Tutorial: Flappy Bird#

In this chapter, we will create a Flappy Bird game step-by-step using the miniworlds_physics engine.

Flappy Bird Game

Step 1: Importing the Physics Engine#

Install the miniworlds_physics package just like you installed miniworlds. Then, import PhysicsWorld:

import random
from miniworlds import Actor, Number, Text
from miniworlds_physics import PhysicsWorld  # Import the physics engine

world = PhysicsWorld(800, 600)
# Your code goes here
world.run()

Step 2: Creating the Pipes#

Add Pipes and Store Them in a List#

Add several pipes and store them in a list so their properties can be managed easily:

pipes = [
    Actor(position=(300, world.height - 280)),
    Actor(position=(500, 0)),
    Actor(position=(700, world.height - 280)),
    Actor(position=(900, 0))
]

Set Pipe Properties#

Use a loop to set properties for all pipes:

for pipe in pipes:
    pipe.direction = 0
    pipe.add_costume("images/pipe1.png")
    pipe.size = (50, 280)
    pipe.passed = False
    pipe.physics.simulation = "manual"
    pipe.physics.velocity_x = -150
    pipe.origin = "topleft"

For the 2nd and 4th pipes (which face down), rotate them 180 degrees:

pipes[1].costume.orientation = -180
pipes[3].costume.orientation = -180

Register Pipe Methods#

Add two important methods to the pipes:

for pipe in pipes:
    @pipe.register
    def act(self):
        if self.x < 75 and not self.passed:
            self.passed = True

    @pipe.register
    def on_detecting_left_border(self):
        self.move_to((self.x + random.randint(750, 800), self.y))
        self.passed = False

Step 3: Creating the Bird#

Set Bird Attributes#

The bird is an Actor with physics:

bird = Actor()
bird.position = (75, 200)
bird.add_costume("images/fly.png")
bird.size = (60, 60)
bird.physics.simulation = "simulated"
bird.is_flipped = True
bird.physics.size = (0.8, 0.8)
bird.physics.shape_type = "circle"
bird.is_rotatable = False

Register Bird Methods#

Detect Screen Borders#

If the bird hits the top or bottom, end the game:

@bird.register
def on_detecting_borders(self, borders):
    if "bottom" in borders or "top" in borders:
        end = Text("Game over!", position=(400, 200))
        world.game_over = True
        world.stop()

Detect Collisions with Pipes#

If the bird hits a pipe, end the game:

@bird.register
def on_detecting_actor(self, other):
    if other in pipes:
        end = Text("Game over!", position=(200, 200))
        world.game_over = True
        world.stop()

Detect Key Input#

When the space bar is pressed, the bird moves upward:

@bird.register
def on_key_down_space(self):
    self.physics.velocity_y = -200
    if not world.is_running and not world.game_over:
        world.start()

Step 4: Adding a Score#

The score is shown with a static Number object:

score = Number()
score.position = (30, 30)
score.size = (40, 40)
score.physics.simulation = "static"

In the pipe’s act method, increase the score:

@pipe.register
def act(self):
    if self.x < 75 and not self.passed:
        self.passed = True
        score.inc()

Complete Code#

import random
from miniworlds import Actor, Number, Text
from miniworlds_physics import PhysicsWorld

world = PhysicsWorld(800, 600)
world.game_over = False
world.add_background("images/background.png")

pipes = [
    Actor(position=(300, world.height - 280)),
    Actor(position=(500, 0)),
    Actor(position=(700, world.height - 280)),
    Actor(position=(900, 0))
]

for pipe in pipes:
    pipe.add_costume("images/pipe1.png")
    pipe.size = (50, 280)
    pipe.passed = False
    pipe.physics.simulation = "manual"
    pipe.physics.velocity_x = -150
    pipe.origin = "topleft"

    @pipe.register
    def act(self):
        if self.x < 75 and not self.passed:
            self.passed = True
            score.inc()

    @pipe.register
    def on_detecting_left_border(self):
        self.move_to((self.x + random.randint(750, 800), self.y))
        self.passed = False

pipes[1].costume.orientation = -180
pipes[3].costume.orientation = -180

score = Number()
score.position = (30, 30)
score.size = (40, 40)
score.physics.simulation = "static"

bird = Actor()
bird.position = (75, 200)
bird.add_costume("images/fly.png")
bird.size = (60, 60)
bird.physics.simulation = "simulated"
bird.is_flipped = True
bird.physics.size = (0.8, 0.8)
bird.is_rotatable = False

@bird.register
def on_detecting_borders(self, borders):
    if "bottom" in borders or "top" in borders:
        end = Text("Game over!", position=(400, 200))
        world.game_over = True
        world.stop()

@bird.register
def on_detecting_actor(self, other):
    if other in pipes:
        end = Text("Game over!", position=(200, 200))
        world.game_over = True
        world.stop()

@bird.register
def on_key_down_space(self):
    self.physics.velocity_y = -200
    if not world.is_running and not world.game_over:
        world.start()

world.run()

Tutorial: Flappy Bird

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