2016-12-29 乌龟的绕窗口移动的四种状态分析

'''

或许你会对 position.left = width - turtle_rect.width 感到疑惑,因为你仔细看一下上图右侧乌龟的那两种状态,明显

Twidth和Theight是不一样对吧!那为什么乌龟依然可以正常爬行呢???

这是因为 position = turtle_rect = turtle.get_rect() 这行代码用来获取乌龟旋转后状态的缘故,无论你怎样旋转乌龟,

它都能乌龟的Twidth和Theight,那么上面的问题就解决了

注: Twidth 代表 turtle.width, Theight 代表 turtle.height

'''

import pygame
from pygame.locals import *
from sys import exit

pygame.init()

bg = (255,255,255)
size = width,height = 600,400
screen = pygame.display.set_mode(size)
pygame.display.set_caption('Turtle')

speed = [5,0]
turtle = pygame.image.load('turtle.png')
position = turtle.get_rect()

turtle_top = pygame.transform.rotate(turtle, 180) # 窗口顶部
turtle_right = pygame.transform.rotate(turtle, 90)# 窗口右侧
turtle_bottom = turtle                                          # 窗口底部
turtle_left = pygame.transform.rotate(turtle, 270)# 窗口左侧
turtle = turtle_top #初始状态为窗口顶部

while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            exit()

    position = position.move(speed)

    if position.right > width:      #由顶部转向右侧
        turtle = turtle_right       #进入右侧状态
        position = turtle_rect = turtle.get_rect()
        position.left = width - turtle_rect.width #  L
        speed = [0,5]#向下移动

    if position.bottom > height:    #由右侧转向底部
        turtle = turtle_bottom      #进入底部状态
        position = turtle_rect = turtle.get_rect()
        position.left = width - turtle_rect.width # L
        position.top = height - turtle_rect.height# T
        speed = [-5,0]#向左移动

    if position.left < 0:           #由底部转向左侧
        turtle = turtle_left        #进入左侧状态
        position = turtle_rect = turtle.get_rect()
        position.top = height - turtle_rect.height# T
        speed = [0,-5]#向上移动
       
    if position.top < 0:            #由左侧转向顶部
        turtle = turtle_top         #进入顶部状态
        speed = [5,0] #向右移动

    screen.fill(bg)
    screen.blit(turtle, position)
    pygame.display.update()
    pygame.time.delay(35)