Python Arcade – Collision Detection

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

Installation

You can install the Arcade module using the below command:

pip install arcade

Example 1:

In this example, we are going to use the check_for_collision() function to add collision between 2 sprites.

Syntax: arcade.check_for_collision( sprite1, sprite2)

Parameters:

• sprite1:- First sprite
• sprite2:- Second sprite

Returns: Boolean value

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 Player1 and Player2
        self.vel_x1 = 380
        self.vel_x2 = 380

        self.scene = None

        # Creating variable to store player sprite
        self.player1 = None

        # Creating variable to store player sprite
        self.player2 = None

    # Creating on_draw() function to draw on the screen
    def on_draw(self):
        arcade.start_render()

        # Drawing the scene
        self.scene.draw()

    def setup(self):

        # Creating scene
        self.scene = arcade.Scene()

        # Adding player sprite
        self.player_sprite1 = arcade.Sprite("Player.png", 1)
        self.player_sprite2 = arcade.Sprite("Player2.png", 1)

        # Adding coordinates for the center of the sprite
        self.player_sprite1.center_x = 20
        self.player_sprite1.center_y = 300

        # Adding coordinates for the center of the sprite
        self.player_sprite2.center_x = 580
        self.player_sprite2.center_y = 300

        # Adding sprites in scene
        self.scene.add_sprite('Player', self.player_sprite1)
        self.scene.add_sprite('Player', self.player_sprite2)

    # Creating on_update function to
    # update the x coordinate
    def on_update(self, delta_time):

        # Changing x coordinate of players
        self.player_sprite1.center_x += self.vel_x1 * delta_time
        self.player_sprite2.center_x -= self.vel_x2 * delta_time

        # Checking if sprites are colliding or not
        colliding = arcade.check_for_collision(
            self.player_sprite1, self.player_sprite2)

        # If sprites are colliding then changing direction
        if colliding:
            self.vel_x1 *= -1
            self.vel_x2 *= -1

        # Changing the direction if sprites crosses the screen boundary
        if self.player_sprite1.center_x > 600 or self.player_sprite1.center_x < 0:
            self.vel_x1 *= -1

        if self.player_sprite2.center_x > 600 or self.player_sprite2.center_x < 0:
            self.vel_x2 *= -1


# Calling MainGame class
game = MainGame()
game.setup()
arcade.run()

Output:

Example 2:

In this example, we are going to use PhysicsEnginePlatformer() function to add collision between our player and platform.

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

Parameters:

• player_sprite:- The player sprite
• platforms:- The platform sprite list
• gravity:- Amount of gravity
• ladders:- Ladders the user can climb on

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 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()

        # 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 = 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: