我想防止 Pygame 中的对角线运动答案

【问题标题】：I want to prevent diagonal movement in Pygame我想防止 Pygame 中的对角线运动
【发布时间】：2020-02-16 20:09:21
【问题描述】：

我正在制作游戏蛇的版本，并试图防止对角线移动。有没有办法防止多个KEYDOWN 事件

这是检测KEYDOWN 事件的辅助函数。

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

【问题讨论】：

标签： python python-3.x pygame

【解决方案1】：

您必须确保只设置了self.snake.move_right、self.snake.move_left、self.snake.move_up 或self.snake.move_down，但不能同时设置两个或多个状态。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。
使用单个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 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)

当然你可以直接声明移动向量：

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]

【讨论】：

【解决方案2】：

您可能希望将运动方向变量转换为单个增量值：

if event.key == pg.K_RIGHT:
    self.snake.move_dir = (+1, 0)
elif event.key == pg.K_LEFT:
    self.snake.move_dir = (-1, 0)
elif event.key == pg.K_UP:
    self.snake.move_dir = (0, -1)
elif event.key == pg.K_DOWN:
    self.snake.move_dir = (0, +1)

无论你将蛇移动到哪里，

dx, dy = self.move_dir
x += dx
y += dy

【讨论】：