代码
#-*-encoding=utf-8-*-
# Wormy(a Nibbles clone)
# By Al Sweigart al@inventwithpython.com
# http://inventwithpython.com/pygame
# Copied by Lei Song@1743207528@qq.com
import random,pygame,sys
from pygame.locals import *
FPS = 15
WINDOWWIDTH = 640
WINDOWHEIGHT = 480
CELLSIZE = 20 # 指一个单独的格子的尺寸
assert WINDOWWIDTH%CELLSIZE == 0,'Window width must be a multiple of cell size.' # 断言，窗口宽度必须是一个格子尺寸的整数倍
assert WINDOWHEIGHT%CELLSIZE == 0,'Window height must be a multiple of cell size.' # 断言，窗口高度必须是一个格子尺寸的整数倍
CELLWIDTH = int(WINDOWWIDTH /CELLSIZE)
CELLHEIGHT = int (WINDOWHEIGHT/CELLSIZE)
# R G B
WHITE = (255,255,255)
BLACK = (0,0,0)
RED = (255,0,0)
GREEN = (0,255,0)
DARKGREEN = (0,155,0)
DARKGRAY = (40,40,40)
BGCOLOR = BLACK
UP = 'up'
DOWN = 'down'
LEFT = 'left'
RIGHT = 'right'
HEAD = 0 # syntactic sugar:index of the worm's head 语法糖，头部为0
def main():
global FPSCLOCK,DISPLAYSURF,BASICFONT
pygame.init() # 初始化
FPSCLOCK = pygame.time.Clock()
DISPLAYSURF = pygame.display.set_mode((WINDOWWIDTH,WINDOWHEIGHT))
BASICFONT = pygame.font.Font('freesansbold.ttf',18)
pygame.display.set_caption('Wormy')
showStartScreen()
while True:
runGame()
showGameOverScreen()
def runGame():
# 确定一个随机的开始点
startx = random.randint(5,CELLWIDTH - 6)
starty = random.randint(5,CELLHEIGHT - 6)
wormCoords = [{'x':startx,'y':starty},
{'x':startx-1,'y':starty},
{'x':startx-2,'y':starty}]#存储了身体，初始长度为3
direction = RIGHT
# 把苹果置于一个随机处
apple = getRandomLocation()
while True:# main game loop
for event in pygame.event.get():# event handling loop
if event.type==QUIT:
terminate()
elif event.type == KEYDOWN:# 按下键盘,wasd或者箭头
if(event.key == K_LEFT or event.key == K_a)and direction != RIGHT:# 不能直接回头撞自己
direction = LEFT
elif(event.key == K_RIGHT or event.key == K_d)and direction != LEFT:
direction = RIGHT
elif(event.key == K_UP or event.key == K_w)and direction != DOWN:
direction = UP
elif(event.key == K_DOWN or event.key == K_s)and direction != UP:
direction = DOWN
elif event.key == K_ESCAPE:
terminate()
# 检查它是否碰到自己或撞墙
if wormCoords[HEAD]['x']==-1 or wormCoords[HEAD]['x']==CELLWIDTH or wormCoords[HEAD]['y']==-1 or wormCoords[HEAD]['y']==CELLHEIGHT:
return# game over
for wormBody in wormCoords[1:]:
if wormBody['x']==wormCoords[HEAD]['x'] and wormBody['y']==wormCoords[HEAD]['y']:
return# game over
# 检查它是否恰到苹果
if wormCoords[HEAD]['x']==apple['x'] and wormCoords[HEAD]['y']==apple['y']:
apple = getRandomLocation()
else:
del wormCoords[-1]# 删除尾部
# 如何做出移动的动画效果呢？方法是在蛇头前不断添加一个格子
if direction == UP:
newHead = {'x':wormCoords[HEAD]['x'],'y':wormCoords[HEAD]['y']-1}# 因为向下为正
elif direction == DOWN:
newHead = {'x':wormCoords[HEAD]['x'],'y':wormCoords[HEAD]['y']+1}
elif direction == LEFT:
