;; Flip effect - flips image horizontally or vertically

(define-effect flip
  :params (
    (horizontal :type bool :default true)
    (vertical :type bool :default false)
  )
  (let ((result frame))
    (if horizontal
        (set! result (flip-h result))
        nil)
    (if vertical
        (set! result (flip-v result))
        nil)
    result))