Include the ofxOsc addon's header to the ofApp.h file by inserting the following line after the #include "ofxGui.h" line:

#include "ofxOsc.h"

Add a declaration of the OSC receiver object to the ofApp class:

ofxOscReceiver oscReceiver;

Set up the OSC receiver in setup():

oscReceiver.setup( 12345 );

The argument of the setup() method is the networking port number. After executing this command, oscReceiver begins listening on this port for incoming OSC messages. Each received message is added to a special message queue for further processing.

Add the processing of incoming...