Hello guys I have connected 3 rgb leds to arduino and I want processing to read its value and set it as background.

Here is the arduino code which works perfectly fine(by the way its analog fading led program)

// Fading LED
// Dhruv Adhia - Right now trying to send colors to processing

int value = 0;                            // variable to keep the actual value
int green_ledpin = 9;                     // light connected to digital pin 9
int blue_ledpin = 10;
int red_ledpin=11;

void setup()
{

/*pinMode(green_ledpin,OUTPUT);
pinMode(red_ledpin,OUTPUT);
pinMode(blue_ledpin,OUTPUT);*/
Serial.begin(9600);

}

void loop()
{

green_natural_light();
delay(1000);
blue_natural_light();
delay(1000);
red_natural_light();
}

void green_natural_light()
{

  for(value = 0 ; value <= 255; value+=5) // fade in (from min to max)
{
  Serial.print("G");
  Serial.println(analogRead(green_ledpin));
  analogWrite(green_ledpin, value);           // sets the value (range from 0 to 255)
  delay(30);                            // waits for 30 milli seconds to see the dimming effect
}
for(value = 255; value >=0; value-=5)   // fade out (from max to min)
{
  Serial.print("G");
  Serial.println(analogRead(green_ledpin));
  analogWrite(green_ledpin, value);
  delay(30);
}
}

void red_natural_light()
{

  for(value = 0 ; value <= 255; value+=5) // fade in (from min to max)
{
  Serial.print("R");
  Serial.println(analogRead(red_ledpin));
  analogWrite(red_ledpin, value);           // sets the value (range from 0 to 255)
  delay(30);                            // waits for 30 milli seconds to see the dimming effect
}
for(value = 255; value >=0; value-=5)   // fade out (from max to min)
{
  Serial.print("R");
  Serial.println(analogRead(red_ledpin));
  analogWrite(red_ledpin, value);
  delay(30);
}
}

void blue_natural_light()
{

 for(value = 0 ; value <= 255; value+=5) // fade in (from min to max)
{
  Serial.print("B");
  Serial.println(analogRead(blue_ledpin));
  analogWrite(blue_ledpin, value);           // sets the value (range from 0 to 255)
  delay(30);                            // waits for 30 milli seconds to see the dimming effect
}
for(value = 255; value >=0; value-=5)   // fade out (from max to min)
{
  Serial.print("B");
  Serial.println(analogRead(blue_ledpin));
  analogWrite(blue_ledpin, value);
  delay(30);
}

}

and here is the processing program where I get "StringIndexOutOfBoundsException: String index out of range: 0"

int targetColor;
import processing.serial.*;
String buff = "";
int rval = 0 , gval = 0 , bval = 0;
int NEWLINE =10;
color c1;

Serial port;

void setup() {
size(640,480);
println("Available serial ports:");
println(Serial.list());
port = new Serial(this, Serial.list()[0],9600);
}


void draw() {
while(port.available()>0) {
  serialEvent(port.read());
}
background(c1);
}

void serialEvent(int serial)
{
if(serial != NEWLINE) {
  buff += char(serial);
} else {
  // The first character tells us which color this value is for
  char c = buff.charAt(0); // here is the place where it shows an error
  // Remove it from the string
  buff = buff.substring(1);
  // Discard the carriage return at the end of the buffer
  buff = buff.substring(0, buff.length()-1);
  // Parse the String into an integer
  if (c == 'R')
    rval = Integer.parseInt(buff);
  else if (c == 'G')
    gval = Integer.parseInt(buff);
  else if (c == 'B')
    bval = Integer.parseInt(buff);
  // Clear the value of "buff"
  c1=color(rval,gval,bval);
  buff = "";
  port.clear();
}
}


any thoughts friends?

Thank you,
Dhruv