newHead = {'x':wormCoords[HEAD]['x']-1,'y':wormCoords[HEAD]['y']}
elif direction == RIGHT:
newHead = {'x':wormCoords[HEAD]['x']+1,'y':wormCoords[HEAD]['y']}
wormCoords.insert(0,newHead)# 加新头
# 绘制屏幕Drawing the Screen
DISPLAYSURF.fill(BGCOLOR)
drawGrid()
drawWorm(wormCoords)
drawApple(apple)
drawScore(len(wormCoords)-3)
pygame.display.update()# 这一句draws the display Surface to the actual computer screen
FPSCLOCK.tick(FPS/4)
# 绘制“Press a key”文本到屏幕上
def drawPressKeyMsg():
pressKeySurf = BASICFONT.render('Press a key to play.',True,DARKGRAY)
pressKeyRect = pressKeySurf.get_rect()
pressKeyRect.topleft = (WINDOWWIDTH-200,WINDOWHEIGHT-30)
DISPLAYSURF.blit(pressKeySurf,pressKeyRect)
#这个函数将被showStartScreen()和showGameOverScreen()两个函数调用
def checkForKeyPress():
if len(pygame.event.get(QUIT))>0:# 返回一个列表，列表里是在事件队列中所有QUIT的事件，若无QUIT事件则返回空列表[]
terminate()
keyUpEvents = pygame.event.get(KEYUP)
if len(keyUpEvents)==0:
return None
if keyUpEvents[0].key == K_ESCAPE:# 按了Esc键
terminate()
return keyUpEvents[0].key
# 开始屏幕
def showStartScreen():
titleFont = pygame.font.Font('freesansbold.ttf',100)
titleSurf1 = titleFont.render('Wormy!',True,WHITE,DARKGREEN)# 白字，墨绿背景
titleSurf2 = titleFont.render('Wormy!',True,GREEN)# 绿字，透明背景
degrees1 = 0
degrees2 = 0
while True:
DISPLAYSURF.fill(BGCOLOR)
rotatedSurf1 = pygame.transform.rotate(titleSurf1,degrees1)# 不会改变titleSurf1，而是返回一个新的Surface，上面画着旋转后的图像
rotatedRect1 = rotatedSurf1.get_rect()
rotatedRect1.center = (WINDOWWIDTH/2,WINDOWHEIGHT/2)
DISPLAYSURF.blit(rotatedSurf1,rotatedRect1)
# 新的矩形往往比原先的大。旋转的角度逆时针为正，顺时针为负。pygame会把你传的大于等于360°的度数不断减去360°直到其小于360°
rotatedSurf2 = pygame.transform.rotate(titleSurf2,degrees2)
rotatedRect2 = rotatedSurf2.get_rect()
rotatedRect2.center = (WINDOWWIDTH/2,WINDOWHEIGHT/2)
DISPLAYSURF.blit(rotatedSurf2,rotatedRect2)
# 我们之所以不直接旋转rotatedSurf1和2是因为：1.旋转后的图形会失真，就像一张照片复印后再复印后不会与原来完全一样。不过如果旋转的角度为90°的倍数则不会出现这个问题。2.旋转后的矩形会变大，最终会超出pygame的承受范围
drawPressKeyMsg()
if checkForKeyPress():
pygame.event.get()# 清空事件队列
return
pygame.display.update()
FPSCLOCK.tick(FPS)
degrees1 += 3# 每帧转3°
degrees2 += 7# 每帧转7°
def terminate():
pygame.quit()
sys.exit()
def getRandomLocation():
return {'x':random.randint(0,CELLWIDTH-1),'y':random.randint(0,CELLHEIGHT - 1)}
# 决定苹果出现的位置
def showGameOverScreen():
gameOverFont = pygame.font.Font('freesansbold.ttf',150)
gameSurf = gameOverFont.render('Game',True,WHITE)
overSurf = gameOverFont.render('Over',True,WHITE)
gameRect = gameSurf.get_rect()
overRect = overSurf.get_rect()
gameRect.midtop = (WINDOWWIDTH/2,10)
overRect.midtop = (WINDOWWIDTH/2,gameRect.height+10+25)
DISPLAYSURF.blit(gameSurf,gameRect)
DISPLAYSURF.blit(overSurf,overRect)
drawPressKeyMsg()
pygame.display.update()
pygame.time.wait(500)# 500毫秒，也就是半秒
