问了解Python Arcade中的类

EN

import arcade
import random

""" Universal variables """

SPRITE_SCALING_PLAYER = 0.5
SPRITE_SCALING_ASTEROID = 0.35

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600

MOVEMENT_SPEED = 5

class Player(arcade.Sprite):
    # PLAYER
    def update(self):
        # COLLISION
        self.center_x += self.change_x
        self.center_y += self.change_y

        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 Asteroid(arcade.Sprite):
    # ASTEROID
    def __init__(self, filename, sprite_scaling):

        super().__init__(filename, sprite_scaling)

        self.change_x = 0
        self.change_y = 0

    def update(self):

        # Move the asteroid
        self.center_x += self.change_x
        self.center_y += self.change_y

        # rebound
        if self.left < 0:
            self.change_x *= -1

        if self.right > SCREEN_WIDTH:
            self.change_x *= -1

        if self.bottom < 0:
            self.change_y *= -1

        if self.top > SCREEN_HEIGHT:
            self.change_y *= -1

# MAIN GAME CLASS
class MyGame(arcade.Window):
    """ Our custom Window Class"""

    def __init__(self):
        """ Initializer """
        # Call the parent class initializer
        super().__init__(SCREEN_WIDTH, SCREEN_HEIGHT, "Alien")

        # Background image will be stored in this variable
        self.background = ("space_bg.png")

        # Variables that will hold sprite lists
        self.all_sprite_list = ["ufo_sprite.png", "asteroid.gif"]

        # Set up player
        self.player_sprite = self.all_sprite_list[0]

        # Set up asteroid
        self.asteroid_sprite = self.all_sprite_list[1]

        # Don't show the mouse cursor
        self.set_mouse_visible(False)

        # arcade.set_background_color(arcade.color.BLACK)

    def setup(self):
        """ Set up the game and initialize the variables. """
        # background
        self.background = arcade.load_texture(self.background)

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

        # Set up the player
        self.player_sprite = Player("ufo_sprite.png", SPRITE_SCALING_PLAYER)
        self.player_sprite.center_x = (SCREEN_WIDTH * 0.50)
        self.player_sprite.center_y = (SCREEN_HEIGHT * 0.50)
        self.all_sprite_list.append(self.player_sprite)

        # Set up asteroid
        self.asteroid_sprite = Asteroid("asteroid.gif", SPRITE_SCALING_ASTEROID)
        Asteroid.center_x = random.randrange(SCREEN_WIDTH)
        Asteroid.center_y = random.randrange(SCREEN_HEIGHT)
        Asteroid.change_x = random.randrange(-4, 4)
        Asteroid.change_y = random.randrange(-4, 4)
        self.all_sprite_list.append(self.asteroid_sprite)

    def on_draw(self):
        # needed before other drawn elements
        arcade.start_render()

        # draw background
        arcade.draw_texture_rectangle(SCREEN_WIDTH // 2, SCREEN_HEIGHT // 2,
                                      SCREEN_WIDTH, SCREEN_HEIGHT, self.background)
        # draw sprites
        self.all_sprite_list.draw()

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

        self.all_sprite_list.update()


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

        if key == arcade.key.W:
            self.player_sprite.change_y = MOVEMENT_SPEED
        elif key == arcade.key.S:
            self.player_sprite.change_y = -MOVEMENT_SPEED
        elif key == arcade.key.A:
            self.player_sprite.change_x = -MOVEMENT_SPEED
        elif key == arcade.key.D:
            self.player_sprite.change_x = MOVEMENT_SPEED
    #    elif key == arcade.key.SPACE:
    #        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.W or key == arcade.key.S:
            self.player_sprite.change_y = 0
        elif key == arcade.key.A or key == arcade.key.D:
            self.player_sprite.change_x = 0
    #    elif key == arcade.key.SPACE:
    #        self.player_sprite.change_y = (SCREEN_HEIGHT * 0.005)


def main():
    """ Main method """
    window = MyGame()
    window.setup()
    arcade.run()

    arcade.schedule(update, 1 / 80)

if __name__ == "__main__":
    main()