void setup() {
  size(700,200);
  background(192,64,0);
  stroke(0);
}
void draw() {
  stroke(220,220,220,20);    strokeWeight(1);
  fill(220,200,120,20);
  float sigma=width/10;
  float mu = width/2;
  // Box-Muller method for generating normal distributed 
  // numbers X and Y: 
  float U = random(1);
  float V = random(1);
  float X = sqrt(-2*log(U))*cos(2*PI*V);
  float Y = sqrt(-2*log(U))*sin(2*PI*V);
  ellipse(X*sigma+mu,random(height),20,20);
  ellipse(Y*sigma+mu,random(height),20,20);
  stroke(0,0,0);  strokeWeight(0.5);
  line(X*sigma+mu,height/2-10,X*sigma+mu,height/2+50);
  line(Y*sigma+mu,height/2-10,Y*sigma+mu,height/2+50);
  
  // the Gauss curve
  beginShape();
  stroke(0,0,0,2);    strokeWeight(10);
  noFill();
  float x,y;
  for (x=0;x<width;x+=10) {
    y=height*height*exp(-0.5*pow((x-mu)/sigma,2))/(sqrt(2*PI)*sigma);
    curveVertex(x,height-1-0.8*y);
    //println(""+x+" , "+y);
  }
  endShape();
}

// restart the painting
void mousePressed() {
  background(192,64,0);
}