In this article, we will learn How we can add enemies in arcade.
Adding Enemies
To add enemy to our game we are going to follow the below steps:
- First, we will create a variable to store the enemy sprite.
Syntax:
self.enemy = None
- After that, we will create one more variable to store the velocity of the enemy.
Syntax:
self.enemy_move = velocity
- Store our enemy sprite in the enemy variable.
Syntax:
self.enemy = arcade.Sprite("path",1)- Set the initial coordinates.
Syntax:
self.enemy.center_x = value self.enemy.center_y = value
- Add the enemy sprite in the scene.
Syntax:
self.scene.add_sprite("Enemy", self.enemy)- Move the enemy by changing the x coordinate.
Syntax:
self.enemy.center_x += self.enemy_move
- Check for collisions between the player and enemy.
Syntax:
enemy_collide = arcade.check_for_collision_with_list(
self.player_sprite, self.scene.get_sprite_list(“Enemy”)
)
- If they are colliding then remove the player sprite.
Syntax:
for enemy in enemy_collide:
self.player_sprite.remove_from_sprite_lists()
Functions Used:
- draw_text(): This function is used to draw text to the screen using Pyglet’s label.
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
- Camera(): The Camera class is used for controlling the visible viewport.
Syntax: arcade.Camera( width , height, window)
Parameters:
width: width of the viewport
height: height of the viewport
window: Window to associate with this camera
- Scene(): A class that represents a scene object.
Syntax: arcade.Scene(sprite_lists , name_mapping)
Parameters:
sprite_lists: A list of SpriteList objects
name_mapping: A dictionary of SpriteList objects
- PhysicsEnginePlatformer(): Simplistic physics engine, used for platform.
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
Sprites Used:
PLATFORM
PLAYER
ENEMY
In the below example, we are going to create a MainGame() class. Inside this class first, we are going to initialize some variables for velocity, camera, score, level, enemy, enemy sprite, and player’s sprite then we will create 6 functions inside this class.
- on_draw(): Inside this function, we will use our camera and draw the scene and our score text on the screen.
- setup(): In this function, we will initialize our camera and scene object then we will load our player and platform’s sprites then we will load our enemy sprite and initialize the starting x and y coordinate. After that, we will call the PhysicsEnginePlatformer() function.
- on_update(): In this function, we will update the x coordinates of the player’s sprite, camera, and physics engine. We will also add our enemy_move variable in the x coordinates of the enemy sprite. Then we will check the collision between the enemy and the player. And if the player is colliding with the enemy then we will remove the player sprite.
- on_key_press() and on_key_release(): In this function, we will change the value of the velocity variable according to the keyboard key that is pressed or released.
- camera_move(): In this function, we will move our camera according to our player’s current position.
Example: Adding enemy
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 variable to store current score
self.score = 0
# Creating variable to move the enemy
self.enemy_move = 5
# Creating variable for enemy sprite
self.enemy = 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()
# Drawing the text
arcade.draw_text('Score :- '+str(self.score),
self.player_sprite.center_x - 500 / 2,
self.player_sprite.center_y + 200,
arcade.color.WHITE, 30, 5000, 'left')
# 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)
# Loading enemy sprite
self.enemy = arcade.Sprite("Enemy.png", 1)
# Initializing the starting coordinates
self.enemy.center_x = 500
self.enemy.center_y = 110
# Adding the enemy sprite in the scene
self.scene.add_sprite("Enemy", self.enemy)
# 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):
# Moving the position of enemy
self.enemy.center_x += self.enemy_move
# Changing the direction of enemy movement
if self.enemy.center_x > 500 or self.enemy.center_x < 160:
self.enemy_move *= -1
# Checking if the enemy is colliding with player or not
enemy_collide = arcade.check_for_collision_with_list(
self.player_sprite, self.scene.get_sprite_list("Enemy")
)
# Looping through each enemy and removing the player
# if colliding
for enemy in enemy_collide:
# Remove the coin
self.player_sprite.remove_from_sprite_lists()
# 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
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:
Killing the Enemy
Now we want to kill the enemy when the player jumps on top of it. For this, we will check if the bottom other player is equal to the top of the enemy or not. If it is equal then we will remove the layer sprite.
- For this first, we will store the coordinate of the bottom of the player in a variable.
Syntax:
x = int(self.player_sprite.center_y – 14)
- Similarly the coordinate of the top of the enemy in a different variable.
Syntax:
y = int(self.enemy.center_y + 25)
- Then, if x and y are equal and the enemy and player are colliding then we will remove our enemy sprite.
Syntax:
if x == y:
self.enemy.remove_from_sprite_lists()
Example: Killing an enemy using Arcade
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 variable to store current score
self.score = 0
# Creating variable to move the enemy
self.enemy_move = 2
# Creating variable for enemy sprite
self.enemy = 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()
# Drawing the text
arcade.draw_text('Score :- '+str(self.score),
self.player_sprite.center_x - 500 / 2,
self.player_sprite.center_y + 200,
arcade.color.WHITE, 30, 5000, 'left')
# 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)
# Loading enemy sprite
self.enemy = arcade.Sprite("Enemy.png", 1)
# Initializing the starting coordinates
self.enemy.center_x = 500
self.enemy.center_y = 110
# Adding the enemy sprite in the scene
self.scene.add_sprite("Enemy", self.enemy)
# 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):
# Moving the position of enemy
self.enemy.center_x += self.enemy_move
# Changing the direction of enemy movement
if self.enemy.center_x > 500 or self.enemy.center_x < 160:
self.enemy_move *= -1
# Checking if the enemy is colliding with player or not
enemy_collide = arcade.check_for_collision_with_list(
self.player_sprite, self.scene.get_sprite_list("Enemy")
)
# Looping through each enemy and removing the player if colliding
for enemy in enemy_collide:
# Checking the top of enemy and bottom of player
x = int(self.player_sprite.center_y - 14)
y = int(self.enemy.center_y + 25)
if x == y:
self.enemy.remove_from_sprite_lists()
else:
# Remove the coin
self.player_sprite.remove_from_sprite_lists()
# 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
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:
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