float x,y;

void setup()
{
  size(400,400);
  background(0);
  frameRate(50);
  noStroke();
  smooth();
}
void draw()
{  
  if (mousePressed==true)
  { fill(random(0,255),random(0,255),random(0,255), random(50,100));
    x=random(0,400);
    y=random(0,400);
    ellipse(x,y,50,50);}
    else {
    background(0);
  }
}