Mehackit Visual arts with Processing, Chapter 0: Self portrait

Self_portrait_webcam.pde

/*
 * Visual arts with Processing
 * Chapter 0, The Beginning
 * Otso Sorvettula, Mehackit (CC BY-SA 4.0)
 *
 * This program takes the webcam feed and transforms it into a binary image. 
 You can draw on the by image using the mouse.
 *
 * Change the threshold by pressing '+' and '-'.
 * Toggle webcam feed on and off with 't'.
 * Save image with 's'
 *
 */

// Import external libraries
import processing.video.*; // Import a library for webcam

// Create global variables for the whole program to use
Capture cam;
boolean webcamFeedOn = true;
int threshold = 100;

/*
 * The setup-function is executed once when the program starts
 *
 * Check that a camera is found and start camera.
 */
void setup() {  
  size(640, 480);
  String[] cameras = Capture.list();

  if (cameras.length == 0) {
    println("No cameras found. Exiting.");
    exit();
  } else {
    cam = new Capture(this, 640, 480, 30);
    cam.start();
  }
}

/*
 * The draw-function is looped again and again as long as the program runs.
 *
 * Draw next image in the webcam feed if the feed is toggled on and draw mouse actions.
 */
void draw() {
  drawWebcamImage(); // Manipulate and draw the webcam image

  // Draw something on top of the image if the mouse is pressed. You can try to change, comment or uncomment some of these lines.
  if (mousePressed) {
    stroke(0, 20); // set stroke to almost transparent black
    // noStroke(); // turn stroke (outlines) off
    // fill(random(100, 255), random(100, 255), random(200, 255), 5); // generate and set almost random fill color
    // float r = random(0, 50); // Generate a random value and save it to a variable
    // ellipse(mouseX, mouseY, r, r); // Draw a circle to the mouse location with the random diameter
    line(mouseX, mouseY, mouseX + random(-50,50), mouseY + random(-50,50)); // Draw a line from the mouse location to a point in 50 pixel radius
  }
}

/*
 * Manipulate and draw the webcam image
 *
 * Draw webcam image if webcam feed is toggled on and there's a new image in the webcam feed.
 * The new frame is loaded as an array of pixels and the array is iterated over with for loops.
 * The brightness on each pixel is checked against a threshold.
 * If the brightness is lower than the threshold the pixel is set black, otherwise white.
 */
void drawWebcamImage() {
  if (cam.available() && webcamFeedOn) {
    cam.read(); 
    loadPixels(); 
    // Iterate through all the pixels of the frame
    for (int x = 0; x < cam.width; x++) { 
      for (int y = 0; y < cam.height; y++) { 
        int coordinate = x + y * cam.width;
        float pixelBrightness = brightness(cam.pixels[coordinate]); // Calculate the brightness of the given pixel in the cameras new frame
        if (pixelBrightness < threshold) { // If the pixel is darker than the threshold...
          pixels[coordinate] = color(0); // ...set the color of the pixel to this
        } else { // If the pixel is lighter than the threshold...
          pixels[coordinate] = color(255); // ...set the color of the pixel to this
        }
      }
    }
    updatePixels();
  }
}

/* 
 * Listen to key presses and match keys to actions.
 */
void keyPressed() {
  if (key == '+') {
    threshold++; 
    threshold = min(threshold, 255);
    println("Threshold set to " + threshold); 
  } else if (key == '-') { 
    threshold--; 
    threshold = max(threshold, 0);
    println("Threshold set to " + threshold); 
  } else if (key == 't' || key == 'T') { 
    webcamFeedOn = !webcamFeedOn;
    println("Update screen set to " + String.valueOf(webcamFeedOn)); 
  } else if (key == 's' || key == 'S') { 
    saveFrame("Processing-portrait-###.png");
    println("Image saved"); 
  }
}