int red = 0;
int green = 0;
int blue = 0;

const int redPin = 9;
const int bluePin = 10;
const int greenPin = 11;

void setup()
{
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
}


void goForward()
{
  if (red < 255)
  {
    red++;
    analogWrite(redPin, red);
    delay(100);
  }
  else if (red = 255)
  {
    if (blue < 255)
    {
      blue++;
      analogWrite(bluePin, blue);
      delay(100);
    }
  }
  else if (red == 255 & blue == 255)
  {
    if (green < 255)
    {
      green++;
      analogWrite(greenPin, green);
      delay(100);
    }
  }
  else if (red == 255 || blue == 255 || green == 255)
  {
    goReverse;
  }
}


void goReverse()
{
if (red > 0)
  {
    red--;
    analogWrite(redPin, red);
    delay(100);
  }
  else if (red == 0)
  {
    if (blue > 0)
    {
      blue--;
      analogWrite(bluePin, blue);
      delay(100);
    }
  }
  else if (red == 0 || blue == 0)
  {
    if (green > 0)
    {
      green--;
      analogWrite(greenPin, green);
      delay(100);
    }
  }
  else if (red == 0 || blue == 0 || green == 0)
  {
    goForward;
  }
}
void loop()
{
   goForward();
   goReverse();
}