Pygame Ping Pong游戏运行不正常？

Question

我正在python中制作一个简单的乒乓球游戏。我使用的Python版本是Python 3.3.3。每当我运行游戏时，它只显示一个黑屏，而不是它。这是为了展示蝙蝠和竞技场。

import pygame, sys
from pygame.locals import *

# Number of frames per second
# Change this value to speed up or slow down your game
FPS = 200

#Global Variables to be used through our program
WINDOWWIDTH = 400
WINDOWHEIGHT = 300

#Main function
def main():
    pygame.init()
    global DISPLAYSURF

    FPSCLOCK = pygame.time.Clock()
    DISPLAYSURF = pygame.display.set_mode((WINDOWWIDTH,WINDOWHEIGHT))
    pygame.display.set_caption('Pong')

    while True: #main game loop
        for event in pygame.event.get():
            if event.type == QUIT:
                pygame.quit()
                sys.exit()

        pygame.display.update()
        FPSCLOCK.tick(FPS)

if __name__=='__main__':
    main()

LINETHICKNESS = 10
PADDLESIZE = 50
PADDLEOFFSET = 20

# Set up the colours
BLACK     = (0 ,0 ,0  )
WHITE     = (255,255,255)


#Initiate variable and set starting positions
#any future changes made within rectangles
ballX = WINDOWWIDTH/2 - LINETHICKNESS/2
ballY = WINDOWHEIGHT/2 - LINETHICKNESS/2
playerOnePosition = (WINDOWHEIGHT - PADDLESIZE) /2
playerTwoPosition = (WINDOWHEIGHT - PADDLESIZE) /2

#Draws the starting position of the Arena
drawArena()
drawPaddle(paddle1)
drawPaddle(paddle2)
drawBall(ball)

#Draws the arena the game will be played in
def drawArena():
    DISPLAYSURF.fill((0,0,0))
    #Draw outline of arena
    pygame.draw.rect(DISPLAYSURF, WHITE, ((0,0),(WINDOWWIDTH,WINDOWHEIGHT)), LINETHICKNESS*2)
    #Draw centre of line
    pygame.draw.line(DISPLAYSURF, WHITE, ((WINDOWWIDTH/2),0),((WINDOWWINDOW/2), WINDOWHEIGHT) (LINETHICKNESS/4))

#Draws the paddle
def drawPaddle(paddle):
    #Stops paddle moving too low
    if paddle.bottom > WINDOWHEIGHT - LINETHICKNESS:
        paddle.bottom = WINDOWHEIGHT - LINETHICKNESS
    #Stops paddle moving too high
    elif paddle.top < LINETHICKNESS:
        paddle.top = LINETHICKNESS
    #Draws paddle
    pygame.draw.rect(DISPLAYSURF, WHITE, paddle)