How to create a pause button in Pygame?

Question

I've been trying to make a game, and everything in there works so far except that the pause button , that when pressed the button P should pause and when pressed S should continue. I kinda understand the problem such that once in enters the while loop in the main code it wont get out. I tried putting the pause function inside the while loop. Please do help or provide tips to fix if possible thank you.

import pygame

# Colors
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
Blue = (2,55,55)



def recursive_draw(x, y, width, height):
    """ Recursive rectangle function. """
    pygame.draw.rect(screen, WHITE,
                     [x, y, width, height],
                     1)
    speed = [10,0]
    rect_change_x = 10
    rect_change_y = 10




    # Is the rectangle wide enough to draw again?
    if (width > 25):
        # Scale down
        x += width * .1
        y += height * .1
        width *= .8
        height *= .8


               # Recursively draw again
        recursive_draw(x, y, width, height)

def recursive_draw2(x, y, width, height):
    """ Recursive rectangle function. """
    pygame.draw.rect(screen, Blue,
                     [x, y, width, height],
                     1)
    speed = [10,0]
    rect_change_x = 10
    rect_change_y = 10




    # Is the rectangle wide enough to draw again?
    if (width > 25):
        x += width * .1
        y += height * .1
        width *= .8
        height *= .8



               # Recursively draw again
        recursive_draw2(x, y, width, height)
def paused():
    screen.fill(black)

    largeText = pygame.font.SysFont("comicsansms",115)
    TextSurf, TextRect = text_objects("Paused", largeText)
    TextRect.center = ((display_width/2),(display_height/2))
    gameDisplay.blit(TextSurf, TextRect)


    while pause:
        for event in pygame.event.get():

            if event.type == pygame.QUIT:
                pygame.quit()
                quit()

        #gameDisplay.fill(white)


        button("Continue",150,450,100,50,green,bright_green,unpause)
        button("Quit",550,450,100,50,red,bright_red,quitgame)

        pygame.display.update()
        clock.tick(15)  


pygame.init()
#rectanglelist = [big()] 
# Set the height and width of the screen
size = [700, 500]
screen = pygame.display.set_mode(size)

pygame.display.set_caption("My Game")

# Loop until the user clicks the close button.
done = False

# Used to manage how fast the screen updates
clock = pygame.time.Clock()
black=(0,0,0)

end_it=False
time = 100

USEREVENT = 0

pygame.time.set_timer(USEREVENT+1, 10)
milliseconds = 0
seconds = 0
start_it = False
while (end_it==False):
    screen.fill(black)
    myfont=pygame.font.SysFont("Britannic Bold", 40)
    nlabel=myfont.render("Welcome to "+ " Jet shooter ", 1, (255, 0, 0))
    label=myfont.render("Click on the mouse to start ", 1, (255, 0, 0))
    for event in pygame.event.get():
        if event.type == pygame.MOUSEBUTTONDOWN:
            end_it=True

    screen.blit(nlabel,(200, 100))
    screen.blit(label, (170,300))
    pygame.display.flip()

while (start_it==False):

    screen.fill(black)
    myfont2=pygame.font.SysFont("Britannic Bold", 40)
    label2=myfont2.render("Ready?", 1, (255, 0, 0))
    screen.blit(label2, (300,250))
    pygame.display.flip()
    pygame.time.wait(3000)
    start_it = True
fall = False   
while (fall==False):
    nlist = [3,2,1]
    for i in (nlist):


        screen.fill(black)
        n = str(i)
        myfont3=pygame.font.SysFont("Britannic Bold", 40)
        score = myfont3.render(n,1,(255,0,0))
        screen.blit((score), (350,250))
        pygame.display.flip()
        pygame.time.wait(1000)
    screen.fill(black)
    myfont4=pygame.font.SysFont("Britannic Bold", 40)
    label4=myfont3.render("GOOO!!!", 1, (255, 0, 0))
    screen.blit(label4, (300,250))
    pygame.display.flip()
    pygame.time.wait (1000)

    fall = True
pause = 0             
b = 0

# -------- Main Program Loop -----------
while not done:
        for event in pygame.event.get():

             if event.type == pygame.KEYUP:
                 if event.key==K_p:
                     pause=True
                 if pause == True:
                     screen.fill(black)
                     font=pygame.font.SysFont("Britannic Bold", 40)
                     nlabelBB=myfont.render("Pause", 1, (255, 0, 0))
                     screen.blit(nlabelBB,(200, 100))
                     pygame.display.flip()



