Hello,
I am trying to use the PrintWriter function to export a list of points (printIn values) which are created from a color tracking sketch, but every time the .txt file is blank.  How can I get the .txt to list the points? 

Any help would be appreciated.
Thanks.


import processing.video.*;

Capture cam;
PGraphics img;
   

PrintWriter output;
color selected = color(0,255,0); // selected color

void setup()
{
  size(640,480);
  smooth();
  cam = new Capture(this,640,480);
  img = createGraphics(640,480,JAVA2D);
  output = createWriter("positions.txt");
}

void draw()
{
  if (cam.available()) {
    cam.read(); cam.loadPixels();
   
    // pick a different selected color, if you want
    if(mousePressed) selected = cam.pixels[mouseX+mouseY*cam.width];
   
    // search for the pixel closer to the selected color
    int sx = 0, sy = 0; // selected position
    float minDist = 1000; // put a huge number so we do not have to care
    for(int y = 0; y < cam.height; y ++) {
      for(int x = 0; x < cam.width; x ++) {
        color c = cam.pixels[x+y*cam.width];
        float d = dist(red(c),green(c),blue(c),
                       red(selected),green(selected),blue(selected));
        if(d < minDist) { minDist = d; sx = x; sy = y; }
      }
    }
   
    // update the painted image
    img.beginDraw();
    img.smooth();
    img.fill(selected,100); img.noStroke();
    img.ellipse(sx,sy,25,25);
    img.endDraw();
   
    // draw the cam image and on top of that draw the painted image
    image(cam,0,0);
    image(img,0,0);
    noFill(); stroke(200,255,200); strokeWeight(5);
    ellipse(sx,sy,50,50);
    println("sx = "+sx+", sy = "+sy);
    output.println("sx = "+sx+", sy = "+sy); // Write the coordinate to the file
  }
}


void keyPressed() {
  // clear
  if(key == ' ') img = createGraphics(cam.width,cam.height,JAVA2D);
  output.flush(); // Writes the remaining data to the file
  output.close(); // Finishes the file
  exit(); // Stops the program
}