How do I change the background in Processing from an Arduino - arduino

Question

I am trying to use three potentiometers that are connected to an Arduino to adjust the color background of Processing. I am super new at this.
Here is my Arduino code:
int potPin = 0;
int potPinB = 1;
int potPinC = 2;
void setup()
{
Serial.begin(9600);
}
void loop()
{
int val = map(analogRead(potPin), 0, 1023, 0, 255);
Serial.print(val);
delay(500);
Serial.print(",");
int valB = map(analogRead(potPinB), 0, 1023, 0, 255);
Serial.print(valB);
delay(500);
Serial.print(",");
int valC = map(analogRead(potPinC), 0, 1023, 0, 255);
Serial.println(valC);
delay(500);
}
Here is my processing code:
Which I know is wrong. My screen just shows up black.
import processing.serial.*;
Serial myPort;
float val = 0;
void setup()
{
size(500, 500);
port = new Serial(this, "/dev/cu.usbmodem1451", 9600);
//port.bufferUntil('\n');
if (frame != null);
frame.setResizable(true);
}
void draw ()
{
background(val);
}
void serialEvent (Serial port)
{
val = float(port.readStringUntil('\n'));
}

Answer 1

It looks like you might be using linux, you may want to check this:
"/dev/cu.usbmodem1451" -> mine is -> "/dev/ttyUSB0"
Here's an example I made from your posted code. It works on my machine, let me know if you have any difficulties.
Arduino Sketch (same)
int potPin = 0;
int potPinB = 1;
int potPinC = 2;
void setup()
{
Serial.begin(9600);
}
void loop()
{
int val = map(analogRead(potPin), 0, 1023, 0, 255);
Serial.print(val);
delay(500);
Serial.print(",");
int valB = map(analogRead(potPinB), 0, 1023, 0, 255);
Serial.print(valB);
delay(500);
Serial.print(",");
int valC = map(analogRead(potPinC), 0, 1023, 0, 255);
Serial.println(valC);
delay(500);
}
Processing Sketch
The processing sketch has been changed, some code was taken from the Arduino - Graph tutorial.
import processing.serial.*;
Serial myPort; // The serial port
int xPos = 1; // horizontal position of the graph
void setup () {
// set the window size:
size(400, 300);
// List all the available serial ports
println(Serial.list());
// Open whatever port is the one you're using.
myPort = new Serial(this, "/dev/ttyUSB0", 9600);
// don't generate a serialEvent() unless you get a newline character:
myPort.bufferUntil('\n');
// set inital background:
background(0);
}
void draw () {
// everything happens in the serialEvent()
}
void serialEvent (Serial myPort) {
// read first string
String inStringA = myPort.readStringUntil(',');
// make sure it's not empty
if (inStringA != null){
// read following strings
String inStringB = myPort.readStringUntil(',');
String inStringC = myPort.readStringUntil('\n');
// convert to an int and map to the screen height:
float valA = float(inStringA);
float valB = float(inStringB);
float valC = float(inStringC);
// assign to rgb background
background(valA,valB,valC);
}
}