Class: DXOpal::SoundEffect

Inherits:
Sound show all
Defined in:
lib/dxopal/sound_effect.rb

Overview

User-generated sound

Example:

v = 80
SoundEffect.register(:sound1, 4000, WAVE_RECT, 5000) do
  v = v - 0.03
  [rand(300), v]
end

This will generate a sound with WebAudio.

Defined Under Namespace

Modules: WaveTypes

Instance Attribute Summary

Attributes inherited from Sound

#decoded

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Sound

audio_context, #initialize, #play, #stop

Methods inherited from RemoteResource

[], _klass_name, _load_resources, add_class, register

Constructor Details

This class inherits a constructor from DXOpal::Sound

Class Method Details

._load(time, wave_type = WAVE_RECT, resolution = 1000, &block) ⇒ Object

time : Total number of ticks

When resolution=1000(default), `time` is equivalent to the 
total length of the sound in milliseconds.

wave_type : Type of wave form resolution : Number of ticks per second block : Should return [freq(0~44100), volume(0~255)]



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# File 'lib/dxopal/sound_effect.rb', line 28

def self._load(time, wave_type=WAVE_RECT, resolution=1000, &block)
  snd = new("(soundeffect)")
  snd_promise = %x{
    new Promise(function(resolve, reject){
      var n_channels = 1;
      var context = #{Sound.audio_context};
      var n_ticks = #{time};
      var totalSeconds = #{time / resolution};
      var valuesPerSecond = context.sampleRate;
      var n_values = totalSeconds * valuesPerSecond;
      var myArrayBuffer = context.createBuffer(n_channels, n_values, valuesPerSecond);
      var values = myArrayBuffer.getChannelData(0);
      var n = 0;
      for (var i = 0; i < n_ticks; i++) {
        var ret = #{block.call};
        var freq = ret[0], volume = ret[1];
        if (freq < 0) freq = 0;
        if (freq > 44100) freq = 44100;
        if (volume < 0) volume = 0;
        if (volume > 255) volume = 255;
        var vol = volume / 255;   // 0.0~1.0

        var period = valuesPerSecond * 1 / freq;
        for (; n < ((i+1) / n_ticks * n_values); n++) {
          var phase = (n % period) / period; // 0.0~1.0
          var value; // -1.0~1.0
          switch(#{wave_type}) {
          case "sine":
            value = Math.sin(2 * Math.PI * phase) * 2 - 1;
            break;
          case "sawtooth":
            value = phase * 2 - 1;
            break;
          case "triangle":
            value = phase < 0.25 ?  0+phase*4 :
                    phase < 0.5  ?  1-(phase-0.25)*4 :
                    phase < 0.75 ?  0-(phase-0.5)*4 :
                                   -1+(phase-0.75)*4;
            break;
          case "square":
            value = (phase < 0.5 ? 1 : -1);
            break;
          default:
            #{raise "unknown wave_type: " + wave_type.inspect};
          }
          values[n] = value * vol;
        }
      }
      snd['$decoded='](myArrayBuffer);
      resolve();
    });
  }
  return snd, snd_promise
end

Instance Method Details

#add(wave_type = WAVE_RECT, resolution = 1000) ⇒ Object 



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# File 'lib/dxopal/sound_effect.rb', line 83

def add(wave_type=WAVE_RECT, resolution=1000)
  TODO
end