39 lines
948 B
Go
39 lines
948 B
Go
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package synth
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import "math"
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// Oscillator is a phase-accumulator oscillator that generates additive sine waveforms.
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type Oscillator struct {
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phase float64
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freq float64
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sr float64
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}
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// NewOscillator creates an oscillator at the given frequency and sample rate.
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func NewOscillator(freq float64, sampleRate int) *Oscillator {
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return &Oscillator{freq: freq, sr: float64(sampleRate)}
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}
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// Advance returns one sample: fundamental + harmonics summed and normalized to [-1, 1].
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func (o *Oscillator) Advance(harmonics []HarmonicDef) float64 {
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sum := 0.0
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totalWeight := 0.0
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for _, h := range harmonics {
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sum += h.Amplitude * math.Sin(2*math.Pi*o.phase*float64(h.Ratio))
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totalWeight += h.Amplitude
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}
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o.phase += o.freq / o.sr
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if o.phase >= 1.0 {
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o.phase -= 1.0
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}
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if totalWeight > 0 {
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return sum / totalWeight
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}
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return 0
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}
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// Phase returns the current phase (for testing).
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func (o *Oscillator) Phase() float64 {
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return o.phase
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}
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