func NewBeatsKey(idx int) Key {
osc := snd.NewOscil(sawsine, notes[idx], snd.NewOscil(triangle, 4, nil))
dmp := snd.NewDamp(bpm.Dur(), osc)
d := snd.BPM(float64(bpm) * 1.25).Dur()
dmp1 := snd.NewDamp(d, osc)
drv := snd.NewDrive(d, osc)
mix := snd.NewMixer(dmp, dmp1, drv)
frz := snd.NewFreeze(bpm.Dur()*4, mix)
adsr := snd.NewADSR(250*ms, 500*ms, 300*ms, 400*ms, 0.85, 1.0, frz)
key := &BeatsKey{snd.NewInstrument(adsr), adsr}
key.Off()
return key
}
func (key *PianoKey) Freeze() {
key.On()
key.frz = snd.NewFreeze(key.dur, key.gain)
key.Instrument = snd.NewInstrument(key.frz)
key.Off()
}