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//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//	FilterKernel::CalculateLopassParams()////		inFreq is normalized frequency 0 -> 1//		inResonance is in decibels//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~void FilterKernel::CalculateLopassParams(	double inFreq,											double inResonance ){    double r = pow(10.0, 0.05 * -inResonance);		// convert from decibels to linear        double k = 0.5 * r * sin(M_PI * inFreq);    double c1 = 0.5 * (1.0 - k) / (1.0 + k);    double c2 = (0.5 + c1) * cos(M_PI * inFreq);    double c3 = (0.5 + c1 - c2) * 0.25;        mA0 = 2.0 *   c3;    mA1 = 2.0 *   2.0 * c3;    mA2 = 2.0 *   c3;    mB1 = 2.0 *   -c2;    mB2 = 2.0 *   c1;}//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//	FilterKernel::GetFrequencyResponse()////		returns scalar magnitude response//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~double FilterKernel::GetFrequencyResponse( double inFreq /* in Hertz */ ){	float srate = GetSampleRate();		double scaledFrequency = 2.0 * inFreq / srate;		// frequency on unit circle in z-plane	double zr = cos(M_PI * scaledFrequency);	double zi = sin(M_PI * scaledFrequency);		// zeros response	double num_r = mA0*(zr*zr - zi*zi) + mA1*zr + mA2;	double num_i = 2.0*mA0*zr*zi + mA1*zi;		double num_mag = sqrt(num_r*num_r + num_i*num_i);		// poles response	double den_r = zr*zr - zi*zi + mB1*zr + mB2;	double den_i = 2.0*zr*zi + mB1*zi;		double den_mag = sqrt(den_r*den_r + den_i*den_i);		// total response	double response = num_mag  / den_mag;		return response;}//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~//	FilterKernel::Process(int inFramesToProcess)////		We process one non-interleaved stream at a time//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~void FilterKernel::Process(	const Float32 	*inSourceP,							Float32 		*inDestP,							UInt32 			inFramesToProcess,							UInt32			inNumChannels,	// for version 2 AudioUnits inNumChannels is always 1							bool &			ioSilence){	double cutoff = GetParameter(kFilterParam_CutoffFrequency);    double resonance = GetParameter(kFilterParam_Resonance );    	// do bounds checking on parameters	//    if(cutoff < kMinCutoffHz) cutoff = kMinCutoffHz;	if(resonance < kMinResonance ) resonance = kMinResonance;	if(resonance > kMaxResonance ) resonance = kMaxResonance;		// convert to 0->1 normalized frequency	float srate = GetSampleRate();		cutoff = 2.0 * cutoff / srate;	if(cutoff > 0.99) cutoff = 0.99;		// clip cutoff to highest allowed by sample rate...		// only calculate the filter coefficients if the parameters have changed from last time	if(cutoff != mLastCutoff || resonance != mLastResonance )	{		CalculateLopassParams(cutoff, resonance);				mLastCutoff = cutoff;		mLastResonance = resonance;			}		const Float32 *sourceP = inSourceP;	Float32 *destP = inDestP;	int n = inFramesToProcess;		// Apply the filter on the input and write to the output	// This code isn't optimized and is written for clarity...	//	while(n--)	{		float input = *sourceP++;				float output = mA0*input + mA1*mX1 + mA2*mX2 - mB1*mY1 - mB2*mY2;		mX2 = mX1;		mX1 = input;		mY2 = mY1;		mY1 = output;				*destP++ = output;	}}