pygame 精灵的行走及二段跳实现方法

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

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

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()

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。