Mastering openFrameworks by Yanc Chris

Author:Yanc, Chris
Language: eng
Format: epub
Publisher: Packt Publishing

The update() function gets the spectrum of the currently played sound, computes its smoothed values to the spectrum array, and recalculates the Rad and Vel parameters. Finally, it calculates new point positions:

void testApp::update(){ //Update sound engine ofSoundUpdate(); //Get current spectrum with N bands float *val = ofSoundGetSpectrum( N ); //We should not release memory of val, //because it is managed by sound engine //Update our smoothed spectrum, //by slowly decreasing its values and getting maximum with val //So we will have slowly falling peaks in spectrum for ( int i=0; i<N; i++ ) { spectrum[i] *= 0.97; //Slow decreasing spectrum[i] = max( spectrum[i], val[i] ); } //Update particles using spectrum values //Computing dt as a time between the last //and the current calling of update() float time = ofGetElapsedTimef(); float dt = time - time0; dt = ofClamp( dt, 0.0, 0.1 ); time0 = time; //Store the current time //Update Rad and Vel from spectrum //Note, the parameters in ofMap's were tuned for best result //just for current music track Rad = ofMap( spectrum[ bandRad ], 1, 3, 400, 800, true ); Vel = ofMap( spectrum[ bandVel ], 0, 0.1, 0.05, 0.5 ); //Update particles positions for (int j=0; j<n; j++) { tx[j] += Vel * dt; //move offset ty[j] += Vel * dt; //move offset //Calculate Perlin's noise in [-1, 1] and //multiply on Rad p[j].x = ofSignedNoise( tx[j] ) * Rad; p[j].y = ofSignedNoise( ty[j] ) * Rad; } }

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