Python球加速游戏

Question

我已经创建了一个草图代码，应该移动球后，按下键加速。球将按键盘箭头的方向加速，然后从窗口的活动边缘反弹。以下是代码：

import pygame, sys
pygame.init()


def main():

    clock = pygame.time.Clock()
    
    pygame.display.set_caption('BasketBall')
    icon = pygame.image.load('/home/michael/game/ballgame.png')
    pygame.display.set_icon(icon)
    
    pygame.mixer.music.load(r'/home/michael/game/soundtrack.mp3')
    pygame.mixer.music.play(-1)
    
    size = width, height = 800, 600
    screen = pygame.display.set_mode(size)
    
    speed = [0, 0]
    accel = [0.1, 0.1]

    
    image = pygame.image.load(r'/home/michael/game/background.png')
    image = pygame.transform.scale(image, size)
    
    surf_center = (
        (width-image.get_width())/2,
        (height-image.get_height())/2
    )
    
    screen.blit(image, surf_center)
    ball = pygame.image.load('/home/michael/game/ball.png')
    ball = pygame.transform.scale(ball, (ball.get_width()//10, ball.get_height()//10))

    screen.blit(ball, (width/10, height/10))
    ballrect = ball.get_rect(center=(width/2, height/2))
    pygame.display.flip()


    while True:
        clock.tick(60)
        pygame.time.delay(50)
        for event in pygame.event.get():
            if event.type == pygame.QUIT: sys.exit()
        keys = pygame.key.get_pressed()
        if keys[pygame.K_ESCAPE]: sys.exit()
        if keys[pygame.K_UP]:

            ballrect = ballrect.move([0,-50])
        elif keys[pygame.K_DOWN]:
            ballrect = ballrect.move([0,50])
        elif keys[pygame.K_LEFT]:
            ballrect = ballrect.move([-50,0])
        elif keys[pygame.K_RIGHT]:
            ballrect = ballrect.move([50,0])
        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]

        
        screen.blit(image,surf_center)
        screen.blit(ball,ballrect)
        pygame.display.flip()


if __name__ == '__main__':
    main()
    pygame.quit()
    sys.exit()

这看起来很复杂，也许是因为我还在学习游戏库，但是我想加速球，直到按下键。理想情况下，球应该从活跃的窗口边缘弹回。

Answer 1

因为pygame.Rect应该表示屏幕上的一个区域，所以pygame.Rect对象只能存储积分数据。

-- Rect对象的坐标都是整数。..。

如果要以浮点精度存储对象位置，则必须将对象的位置分别存储在单独的变量属性中，并同步pygame.Rect对象。

为球的位置、速度、加速度建立变量。还为摩擦力(1表示没有摩擦力)和最大速度添加一个变量：

ball_rect = ball.get_rect(center = surf_center)
ball_pos = list(ball_rect.center)
speed = [0, 0]
accel = [0.1, 0.1]
max_speed = 10
friction = 0.99

当按下按钮时，速度取决于加速度和摩擦力：

keys = pygame.key.get_pressed()
dx = keys[pygame.K_RIGHT] - keys[pygame.K_LEFT]
dy = keys[pygame.K_DOWN] - keys[pygame.K_UP]
        
speed[0] = speed[0] * friction + accel[0] * dx
speed[1] = speed[1] * friction + accel[1] * dy

以最大速度限制速度：

speed[0] = max(-max_speed, min(max_speed, speed[0]))
speed[1] = max(-max_speed, min(max_speed, speed[1]))

根据速度移动球：

ball_pos[0] += speed[0]
ball_pos[1] += speed[1]
ball_rect.center = round(ball_pos[0]), round(ball_pos[1])

从墙上弹起球时要小心(参见Sometimes the ball doesn't bounce off the paddle in pong game)：

border_rect = screen.get_rect()
if not border_rect.contains(ball_rect):
    if ball_rect.left < 0 or ball_rect.right > width:
        speed[0] = -speed[0]
    if ball_rect.top < 0 or ball_rect.bottom > height:
        speed[1] = -speed[1]
    border_rect.clamp_ip(border_rect)
    ball_pos = list(ball_rect.center)

完整的应用循环：

def main():
    # [...]
    
    ball_rect = ball.get_rect(center = surf_center)
    ball_pos = list(ball_rect.center)
    speed = [0, 0]
    accel = [0.1, 0.1]
    max_speed = 10
    friction = 0.99

    run = True
    while run:
        clock.tick(60)
        pygame.time.delay(50)
        for event in pygame.event.get():
            if event.type == pygame.QUIT: 
                run = False

        keys = pygame.key.get_pressed()
        dx = keys[pygame.K_RIGHT] - keys[pygame.K_LEFT]
        dy = keys[pygame.K_DOWN] - keys[pygame.K_UP]
        
        speed[0] = speed[0] * friction + accel[0] * dx
        speed[1] = speed[1] * friction + accel[1] * dy
        speed[0] = max(-max_speed, min(max_speed, speed[0]))
        speed[1] = max(-max_speed, min(max_speed, speed[1]))

        ball_pos[0] += speed[0]
        ball_pos[1] += speed[1]
        ball_rect.center = round(ball_pos[0]), round(ball_pos[1])
        
        border_rect = screen.get_rect()
        if not border_rect.contains(ball_rect):
            if ball_rect.left < 0 or ball_rect.right > width:
                speed[0] = -speed[0]
            if ball_rect.top < 0 or ball_rect.bottom > height:
                speed[1] = -speed[1]
            border_rect.clamp_ip(border_rect)
            ball_pos = list(ball_rect.center)

        screen.blit(image, (0, 0))
        screen.blit(ball, ball_rect)
        pygame.display.flip()

最起码的例子：

​

​

import pygame, sys
pygame.init()

def main():
    clock = pygame.time.Clock()
    screen = pygame.display.set_mode((400, 400))
    image = pygame.Surface(screen.get_size())
    surf_center = screen.get_rect().center
    ball = pygame.Surface((30, 30), pygame.SRCALPHA)
    pygame.draw.circle(ball, "white", (15, 15), 15)
    
    ball_rect = ball.get_rect(center = surf_center)
    ball_pos = list(ball_rect.center)
    speed = [0, 0]
    accel = [0.5, 0.5]
    max_speed = 20
    friction = 0.99

    run = True
    while run:
        clock.tick(60)
        pygame.time.delay(50)
        for event in pygame.event.get():
            if event.type == pygame.QUIT: 
                run = False
            if event == pygame.KEYDOWN  and event.key == pygame.K_ESCAPE:
                run = False

        keys = pygame.key.get_pressed()
        dx = keys[pygame.K_RIGHT] - keys[pygame.K_LEFT]
        dy = keys[pygame.K_DOWN] - keys[pygame.K_UP]
        
        speed[0] = speed[0] * friction + accel[0] * dx
        speed[1] = speed[1] * friction + accel[1] * dy
        speed[0] = max(-max_speed, min(max_speed, speed[0]))
        speed[1] = max(-max_speed, min(max_speed, speed[1]))

        ball_pos[0] += speed[0]
        ball_pos[1] += speed[1]
        ball_rect.center = round(ball_pos[0]), round(ball_pos[1])
        
        border_rect = screen.get_rect().inflate(-50, -50)
        if not border_rect.contains(ball_rect):
            if ball_rect.left < border_rect.left or ball_rect.right > border_rect.right:
                speed[0] = -speed[0]
            if ball_rect.top < border_rect.top or ball_rect.bottom > border_rect.bottom:
                speed[1] = -speed[1]
            border_rect.clamp_ip(border_rect)
            ball_pos = list(ball_rect.center)

        screen.blit(image, (0, 0))
        pygame.draw.rect(screen, "red", border_rect, 3)
        screen.blit(ball, ball_rect)
        pygame.display.flip()

if __name__ == '__main__':
    main()
    pygame.quit()
    sys.exit()