当一个游戏精灵撞到它的尾巴时，如何检测并结束游戏？

Question

我创建了一个类似蛇的游戏，用户移动精灵，精灵会留下痕迹。如果用户遇到他创建的轨迹，我希望游戏结束，玩家输

我的一个想法是跟踪精灵过去的位置（可能在列表中），然后创建一个if语句，这将导致游戏失败（然而，我有点不清楚如何做到这一点）

我收到了这个问题的答案，这个答案编码如下：

"I think you could declare a two dimensional list like this: pastPositions = [[400, 300]] Then every time the player's position moves, check the list:
for row in pastPositions: If (player.rect.x == pastPositions[row][0] and player.rect.y == pastPositions[row][1]): done = true # game over If the player hasn't been there yet, then add that position to the list. pastPositions.append([player.rect.x, player.rect.y])

这看起来应该可以工作，但是当我尝试运行代码（在Python Interactive中）时，会收到一条错误消息："line 86, in <module> if player.rect.x == astPositions[row][0] and player.rect.y == pastPositions[row][1]: IndexError: list index out of range"

你建议我把范围改成什么，这样就不会发生这种情况了？我试着把它设置为pygame窗口的宽度和高度

import pygame

BLACK = (0, 0, 0)
WHITE = (255, 255, 255)

class Player(pygame.sprite.Sprite):

   def __init__(self, x, y):
       super().__init__()

       self.image = pygame.Surface([15, 15])
       self.image.fill(WHITE)

       self.rect = self.image.get_rect()
       self.rect.x = x
       self.rect.y = y

       self.change_x = 0
       self.change_y = 0


   def changespeed(self, x, y):
       self.change_x += x
       self.change_y += y


   def update(self):
       self.rect.x += self.change_x
       self.rect.y += self.change_y

pygame.init()

screen = pygame.display.set_mode([800, 600])

pygame.display.set_caption('The Etch-a-Sketch Game')

myfont = pygame.font.SysFont('Times', 20)
textsurface = myfont.render('This is the Etch-a-Sketch Game', False, (255, 255, 255))
screen.blit(textsurface,(0,0))

myfont = pygame.font.SysFont('Times', 15)
textsurface = myfont.render('Feel free to draw, but if you cross your own    path, you will die.', False, (255, 255, 255))
screen.blit(textsurface,(0,20))


player = Player(400, 300)
all_sprites_list = pygame.sprite.Group()
all_sprites_list.add(player)

clock = pygame.time.Clock()
done = False

while not done:

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True

        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                player.changespeed(-3, 0)
            elif event.key == pygame.K_RIGHT:
                player.changespeed(3, 0)
            elif event.key == pygame.K_UP:
                player.changespeed(0, -3)
            elif event.key == pygame.K_DOWN:
                player.changespeed(0, 3)

        elif event.type == pygame.KEYUP:
            if event.key == pygame.K_LEFT:
                player.changespeed(3, 0)
            elif event.key == pygame.K_RIGHT:
                player.changespeed(-3, 0)
            elif event.key == pygame.K_UP:
                player.changespeed(0, 3)
            elif event.key == pygame.K_DOWN:
                player.changespeed(0, -3)

    player.update()

    all_sprites_list.draw(screen)

    pygame.display.flip()
    clock.tick(75)

pygame.quit ()

Answer 1

记录一条很长的路径上的点似乎是一种检查是否撞到自己尾巴的慢方法

如果背景是一种已知的颜色，那么在播放器即将进入的区域中检查非背景像素的颜色

可以使用Surface.get_at()函数获取单个像素的颜色。这将返回一个RGBA颜色，此颜色可以与单个背景颜色（或该点位图中的已知背景颜色）进行比较，从而确定冲突

在player.update()中：

if (screen.get_at((player_next_x, player_next_y)) != BACKGROUND_COLOUR):
    # player hit tail

当然，可能有必要检查玩家精灵的两个角落（在行进方向）