如何更新Pygame乒乓球游戏中P1_score与P2_score的显示文本？

基于ClearCode2020年的乒乓球游戏视频开发适配Python3.9的Pong游戏，代码已适配可运行，但存在分数更新后文本不刷新的问题：P1_score或P2_score加1后，屏幕上的分数文本没有变化，重复调用screen.blit也无法解决。

问题原因 #

你当前的代码中，P1_text和P2_text仅在程序初始化时调用game_font.render()生成了一次文本表面。之后即使P1_score/P2_score数值变化，你依然在主循环中blit最初生成的旧文本表面，所以屏幕上的分数不会更新。

解决方案 #

需要在每次主循环迭代时，根据当前最新的分数值重新渲染文本表面，再将其blit到屏幕上。这样分数变化时，新的文本会被渲染并显示。

修改后的完整代码 #

import pygame, sys, random

pygame.init()
clock = pygame.time.Clock()

Width = 1600
Length = 900
Line_Width = 15
Line_Color = (255, 255, 255)

Color = (0, 0, 0)
NetColor = (150, 150, 150)

screen = pygame.display.set_mode((Width, Length))
pygame.display.set_caption('Spy-pong!')
screen.fill(Color)

ball = pygame.Rect(Width/2 - 15, Length/2 - 15, 30, 30)
play_paddle = pygame.Rect(Width - 20, Length/2 - 70, 10, 140)
com_paddle = pygame.Rect(10, Length/2 - 70, 10, 140)

def ball_animation():   
    global ball_mspeed_x, ball_mspeed_y, P1_score, P2_score
    ball.x += ball_mspeed_x
    ball.y += ball_mspeed_y
    
    if ball.top <= 0 or ball.bottom >= Length:
        ball_mspeed_y *= -1
        
    if ball.left <= 0:
        P1_score += 1
        ball_restart()
        
    if ball.right >= Width:     
        P2_score += 1
        ball_restart()             
    
    if ball.colliderect(play_paddle) or ball.colliderect(com_paddle):
        ball_mspeed_x *= -1
        
ball_mspeed_x = 15 * random.choice((1, -1))
ball_mspeed_y = 15 * random.choice((1, -1))
player_speed = 0
com_speed = 13        

P1_score = 0
P2_score = 0
game_font = pygame.font.Font("freesansbold.ttf",32)

def play_paddle_animation():
    play_paddle.y += player_speed
    if play_paddle.top <= 0:
        play_paddle.top = 0
    if play_paddle.bottom >= Length:
        play_paddle.bottom = Length

def com_paddle_ai():
    if com_paddle.top < ball.y:
        com_paddle.top += com_speed
    if com_paddle.bottom > ball.y:
        com_paddle.bottom -= com_speed
    if com_paddle.top <= 0:
        com_paddle.top = 0
    if com_paddle.bottom >= Length:
        com_paddle.bottom = Length  

def ball_restart():
    global ball_mspeed_x, ball_mspeed_y
    ball.center = (Width/2, Length/2)
    ball_mspeed_x *= random.choice((1,-1))
    ball_mspeed_y *= random.choice((1,-1))
 
def draw_rect():
    pygame.draw.rect(screen, Line_Color, play_paddle)
    pygame.draw.rect(screen, Line_Color, com_paddle)
        
def draw_ellipse():
    pygame.draw.ellipse(screen, Line_Color, ball)
            
def draw_aaline():
    pygame.draw.aaline(screen, NetColor, (Width/2, 0), (Width/2, Length))
     
while True:
    screen.fill(Color)
    
    # 关键修改：每次循环都根据当前分数重新渲染文本
    P1_text = game_font.render(f"{P1_score}", False, Line_Color)
    screen.blit(P1_text,(835, 450))
    
    P2_text = game_font.render(f"{P2_score}", False, Line_Color)
    screen.blit(P2_text,(750, 450))
    
    draw_rect()
    draw_ellipse()
    draw_aaline()
    
    for event in pygame.event.get():
         if event.type == pygame.QUIT:
             pygame.quit()
             sys.exit()
             
         if event.type == pygame.KEYDOWN:    
             if event.key == pygame.K_DOWN: 
                 player_speed += 15
             if event.key == pygame.K_UP:
                 player_speed -= 15
         if event.type == pygame.KEYUP:    
             if event.key == pygame.K_DOWN: 
                 player_speed -= 15
             if event.key == pygame.K_UP:
                 player_speed += 15  
    
    
    ball_animation()
    play_paddle_animation()
    com_paddle_ai()           
    
    pygame.display.update()
    clock.tick(60)

修改说明 #

• 删除了初始化阶段的P1_text/P2_text渲染和blit代码
• 在主循环内，每次填充背景后，先调用game_font.render()根据当前的P1_score/P2_score生成新的文本表面，再执行screen.blit()将其绘制到屏幕上
• 修正了原代码中的pygame.QUIT()错误，改为pygame.quit()（小写q）

这样修改后，每次分数变化时，主循环会在下一次迭代中渲染新的分数文本并显示，解决了分数不更新的问题。

内容的提问来源于stack exchange，提问作者Drakenforge42