Python Arcade - 在游戏中添加子弹

在本文中，我们将学习如何使用Python在 Arcade 中为游戏添加子弹。

添加子弹

在本例中，我们将向屏幕添加项目符号。为此，我们将使用一些函数：

draw_text()：该函数用于使用 Pyglet 的标签在屏幕上绘制文本。

Syntax: arcade.draw_text(text, x, y, color, size, width, align, font_name)

Parameters:

• text: Text we want to display
• x : x coordinate
• y : y coordinate
• color : color of the text
• size : Size of the font
• width : Width of the text
• align : Alignment of the text
• font_name : Name of the font

PhysicsEnginePlatformer()：用于平台游戏的简单物理引擎。

Syntax: arcade.PhysicsEnginePlatformer( player_sprite , platforms, gravity, ladders)

Parameters:

• player_sprite: sprite of the player
• platforms: The sprites it can’t move through
• gravity: Downward acceleration per frame
• ladders: Ladders the user can climb on

使用的精灵（）：

在下面的示例中，我们将创建一个 MainGame() 类。首先在这个类中，我们将初始化一些变量，用于速度、场景、子弹精灵和玩家的精灵，然后我们将在这个类中创建 4 个函数。

• on_draw()：在这个函数中，我们将在屏幕上使用我们的场景。
• setup()：在这个函数中，我们将初始化我们的场景对象，然后我们将加载我们的播放器和平台的精灵。之后，我们将调用 PhysicsEnginePlatformer()函数。
• on_update()：在这个函数中，我们将更新物理引擎、玩家精灵的 x 坐标和子弹的 y 坐标。
• on_key_press() 和 on_key_release()：在这个函数中，我们将根据按下或释放的键盘键来改变速度变量的值。当用户按下向下箭头键时，我们将加载子弹精灵。

下面是实现：

Python3

# Importing arcade module
import arcade
  
# Creating MainGame class
class MainGame(arcade.Window):
    def __init__(self):
        super().__init__(600, 600,
                         title="Player Movement")
  
        # Initializing a variable to store
        # the velocity of the player
        self.vel_x = 0
  
        # Creating variable for bullet sprite
        self.bullet = None
  
        # Creating variable to store player sprite
        self.player = None
  
        # Creating variable for our game engine
        self.physics_engine = None
  
    # Creating on_draw() function to draw on the screen
    def on_draw(self):
        arcade.start_render()
  
        # Drawing our scene
        self.scene.draw()
  
    def setup(self):
         # Initialize Scene object
        self.scene = arcade.Scene()
  
        # Creating different sprite lists
        self.scene.add_sprite_list("Player")
        self.scene.add_sprite_list("Platforms",
                                   use_spatial_hash=True)
  
        # Adding player sprite
        self.player_sprite = arcade.Sprite("Player.png", 1)
  
        # Adding coordinates for the center of the sprite
        self.player_sprite.center_x = 64
        self.player_sprite.center_y = 90
  
        # Adding Sprite in our scene
        self.scene.add_sprite("Player", self.player_sprite)
  
        # Adding platform sprite according to level
        platform = arcade.Sprite(f"Platform.png", 1)
          
        # Adding coordinates for the center of the platform
        platform.center_x = 300
        platform.center_y = 32
        self.scene.add_sprite("Platforms", platform)
  
        # Creating Physics engine
        self.physics_engine = arcade.PhysicsEnginePlatformer(
            self.player_sprite, self.scene.get_sprite_list("Platforms"), 0.5
        )
  
    # Creating on_update function to
    # update the x coordinate
    def on_update(self, delta_time):
  
        # Changing x coordinate of player
        self.player_sprite.center_x += self.vel_x * delta_time
          
        # Updating the physics engine to move the player
        self.physics_engine.update()
  
        # If self.bullet has sprites
        if self.bullet != None:
  
            # Iterating over every bullet and changing y coordinate
            for bullet in self.scene.get_sprite_list("Bullet"):
                bullet.center_y += 5
  
    # Creating function to change the velocity
    # when button is pressed
    def on_key_press(self, symbol, modifier):
  
        # Checking the button pressed
        # and changing the value of velocity
        if symbol == arcade.key.LEFT:
            self.vel_x = -300
        elif symbol == arcade.key.RIGHT:
            self.vel_x = 300
        elif symbol == arcade.key.UP:
            if self.physics_engine.can_jump():
                self.player_sprite.change_y = 15
        elif symbol == arcade.key.DOWN:
            
            # Loading bullet sprite
            self.bullet = arcade.Sprite("Bullet.png", 1)
  
            # Initializing the starting coordinates
            self.bullet.center_x = self.player_sprite.center_x
            self.bullet.bottom = self.player_sprite.top
  
            # Adding the bullet sprite in the scene
            self.scene.add_sprite("Bullet", self.bullet)
  
    # Creating function to change the velocity
    # when button is released
    def on_key_release(self, symbol, modifier):
  
        # Checking the button released
        # and changing the value of velocity
        if symbol == arcade.key.LEFT:
            self.vel_x = 0
        elif symbol == arcade.key.RIGHT:
            self.vel_x = 0
  
  
# Calling MainGame class
game = MainGame()
game.setup()
arcade.run()

输出：