nice fm drum synth

fmbeat.cpp

#include "LiveAudio.h"
#include <math.h>

class MyLiveAudio : public LiveAudio {
public:

	int pos = 0;
	double ph = 0;
	float period = 15050;














	// these are the coefficients - need to get the scale mapping right
	float baseFreq = 50;
	
	// amplitude
	float ampCurve = 1.2;
	float attackAmt = 40;
	float releaseAmt = 10000;
	
	// fm 
	float ratio = 2.0f;
	float fmAmt = 2.0f;
	float fmFeedback = 0.1f;
	float fmRelease = 5000;
	float fmCurve = 1.2;
	

	// pitch
	float pitchAmt = 200;
	float pitchRelease = 10000;
	float pitchCurve = 10;
	
	
	












	float lastOp1 = 0.f;




	float getSample() {
		pos++;
		
		if(pos %((int)period)==0) {
			ph =  0;
			pos = 0;
		}

		float env = 0.f;
		
		if(pos<attackAmt) {
			env = pos / attackAmt;
		} else {
			env = 1.f - (pos - attackAmt) / releaseAmt;
			if(env<0) env = 0.f;
		}
		env = pow(env, ampCurve);


		float fmEnv = 1.f - (pos / fmRelease);
		if(fmEnv<0) fmEnv = 0;
		fmEnv = pow(fmEnv, fmCurve);
		
		float pitchEnv = 1.f - (pos / pitchRelease);
		if(pitchEnv<0) pitchEnv = 0;
		pitchEnv = pow(pitchEnv, pitchCurve);

		
		float op1 = sin(ph*ratio + lastOp1*fmFeedback);
		lastOp1 = op1;
		float op2 = sin(ph + op1*fmEnv*fmAmt);


		float w = 2.0 * M_PI / 44100.f;
		
		ph += w * (baseFreq + pitchEnv * pitchAmt);


		return op2 * env;
	}

	void audioOut(float *samples, int length, int numChans) override {
		for(int i = 0; i < length; i++) {
			samples[i*2] = samples[i*2+1] = getSample() * 0.1;
			
		}
	}	
};