vars. I want to get the value of $temp2 and $temp as well.