;; Wave effect - sine wave displacement distortion
;; @param amplitude float [0, 100] default 10
;; @param wavelength float [10, 500] default 50
;; @param speed float [0, 10] default 1
;; @param direction string default "horizontal"

(define-effect wave
  ((amplitude 10) (wavelength 50) (speed 1) (direction "horizontal"))
  (let* ((w (width frame))
         (h (height frame))
         ;; Use _time for animation phase
         (phase (* (or _time 0) speed 2 pi))
         ;; Calculate frequency: waves per dimension
         (freq (/ (if (= direction "vertical") w h) wavelength))
         (axis (cond
                 ((= direction "horizontal") "x")
                 ((= direction "vertical") "y")
                 (else "both")))
         (coords (wave-displace w h axis freq amplitude phase)))
    (remap frame (coords-x coords) (coords-y coords))))