Arduino 1.9

#define RED_PIN 11
#define BLUE_PIN 10
#define GREEN_PIN 9
#define DELTA 3

void setup(){
pinMode(BLUE_PIN, OUTPUT);
pinMode(RED_PIN, OUTPUT);
pinMode(GREEN_PIN, OUTPUT);
}

int blue = 0;
boolean blueWasOn = false;
int red = 0;
boolean redWasOn = true;
int green = 0;
boolean greenWasOn = false;

void loop(){
if(blue < 255 && !blueWasOn){
Plus(blue, blueWasOn, BLUE_PIN, redWasOn);
Minus(green, greenWasOn, GREEN_PIN);
}

if(red < 255 && !redWasOn){
Plus(red, redWasOn, RED_PIN, greenWasOn);
Minus(blue, blueWasOn, BLUE_PIN);
}

if(green < 255 && !greenWasOn){
Plus(green, greenWasOn, GREEN_PIN, blueWasOn);
Minus(red, redWasOn, RED_PIN);
}
}

void Plus(int &color, boolean &colorWasOn, int pin, boolean &prePreColorWasOn){
color = constrain(color + DELTA, 0, 255);
if(color >= 252){
colorWasOn = !colorWasOn;
color = 255;
prePreColorWasOn = false;
}
analogWrite(pin, color);
delay(25);
}

void Minus(int &preColor, boolean &preColorWasOn, int prePin){
preColor = constrain(preColor - DELTA, 0, 255);
if(preColor <= 3){
preColor = 0;
preColorWasOn = true;
}
analogWrite(prePin, preColor);
delay(25);
}