;; Bloom effect - glow on bright areas
;; @param intensity float [0, 2] default 0.5
;; @param threshold int [0, 255] default 200
;; @param radius int [1, 50] default 15

(define-effect bloom
  ((intensity 0.5) (threshold 200) (radius 15))
  (let* ((bright (map-pixels frame
                   (lambda (x y c)
                     (if (> (luminance c) threshold)
                         c
                         (rgb 0 0 0)))))
         (blurred (blur bright radius)))
    (blend-mode frame blurred "add")))