pygame 精灵的行走及二段跳实现方法

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不得不承认《Python游戏编程入门》这本书翻译、排版非常之烂，但是里面的demo还是很好的，之前做了些改编放到这里。

先是素材：

背景

精灵

所有素材均取自此书

接下来就是精灵类的创建了：

class MySprite(pygame.sprite.Sprite):

def __init__(self, target):

pygame.sprite.Sprite.__init__(self)

self.master_image = None

self.frame = 0

self.old_frame = -1

self.frame_width = 1

self.frame_height = 1

self.first_frame = 0

self.last_frame = 0

self.columns = 1

self.last_time = 0

#　　使用property方法，让精灵类对坐标操作更方便

def _getx(self):

return self.rect.x

def _setx(self, value):

self.rect.x = value

X = property(_getx, _setx)

def _gety(self):

return self.rect.y

def _sety(self, value):

self.rect.y = value

Y = property(_gety, _sety)

def _getpos(self):

return self.rect.topleft

def _setpos(self, pos):

self.rect.topleft = pos

position = property(_getpos, _setpos)

#　　load方法中定义了图片位置，长宽和帧的列数，由此来将素材切成一帧一帧

def load(self, filename, width, height, columns):

self.master_image = pygame.image.load(filename).convert_alpha()

self.frame_width = width

self.frame_height = height

self.rect = Rect(0, 0, width, height)

self.columns = columns

rect = self.master_image.get_rect()

self.last_frame = (rect.width // width) * (rect.height // height) - 1

def update(self, current_time, rate=30):

#　　更新帧数

if current_time > self.last_time + rate:

self.frame += 1

if self.frame > self.last_frame:

self.frame = self.first_frame

self.last_time = current_time

#　　当帧数发生改变时，创建新的图片

if self.frame != self.old_frame:

frame_x = (self.frame % self.columns) * self.frame_width

frame_y = (self.frame // self.columns) * self.frame_height

rect = Rect(frame_x, frame_y, self.frame_width, self.frame_height)

self.image = self.master_image.subsurface(rect)

self.old_frame = self.frame

将精灵类“放置”到游戏屏幕上，并加上背景

pygame.init()

screen = pygame.display.set_mode((800, 600))

font = pygame.font.Font(None, 24)

framerate = pygame.time.Clock()

bg = pygame.image.load("background.png").convert_alpha()

pl = pygame.image.load('caveman.png').convert_alpha()

# 创建精灵组

group = pygame.sprite.Group()

player = MySprite(screen)

player.load("caveman.png", 50, 64, 8)

player.first_frame = 1

player.last_frame = 7

player.position = 400, 303

group.add(player)

while True:

for event in pygame.event.get():

if event.type == QUIT:

sys.exit()

# 设置帧数

framerate.tick(30)

ticks = pygame.time.get_ticks()

这样的话精灵就在画布上了，我们得让它能左右移动：

keys = pygame.key.get_pressed()

if keys[K_ESCAPE]:

sys.exit()

if keys[K_RIGHT]:

player.X += 8

if keys[K_LEFT]:

if player.X > 0:

player.X -= 8

然后实现跳跃及二段跳跃

这里需要说下二段跳跃的注意点：

1.直到落地前，只能跳两次，也就是说精灵进行二次跳跃后不能再跳了

2.按下空格后，精灵的加速度重置

,这需要修改前面的代码:

jump_vel = 0.0

# 设置一个记录跳跃次数的变量

space_number = 0

# 跳跃判断

player_jumping = False

player_start_y = player.Y

while True:

for event in pygame.event.get():

if event.type == QUIT:

sys.exit()

if event.type == KEYDOWN:

if event.key == K_SPACE:

# 跳跃次数小于2次时，

if space_number < 2:

jump_vel = -15.0

space_number += 1

player_jumping = True

keys = pygame.key.get_pressed()

if keys[K_ESCAPE]:

sys.exit()

if keys[K_RIGHT]:

player.X += 8

if keys[K_LEFT]:

if player.X > 0:

player.X -= 8

# 设置帧数

framerate.tick(30)

ticks = pygame.time.get_ticks()

