29 lines
935 B
Common Lisp
29 lines
935 B
Common Lisp
;; Oscillating Spin Scan
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;;
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;; Accumulates rotation angle on each beat, reversing direction
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;; periodically for an oscillating effect.
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;;
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;; Required context:
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;; - music: audio analyzer from (streaming:make-audio-analyzer ...)
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;;
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;; Provides scan: spin
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;; Bind with: (bind spin :angle) ;; cumulative rotation angle
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;;
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;; Behavior:
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;; - Rotates 14.4 degrees per beat (completes 360 in 25 beats)
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;; - After 20-30 beats, reverses direction
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;; - Creates a swinging/oscillating rotation effect
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;;
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;; Usage:
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;; (include :path "../templates/scan-oscillating-spin.sexp")
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;;
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;; In frame:
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;; (rotate frame :angle (bind spin :angle))
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(scan spin (streaming:audio-beat music t)
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:init {:angle 0 :dir 1 :left 25}
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:step (if (> left 0)
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(dict :angle (+ angle (* dir 14.4)) :dir dir :left (- left 1))
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(dict :angle angle :dir (* dir -1)
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:left (+ 20 (mod (streaming:audio-beat-count music t) 11)))))
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