float r = 0.0;
float a = 0.0;
float a1 = 360;
void setup()
{
background(122,122,122);
size(600,600); 
}

void draw()
{

ellipse(250+r*sin(a),250+r*cos(a),10,10);
ellipse(250+r*sin(a1),250+r*cos(a1),10,10);
r = r + 1.0;
a = a + 0.1;
a1 = a1 - 0.1;
if (a > 360.0)
{
r = 0.1;
a = 0.0;
a1 = 360;
}

if (a == 0) background(122,122,122);
}