import processing.video.*;
  
  // Size of each cell in the grid
  int cellSize = 20;
  // Number of columns and rows in our system
  int cols, rows;
  // Variable for capture device
  Capture video;
  
  void setup() {
    size(640, 480, P3D);
    frameRate(30);
    cols = width / cellSize;
    rows = height / cellSize;
    colorMode(RGB, 255, 255, 255, 100);
  
    // Uses the default video input, see the reference if this causes an error
    video = new Capture(this, width, height, 12);
    
    background(0);
  }
  
  void draw() { 
    if (video.available()) {
      video.read();
      video.loadPixels();
      
      // Not bothering to clear background
      // background(0);
    
      // Begin loop for columns
      for (int i = 0; i < cols; i++) {
        // Begin loop for rows
        for (int j = 0; j < rows; j++) {
        
          // Where are we, pixel-wise?
          int x = i*cellSize;
          int y = j*cellSize;
          int loc = (video.width - x - 1) + y*video.width; // Reversing x to mirror the image
        
          float r = red(video.pixels[loc]);
          float g = green(video.pixels[loc]);
          float b = blue(video.pixels[loc]);
          // Make a new color with an alpha component
          color c = color(r, g, b, 75);
        
          // Code for drawing a single rect
          // Using translate in order for rotation to work properly
          pushMatrix();
          translate(x+cellSize/2, y+cellSize/2);
          // Rotation formula based on brightness
          rotate((2 * PI * brightness(c) / 255.0));
          rectMode(CENTER);
          fill(c);
          noStroke();
          // Rects are larger than the cell for some overlap
          rect(0, 0, cellSize+6, cellSize+6);
          popMatrix();
        }
      }
    }
  }