有一个创建弹跳球的教程,我认为这可能对您有所帮助。
现在,要为该模拟添加重力,您只需在每次通过循环时在 y 方向添加一些额外的速度:
speed[1] += gravity
但是,您最终得到的结果有点愚蠢,因为图像迅速下降到窗口底部以下,再也看不到了:)
因此,下一步是剪辑球的位置,使其必须保留在窗口中:
import os
import sys, pygame
pygame.init()
size = width, height = 320, 240
speed = [1, 1]
black = 0, 0, 0
gravity = 0.1
screen = pygame.display.set_mode(size)
image_file = os.path.expanduser("~/pybin/pygame_examples/data/ball.png")
ball = pygame.image.load(image_file)
ballrect = ball.get_rect()
def clip(val, minval, maxval):
return min(max(val, minval), maxval)
while 1:
for event in pygame.event.get():
if event.type == pygame.QUIT: sys.exit()
speed[1] += gravity
ballrect = ballrect.move(speed)
if ballrect.left < 0 or ballrect.right > width:
speed[0] = -speed[0]
if ballrect.top < 0 or ballrect.bottom > height:
speed[1] = -speed[1]
# clip the position to remain in the window
ballrect.left = clip(ballrect.left, 0, width)
ballrect.right = clip(ballrect.right, 0, width)
ballrect.top = clip(ballrect.top, 0, height)
ballrect.bottom = clip(ballrect.bottom, 0, height)
screen.fill(black)
screen.blit(ball, ballrect)
pygame.display.flip()
好的,现在您可以将其合并到您当前的代码中,然后您就可以开始运行了。但是,您可以做一些事情来使您的代码更有条理,减少重复性。
例如,考虑后面的if...then
大块
for event in pygame.event.get():
您可以将其重写为:
delta = {
pygame.K_LEFT: (-20, 0),
pygame.K_RIGHT: (+20, 0),
pygame.K_UP: (0, -20),
pygame.K_DOWN: (0, +20),
}
for event in pygame.event.get():
if event.type == pygame.KEYDOWN:
deltax, deltay = delta.get(event.key, (0, 0))
ball.speed[0] += deltax
ball.speed[1] += deltay
您还可以受益于将与图像移动相关的所有逻辑放入一个类中:
class Ball(pygame.sprite.Sprite):
def __init__(self):
pygame.sprite.Sprite.__init__(self)
self.image = pygame.image.load(image_file)
self.rect = self.image.get_rect()
self.speed = [0, 0]
area = pygame.display.get_surface().get_rect()
self.width, self.height = area.width, area.height
def update(self):
self.rect = self.rect.move(self.speed)
if self.rect.left < 0 or self.rect.right > self.width:
self.speed[0] = -self.speed[0]
if self.rect.top < 0 or self.rect.bottom > self.height:
self.speed[1] = -self.speed[1]
self.rect.left = clip(self.rect.left, 0, self.width)
self.rect.right = clip(self.rect.right, 0, self.width)
self.rect.top = clip(self.rect.top, 0, self.height)
self.rect.bottom = clip(self.rect.bottom, 0, self.height)
请注意,该update
方法与教程中提供的代码非常相似。创建 Ball 类的好处之一是程序的其余部分不需要了解 Ball 如何移动。所有的逻辑都在Ball.update
. 此外,它可以很容易地实例化许多球。您还可以创建其他移动方式也不同的类(飞机、鸟类、桨等),并将它们添加到您的模拟中相对轻松。
所以,把它们放在一起,你最终会得到这样的东西:
"""
http://stackoverflow.com/a/15459868/190597 (unutbu)
Based on http://www.pygame.org/docs/tut/intro/intro.html
Draws a red ball bouncing around in the window.
Pressing the arrow keys moves the ball
"""
import sys
import pygame
import os
image_file = os.path.expanduser("~/pybin/pygame_examples/data/ball.png")
delta = {
pygame.K_LEFT: (-20, 0),
pygame.K_RIGHT: (+20, 0),
pygame.K_UP: (0, -20),
pygame.K_DOWN: (0, +20),
}
gravity = +1
class Ball(pygame.sprite.Sprite):
def __init__(self):
pygame.sprite.Sprite.__init__(self)
self.image = pygame.image.load(image_file)
self.rect = self.image.get_rect()
self.speed = [0, 0]
area = pygame.display.get_surface().get_rect()
self.width, self.height = area.width, area.height
def update(self):
self.rect = self.rect.move(self.speed)
if self.rect.left < 0 or self.rect.right > self.width:
self.speed[0] = -self.speed[0]
if self.rect.top < 0 or self.rect.bottom > self.height:
self.speed[1] = -self.speed[1]
self.rect.left = clip(self.rect.left, 0, self.width)
self.rect.right = clip(self.rect.right, 0, self.width)
self.rect.top = clip(self.rect.top, 0, self.height)
self.rect.bottom = clip(self.rect.bottom, 0, self.height)
def clip(val, minval, maxval):
return min(max(val, minval), maxval)
class Main(object):
def __init__(self):
self.setup()
def setup(self):
pygame.init()
size = (self.width, self.height) = (640,360)
self.screen = pygame.display.set_mode(size, 0, 32)
self.ball = Ball()
self.setup_background()
def setup_background(self):
self.background = pygame.Surface(self.screen.get_size())
self.background = self.background.convert()
self.background.fill((0, 0, 0))
self.screen.blit(self.background, (0, 0))
pygame.display.flip()
def draw(self):
self.screen.blit(self.background, (0, 0))
self.screen.blit(self.ball.image, self.ball.rect)
pygame.display.flip()
def event_loop(self):
ball = self.ball
friction = 1
while True:
for event in pygame.event.get():
if ((event.type == pygame.QUIT) or
(event.type == pygame.KEYDOWN and
event.key == pygame.K_ESCAPE)):
sys.exit()
elif event.type == pygame.KEYDOWN:
deltax, deltay = delta.get(event.key, (0, 0))
ball.speed[0] += deltax
ball.speed[1] += deltay
friction = 1
elif event.type == pygame.KEYUP:
friction = 0.99
ball.speed = [friction*s for s in ball.speed]
ball.speed[1] += gravity
ball.update()
self.draw()
pygame.time.delay(10)
if __name__ == '__main__':
app = Main()
app.event_loop()