;; Fisheye effect - barrel/pincushion lens distortion
;; @param strength float [-1, 1] default 0.3
;; @param center_x float [0, 1] default 0.5
;; @param center_y float [0, 1] default 0.5
;; @param zoom_correct bool default true

(define-effect fisheye
  ((strength 0.3) (center_x 0.5) (center_y 0.5) (zoom_correct true))
  (let* ((w (width frame))
         (h (height frame))
         (cx (* w center_x))
         (cy (* h center_y))
         (coords (fisheye-displace w h strength cx cy zoom_correct)))
    (remap frame (coords-x coords) (coords-y coords))))