pygame中的敌人

Question

Hey i'm making this space shooter game in pygame and want to spawn 10 enemies at a time. Here is the code i used:

    blocks.append([random.randrange(0, display_width),0])


    for block in blocks:
        pygame.draw.rect(game_display, green, (block[0],block[1], 30, 40))


    for leng in range(len(blocks)):
        blocks[leng][1]+=10


        for block in blocks:
            if block[1]<0:
                blocks.remove(block)

Using this code, my screen gets filled with enemies(green rects). Is there any way i can spawn a certain number of enemies at a time and keep spawning more if the enemy goes off the screen or dies?

Answer 1

Instead of a List that represent your enemies, start using the Rect class (in fact, you should use the Sprite class, but one step at a time).

So instead of

blocks.append([random.randrange(0, display_width),0])


for block in blocks:
    pygame.draw.rect(game_display, green, (block[0],block[1], 30, 40))

we can write

blocks.append(pygame.Rect(random.randrange(0, display_width), 0, 30, 40))

for block in blocks:
    pygame.draw.rect(game_display, green, block)

and instead of

for leng in range(len(blocks)):
    blocks[leng][1]+=10


    for block in blocks:
        if block[1]<0:
            blocks.remove(block)

we can use (see how much clearer the code becomes):

for block in blocks[:]:
    block.move_ip(0, 10)
    if not game_display.get_rect().contains(block):
        blocks.remove(block)
        blocks.append(pygame.Rect(random.randrange(0, display_width), 0, 30, 40))

which will also add a new enemy whenever one leaves the screen. We could also just reset its position, like this:

for block in blocks:
    block.move_ip(0, 10)
    if not game_display.get_rect().contains(block):
        block.x = random.randrange(0, display_width)

So, whenever you want a new rect to appear, just call

blocks.append(pygame.Rect(random.randrange(0, display_width), 0, 30, 40))

which you may want to put into a function, or better use the Sprite class instead