配套视频教程
本节最终效果：
image
向上弹跳其实很简单，按下空格触发时，只要把y轴速度给一个向上的速度即可。
调用该方法，会使方块具有向上20px的速度，然后由于重力依然在起作用，所以二者结合，就会形成向上弹跳的效果。
main.py
sprites.py新增jump方法。
def jump(self):
# jump only if standing on a platform
self.rect.x += 1
hits = pg.sprite.spritecollide(self, self.game.platforms, False)
self.rect.x -= 1
if hits:
self.vel.y = -20
上面冲突检测的代码是保证只有站在挡板上才可以起跳，否则可以在空中连跳。
多加一些挡板
settings.py
main.py的new方法修改如下：
image.png
一个遗留问题
运行程序，发现一个问题：向上跳时，如果上方有档板，永远不可能跳过档板，只要一接近档板，就自动吸附上去了。
是因为main.py中，一直在检测碰撞，向上跳的过程中，如果头顶有档板，一碰到档板，代码逻辑就强制把方块固定在档板上了（即：认为方块落在档板上了）。改进方法：仅在下降过程中，才做碰撞检测，update方法修改如下：
image.png
相比之前，加了一个碰撞检测判断，如果不加这个条件，就会出现以下现象：
其他一些小改动
image.png
完整代码：
settings.py
# game options/settings
TITLE = "Jumpy!"
WIDTH = 480
HEIGHT = 600
FPS = 60
# Player properties
PLAYER_ACC = 0.5
PLAYER_FRICTION = -0.12
PLAYER_GRAV = 0.8
# Starting platforms
PLATFORM_LIST = [(0, HEIGHT - 40, WIDTH, 40),
(WIDTH / 2 - 50, HEIGHT * 3 / 4, 100, 20),
(125, HEIGHT - 350, 100, 20),
(350, 200, 100, 20),
(175, 100, 50, 20)]
# define colors
WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)
YELLOW = (255, 255, 0)
LIGHTBLUE = (0, 155, 155)
main.py
import pygame as pg
import random
from settings import *
from sprites import *
class Game:
def __init__(self):
# initialize game window, etc
pg.init()
pg.mixer.init()
self.screen = pg.display.set_mode((WIDTH, HEIGHT))
pg.display.set_caption(TITLE)
self.clock = pg.time.Clock()
self.running = True
def new(self):
# start a new game
self.all_sprites = pg.sprite.Group()
self.platforms = pg.sprite.Group()
self.player = Player(self)
self.all_sprites.add(self.player)
for plat in PLATFORM_LIST:
p = Platform(*plat)
self.all_sprites.add(p)
self.platforms.add(p)
self.run()
def run(self):
# Game Loop
self.playing = True
while self.playing:
self.clock.tick(FPS)
self.events()
self.update()
self.draw()
def update(self):
# Game Loop - Update
self.all_sprites.update()
# check if player hits a platform - only if falling
# if self.player.vel.y > 0:
hits = pg.sprite.spritecollide(self.player, self.platforms, False)
if hits:
self.player.pos.y = hits[0].rect.top
self.player.vel.y = 0
def events(self):
# Game Loop - events
for event in pg.event.get():
# check for closing window
if event.type == pg.QUIT:
if self.playing:
self.playing = False
self.running = False
if event.type == pg.KEYDOWN:
if event.key == pg.K_SPACE:
self.player.jump()
def draw(self):
# Game Loop - draw
self.screen.fill(BLACK)
self.all_sprites.draw(self.screen)
# *after* drawing everything, flip the display
pg.display.flip()
def show_start_screen(self):
# game splash/start screen
pass
def show_go_screen(self):
# game over/continue
pass
g = Game()
g.show_start_screen()
while g.running:
g.new()
g.show_go_screen()
pg.quit()
sprites.py
# Sprite classes for platform game
import pygame as pg
from settings import *
vec = pg.math.Vector2
class Player(pg.sprite.Sprite):
def __init__(self, game):
pg.sprite.Sprite.__init__(self)
self.game = game
self.image = pg.Surface((30, 40))
self.image.fill(YELLOW)
self.rect = self.image.get_rect()
self.rect.center = (WIDTH / 2, HEIGHT / 2)
self.pos = vec(WIDTH / 2, HEIGHT / 2)
self.vel = vec(0, 0)
self.acc = vec(0, 0)
def jump(self):
# jump only if standing on a platform
self.rect.x += 1
hits = pg.sprite.spritecollide(self, self.game.platforms, False)
self.rect.x -= 1
if hits:
self.vel.y = -20
def update(self):
self.acc = vec(0, PLAYER_GRAV)
keys = pg.key.get_pressed()
if keys[pg.K_LEFT]:
self.acc.x = -PLAYER_ACC
if keys[pg.K_RIGHT]:
self.acc.x = PLAYER_ACC
# apply friction
self.acc.x += self.vel.x * PLAYER_FRICTION
# equations of motion
self.vel += self.acc
self.pos += self.vel + 0.5 * self.acc
# wrap around the sides of the screen
if self.pos.x > WIDTH:
self.pos.x = 0
if self.pos.x < 0:
self.pos.x = WIDTH
self.rect.midbottom = self.pos
class Platform(pg.sprite.Sprite):
def __init__(self, x, y, w, h):
pg.sprite.Sprite.__init__(self)
self.image = pg.Surface((w, h))
self.image.fill(GREEN)
self.rect = self.image.get_rect()
self.rect.x = x
self.rect.y = y
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