Question

我正在进行的任务的一部分是让球在屏幕上反弹，我可以让它移动，但我的边界测试似乎没有起作用：球只是朝着方向而不是改变方向移动。所以要澄清一下，我想要做的就是在击中屏幕边缘时改变方向。

import sys
import pygame

SCREEN_SIZE = 750, 550
BALL_DIAMETER = 16
BALL_RADIUS = BALL_DIAMETER // 2
MAX_BALL_X = SCREEN_SIZE[0] - BALL_DIAMETER
MAX_BALL_Y = SCREEN_SIZE[1] - BALL_DIAMETER
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)

LEFT = 11
RIGHT = 12
pygame.init()
clock = pygame.time.Clock()
pygame.display.init()
font = pygame.font.SysFont("impact", 20)

pygame.display.set_caption("Breakout")

screen = pygame.display.set_mode(SCREEN_SIZE)

class Ball:
    def __init__(self):
        ''' '''
        self.ball = pygame.Rect(300, 730 -
                                BALL_DIAMETER,
                                BALL_DIAMETER, BALL_DIAMETER)

    # Draw ball
    def draw_ball(self):
        pygame.draw.circle(screen,
                           WHITE, (self.ball.left
                           + BALL_RADIUS, self.ball.top +
                           BALL_RADIUS), BALL_RADIUS)

    # Updates the coordinates by adding the speed components
    def move_ball(self, x, y):
        self.xspeed = x
        self.yspeed = y
        self.ball = self.ball.move(self.xspeed, self.yspeed)


        # bounds check
        if self.ball.left <= 0:
            self.ball.left = 0
            self.xspeed = -self.xspeed
        elif self.ball.left >= MAX_BALL_X:
            self.ball.left = MAX_BALL_X
            self.xspeed = -self.xspeed
        if self.ball.top < 0:
            self.ball.top = 0
            self.yspeed = -self.yspeed
        elif self.ball.top >= MAX_BALL_Y:
            self.ball.top = MAX_BALL_Y
            self.yspeed = -self.yspeed

# shows a message on screen, for testing purposes
class Text:
    def show_message(self, message):
        self.font = pygame.font.SysFont("impact", 20)
        font = self.font.render(message,False, WHITE)
        screen.blit(font, (200, 400))


class Game:
    def __init__(self):
        ''' '''
    def run(self):
        b = Ball()
        while 1:
            for event in pygame.event.get():
                if event.type == pygame.QUIT:
                    sys.exit()
            keys = pygame.key.get_pressed()

            # fps lock, screen fill and method call for input
            clock.tick(60)
            screen.fill(BLACK)
            b.draw_ball()
            b.move_ball(5, -5)

            # used to keep track of various elements
            # Text().show_message("P: " + str(p))

            pygame.display.flip()

# Creates instance of the game class, and runs it
if __name__ == "__main__":
    Game().run()

Answer 1

您对move_ball的唯一调用使用常量向量。由于您永远不会更改调用参数，因此球只会移动。

b.move_ball(5, -5)

是的，当你碰到一堵墙时，你会改变move_ball内的矢量组件。但是，在下一个调用中，您将它们更改回原始值并沿原始方向移动球。

您必须初始化 {/ 1>}之外的向量，然后让例程在调用它时访问现有向量。

pygame的。如何在碰撞时进行矩形改变方向（边界检查）

1 个答案: