If _pt_distance is negative, it causes the final distance to be negative
in the repeat-reflect case. Moving the scaling by _pt_distance earlier
avoids this problem, and simplifies some equations as a bonus.
Bugzilla: https://bugs.freedesktop.org/98508
Signed-off-by: Jeff Smith <whydoubt@gmail.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>