gibberish-dsp/js/instruments/hat.js

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

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

module.exports = function( Gibberish ) {

  let Hat = argumentProps => {
    let hat = Object.create( instrument ),
        tune  = g.in( 'tune' ),
        scaledTune = g.memo( g.add( .4, tune ) ),
        decay  = g.in( 'decay' ),
        gain  = g.in( 'gain' ),
        loudness = g.in( 'loudness' ),
        triggerLoudness = g.in( '__triggerLoudness' )

    let props = Object.assign( {}, Hat.defaults, argumentProps )

    let baseFreq = g.mul( 325, scaledTune ), // range of 162.5 - 487.5
        bpfCutoff = g.mul( g.param( 'bpfc', 7000 ), scaledTune ),
        hpfCutoff = g.mul( g.param( 'hpfc', 11000 ), scaledTune ),  
        s1 = Gibberish.oscillators.factory( 'square', baseFreq, false ),
        s2 = Gibberish.oscillators.factory( 'square', g.mul( baseFreq,1.4471 ) ),
        s3 = Gibberish.oscillators.factory( 'square', g.mul( baseFreq,1.6170 ) ),
        s4 = Gibberish.oscillators.factory( 'square', g.mul( baseFreq,1.9265 ) ),
        s5 = Gibberish.oscillators.factory( 'square', g.mul( baseFreq,2.5028 ) ),
        s6 = Gibberish.oscillators.factory( 'square', g.mul( baseFreq,2.6637 ) ),
        sum = g.add( s1,s2,s3,s4,s5,s6 ),
        eg = g.decay( g.mul( decay, g.gen.samplerate * 2 ), { initValue:0 }), 
        bpf = g.svf( sum, bpfCutoff, .5, 2, false ),
        envBpf = g.mul( bpf, eg ),
        hpf = g.filter24( envBpf, 0, hpfCutoff, 0 ),
        out = g.mul( hpf, g.mul( gain, g.mul( loudness, triggerLoudness ) ) )

    hat.env = eg 
    hat.isStereo = false

    const __hat = Gibberish.factory( hat, out, ['instruments','hat'], props  )
    

    return __hat
  }
  
  Hat.defaults = {
    gain:  .5,
    tune: .6,
    decay:.1,
    loudness:1,
    __triggerLoudness:1
  }

  return Hat

}