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modularizing chuck files

Posted by Nikolaus Gradwohl Sat, 17 Jan 2009 12:11:00 GMT

I wrote a simple chuck script that generates a drum loop and a bass-sequence. later i wanted to reuse the sounds and started to search how to modularize the code.

so i started to convert my instrument declarations in classes. The instrument classes don't get connected to 'dac' directly. They have a "connect"-method that can be used by the main script.

to run the loop all the scripts must be given on the commandline

chuck Bass.ck DrumSet.ck loop.ck

The main script (loop.ck) instanciates a DrumSet and a Bass class and connects them to "dac". Than it generates a walking bass and a simple electronic drum loop.

DrumSet drm;
drm.connect( dac );

Bass bass;
bass.connect( dac );

[ 41, 41, 44, 46] @=> int bline[];
0 => int pos;
0 => int count;

while ( true ) {
    drm.hh();
    if ( count % 2 == 0 ) { drm.bd(); }
    if ( count % 4 == 2 ) { drm.sn(); }

    if ( count % 2 == 0 ) { spork ~ bass.bass( bline[ pos % 4 ]); }
    if ( count % 2 == 1 ) { spork ~ bass.bass( 12 + bline[ pos % 4 ]); }


    1 + count => count;
    if ( count % 4 == 0 ) { 1 + pos => pos; }
    250::ms => now;
}

In Bass.ck a simple saw-wave based electronic bass is declared. The notes are triggerd by the "bass"-method. The notes are all played the same length. Therefore this method must be called in a thread otherwise the main loop would wait for the notes to end.

spork ~ bass.bass( 40 )

playes the bass on midinote 40

public class Bass {
    // BASS
    SawOsc sb => LPF filt => ADSR a => Gain g2;
    440 => filt.freq;
    0.3 => filt.Q;
    0.0 => g2.gain;
    (10::ms, 45::ms, 0.5, 40::ms) => a.set; // Set ADSR envelope

    public void connect( UGen u ) {
        g2 => u;
    }

    public void bass( int tone ) {
        Std.mtof( tone ) =>  sb.freq;
        0.3 => g2.gain;
        1 => a.keyOn;
        125::ms => now;
        1=> a.keyOff;
    }
}

In DrumSet.ck three instruments get declared (a basedrum, a snare and a hihat) and each gets a method that can be used to trigger the sounds.

public class DrumSet {
    // define hihat
    Shakers hhs => JCRev r;
    .025 => r.mix;
    Std.mtof( 76 ) => hhs.freq;

    // Define Bassdrum
    SinOsc s => ADSR bda;
    80 => s.freq;
    (0::ms, 10::ms, 0.0, 0::ms ) => bda.set;

    // define snare drum
    Noise n => ADSR sna => Gain g => dac;
    0.3 => g.gain;
    (0::ms, 25::ms, 0.0, 0::ms) => sna.set;


    public void connect( UGen ugen ) {
        r => ugen;
        bda => ugen;
        g => ugen;
    }

    public void hh() {
        1 => hhs.noteOn;
    }

    public void bd() {
        1 => bda.keyOn;
    }

    public void sn() {
        1 => sna.keyOn;
    }
}