gibberish-dsp/js/instruments/tom.js

Gibberish is designed to be an optimized API for audio synthesis using per-sample techniques.

const g = require( 'genish.js' ),
      instrument = require( './instrument.js' )

module.exports = function( Gibberish ) {

  const Tom = argumentProps => {
    let tom = Object.create( instrument )
    
    const decay   = g.in( 'decay' ),
          pitch   = g.in( 'frequency' ),
          gain    = g.in( 'gain' ),
          loudness = g.in( 'loudness' ),
          triggerLoudness = g.in( '__triggerLoudness' )

    const props = Object.assign( {}, Tom.defaults, argumentProps )

    const trigger = g.bang(),
          impulse = g.mul( trigger, 1 ),
          eg = g.decay( g.mul( decay, g.gen.samplerate * 2 ), { initValue:0 } ), 
          bpf = g.mul( g.svf( impulse, pitch, .0175, 2, false ), 10 ),
          noise = g.gtp( g.noise(), 0 ), // rectify noise
          envelopedNoise = g.mul( noise, eg ),
          lpf = g.mul( g.svf( envelopedNoise, 120, .5, 0, false ), 2.5 ),
          out = g.mul( g.add( bpf, lpf ), g.mul( gain, g.mul( loudness, triggerLoudness ) ) )

    tom.env = {
      trigger: function() {
        eg.trigger()
        trigger.trigger()
      }
    }

    tom.isStereo = false

    tom = Gibberish.factory( tom, out, ['instruments', 'tom'], props  )
    
    return tom
  }
  
  Tom.defaults = {
    gain: 1,
    decay:.7,
    frequency:120,
    loudness:1,
    __triggerLoudness:1
  }

  return Tom
}