python - 我想防止 Pygame 中的对角线移动

Question

我正在制作蛇游戏的一个版本，并试图防止对角线移动。有没有办法防止多个 KEYDOWN 事件

这是我的辅助函数，用于检测 KEYDOWN 事件。

def _keydown_events(self, event):
    '''Responds to pressing keystrokes'''
    if event.type == pg.KEYDOWN:
        if event.key == pg.K_q:
            pg.display.quit()
            running = False
            sys.exit()
        elif event.key == pg.K_RIGHT:
            self.snake.move_right = True
        elif event.key == pg.K_LEFT:
            self.snake.move_left = True
        elif event.key == pg.K_UP:
            self.snake.move_up = True 
        elif event.key == pg.K_DOWN:
            self.snake.move_down = True

Answer 1

您必须确保仅 self.snake.move_right、self.snake.move_left、self.snake.move_up 或 self.snake.move_down 已设置，但绝不会同时设置 2 个或更多状态。例如:

def _keydown_events(self, event):
    '''Responds to pressing keystrokes'''
    if event.type == pg.KEYDOWN:
        if event.key == pg.K_q:
            pg.display.quit()
            running = False
            sys.exit()
        elif if event.key in [pg.K_RIGHT, pg.K_LEFT, pg.K_UP, pg.K_DOWN]:
            self.snake.move_right = False
            self.snake.move_left = False
            self.snake.move_up = False
            self.snake.move_down = False
            if event.key == pg.K_RIGHT:
                self.snake.move_right = True
            elif event.key == pg.K_LEFT:
                self.snake.move_left = True
            elif event.key == pg.K_UP:
                self.snake.move_up = True
            elif event.key == pg.K_DOWN:
                self.snake.move_down = True

---

无论如何，我建议删除状态 self.snake.move_right、self.snake.move_left、self.snake.move_up 或 self.snake.move_down.
使用单一状态来指示蛇的方向。添加状态 move_dir 并分配 pygame.key.name(event.key) 。对于 RIGHT、LEFT、UP，move_dir 的值分别变为“right”、“left”、“up”和“down” 或向下。例如:

def _keydown_events(self, event):
    '''Responds to pressing keystrokes'''
    if event.type == pg.KEYDOWN:
        if event.key == pg.K_q:
            pg.display.quit()
            running = False
            sys.exit()

        elif if event.key in [pg.K_RIGHT, pg.K_LEFT, pg.K_UP, pg.K_DOWN]:
            # move_dir becomes "right", "left", "up" or "down"
            self.snake.move_dir = pygame.key.name(event.key)

---

当然你可以直接给出移动向量:

def _keydown_events(self, event):
    '''Responds to pressing keystrokes'''
    if event.type == pg.KEYDOWN:
        if event.key == pg.K_q:
            pg.display.quit()
            running = False
            sys.exit()

        elif if event.key in [pg.K_RIGHT, pg.K_LEFT, pg.K_UP, pg.K_DOWN]:

            move_dirs = {pg.K_RIGHT: (1, 0), pg.K_LEFT: (-1, 0), 
                         pg.K_UP: (0, -1), pg.K_DOWN: (0, 1)}
            self.snake.move_dir = move_dirs[event.key]