问题描述
我正在研究Python Crash Course v2中的一个练习。我复制了外星人舰队上下移动(而不是左右移动)的“太空侵略者”。现在,我要修改其中的一部分,以创建另一个带有狗的游戏,当它到达屏幕的顶部和底部时,它应该上下移动。
问题:狗从右中角开始,然后向下移动到右下角,但不向上移动。它像它认为到达顶部然后迅速回落一样在那里抖动。我一直在断断续续地盯着它看了几周,非常感谢发现我的错误的帮助。
以下代码将dog元素隔离在单个.py文件中。 (如果您不使用IDE,请编辑pygame.QUIT代码,使其正常关闭。)
您可以从我的[Github for PlayBall pygame] [1]的图像文件夹中获取狗图像。也可以替换任何96 x 56像素左右的图像。
# -*- coding: utf-8 -*-
"""
Created on Mon Aug 31 19:25:26 2020
@author: Cathig
"""
import sys
import pygame
import pygame.font
class Settings:
"""A class to store all settings for Play Catch."""
def __init__(self):
"""Initialize the game's settings."""
# Screen settings
self.screen_width = 1200
self.screen_height = 800
self.bg_color = (20,230,80)
# Dog settings
self.dog_speed = 1.0
# dog direction of 1 represents down; -1 represents up.
self.dog_direction = 1
class Dog:
def __init__(self,pb_game):
"""Initialize the dog and set its starting position."""
self.screen = pb_game.screen
self.settings = pb_game.settings
self.screen_rect = pb_game.screen.get_rect()
# Load the dog image and get its rect.
self.image = pygame.image.load('images/dog.png')
self.rect = self.image.get_rect()
# Start the dog at the center right of the screen.
self.rect.midright = self.screen_rect.midright
# Store a decimal value for the dog's vertical position.
self.y = float(self.rect.y)
def check_edges(self):
"""Return True if the dog is at the edge of the screen."""
screen_rect = self.screen.get_rect()
if self.rect.bottom >= screen_rect.bottom or self.rect.top <= 0:
return True
def update(self,dog_direction):
"""Move the dog down or up."""
self.y += (self.settings.dog_speed * dog_direction)
self.rect.y = float(self.y)
def center_dog(self):
self.rect.midright = self.screen_rect.midright
self.y = float(self.rect.y)
def blitme(self):
"""Draw the dog at its current location."""
self.screen.blit(self.image,self.rect)
class PlayBall:
"""Overall class to manage game assets and behavior."""
def __init__(self):
"""Initialize the game,and create game resources."""
pygame.init()
self.settings = Settings()
# Set the window size and title bar text
# Windowed
self.screen = pygame.display.set_mode(
(self.settings.screen_width,self.settings.screen_height))
# Full screen
# self.screen = pygame.display.set_mode((0,0),pygame.FULLSCREEN)
# self.settings.screen_width = self.screen.get_rect().width
# self.settings.screen_height = self.screen.get_rect().height
pygame.display.set_caption("Dog test")
self.dog = Dog(self)
def run_game(self):
"""Start the main loop for the game."""
while True:
self._check_events()
self._update_dog()
self._update_screen()
def _update_dog(self):
"""Respond appropriately if the dog has reached an edge."""
dog_direction = self.settings.dog_direction
if self.dog.check_edges():
dog_direction *= -1
self.dog.update(dog_direction)
def _check_events(self):
"""Respond to key presses and mouse events."""
# Gracefully exit when 'X' or alt+F4 close the window
for event in pygame.event.get():
if event.type == pygame.QUIT:
pygame.quit() # Use with IDE
# sys.exit() # If not using IDE,use sys.exit()
def _start_game(self):
"""Start a new game."""
self.dog.center_dog()
def _update_screen(self):
"""Update images on the screen,and flip to the new screen."""
self.screen.fill(self.settings.bg_color)
self.dog.blitme()
# Make the most recently drawn screen visible.
pygame.display.flip()
if __name__ == '__main__':
# Make a game instance,and run the game.
pb = PlayBall()
pb.run_game()
解决方法
在_update_dog
方法中,您将方向复制到临时变量,然后在碰到边缘时反转该临时变量。更改在下一个循环中丢失。要保留更改,请同时更新设置变量。
这是更新的代码:
def _update_dog(self):
"""Respond appropriately if the dog has reached an edge."""
dog_direction = self.settings.dog_direction
if self.dog.check_edges():
dog_direction *= -1
self.settings.dog_direction *= -1 # need to update settings also
self.dog.update(dog_direction)