void setup() { 
  size(400,400); 
  noStroke();
  ellipseMode(CENTER_DIAMETER);
  smooth();
}

void loop() {
  background(0,0,0);
noStroke();
fill(255,0,0, 100);  
  ellipse(125,210, 240,240);
fill(0,255,0, 120);  
  ellipse(200,140, 240,240);
fill(0,0,255, 180);  
  ellipse(275,210, 240,240);
}