python街机游戏模块如何设置角色的左右造型？

"""角色向左向右造型示例程序，根据水平方向来决定使用向左还是向右的造型。本程序使用arcade制作，如果没有安装，请先在cmd下输入pip install arcade
"""

import arcade
import os

SPRITE_SCALING = 0.5

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600
SCREEN_TITLE = "角色向左向右造型示例程序"

MOVEMENT_SPEED = 5

TEXTURE_LEFT = 0
TEXTURE_RIGHT = 1

class Player(arcade.Sprite):

    def __init__(self):
        super().__init__()

        # 加载一个向左和向右的造型.
        # mirrored=True 会对图像进行镜像转换
        texture = arcade.load_texture("images/princess.png", mirrored=True, scale=SPRITE_SCALING)
        self.textures.append(texture)
        texture = arcade.load_texture("images/princess.png", scale=SPRITE_SCALING)
        self.textures.append(texture)
        print(self.textures)
        # 缺省为向右造型
        self.set_texture(TEXTURE_RIGHT)
        print(TEXTURE_LEFT)
        print(TEXTURE_RIGHT)

    def update(self):
        self.center_x += self.change_x
        self.center_y += self.change_y

        # 根据水平速度的正负决定造型
        if self.change_x < 0:
            self.set_texture(TEXTURE_LEFT)
        if self.change_x > 0:
            self.set_texture(TEXTURE_RIGHT)

        if self.left < 0:
            self.left = 0
        elif self.right > SCREEN_WIDTH - 1:
            self.right = SCREEN_WIDTH - 1

        if self.bottom < 0:
            self.bottom = 0
        elif self.top > SCREEN_HEIGHT - 1:
            self.top = SCREEN_HEIGHT - 1


class MyGame(arcade.Window):
    """
     程序的游戏类，它继承自arcade.Window
    """

    def __init__(self, width, height, title):
        """
        初始化方法
        """

        # Call the parent class initializer
        super().__init__(width, height, title)

 
        # 所有角色列表
        self.all_sprites_list = None

        # 定义玩家
        self.player_sprite = None
        self.score = 0

        # 设置背景颜色
        arcade.set_background_color(arcade.color.AMAZON)

    def setup(self):
        """ 设置变量的初始值. """

        # Sprite lists
        self.all_sprites_list = arcade.SpriteList()

        # Set up the player
        self.score = 0
        self.player_sprite = Player()
        self.player_sprite.center_x = SCREEN_WIDTH / 2
        self.player_sprite.center_y = SCREEN_HEIGHT / 2
        self.all_sprites_list.append(self.player_sprite)

    def on_draw(self):
        """
        渲染屏幕上的所有对象
        """

        # This command has to happen before we start drawing
        arcade.start_render()

        # Draw all the sprites.
        self.all_sprites_list.draw()

    def update(self, delta_time):
        """ 移动与游戏逻辑在这里编写 """

        # 所有角色更新坐标
        self.all_sprites_list.update()

    def on_key_press(self, key, modifiers):
        """当按下键时调用此方法. """

        if key == arcade.key.UP:
            self.player_sprite.change_y = MOVEMENT_SPEED
        elif key == arcade.key.DOWN:
            self.player_sprite.change_y = -MOVEMENT_SPEED
        elif key == arcade.key.LEFT:
            self.player_sprite.change_x = -MOVEMENT_SPEED
        elif key == arcade.key.RIGHT:
            self.player_sprite.change_x = MOVEMENT_SPEED

    def on_key_release(self, key, modifiers):
        """当松开键时调用此方法. """

        if key == arcade.key.UP or key == arcade.key.DOWN:
            self.player_sprite.change_y = 0
        elif key == arcade.key.LEFT or key == arcade.key.RIGHT:
            self.player_sprite.change_x = 0


def main():
    """ Main method """
    window = MyGame(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
    window.setup()
    arcade.run()


if __name__ == "__main__":
    main()