In this article, we will discuss how to add moving platforms to our arcade games in Python.
Adding Moving Platform
We can easily add moving platforms in our arcade game by following the below steps:
- Create 2 new variables for sprite and velocity of moving platform.
self.moving_vel = 3 self.moving_platform = None
- Load the sprite and add the initial coordinates.
self.moving_platform = arcade.Sprite("Moving.png",1)
self.moving_platform.center_x = 500
self.moving_platform.center_y = 500- Update the y-coordinate of the platform.
self.moving_platform.center_y -= self.moving_vel
- Change the direction of the platform if the platform crosses the boundary.
if self.moving_platform.center_y < 100 or self.moving_platform.center_y>600: self.moving_vel *= -1
Sprites Used:
For this, we are going to create a MainGame() class. Inside this class first, we are going to initialize some variables for player's velocity, platform velocity, camera, player sprite, physics engine, and our scene. After that, we will create 6 functions inside this class.
- on_draw(): Inside this function, we will use our camera, and then we will draw our scene.
- setup(): In this function, we will initialize our camera and scene object then we will load our player and platform's sprites. After that, we will call the PhysicsEnginePlatformer() function.
- on_update(): In this function, we will update the x coordinate of the player's sprite by adding the value of the velocity variable and we also update the y coordinate of our moving platform. After that, we will call our camera_move() function.
- on_key_press(): In this function, we will change the value of the vel_x variable according to the keyboard key that is pressed.
- on_key_release(): In this function, we will change the value of the vel_x variable according to the keyboard key that is released.
- camera_move(): In this function, we will change the position of the camera according to the current position of the player.
Below is the implementation:
# 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 variable for moving velocity
self.moving_vel = 3
# Creating variable for Platform
self.moving_platform = 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(600,600)
# 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 moving Platform sprite
self.moving_platform = arcade.Sprite("Moving.png",1)
# Adding starting coordinates
self.moving_platform.center_x = 500
self.moving_platform.center_y = 500
# Adding to Platforms sprite group
self.scene.add_sprite("Platforms", self.moving_platform)
# 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()
# Adding moving velocity in moving platform
self.moving_platform.center_y -= self.moving_vel
# Changing the direction
if self.moving_platform.center_y < 100 or
self.moving_platform.center_y>600:
self.moving_vel *= -1
# 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
elif symbol == arcade.key.UP:
if self.physics_engine.can_jump():
self.player_sprite.change_y = 15
# 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:
