Question

在弹球游戏中，如何开始在屏幕上移动球。当到达边界时，我尝试将球的时间减为-1，但我认为代码编写不正确。我需要球像普通弹球游戏中的球一样运动。我对碰撞等不太熟悉，但是我正在尝试学习它。

import pygame

pygame.init()
win = pygame.display.set_mode((1000, 700))
pygame.display.set_caption("First Game")
clock = pygame.time.Clock()
balls = []
run = True

class player():
    def __init__(self, x, y, width, height):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.vel = 10


def redrawGameWindow():
    win.fill((0, 0, 0))
    pygame.draw.rect(win, (255, 0, 0), (player1.x, player1.y, player1.width, player1.height))
    pygame.draw.rect(win, (255, 0, 0), (player2.x, player2.y, player2.width, player2.height))
    pygame.draw.circle(win, ball.colour, (ball.x, ball.y), ball.radius)
    pygame.display.update()


class projectile(object):
    def __init__(self, x, y, radius, colour):
        self.x = x
        self.y = y
        self.radius = radius
        self.colour = colour
        self.vel = 7


ball = projectile(500, 350, 15, (225,225,225))
player1 = player(30, 275, 30, 150)
player2 = player(940, 275, 30, 150)

while run:
    clock.tick(30)
    neg = -1

    keys = pygame.key.get_pressed()
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
    if keys[pygame.K_w] and player1.y > player1.vel:
        player1.y -= player1.vel
    if keys[pygame.K_s] and player1.y < 700 - player1.height - player1.vel:
        player1.y += player1.vel
    if keys[pygame.K_UP] and player2.y > player2.vel:
        player2.y -= player2.vel
    if keys[pygame.K_DOWN] and player2.y < 700 - player2.height - player2.vel:
        player2.y += player2.vel

    if keys[pygame.K_SPACE]:
        if ball.x > 0 and ball.y > 0:
            ball.y -= ball.vel
            ball.x -= ball.vel
        if ball.y == 1:
            ball.y *= neg

    redrawGameWindow()

pygame.quit()

Answer 1

if ball.y == 1:
    ball.y *= neg

这看起来非常很奇怪，否定了球的位置。通常有一个位置和一个矢量（在数学上是“量级和方向”，而不是在编程上是“数组”），指示如何随时间改变位置^（a）。

例如，固定位置y处向右1的球将类似于：

xpos = 0, ypos = 20
xincr = 1, yincr = 0
while true:
    xpos += xincr
    ypos += yincr
    drawAt(xpos, ypos)

然后，您可以根据条件调整矢量（xincr和yincr的值），例如从墙壁弹跳（Python样式的伪代码）：

xpos = radius, ypos = radius, xincr = 1, yincr = 1
while true:
    xpos += xincr, ypos += yincr
    drawAt(xpos, ypos)
    if xpos == radius or xpos == screenWidth - radius - 1:
        xincr *= -1
    if ypos == radius or ypos == screenHeight - radius - 1:
        yincr *= -1

^（a）是的，我可以看到您有一个速度变量，但是：

它并没有真正拆分为x和y组件，因此不合适。和
它永远不会改变。

我如何获得一个球来开始运动？

1 个答案: