//  init
Test my_test;
Vector stack;

void setup ()
{
 size (800, 600);
 framerate (30);
 background (255);
 //
 my_test = new Test (width/2, height/2);
 stack = new Vector ();
 //
 stack.add (my_test);
}

void draw ()
{
 AbstractTest current = (AbstractTest) stack.get(0);
 
 //  translate (-current._x+width/2, 0);
 
 current.main ();
 //
 copy (0,0, width,height, -1,0, width-1,height);
}




class Test extends AbstractTest
{
 //  constr
 Test (float x, float y)
 {
   a = -1;
   _x = oldx = x;
   _y = oldy = y;
 }
 
 //  methods
 void main ()
 {
   ceta = 1.6 * sin (a);
   _x += 4 * cos (ceta);
   _y += 4 * sin (ceta);
   a += PI/180 * 1.6;
   //
   stroke (0, 255);
   line (_x, _y, oldx, oldy);
   //
   oldx = _x;
   oldy = _y;
 }
}

class AbstractTest
{
 //  properties
 float _x, _y, oldx, oldy;
 float ceta, a;
 
 AbstractTest (){}
 
 //  callbacks
 void main (){}
}