Get 3 Values from processing to Arduino - arduino

Question

I have a color tracking program in Processing, which works with a Kinect. When I click somewhere in the picture it saves this color and draws an ellipse around it. I just want to send 3 int values (one for red, green and blue) over myPort.write() to Arduino and save these 3 values in Arduino in 2 variables. My goal is to light a red LED if the red variable is the highest, and the green LED if green is the highest and so on.
I've tried several examples I found whiel googling, but nothing works. I don't know how Arduino should get the correct values in the variables!
EDIT: Here you have my Processing code. I glued it together from several other tutorials until I nearly cried..
import processing.serial.*;
Serial myPort;
import SimpleOpenNI.*;
SimpleOpenNI kinect;
// Frame
PImage currentFrame;
color trackColor;
int r1, g1, b1, r2, g2, b2;
void setup()
{
size(640, 480);
String portName = Serial.list()[0]; //change the 0 to a 1 or 2 etc. to match your port
myPort = new Serial(this, portName, 9600);
kinect = new SimpleOpenNI(this);
kinect.enableRGB();
trackColor = color (255, 0, 0);
smooth ();
currentFrame = createImage (640, 480, RGB);
}
void draw()
{
kinect.update();
currentFrame = kinect.rgbImage ();
image(currentFrame, 0, 0);
currentFrame.loadPixels();
// Before we begin searching, the "world record" for closest color is set to a high number that is easy for the first pixel to beat.
float worldRecord = 500;
// XY coordinate of closest color
int closestX = 0;
int closestY = 0;
// Begin loop to walk through every pixel
for (int x = 0; x < currentFrame.width; x ++ ) {
for (int y = 0; y < currentFrame.height; y ++ ) {
int loc = x + y*currentFrame.width;
// What is current color
color currentColor = currentFrame.pixels[loc];
r1 = (int)red(currentColor);
g1 = (int)green(currentColor);
b1 = (int)blue(currentColor);
r2 = (int)red(trackColor);
g2 = (int)green(trackColor);
b2 = (int)blue(trackColor);
// Using euclidean distance to compare colors
float d = dist(r1, g1, b1, r2, g2, b2); // We are using the dist( ) function to compare the current color with the color we are tracking.
// If current color is more similar to tracked color than
// closest color, save current location and current difference
if (d < worldRecord) {
worldRecord = d;
closestX = x;
closestY = y;
}
}
}
// We only consider the color found if its color distance is less than 10.
// This threshold of 10 is arbitrary and you can adjust this number depending on how accurate you require the tracking to be.
if (worldRecord < 10) {
// Draw a circle at the tracked pixel
fill(trackColor);
strokeWeight(4.0);
stroke(0);
ellipse(closestX, closestY, 30, 30);
}
if (mousePressed == true) {
color c = get(mouseX, mouseY);
//println("r: " + red(c) + " g: " + green(c) + " b: " + blue(c));
// Save color where the mouse is clicked in trackColor variable
int loc = mouseX + mouseY*(currentFrame.width);
trackColor = currentFrame.pixels[loc];
println("red " + r2);
println("green " + g2);
println("blue " + b2);
int colors[] = {r2, g2, b2};
for(int i=0; i < 3; i++) {
myPort.write(colors[i]);
}
}
println("ClosestX " + closestX);
myPort.write(closestX);
}
And my Arduino Code, where I don't know how to get several values.
int val;
int ledPin = 13;
int freq;
int piezoPin = 9;
int redLED = 3;
int greenLED = 5;
int blueLED = 7;
int red, green, blue;
void setup() {
pinMode(ledPin, OUTPUT); // Set pin as OUTPUT
Serial.begin(9600); // Start serial communication at 9600 bps
digitalWrite(ledPin, LOW);
}
void loop() {
if (Serial.available() > 0)
{ // If data is available to read,
val = Serial.read(); // read it and store it in val
}
if(red > green && red > blue) {
digitalWrite(redLED, HIGH); //light Red LED
}
if(green > red && green > blue) {
digitalWrite(greenLED, HIGH); //light Red LED
}
if(blue > red && blue > green) {
digitalWrite(blueLED, HIGH); //light Red LED
}
//Piezo buzzing higher when X-Position of tracked color is higher.
if (val < 100) {
freq = 50;
}
else if (val < 200) {
freq = 200;
}
else if (val < 300) {
freq = 400;
}
else if (val < 400) {
freq = 600;
}
else if (val < 500) {
freq = 800;
}
else (freq = 1000);
tone(piezoPin, freq);
}
EDIT2: Yes, additionally to lighing the LEDs I also want to have a sound from a piezo buzzer, but that works pretty well, so no questions on that... yet.
Help, please!!

Answer 1

Serial communication to your arduino works with a single byte at a time.
As luck would have it, the three components of a Processing Color are also three bytes.
One for red(0-255)
One for green(0-255)
One for blue(0-255)
Now all we need is a little more info so we can keep them separate.
Because a byte's minimum and maximum values are 0-255, there's no safe character we can use to keep track of the three different bytes, so we need a way to figure out where the info we send begins and ends.
An easy way to do this, is to set up a header and a footer for your messages ; something like :
<color>[byte (red)][byte (green)][byte (blue)]</color>
If we are going to read and decipher messages formatted like this, we are going to need a little buffer that will store the values we receive from Processing, so we can read them back and see if we can match the message format.
So, on the Arduino side, we need this :
String buffer = "";
String messageBegin = "<color>";
String messageEnd = "</color>";
//we read our serial data in the SerialEvent() function
//this is called *after* a loop(), and only if there is serial data in the buffer.
void serialEvent()
{
while(Serial.available())
{
buffer += (char)Serial.read();
}
}
void loop()
{
//now, inside loop, we no longer need to worry about gathering data from serial.
//we do still need to figure out if our message is complete, and then parse it.
//if our buffer contains both the beginning and the end of a message
//in the right order.
int beginIndex = buffer.lastIndexOf(messageBegin);
int endIndex = buffer.lastIndexOf(messageEnd);
if(beginIndex != -1 && endIndex != -1 && beginIndex < endIndex)
{
//we have a complete message!
//our red color starts 7 characters after where the message begins,
//because our "messageBegin" is 7 characters long
string lastMessage = buffer.substring(beginIndex+7);
//this is arguably not the prettiest way to get our byte values back.
//see if you can do better for bonus points!
byte messageAsBytes[80];
lastMessage.getBytes(messageAsBytes, messageAsBytes.length());
//we can now finally reconstruct the value we had from processing!
byte r = (byte)messageAsBytes[0];
byte g = (byte)messageAsBytes[1];
byte b = (byte)messageAsBytes[2];
//if we get a complete message, we can clear our buffer. (don't forget to do this!)
buffer = "";
}
}
On the processing side, all we need to do is make sure our messagebegin and messageend are sent along for the ride :
myPort.write("<color">);
for(int i=0; i < 3; i++) {
myPort.write(colors[i]);
}
myPort.write("</color">);