Squashed 'test/' content from commit f2edc20

git-subtree-dir: test
git-subtree-split: f2edc20cba865a6ef67ca807c2ed6cee8e6c2836

sexp_effects/effects/scanlines.sexp

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+;; Scanlines effect - VHS-style horizontal line shifting
+(require-primitives "core")
+
+(define-effect scanlines
+  :params (
+    (amplitude :type int :default 10 :range [0 100])
+    (frequency :type int :default 10 :range [1 100])
+    (randomness :type float :default 0.5 :range [0 1])
+  )
+  (map-rows frame
+    (lambda (y row)
+      (let* ((sine-shift (* amplitude (sin (/ (* y 6.28) (max 1 frequency)))))
+             (rand-shift (core:rand-range (- amplitude) amplitude))
+             (shift (floor (lerp sine-shift rand-shift randomness))))
+        (roll row shift 0)))))