checkForKeyPress()# 清空事件队列中的任何按键
while True:
if checkForKeyPress():
pygame.event.get()# 清空事件队列
return
def drawScore(score):
scoreSurf = BASICFONT.render('Score:%s'%(score),True,WHITE)
scoreRect = scoreSurf.get_rect()
scoreRect.topleft = (WINDOWWIDTH-120,10)
DISPLAYSURF.blit(scoreSurf,scoreRect)
def drawWorm(wormCoords):
for coord in wormCoords:
x = coord['x']*CELLSIZE
y = coord['y']*CELLSIZE
wormSegmentRect = pygame.Rect(x,y,CELLSIZE,CELLSIZE)
pygame.draw.rect(DISPLAYSURF,DARKGREEN,wormSegmentRect)
wormInnerSegmentRect = pygame.Rect(x+4,y+4,CELLSIZE-8,CELLSIZE-8)
pygame.draw.rect(DISPLAYSURF,GREEN,wormInnerSegmentRect)
def drawApple(coord):
x = coord['x']*CELLSIZE
y = coord['y']*CELLSIZE
appleRect = pygame.Rect(x,y,CELLSIZE,CELLSIZE)
pygame.draw.rect(DISPLAYSURF,RED,appleRect)
def drawGrid():
for x in range(0,WINDOWWIDTH,CELLSIZE):# draw vertical lines
pygame.draw.line(DISPLAYSURF,DARKGRAY,(x,0),(x,WINDOWHEIGHT))
for y in range(0,WINDOWHEIGHT,CELLSIZE):# draw horizontal lines
pygame.draw.line(DISPLAYSURF,DARKGRAY,(0,y),(WINDOWWIDTH,y))
if __name__=='__main__':
main()
遇到的问题
在参考的源代码中，有下面这样一段（apple打错了，打成了apply）：
# check if worm has eaten an apply
if wormCoords[HEAD]['x'] == apple['x'] and wormCoords[HEAD]['y'] == apple['y']:
# don't remove worm's tail segment
apple = getRandomLocation() # set a new apple somewhere
else:
del wormCoords[-1] # remove worm's tail segment
# move the worm by adding a segment in the direction it is moving
if direction == UP:
newHead = {'x': wormCoords[HEAD]['x'], 'y': wormCoords[HEAD]['y'] - 1}
elif direction == DOWN:
newHead = {'x': wormCoords[HEAD]['x'], 'y': wormCoords[HEAD]['y'] + 1}
elif direction == LEFT:
newHead = {'x': wormCoords[HEAD]['x'] - 1, 'y': wormCoords[HEAD]['y']}
elif direction == RIGHT:
newHead = {'x': wormCoords[HEAD]['x'] + 1, 'y': wormCoords[HEAD]['y']}
wormCoords.insert(0, newHead)
这段代码的第一个 if-else 意思是，如果蛇恰到了苹果，就重新生成一个苹果的位置，否则删去蛇尾的一个方块。下面的四句 if 和 elif 则是根据蛇运动的不同方向为蛇添加一个新的头部方块。
我一想，这不是多余了吗？为什么每次都要添加头部，在吃不到苹果的时候才删除尾部呢，直接在吃到苹果的时候添加头部不就简单了吗？于是下面是我一开始写的代码：
# 检查它是否恰到苹果
if wormCoords[HEAD]['x']==apple['x'] and wormCoords[HEAD]['y']==apple['y']:
apple = getRandomLocation()
if direction == UP:
newHead = {'x':wormCoords[HEAD]['x'],'y':wormCoords[HEAD]['y']-1}# 因为向下为正
elif direction == DOWN:
newHead = {'x':wormCoords[HEAD]['x'],'y':wormCoords[HEAD]['y']+1}
elif direction == LEFT:
newHead = {'x':wormCoords[HEAD]['x']-1,'y':wormCoords[HEAD]['y']}
elif direction == RIGHT:
newHead = {'x':wormCoords[HEAD]['x']+1,'y':wormCoords[HEAD]['y']}
wormCoords.insert(0,newHead)# 加新头
没想到，运行后开始游戏后蛇完全不动弹！成了一张静止的图片！这是为什么呢？
于是我开始思考，那么蛇到底是怎么移动起来的呢？原来，答案就在上面这段源代码中。蛇“移动”的方式是不断向蛇头添加小块同时删除尾部小块，在吃到苹果时才不删除尾部，这样就能做出“移动”的效果啦。