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Python Arcade – Adding Camera

  • Difficulty Level : Expert
  • Last Updated : 23 Sep, 2021

In this article, we will learn How we can add cameras to arcade games in Python.

Adding Camera

You can create a camera in arcade using the Camera() function.

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Syntax: arcade.Camera( width. height) 



Parameters:

  • width: Width of the camera
  • height: Height of the camera

So to use this camera we are going to create a new variable.

self.camera = None

Then in our setup() function, we will create our camera using the Camera() function.

self.camera= arcade.Camera(200,200)

After that, we will use the camera.use function in our on_draw() function to use the camera.

self.camera.use()

In the below example, we are going to create MainGame() class. Inside our MainGame() class first we will initialize some variables for velocity, camera, scene, player’s sprite, and physics engine after that we will create 5 functions:

  • on_draw(): Inside this function, we will start the rendering using arcade.start_render() then we will draw our scene.
  • setup(): Inside this function, we will call the arcade.Scene() and arcade.Camera() functions and then we will load and store our sprites in a sprite list.
  • on_update(): Here we will update the x coordinate of our player sprite and our physics engine.
  • on_key_press(): Inside this function, we will check which keyboard button is pressed and we will change the value of the velocity variable according to that.
  • on_key_release(): Inside this function, we will check which keyboard button is released and we will change the value of the velocity variable according to that.

Sprites Used:

Below is the implementation:

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 Camera
        self.camera = None
  
        # Creating scene object
        self.scene = 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()
        self.camera.use()
        # Drawing our scene
        self.scene.draw()
  
    def setup(self):
        
        # Initialize Scene object
        self.scene = arcade.Scene()
          
        # Using Camera() function
        self.camera = arcade.Camera(200, 200)
  
        # 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 = 600
  
        # Adding Sprite in our scene
        self.scene.add_sprite("Player", self.player_sprite)
  
        # Adding platform sprite
        platform = arcade.Sprite("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()
  
    # 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
  
    # 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()

Output:

But here you can see our camera is not moving with our player. So to move the Camera with our player we have to create a function.

Moving the Camera

Now we are going to create a new camera_move() function to move our camera with our player. Then we will call this function in our on_update() function.

camera_move():  Inside this function, we will calculate the x and y coordinates of the center of the camera according to our player’s position. Then we will move our camera with the help of the move_to() function.

Below is the implementation:

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 Camera
        self.camera = None
          
        # Creating scene object
        self.scene = 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()
  
        # Using the camera
        self.camera.use()
          
        # Drawing our scene
        self.scene.draw()
  
    def setup(self):
         # Initialize Scene object
        self.scene = arcade.Scene()
          
        # Using Camera() function
        self.camera= arcade.Camera(200,200)
  
        # 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 = 600
  
        #Adding Sprite in our scene
        self.scene.add_sprite("Player",
                              self.player_sprite)
  
        # Adding platform sprite
        platform = arcade.Sprite("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()
  
        # Calling the camera_move function
        self.camera_move()
  
          
    # 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
  
    # 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
  
    def camera_move(self):
        # Getting the x coordinate for the center of camera
        screen_x = self.player_sprite.center_x -
        (self.camera.viewport_width / 2)
          
        # Getting the y coordinate for the center of camera
        screen_y = self.player_sprite.center_y -
        (self.camera.viewport_height / 2)
  
        # Moving the camera
        self.camera.move_to([screen_x, screen_y])  
          
# Calling MainGame class       
game = MainGame()
game.setup()
arcade.run()

Output:




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