python-3.x - 太空入侵者错误 pygame

Question

在终于能够在游戏中制造多个敌人之后，我遇到了有史以来最烦人的错误。我有多个敌人，一艘 spaceship ，我什至可以发射子弹，但是在我将敌人添加到游戏中并按照与 this video 中显示的完全相同的步骤进行操作之后，背景由于某种原因消失了，是什么让玩家角色、敌人和子弹的速度变得疯狂。另外， Sprite 正在复制自己并且不会消失，我唯一能想到的就是“我到底做错了什么？？”因为我觉得我什至无法按照步骤从视频中复制代码(顺便说一句，我没有收到任何错误消息)。无论如何，这是完整的游戏代码。

import pygame
import random
import math

# Initiate pygame
pygame.init()

# Display the game window
screen = pygame.display.set_mode((800, 600))

# Title and Icon
pygame.display.set_caption('Space Invaders')
icon = pygame.image.load('icon.png')
pygame.display.set_icon(icon)

# Background
background = pygame.image.load('background.png')

# Player
playerSprite = pygame.image.load('player.png')
playerX = 370
playerY = 480
playerX_change = 0

# Enemies
enemySprite = []
enemyX = []
enemyY = []
enemyX_change = []
enemyY_change = []

num_of_enemies = 6

for i in range(num_of_enemies):
    enemySprite.append(pygame.image.load('enemy.png'))
    enemyX.append(random.randint(0, 736))
    enemyY.append(random.randint(50, 150))
    enemyX_change.append(4)
    enemyY_change.append(40)

# Bullet
bulletSprite = pygame.image.load('bullet.png')
bulletX = 0
bulletY = 480
bulletY_change = 10

# When bullet_state = 'ready', you can't see the bullet on the screen
# When bullet_state = 'fire', the bullet is currently moving
bullet_state = 'ready'

score = 0


def player(x, y):
    screen.blit(playerSprite, (x, y))


def enemy(x, y, i):
    screen.blit(enemySprite[i], (x, y))


def fire_bullet(x, y):
    global bullet_state
    bullet_state = 'fire'
    screen.blit(bulletSprite, (x + 16, y + 10))


def isCollision(enemyX, enemyY, bulletX, bulletY):
    distance = math.sqrt((math.pow(enemyX - bulletX, 2)) + (math.pow(enemyY - bulletY, 2)))
    if distance < 27:
        return True
    else:
        return False


# Game Loop
running = True
while running:

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

        # If a key is pressed, check if it's the right or left arrow key
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                playerX_change = -5
            if event.key == pygame.K_RIGHT:
                playerX_change = 5
            if event.key == pygame.K_SPACE:
                if bullet_state == 'ready':
                    bulletX = playerX
                    fire_bullet(playerX, bulletY)

        if event.type == pygame.KEYUP:
            if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
                playerX_change = 0

    # Player movement
    playerX += playerX_change

    # Prevents the player from going off the border
    if playerX <= 0:
        playerX = 0
    elif playerX >= 736:
        playerX = 736

    # Enemies movement
    for i in range(num_of_enemies):
        enemyX[i] += enemyX_change[i]
        if enemyX[i] <= 0:
            enemyX_change[i] = 4
            enemyY[i] += enemyX_change[i]
        elif enemyX[i] >= 736:
            enemyX_change[i] = -4
            enemyY[i] += enemyY_change[i]

            # Collision
            collision = isCollision(enemyX[i], enemyY[i], bulletX, bulletY)
            if collision:
                bulletY = 480
                bullet_state = 'ready'
                score += 1
                print(score)
                enemyX[i] = random.randint(0, 736)
                enemyY[i] = random.randint(50, 150)

        enemy(enemyX[i], enemyY[i], i)

    # Bullet movement
    if bulletY <= 0:
        bulletY = 480
        bullet_state = 'ready'

    if bullet_state == 'fire':
        fire_bullet(bulletX, bulletY)
        bulletY -= bulletY_change

    player(playerX, playerY)
    pygame.display.update()

Answer 1

the background is gone for some reason

当然，因为 background从不 blit至 screen .

the sprites are duplicating themselves and wont go away,

那是因为你没有绘制背景。
blit background在主应用程序循环中，在绘制场景对象之前:

while running:
    # [...]

    screen.blit(background, (0, 0))

    # Enemies movement
    for i in range(num_of_enemies):
        # [...]

the speed of the player character, of the enemies and the bullet went like crazy.

使用 pygame.time.Clock() 控制每秒帧数。

clock = pygame.time.Clock()
running = True
while running:
    clock.tick(60)

    # [...]

本教程中可能使用的另一种(不太复杂的)可能性是使用 pygame.time.delay() :

running = True
while running:
    pygame.time.delay(10)

    # [...]