gistfile1.txt

#include "testApp.h"
#include <ofGraphics.h>

void testApp::setup(){
  ofSetFrameRate(60);
  ofSetBackgroundAuto(false);
  ofEnableAlphaBlending();
  ofEnableSmoothing();
  ofBackground(255);
  ofSetColor(0);
}

void testApp::update(){

}

void testApp::draw(){

  float num = ofRandomf();
  float sd = 60;
  float mean = ofGetWidth() / 2;

  float x = (sd * num) + mean;

  ofSetColor(255, 10);
  ofRect(0, 0, ofGetWidth(), ofGetHeight());
  ofSetColor(0);
  ofEllipse(x, ofGetHeight() / 2, 16, 16);
}

gistfile2.txt

#include "testApp.h"
#include <ofGraphics.h>

bool haveNextNextGaussian = false;
float nextNextGaussian;

float ofxGaussian() {
  if (haveNextNextGaussian){
    haveNextNextGaussian = false;
    return nextNextGaussian;
  }
  else {
    float v1, v2, s;
    do {
      v1 = 2 * ofRandomf() - 1;
      v2 = 2 * ofRandomf() - 1;
      s = v1 * v1 + v2 * v2;
    }
    while (s >= 1 || s == 0);

    float multiplier = sqrt(-2 * log(s)/s);
    nextNextGaussian = v2 * multiplier;
    haveNextNextGaussian = true;

    return v1 * multiplier;
  }
}

void testApp::setup(){
  ofSetFrameRate(60);
  ofSetBackgroundAuto(false);
  ofEnableAlphaBlending();
  ofEnableSmoothing();
  ofBackground(255);
  ofSetColor(0);
}

void testApp::update(){

}

void testApp::draw(){

  float num = ofxGaussian();
  float sd = 60;
  float mean = ofGetWidth() / 2;

  float x = (sd * num) + mean;

  ofSetColor(255, 10);
  ofRect(0, 0, ofGetWidth(), ofGetHeight());
  ofSetColor(0);
  ofEllipse(x, ofGetHeight() / 2, 16, 16);
}

What does this line do?
while (s >= 1 || s == 0);