testApp.h:

#ifndef _TEST_APP
#define _TEST_APP

#include "ofMain.h"
#include "ofBall.h"

class testApp : public ofBaseApp{

   public:

      void setup();
      void update();
      void draw();



   private:

                ofBall** myBall;
                int nBalls;


};

#endif



testApp.cpp


#include "testApp.h"



//--------------------------------------------------------------
void testApp::setup(){

        ofBackground(255);
        ofSetFrameRate(30);
        ofSetWindowTitle("balls - class example_4");

        ofEnableSmoothing();
        ofNoFill();

        nBalls = 1;
        myBall = new ofBall*[nBalls];
                for (int i = 0; i < nBalls; i++){
                        float x = 20+(100*i);
                        float y = 20+(100*i);
                        int dim = 10+(i*10);
            ofLog() << "posx " << x;
                        myBall[i] = new ofBall(x,y, dim);

        }

}

//--------------------------------------------------------------
void testApp::update(){

                for (int i = 0; i < nBalls; i++){
                        myBall[i]->update();
                }


}

//--------------------------------------------------------------
void testApp::draw(){

                for (int i = 0; i < nBalls; i++){
                        myBall[i]->draw();
                }


}


ofBall.h:



#ifndef _OF_BALL                // by using this if statement you prevent the class to be called more than once - in other words what we're saying here is
#define _OF_BALL                //if the class has NOT been defined then define it


#include "ofMain.h"


class ofBall {



   public:

                // methods
                void update();
                void draw();

                //constructor
                ofBall(float x, float y, int dim);

                // variables
                ofRectangle blackSnap;
                        float x;
                float y;
                int dim;


        private:


};                                              //don't forget the semicolon in the end of the class definition

#endif


ofBall.cpp:


#include "ofBall.h"


ofBall::ofBall(float _x, float _y, int _dim)
{
        x = _x;
        y = _y;
        dim = _dim;


}


void ofBall::update(){
x++;
y++;

}


void ofBall::draw(){

        ofSetColor(120,120,120);
        ofCircle(x, y, dim);
    	ofRect(x,y,100,200);
}