Tutorial: Red Baron

Tutorial: Red Baron#

In this chapter, we’ll build a side-scrolling shooter step by step.

The techniques of creating parallax backgrounds, handling speed and movement, and generating enemies are common in games. After this tutorial, you’ll be able to apply them in your own projects.

  • Based on: https://github.com/kantel/pygamezero/tree/master/tappyplane

  • License: Attribution-NonCommercial-ShareAlike 4.0 International

  • Prerequisite: Basic knowledge of classes

Step 1: Set Up the Framework#

You need a world where actors can be placed. The final line must be world.run():

from miniworlds import World, Actor, timer, Text
world = World(800, 480)

// your code here

world.run()

Prepare the Folder#

Place your images for background, player, and enemies in the images folder:

my_code
|
|--images
|----planered1.png
|----background.png
|----groundgrass.png
|----shipbeige.png
|----shipblue.png
|----shipgreen.png
|----shippink.png
|----shipyellow.png

(You can find the images here: miniworlds-cookbook - red baron)

Create Backgrounds#

Create two backgrounds side by side to simulate infinite scrolling:

back0 = Actor()
back0.add_costume("background")
back0.size = world.width, world.height
back1 = Actor(world.width, 0)
back1.size = world.width, world.height
back1.add_costume("background")
backs = [back0, back1]

To animate them:

@world.register
def act(self):
    for back in backs:
        back.x -= 1
        if back.x <= -world.width:
            back.x = world.width
    for ground in grounds:
        ground.x -= 2
        if ground.x <= -world.width:
            ground.x = world.width

Step 2: Create the Plane Class#

Define the Plane Class#

class Plane(Actor):
    def on_setup(self):
        self.add_costume("planered1")

Create an Instance#

At the end of your code:

plane = Plane(100, world.height / 2)

Add Physics#

Extend on_setup():

    def on_setup(self):
        self.add_costume("planered1")
        self.gravity = 0.1
        self.velocity_y = 0

Simulate Physics#

    def act(self):
        self.velocity_y += self.gravity
        self.velocity_y *= 0.9  # friction
        self.y += self.velocity_y

Add Upward Force on Key Press#

    def on_key_down_w(self):
        self.velocity_y -= 5

Step 3: Add Enemies#

Import:

from random import randint, choice

Create Enemy Class#

class Enemy(Actor):
    def on_setup(self):
        self.add_costume(choice(enemyships))

    def reset(self):
        self.x = randint(world.width + 50, world.width + 500)
        self.y = randint(25, world.height - 85)

Add Enemies#

enemies = []
for _ in range(10):
    enemy = Enemy()
    enemy.reset()
    enemies.append(enemy)

Move Enemies#

Extend on_setup():

def on_setup(self):
    self.add_costume(choice(enemyships))
    self.speed = -1.5

Then:

def act(self):
    self.x += self.speed
    if self.x <= -self.width:
        self.reset()

Step 4: Add Shooting#

Create the Bullet class:

class Bullet(Actor):
    def on_setup(self):
        self.add_costume("laserred")
        self.x = plane.x
        self.y = plane.y
        self.speed = 25
        self.fire = False
    
    def act(self):
        self.x += self.speed

    def on_detecting_enemy(self, enemy):
        enemy.reset()
        
    def on_detecting_not_on_world(self):
        self.remove()

Full Example Code#

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