pxl8/demo/mod/music.fnl

(local pxl8 (require :pxl8))

(var time 0)
(var step 0)
(var ctx nil)
(var params nil)
(var bass-params nil)
(var playing false)

(local bpm 120)
(local beat (/ 60 bpm))
(local whole (* 4 beat))
(local half (* 2 beat))
(local quarter beat)
(local eighth (/ beat 2))
(local sixteenth (/ beat 4))

(local melody [[60 eighth] [64 eighth] [67 eighth] [72 eighth]
               [67 eighth] [64 eighth] [60 eighth] [64 eighth]
               [67 eighth] [72 eighth] [76 eighth] [72 eighth]
               [67 eighth] [64 eighth] [62 eighth] [66 eighth]
               [69 eighth] [74 eighth] [69 eighth] [66 eighth]
               [62 eighth] [66 eighth] [69 eighth] [74 eighth]
               [78 eighth] [74 eighth] [69 eighth] [66 eighth]])

; (local bass [[36 half] [40 half] [36 half] [38 half]
;              [38 half] [36 half] [40 half] [38 half]])

(local step-duration eighth)

(fn init []
  (set ctx (pxl8.sfx_context_create))

  (local delay (pxl8.sfx_delay_create {:time_l 350 :time_r 500 :feedback 0.6 :mix 0.2}))
  (local reverb (pxl8.sfx_reverb_create {:room 0.25 :damping 0.5 :mix 0.5}))
  (local compressor (pxl8.sfx_compressor_create {:threshold -12 :ratio 4 :attack 10 :release 100}))

  (pxl8.sfx_context_append_node ctx delay)
  (pxl8.sfx_context_append_node ctx reverb)
  (pxl8.sfx_context_append_node ctx compressor)

  (pxl8.sfx_mixer_attach ctx)

  (set params (pxl8.sfx_voice_params
    {:waveform pxl8.SFX_WAVE_TRIANGLE
     :attack 0.01 :decay 0.25 :sustain 0.0 :release 0.01
     :filter_type pxl8.SFX_FILTER_LOWPASS
     :filter_cutoff 2500 :filter_resonance 0.05
     :filter_attack 0.05 :filter_decay 0.1 :filter_sustain 0.2 :filter_release 0.05
     :filter_env_depth 1500
     :fx_send 0.7})))

  ; (set bass-params (pxl8.sfx_voice_params
  ;   {:waveform pxl8.SFX_WAVE_SAW
  ;    :attack 0.02 :decay 0.3 :sustain 0.6 :release 0.4
  ;    :filter_type pxl8.SFX_FILTER_LOWPASS
  ;    :filter_attack 0.02 :filter_decay 0.3 :filter_sustain 0.6 :filter_release 0.4
  ;    :filter_cutoff 90 :filter_resonance 0.25
  ;    :fx_send 0.2})))

(fn start []
  (set playing true)
  (set time 0)
  (set step 0))

(fn stop []
  (set playing false)
  (pxl8.sfx_stop_all ctx))

(fn update [dt]
  (when playing
    (set time (+ time dt))
    (when (>= time step-duration)
      (set time (- time step-duration))
      (local melody-entry (. melody (+ 1 (% step (length melody)))))
      (local note (. melody-entry 1))
      (local dur (. melody-entry 2))
      (pxl8.sfx_play_note ctx note params 0.4 dur)
      ; (when (= (% step 4) 0)
      ;   (local bass-idx (+ 1 (% (math.floor (/ step 4)) (length bass))))
      ;   (local bass-entry (. bass bass-idx))
      ;   (local bass-note (. bass-entry 1))
      ;   (local bass-dur (. bass-entry 2))
      ;   (pxl8.sfx_play_note ctx bass-note bass-params 0.35 bass-dur))
      (set step (+ step 1)))))

{:init init
 :start start
 :stop stop
 :update update
 :is-playing (fn [] playing)}