How can I get my ship to fire multiple shots?

Question

Ok so I'm working on this project for school. I'm supposed to make a space invader type of game. I have finished making my ship to move and fire shots. Now here's the problem, when I try to multi-fire, it erases the previous bullet that was fired and fires a new one which isn't a nice site at all. How can I get it to actually fire multiple shots?

while (running == 1):
    screen.fill(white)
    for event in pygame.event.get():
        if (event.type == pygame.QUIT):
            running = 0
        elif (event.type == pygame.KEYDOWN):
            if (event.key == pygame.K_d):
                dir = "R"
                move = True
            elif (event.key == pygame.K_a):
                dir = "L"
                move = True
            elif (event.key == pygame.K_s):
                dir = "D"
                move = True
            elif (event.key == pygame.K_w):
                dir = "U"
                move = True
            elif (event.key == pygame.K_ESCAPE): 
                sys.exit(0)
            elif (event.key == pygame.K_SPACE):
                shot=True
                xbul=xgun + 18
                ybul=ygun
            #if key[K_SPACE]:
                #shot = True
        if (event.type == pygame.KEYUP):
            move = False

    #OBJECT'S MOVEMENTS
    if ((dir == "R" and xgun<460) and (move == True)):
        xgun = xgun + 5
        pygame.event.wait
    elif ((dir == "L" and xgun>0) and (move == True)):
        xgun = xgun - 5
        pygame.event.wait
    elif ((dir == "D" and ygun<660) and (move == True)):
        ygun = ygun + 5
        pygame.event.wait
    elif ((dir == "U" and ygun>0) and (move == True)):
        ygun = ygun - 5

    screen.blit(gun, (xgun,ygun))

    #PROJECTILE MOTION
    #key = pygame.key.get_pressed()

    if shot == True:
        ybul = ybul - 10
        screen.blit(bullet, (xbul, ybul))

    if xbul>640:
        shot=False

    pygame.display.flip()
    time.sleep(0.012)

You have an indentation error between the first and second line ... — mgilson, Jan 11 '13 at 18:49
You need to keep a [`list`](http://docs.python.org/3.3/tutorial/introduction.html#lists) of the onscreen bullets, and move blit them all during a redraw, etc. — millimoose, Jan 11 '13 at 18:53

score 7 · Answer 1 · answered Jan 11 '13 at 18:51

7

You only have variables for a single bullet--xbul and ybul. If you want multiple bullets, then you should make each of these a list. You can append to each list to add a new bullet, pop to remove an old bullet, and iterate over the lists when drawing.

answered Jan 11 '13 at 18:51

Luke

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how can I do that? I know how to make basic lists but not of this type. Can you give me a piece of code that can do that? I'm really new to this – Whosyourdaddy Jan 14 '13 at 18:41

pradyunsg · Answer 2 · 2013-01-15T11:32:14.520

You can create a class for bullets which contain the x and y co-ordinates and other things related to the bullet.Then for each fire button press, create and append a new instance to a list. This way you can have as many bullets you want.
(Changed code for new move function)

class Bullet:
    def __init__(self,x,y,vx,vy):# you can add other arguments like colour,radius
        self.x = x
        self.y = y
        self.vx = vx # velocity on x axis
        self.vy = vy # velocity on y axis
    def move(self):
        self.x += self.vx
        self.y += self.vy

Example Code to add to for use of list and updating postion of the bullet(move() is above):

if shot == True: # if there are bullets on screen (True if new bullet is fired).
    if new_bullet== True: # if a new bullet is fired
        bullet_list.append(Bullet(n_x,n_y,0,10)) # n_x and n_y are the co-ords
                                                 # for the new bullet.

    for bullet in bullet_list:
        bullet.move()

what do you mean by *other arguments? And also how can I make a list for it? The type of list I know how to do won't work — Whosyourdaddy, Jan 14 '13 at 19:06
@Whosyourdaddy *other args are the other arguments you want to put for the bullet, like color etc, I forgot to mention that ..(Changed) and for the each time a bullet is fired, you can create a new instance of the `Bullet` class and and append it to the list. Added the list implementation code part to the answer.. — pradyunsg, Jan 15 '13 at 11:14

How can I get my ship to fire multiple shots?

2 Answers2