Tone.js/src/component/DryWet.js

///////////////////////////////////////////////////////////////////////////////
//
//  DRY/WET KNOB
//
// 	equal power fading
//	control values:
// 	   -1 = 100% dry
//		1 = 100% wet
///////////////////////////////////////////////////////////////////////////////

define(["core/Tone", "signal/Signal", "signal/Invert", "signal/Scale"], function(Tone){

	Tone.DryWet = function(initialDry){
		Tone.call(this);

		//components
		this.dry = this.context.createGain();
		this.wet = this.context.createGain();
		this.output = this.context.createGain();
		this.equalGain = this.context.createWaveShaper();
		//control signal
		this.control = new Tone.Signal();
		this.invert = new Tone.Invert();
		this.dryScale = new Tone.Scale(0, 1);
		this.wetScale = new Tone.Scale(0, 1);


		//connections
		this.dry.connect(this.output);
		this.wet.connect(this.output);
		//control signal connections
		this.control.connect(this.equalGain);
		//wet chain
		this.chain(this.equalGain, this.wetScale, this.wet.gain);
		//dry chain
		this.chain(this.equalGain, this.invert, this.dryScale, this.dry.gain);

		//setup
		this._equalPowerGainCurve();
		this.dry.gain.value = 0;
		this.wet.gain.value = 0;
		this.setDry(0);
	}

	Tone.extend(Tone.DryWet);

	Tone.DryWet.prototype.setDry = function(val, rampTime){
		rampTime = this.defaultArg(rampTime, 0);
		this.control.linearRampToValueAtTime(val, rampTime);
	}

	Tone.DryWet.prototype.setWet = function(val, rampTime){
		this.setDry(-val, rampTime);
	}

	//generates the values for the waveshaper
	Tone.DryWet.prototype._equalPowerGainCurve = function(){
		var len = this.bufferSize;
		var curve = new Float32Array(len);
		for (var i = 0; i < len; i++){
			//values between -1 to 1
			var baseline = (i / (len - 1)) * 2 - 1;
			// scale it by amount
			curve[i] = this.equalPowerGain(baseline);
			// curve[i] = baseline;
		}
		this.equalGain.curve = curve;
	}

	return Tone.DryWet;
});