在 kivy 游戏中创建多个敌人

Question

我目前正在 kivy 开发 space inavders 游戏。我有一艘 space 飞船，它向敌人发射子弹。敌人向右移动，当他们到达边界时他们向左转，这种情况一次又一次发生。一切都很完美。我可以射击，而敌人正在移动。但问题是我不能制造多个敌人。我必须为每个敌人放一个自己的 class 并一次又一次地编写相同的代码。我的想法是我将创建一个敌人列表，然后从列表中显示它们。以至于看起来有多个敌人。但是我不知道我该怎么做，当你有另一个想法时，我无法从一个 day.Also 做到这一点，如果你提出建议，那就太好了。这是我的代码。

敌人class:

class Enemy(Widget):
    def collision(self,ball,enemy,enemy1):
        if self.collide_widget(ball):
            enemy.y = randint(300,500)
            enemy1.y = randint(300,500)
            ball.x = -1000
            ball.y = self.height / self.width

我的主游戏Class:

class SapceGame(Widget):
enemy = ObjectProperty(None)
    enemy = ObjectProperty(None)
    x_change = NumericProperty(3)
    y_change = NumericProperty(-50)

    def enemy_movement(self, *args):
        self.enemy.x -= self.x_change
        if self.enemy.x  >= self.width -64:
            self.x_change = 3
            self.enemy.y += self.y_change
        elif self.enemy.x  <=0:
            self.x_change = -3
            self.enemy.y += self.y_change
        elif self.enemy.y < 0:
            print('Game Over')
    def update(self,dt):
        self.enemy_movement()

我的kv文件：

<Enemy>:
    size: 64,64
    canvas:
        Rectangle:
            pos:self.pos
            size: self.size
            source:'alien.png'
<SpaceGame>:
    ball: pong_ball
    ship: space_ship
    enemy: enemy_ship
    Enemy:
       id:enemy_ship
       x:root.random_generator(2,root.width-64)
       y:root.random_generator(300,550)

应用程序 class

class SpaceApp(App):

    def build(self):
        game = PongGame()

        # pro second 60 frames are shown
        Clock.schedule_interval(game.update, 1.0/60.0)

        return game



SpaceApp().run()


Now when I want to create more enemies I have to write the same code again and again.

Answer 1

面向对象编程的主要概念之一是每个对象处理自己的行为。所以，你的 Enemy 对象应该知道如何移动。然后，您只需要保留 Enemy 个对象的列表，并告诉每个对象在每次更新时执行其移动行为。

这是您的代码的修改版本：

from random import randint
from kivy.app import App
from kivy.clock import Clock
from kivy.lang import Builder
from kivy.properties import ObjectProperty, NumericProperty, ListProperty
from kivy.uix.widget import Widget


class Enemy(Widget):
    x_change = NumericProperty(3)
    y_change = NumericProperty(-50)

    def collision(self,ball,enemy,enemy1):
        if self.collide_widget(ball):
            enemy.y = randint(300,500)
            enemy1.y = randint(300,500)
            ball.x = -1000
            ball.y = self.height / self.width

    def move(self, *args):
        self.x -= self.x_change
        if self.x  >= self.parent.width -64:
            self.x_change = 3
            self.y += self.y_change
        elif self.x  <=0:
            self.x_change = -3
            self.y += self.y_change
        if self.y < 0:
            print('Game Over')
            App.get_running_app().stop_game()


class SpaceGame(Widget):
    enemies = ListProperty([])

    def add_enemy(self, *args):
        enemy = Enemy()
        enemy.pos = (randint(0, self.width - 64), self.height - 64)
        self.add_widget(enemy)
        self.enemies.append(enemy)

    def update(self,dt):
        for enemy in self.enemies:
            enemy.move()

Builder.load_string('''
<Enemy>:
    size_hint: None, None
    size: 64,64
    canvas:
        Rectangle:
            pos:self.pos
            size: self.size
            source:'alien.png'
''')


class SpaceApp(App):

    def build(self):
        game = SpaceGame()

        # add enemies at 5 second intervals
        self.new_enemy_event = Clock.schedule_interval(game.add_enemy, 5)

        # pro second 60 frames are shown
        self.updateEvent = Clock.schedule_interval(game.update, 1.0/60.0)

        return game

    def stop_game(self):
        self.updateEvent.cancel()
        self.new_enemy_event.cancel()


SpaceApp().run()

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