my @points;

# This will add one point (the first one in your arrays 
# above) to another type of data structure.
my %this_point = {x => 0, y => 0, z => 25};
push @points, \%this_point;

# Do this for as many points as you have. You can
# adapt the method you use to fill your three arrays
# to create this kind of data structure using the 
# example above.

##</code><code>##

# Sort by z first, then sort by x for each point
@points = sort { $a->{x} <=> $b->{x} } 
               sort { $a->{z} <=> $b->{z} }
                    @points;