const int echoPin = 12;
const int triggerPin = 13;
const int redPin = 11;
const int greenPin = 10;
const int bluePin = 9;
int cm = 0;

void setup() {
  Serial.begin(9600);
  pinMode(triggerPin, OUTPUT); 
  pinMode(echoPin, INPUT);
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
}

void loop() {
  cm = 0.01723 * readUltrasonicDistance(triggerPin, echoPin);
  analogWrite(redPin, cm/2);
  analogWrite(greenPin, cm^2);
  analogWrite(bluePin, cm^3);
  Serial.println(cm);
}

long readUltrasonicDistance(int triggerPin, int echoPin)
{
  pinMode(triggerPin, OUTPUT);  
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);
  pinMode(echoPin, INPUT);
  return pulseIn(echoPin, HIGH);
}