无法在两个背景图像之间切换

Question

我正在尝试在 pygame 中检测到碰撞时在两个背景之间切换，但是当检测到碰撞时，它会切换，但是如果在新背景上检测到另一个碰撞，背景保持不变一样。

碰撞发生在 7 个气球和一把枪之间。 请注意，碰撞工作正常。

这是我的代码：

import pygame as pg
import random as r
import sys


pg.init()


bg = pg.image.load('bg.jpg')# Background Image #
bg = pg.transform.scale(bg, (688,387))
new_bg = pg.image.load('new_bg.jpg')
new_bg = pg.transform.scale(new_bg, (688,387))

radius = 30
diameter = 2 * radius
num_balloons = 7

bullets_colors_ls = []
iterator = -1




def create_balloons():
    global balloon_list
    global colors

    for i in range(num_balloons):
        while True:
            candidate = r.randint(0, 500)
            if all(abs(candidate-x) >= diameter for x in balloon_list):
                break
        balloon_list.append(candidate)

def draw_balloons(y):
    for i in range(num_balloons):
        screen.blit(colors[i], (balloon_list[i] , y-50))


def check_collisions(x, y):
    global hit_var
    global hit
    global score
    global scoretext
    global bg_bool
    
    for i in range(num_balloons):
        gun_rect = gun.get_rect(topleft = (x,y))
        gun_mask = pg.mask.from_surface(gun)

        balloon_rect = colors[i].get_rect(topleft = (balloon_list[i], y-100))
        balloon_mask = pg.mask.from_surface(colors[i])

        offset = (balloon_rect.x - gun_rect.x), (balloon_rect.y - gun_rect.y)
        if gun_mask.overlap(balloon_mask, offset):
            bg_bool = True
            hit_var = i
            print(f'hit balloon: {i}')
            colors[i].fill((0,0,0,0))
            screen.fill((0,0,0,0))

            


            


        


        
# Vars #
x = 0
y = 250
velocity = 5
score = 0

bg_bool = False

clock = pg.time.Clock()


screen = pg.display.set_mode((688 ,387)) # Size of the screen #
caption = pg.display.set_caption("Remember") # Title of the window #

balloon_list = []
b1 = pg.image.load('balloons/1.png').convert_alpha()
b1 = pg.transform.scale(b1, (63,131))
b2 = pg.image.load('balloons/2.png').convert_alpha()
b2 = pg.transform.scale(b2, (63,131))
b3 = pg.image.load('balloons/3.png').convert_alpha()
b3 = pg.transform.scale(b3, (63,131))
b4 = pg.image.load('balloons/4.png').convert_alpha()
b4 = pg.transform.scale(b4, (63,131))
b5 = pg.image.load('balloons/5.png').convert_alpha()
b5 = pg.transform.scale(b5, (63,131))
b6 = pg.image.load('balloons/6.png').convert_alpha()
b6 = pg.transform.scale( b6, (63,131))
b7 = pg.image.load('balloons/7.png').convert_alpha()
b7 = pg.transform.scale(b7, (63,131))
colors = [b1, b2, b3, b4, b5, b6, b7]




gun = pg.image.load('game-gun.png').convert_alpha()
gun = pg.transform.scale(gun, (150,150))

create_balloons()



pg.display.flip() # Updating #

running = True # Game loop bool #

while running: # Game loop #
    clock.tick(60)
    #Background switching code#
    if bg_bool == False:
        screen.blit(bg, (0, 0))
        
    elif bg_bool == True:
        screen.blit(new_bg, (0,0))


            
    
    for event in pg.event.get():
        if event.type == pg.QUIT:
            pg.quit()
            sys.exit()
        if event.type == pg.KEYDOWN:
            if event.key == pg.K_ESCAPE:
                running = False
        
            if event.key == pg.K_SPACE: 
                check_collisions(x, y)

    draw_balloons(y)
    
    keys = pg.key.get_pressed()
    x += keys[pg.K_RIGHT] - keys[pg.K_LEFT] * velocity
    x -= keys[pg.K_LEFT] - keys[pg.K_RIGHT] * velocity

        
     
    screen.blit(gun, (x, y))
    pg.display.update()

当我试图在 screen.blit(new_bg, (0,0)) 之后放置 bg_bool = False 时，它所做的只是不断显示第一个背景。您可以在此处下载所有图片：Download images on REPL

（转到代码，您应该会在那里看到所有图像）

如何在检测到碰撞时正确切换背景？

Answer 1

不设置bg_bool = Ture，但在检测到碰撞时切换bg_bool的状态（bg_bool = not bg_bool）：

def check_collisions(x, y):
    # [...]

    global bg_bool
    
    for i in range(num_balloons):
        # [...]

        offset = (balloon_rect.x - gun_rect.x), (balloon_rect.y - gun_rect.y)
        if gun_mask.overlap(balloon_mask, offset):
            
            # bg_bool = True       <-- DELETE
            bg_bool = not bg_bool  <-- INSTERT

            # [...]

无法在两个背景图像之间切换

Cannot switch between two background images

python

pygame

background

pygame-surface