# 当按下空格后，jump_vel变量不断变大，直到接触地面

if player_jumping:

player.Y += jump_vel

jump_vel += 2

# 落地后，重置跳跃速度和其他判断变量

if player.Y >= player_start_y:

player_jumping = False

player.Y = player_start_y

jump_vel = 0

space_number = 0

# 创建背景

screen.blit(bg, (0, 0))

# 精灵组更新

group.update(ticks, 50)

group.draw(screen)

pygame.display.update()

所有代码:

import sys, time, random, math, pygame

from pygame.locals import *

class MySprite(pygame.sprite.Sprite):

def __init__(self, target):

pygame.sprite.Sprite.__init__(self)

self.master_image = None

self.frame = 0

self.old_frame = -1

self.frame_width = 1

self.frame_height = 1

self.first_frame = 0

self.last_frame = 0

self.columns = 1

self.last_time = 0

# 　　使用property方法，让精灵类对坐标操作更方便

def _getx(self):

return self.rect.x

def _setx(self, value):

self.rect.x = value

X = property(_getx, _setx)

def _gety(self):

return self.rect.y

def _sety(self, value):

self.rect.y = value

Y = property(_gety, _sety)

def _getpos(self):

return self.rect.topleft

def _setpos(self, pos):

self.rect.topleft = pos

position = property(_getpos, _setpos)

def load(self, filename, width, height, columns):

self.master_image = pygame.image.load(filename).convert_alpha()

self.frame_width = width

self.frame_height = height

self.rect = Rect(0, 0, width, height)

self.columns = columns

rect = self.master_image.get_rect()

self.last_frame = (rect.width // width) * (rect.height // height) - 1

def update(self, current_time, rate=30):

# 　　更新帧数

if current_time > self.last_time + rate:

self.frame += 1

if self.frame > self.last_frame:

self.frame = self.first_frame

self.last_time = current_time

# 当帧数发生改变时，创建新的图片

if self.frame != self.old_frame:

frame_x = (self.frame % self.columns) * self.frame_width

frame_y = (self.frame // self.columns) * self.frame_height

rect = Rect(frame_x, frame_y, self.frame_width, self.frame_height)

self.image = self.master_image.subsurface(rect)

self.old_frame = self.frame

pygame.init()

screen = pygame.display.set_mode((800, 600))

font = pygame.font.Font(None, 24)

framerate = pygame.time.Clock()

bg = pygame.image.load("background.png").convert_alpha()

pl = pygame.image.load('caveman.png').convert_alpha()

# 创建精灵组

group = pygame.sprite.Group()

player = MySprite(screen)

player.load("caveman.png", 50, 64, 8)

player.first_frame = 1

player.last_frame = 7

player.position = 400, 303

group.add(player)

jump_vel = 0.0

# 设置一个记录跳跃次数的变量

space_number = 0

# 跳跃判断

player_jumping = False

player_start_y = player.Y

while True:

for event in pygame.event.get():

if event.type == QUIT:

sys.exit()

if event.type == KEYDOWN:

if event.key == K_SPACE:

# 跳跃次数小于2次时，

if space_number < 2:

jump_vel = -15.0

space_number += 1

player_jumping = True

keys = pygame.key.get_pressed()

if keys[K_ESCAPE]:

sys.exit()

if keys[K_RIGHT]:

player.X += 8

if keys[K_LEFT]:

if player.X > 0:

player.X -= 8

# 设置帧数

framerate.tick(30)

ticks = pygame.time.get_ticks()

# 当按下空格后，jump_vel变量不断变大，直到接触地面

if player_jumping:

player.Y += jump_vel

jump_vel += 2

# 落地后

if player.Y >= player_start_y:

player_jumping = False

player.Y = player_start_y

jump_vel = 0

space_number = 0

rush_number = 0

# 创建背景

screen.blit(bg, (0, 0))

# 精灵组更新

group.update(ticks, 50)

group.draw(screen)

pygame.display.update()

这样，一个粗糙的、会二段跳的精灵就完成了。

很感谢这本书提供单次跳跃的思路，让我有思考二段跳的想法。其实像二段跳这类看上去容易，但实现其实还是需要思考一番的。