pluck.go

package synthia

import (
//	"math"
	"math/rand"
	"github.com/synthia-synth/synthia/domains"
)

func whitenoise(samples int) []domains.Time {
	sampleSpace := make([]domains.Time, samples)
	for i := 0; i < samples; i++ {
		sampleSpace[i] = domains.Time(rand.Float64())
	}
	return sampleSpace
}

type Plucker struct {
	samplerate float64
}

func NewPlucker(sampleRate float64) ToneSimulator {
	return &Plucker{samplerate: sampleRate}
}

func (p *Plucker) SetSampleRate(sampleRate float64) {
	p.samplerate = sampleRate
}

func (p *Plucker) pluck(freq, time float64) []domains.Time {
	sampleSize := int(p.samplerate / freq)
	loops := int(freq*time)
	sound := whitenoise(sampleSize)
	lastIndex := sampleSize-1
	out := make([]domains.Time, loops*sampleSize)
	k := 0
	for i:=0; i < loops; i++ {
		for j, _ := range(sound) {
			if j==lastIndex {
				sound[j] = (0.996*(sound[j]+sound[0])/2)
			} else {
				sound[j] = (sound[j]+sound[j+1])/2
			}
			out[k] = sound[j]
			k++
		}
	}
	return out
}

func (p *Plucker) Play(freq, seconds float64, vol int32) []domains.Time {
	note := p.pluck(freq, seconds)
	for i, val := range(note) {
		note[i] = domains.Time(vol) * val
	}
	return note
}