plotting x and y coordinates

Tipikosh

greetings, i am trying to plot x and y coordinates from a touchpad connected to my pc via arduino. my arduino gives me a string that looks like that 233,672,0 the first part is my x coordinate, my second part is the y coordinate and that last part, is a 0 or 1 to tell me if there was a touch or not. until now i can see where my coordinates are with ellipse function, but i still cant get it to simply draw a line connecting all positions of my postion on the touchpad. my plan is to use the touchpad to write a letter, and when the letter is done written, i want to compare the letter that was drawn with another saved one on my pc. any help i would be thankful, here is my code

Tipikosh

import processing.serial.*; 

float x, y;
int touch;

void setup() { 
  size(600, 600);
  //fullScreen();
  Serial arduino = new Serial(this, "COM3", 9600); 
  arduino.bufferUntil('\n'); 
} 

void draw() { 
  background(0);
  line(x, y, x, y);
  ellipse(x, y, 10, 10);
}

void serialEvent(Serial p) { 
  String rawString = p.readString();
  rawString = rawString.trim();
  try {
    String[] values = split(rawString,",");
    int serialX = int(values[0]);
    int serialY = int(values[1]);    
    int touch = int(values[2]);
    x = map(serialX, 0, 640, 0, width);
    y = map(serialY, 0, 480, 0, height);
  } catch (Exception e){
    println("Error parsing string from Serial:");
    e.printStackTrace();
  }
}