float x,y,angle,speed;

void setup() {
  size(300,300);
  ellipseMode(CENTER_DIAMETER);
  framerate(20);
  
  angle=random(0,360);
  speed=random(1,5);
  x=width/2;
  y=height/2;
}

void loop() {
//  background(200);  
  
  x=x+cos(radians(angle))*speed;
  y=y+sin(radians(angle))*speed;
  angle=angle+random(-3,3);
//  speed=speed+0.1;
  
  if(x<0) x=width;
  else if(x>width) x=0;
  if(y<0) y=height;
  else if(y>height) y=0;
  
  ellipse(x,y, 10,10);
}