Pygame平台游戏敌人移动

Question

我正在开发一个平台游戏，并试图让我的敌人来回移动一定距离。基本上我需要找到一种方法将 dis 增加到某个数字，将其减少到零，然后再次将其增加到相同的数字。它需要无限期地继续这样做。现在它增加到 10，但随后保持不变。任何帮助将不胜感激。(注意：此代码只是一个测试版本，删除了所有"self"。

speed  = 1
dis = 0
while True:
    if speed > 0:
        dis += 1
    if dis > 10:
        speed = -1
        dis -= 1            
    if dis < 0:
        speed = 1
    print(dis)

Answer 1

你为什么不试着把它拆开呢？根据当前距离，设置速度。然后根据当前速度，增加或减少您的距离。

speed  = 1
dis = 0
while True:
    if dis >= 10:
        # Set speed
    if dis <= 0:
        # Set speed
    # Based on speed, increment or decrement distance

Answer 2

您可以使用

speed  = 1
dis = 0
while True:
    dis += speed
    if dis >= 10:
        speed = -1
    elif dis <= 0:
        speed = 1

dis += speed可以在if/elif之前或之后if/elif以获得预期的结果。

或者您甚至可以使用speed = -speed来改变方向

speed  = 1
dis = 0
while True:
    dis += speed
    if dis <= 0 or dis >= 10:
        speed = -speed

Answer 3

我想通了:)

speed  = 1
dis = 0

while True:
    if speed >= 0:
        dis += 1
    if dis >= 10:
        speed = -1            
    if speed <= 0:
        dis -= 1
    if dis <= 0:
        speed = 1
    print(dis)

Answer 4

您可以检查对象是否在该区域之外，然后反转速度。 pygame.Rect有很多属性，如left和right，在这里会有所帮助。

import pygame as pg

pg.init()
screen = pg.display.set_mode((640, 480))
clock = pg.time.Clock()
BG_COLOR = pg.Color('gray13')
BLUE = pg.Color('dodgerblue1')
rect = pg.Rect(300, 200, 20, 20)
distance = 150
speed = 1
done = False
while not done:
    for event in pg.event.get():
        if event.type == pg.QUIT:
            done = True
    # Check if the rect is outside of the specified
    # area and if it's moving to the left or right.
    if (rect.right > 300+distance and speed > 0
            or rect.left < 300 and speed < 0):
        speed *= -1  # Invert the speed.
    # Add the speed to the rect's x attribute to move it.
    rect.x += speed
    # Draw everything.
    screen.fill(BG_COLOR)
    pg.draw.rect(screen, BLUE, rect)
    pg.display.flip()
    clock.tick(60)
pg.quit()