Lists in Pygame
===============

Goals
-----

- Make use of lists to store the locations of multiple objects.
- Save some squares in a list
- Draw the squares on the screen
- Add squares by clicking the locations

Starter code
------------

- :doc:`pygame-template`


What you need to do
-------------------

1. Better drawing - use pygame.mouse.get_pressed() to check each frame, in game state updates,
   if a mouse buttin is currently being pressed. Then if it is, get the mouse position with
   pygame.mouse.get_pos() and draw a square there.
2. Timed squares - Create a variable to record the frame count. In the loop do frame count += 1.
   If the frame count is divisible by 30 (frames % 30 == 0), random x and y and add that "square" to the list.
3. Move the squares - In the game updates create another loop to change the squares x and y position.
4. ADVANCED Square defense - Separate the randomized moving squares (the enemies) and the user click-generated 
   squares (defenders) into different lists. When an enemy and a defender overlap, they both dissappear. If an
   enemy reaches a particular side of the screen, you lose or lose a life. You may 
   wish to convert your squares to pygame.Rect so you can use pygame.Rect.colliderect(other_rect).

Final Code
----------

.. code-block:: python
    :linenos:
    :emphasize-lines: 21-27, 40-46, 54-57

    # Lists in pygame

    import pygame
    from pygame.constants import MOUSEBUTTONDOWN
    from pygame.locals import K_ESCAPE, KEYDOWN, QUIT

    pygame.init()

    WIDTH = 640
    HEIGHT = 480
    SIZE = (WIDTH, HEIGHT)

    screen = pygame.display.set_mode(SIZE)
    clock = pygame.time.Clock()

    # ---------------------------
    # Initialize global variables

    # position [int, int] -> [x, y]

    squares = [
        [50, 50],
        [200, 300],
        [500, 400],
        [200, 50],
        [500, 100]
    ]

    # ---------------------------

    running = True
    while running:
        # EVENT HANDLING
        for event in pygame.event.get():
            if event.type == KEYDOWN:
                if event.key == K_ESCAPE:
                    running = False
            elif event.type == QUIT:
                running = False
            elif event.type == MOUSEBUTTONDOWN:
                mouse_x = event.pos[0]
                mouse_y = event.pos[1]
                print(mouse_x, mouse_y)

                new_square = [mouse_x, mouse_y]
                squares.append(new_square)
        
        # GAME STATE UPDATES


        # DRAWING
        screen.fill((255, 255, 255))  # always the first drawing command

        for square in squares:
            x = square[0]
            y = square[1]
            pygame.draw.rect(screen, (200, 0, 0), (x, y, 30, 30))

        # Must be the last two lines
        # of the game loop
        pygame.display.flip()
        clock.tick(30)
        #---------------------------


    pygame.quit()