        # Set the screen background
        screen.fill(BLACK)
        flip = 1
        a = 0

    # ALL CODE TO DRAW SHOULD GO BELOW THIS COMMENT


        recursive_draw(0, 0, 700, 500)


        recursive_draw2(35,25, 625, 450)
**###I TRIED TO PUT THE PAUSE GAME HERE AND IF PRESSED P PAUSE AND S CONTINUE
        while  a == 0 :


            if flip == 1 :
                recursive_draw(35,25,625,450)
                recursive_draw2(0, 0, 700, 500)

                flip = flip + 1
                pygame.display.flip()
                if event.type == pygame.KEYUP:
                     if event.key==K_p:
                         a = 1
                         screen.fill(black)
                         font=pygame.font.SysFont("Britannic Bold", 40)
                         nlabelBB=myfont.render("Pause", 1, (255, 0, 0))
                         screen.blit(nlabelBB,(200, 100))
                         pygame.display.flip()
                     if event.key==K_s:
                         a = 0





            if flip == 2 :
                recursive_draw(0, 0, 700, 500)
                recursive_draw2(35, 25, 625, 450)

                flip = flip - 1
                pygame.display.flip()
                if event.type == pygame.KEYUP:
                     if event.key==K_p:
                         a = 1
                         screen.fill(black)
                         font=pygame.font.SysFont("Britannic Bold", 40)
                         nlabelBB=myfont.render("Pause", 1, (255, 0, 0))
                         screen.blit(nlabelBB,(200, 100))
                         pygame.display.flip()
                     if event.key==K_s:
                         a = 0**

        if event.type == pygame.QUIT:
            done = True





    # ALL CODE TO DRAW SHOULD GO ABOVE THIS COMMENT

    # Go ahead and update the screen with what we've drawn.
pygame.display.flip()

    # Limit to 60 frames per second
clock.tick(20)

# Be IDLE friendly. If you forget this line, the program will 'hang'
# on exit.
pygame.quit()

Solution

Just use a single game loop for everything and keep track of the current state (e.g. main menu, pause screen, game scene) of your game..

Here's an example where we keep track of the state by a simple variable called state and act in our game loop accordingly:

import pygame, math, itertools

def magnitude(v): 
    return math.sqrt(sum(v[i]*v[i] for i in range(len(v))))

def sub(u, v):
    return [u[i]-v[i] for i in range(len(u))]

def normalize(v): 
    return [v[i]/magnitude(v)  for i in range(len(v))]

pygame.init()
screen = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()    

path = itertools.cycle([(26, 43), (105, 110), (45, 225), (145, 295), (266, 211), (178, 134), (250, 56), (147, 12)])
target = next(path)
ball, speed = pygame.rect.Rect(target[0], target[1], 10, 10), 3.6
pause_text = pygame.font.SysFont('Consolas', 32).render('Pause', True, pygame.color.Color('White'))

RUNNING, PAUSE = 0, 1
state = RUNNING

while True:
    for e in pygame.event.get():
        if e.type == pygame.QUIT: break
        if e.type == pygame.KEYDOWN:
            if e.key == pygame.K_p: state = PAUSE
            if e.key == pygame.K_s: state = RUNNING
    else:
        screen.fill((0, 0, 0))

        if state == RUNNING:
            target_vector = sub(target, ball.center) 

            if magnitude(target_vector) < 2: 
                target = next(path)
            else:
                ball.move_ip([c * speed for c in normalize(target_vector)])

            pygame.draw.rect(screen, pygame.color.Color('Yellow'), ball)

        elif state == PAUSE:
            screen.blit(pause_text, (100, 100))

        pygame.display.flip()
        clock.tick(60)
        continue
    break

As you can see, the rectangle keeps moving until you press P, which will change the state to PAUSE; and a simple message will now be displayed instead of drawing/moving the rectangle further.

If you press S the state switches back to the normal mode; all done in a single game loop.

Further reading:

• Pygame level/menu states
• Mulitple Displays in Pygame
• Trying to figure out how to track Pygame events and organize the game's functions