精灵：面向左侧或右侧#

../_images/sprite_face_left_or_right1.png
sprite_face_left_or_right.py#
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"""
Sprite Facing Left or Right
Face left or right depending on our direction

Simple program to show basic sprite usage.

Artwork from https://kenney.nl

If Python and Arcade are installed, this example can be run from the command line with:
python -m arcade.examples.sprite_face_left_or_right
"""

import arcade

SPRITE_SCALING = 0.5

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600
SCREEN_TITLE = "Sprite Face Left or Right Example"

MOVEMENT_SPEED = 5

# Index of textures, first element faces left, second faces right
TEXTURE_LEFT = 0
TEXTURE_RIGHT = 1


class Player(arcade.Sprite):

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

        self.scale = SPRITE_SCALING
        self.textures = []

        # Load a left facing texture and a right facing texture.
        # flipped_horizontally=True will mirror the image we load.
        texture = arcade.load_texture(":resources:images/enemies/bee.png")
        self.textures.append(texture)
        texture = arcade.load_texture(":resources:images/enemies/bee.png",
                                      flipped_horizontally=True)
        self.textures.append(texture)

        # By default, face right.
        self.texture = texture

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

        # Figure out if we should face left or right
        if self.change_x < 0:
            self.texture = self.textures[TEXTURE_LEFT]
        elif self.change_x > 0:
            self.texture = self.textures[TEXTURE_RIGHT]


class MyGame(arcade.Window):
    """
    Main application class.
    """

    def __init__(self, width, height, title):
        """
        Initializer
        """

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

        # Variables that will hold sprite lists
        self.player_sprite_list = None

        # Set up the player info
        self.player_sprite = None

        # Set the background color
        arcade.set_background_color(arcade.color.AMAZON)

    def setup(self):
        """ Set up the game and initialize the variables. """

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

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

    def on_draw(self):
        """
        Render the screen.
        """

        # This command has to happen before we start drawing
        self.clear()

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

    def on_update(self, delta_time):
        """ Movement and game logic """

        # Call update on all sprites (The sprites don't do much in this
        # example though.)
        self.player_sprite_list.update()

    def on_key_press(self, key, modifiers):
        """Called whenever a key is pressed. """

        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):
        """Called when the user releases a key. """

        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 function """
    window = MyGame(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
    window.setup()
    arcade.run()


if __name__ == "__main__":
    main()