Image Tiling

import pyglet
from pyglet.gl import *
import sys

try:

    # Get tiling depth argument from command line
    # Throws IndexError if only argument is the script directory when script was called from command line.
    # i.e. the tiling depth was not specified
    n = int(sys.argv[1])

    # Validate argument
    # throws AssertionError if condition is not met
    # i.e. tiling depth is less than one
    assert n >= 1

    # Load image.jpg
    # Throws pyglet.resource.ResourceNotFoundException when image does not exist
    img = pyglet.resource.image('image.jpg')


    img_w = img.width  # Store image width to variable - much more efficient performance-wise
    img_h = img.height  # Store image height to variable
    window = pyglet.window.Window()  # Initialize window

    # Declare graphics batch
    # This will draw all sprites at once in an efficient manner.
    batch = pyglet.graphics.Batch()

    # Declare sprite list.
    # Each element is a pointer to a unique sprite object.
    sprite_list = [pyglet.sprite.Sprite(img, batch=batch) for i in range(n * 3)]

    # Initialize loop variables
    x = 0  # x-coordinate of sprite located in 3rd quadrant; width added every iteration
    y = 0  # y-coordinate of sprite located in 3rd quadrant; height added every iteration
    w = window.width // 2  # width of dimensions to draw in; halved every iteration (x-dimension of 1st quadrant)
    h = window.height // 2  # height of dimensions to draw in; halved every iteration (y-dimension of 1st quadrant)
    j = 0  # sprite_list index navigator
    for j in range(0, n * 3, 3):  # For every third element starting from the first:
        # Set second quadrant sprite attributes
        sprite_list[j].update(scale_x=w / img_w, scale_y=h / img_h, x=x, y=y + h)
        # Set third quadrant sprite attributes
        sprite_list[j + 1].update(scale_x=w / img_w, scale_y=h / img_h, x=x, y=y)
        # Set fourth quadrant sprite attributes
        sprite_list[j + 2].update(scale_x=w / img_w, scale_y=h / img_h, x=x + w, y=y)
        x += w  # add current width to x-coordinate
        y += h  # add current width to y-coordinate
        w //= 2  # half width
        h //= 2  # half height

    # Function called every time the window needs to redraw its elements
    # i.e. Every time an event happens
    @window.event
    def on_draw():
        window.clear()  # Clear window
        batch.draw()  # Draw batch

    pyglet.app.run()  # Starts event loop.
except IndexError:  # No tiling depth argument supplied when running this script from terminal
    print('Please add the tiling depth to the command line arguments.')
except TypeError:  # Tiling depth argument is an integer
    print('Error: Tiling depth must be an integer')
except AssertionError:  # Tiling depth less than 1
    print('Error: Tiling depth must be greater than or equal to one.')
except pyglet.resource.ResourceNotFoundException:  # image.jpg does not exist
    print('Error: Image not found. Please place a JPG image named "image" next to the python script.')