// Learning Processing
  // Daniel Shiffman
  // http://www.learningprocessing.com
  
  // Example 15-6: Setting pixels according to their 2D location
  
  size(200,200);
  loadPixels();
  
   // Two loops allow us to visit every column (x) and every row (y).
   
  // Loop through every pixel column
  for (int x = 0; x < width; x++ ) {
    // Loop through every pixel row
    for (int y = 0; y < height; y++ ) {
      
      // Use the formula to find the 1D location
      int loc = x + y * width; // The location in the pixel array is calculated via our formula: 1D pixel location = x + y * width
      
      if (x % 2 == 0) { // If we are an even column
        pixels[loc] = color(255);
      } else { // If we are an odd column
        pixels[loc] = color(0); //   We use the column number (x) to determine whether the color should be black or white.
      }
    
    }
  }
  
  updatePixels();