24 lines
754 B
Common Lisp
24 lines
754 B
Common Lisp
;; Vignette effect - darkens corners
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(require-primitives "image")
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(define-effect vignette
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:params (
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(strength :type float :default 0.5 :range [0 1])
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(radius :type int :default 1 :range [0.5 2])
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)
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(let* ((w (image:width frame))
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(h (image:height frame))
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(cx (/ w 2))
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(cy (/ h 2))
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(max-dist (* (sqrt (+ (* cx cx) (* cy cy))) radius)))
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(map-pixels frame
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(lambda (x y c)
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(let* ((dx (- x cx))
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(dy (- y cy))
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(dist (sqrt (+ (* dx dx) (* dy dy))))
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(factor (- 1 (* (/ dist max-dist) strength)))
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(factor (clamp factor 0 1)))
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(rgb (* (red c) factor)
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(* (green c) factor)
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(* (blue c) factor)))))))
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