Flappy Bird

In this exercise, we'll create the core mechanic of our Flappy Bird game: the bird's movement. We'll implement gravity to make the bird fall, add a flap mechanism to make it rise, and change its costume to simulate wing movement.

Step 1: Implementing Gravity

First, let's make our bird fall due to gravity. In Scratch, we can simulate gravity by constantly changing the bird's y-position.

when green flag clicked
set [Gravity v] to -1
forever
    change y by (Gravity)
    change [Gravity v] by -0.1
    if <(Gravity) < [-5]> then
        set [Gravity v] to [-5]
    end
end
                            

This script makes the bird fall faster over time, simulating acceleration due to gravity. The bird's fall speed is limited to prevent it from moving too quickly.

Step 2: Flapping to Rise

Now, let's add the ability for the bird to flap and rise when the player presses the spacebar.

when [space v] key pressed
set [Gravity v] to [6]
                            

This script sets the Gravity to a positive value when the spacebar is pressed, causing the bird to rise. The continuous gravity script will then gradually bring the bird back down.

Step 3: Changing Costume for Wing Movement

To make our bird look more dynamic, let's change its costume when it flaps.

when [space v] key pressed
set [Gravity v] to [6]
switch costume to [wings-up v]
wait (0.1) seconds
switch costume to [wings-down v]
                            

This script changes the bird's costume briefly when the spacebar is pressed, creating a flapping animation.

In Flappy Bird, the background appears to scroll while the bird stays mostly in place. This creates an illusion of movement and makes the game more engaging. Let's explore how we can achieve this effect in Scratch!

Understanding Scrolling Backgrounds

A scrolling background is created by moving multiple copies of the same image across the screen. When one copy moves off-screen, another takes its place, creating a seamless, continuous movement.

In the next exercise, we'll implement this scrolling backdrop technique in Scratch!

Now that we understand the concept of scrolling backgrounds, let's implement one in Scratch using clones. This technique will create the illusion of continuous movement in our Flappy Bird game.

Step 1: Creating the Background Sprite

Step 2: Setting Up Cloning

We'll use cloning to create multiple copies of our background sprite. This allows us to have a continuous stream of background elements moving across the screen.

when green flag clicked
hide
go to x: (240) y: (0)
forever
    create clone of [myself v]
    wait (2) seconds
end
                            

This script hides the original sprite, positions it at the right edge of the stage, and creates a new clone every 2 seconds.

Step 3: Moving the Clones

Now, let's make each clone move across the screen from right to left.

when I start as a clone
show
forever
    change x by (-3)
    if <(x position) < [-240]> then
        delete this clone
    end
end
                            

This script makes each clone visible, moves it to the left, and deletes it when it goes off the left edge of the stage.

A key element of any game is the scoring system. In Flappy Bird, the player earns points by successfully navigating through obstacles. Let's implement a basic scoring mechanism for our game.

Step 1: Creating a Score Variable

Step 2: Initializing the Score

We need to set the score to 0 when the game starts.

when green flag clicked
set [Score v] to (0)
                            

Step 3: Increasing the Score

In a full Flappy Bird game, we would increase the score when the bird passes through a gap between pipes. For now, let's simulate this by increasing the score every second the bird stays alive.

when green flag clicked
forever
    wait (1) seconds
    change [Score v] by (1)
end
                            

This script increases the score by 1 every second. In a later lesson, we'll modify this to increase the score when passing obstacles.

Great job on completing the lesson! Now it's time to put everything together and create your own version of Flappy Bird. Here's your homework assignment:

Task: Build Your Flappy Bird Game

Using the concepts we've learned today, create a basic Flappy Bird game. Your game should include:

• A bird character that responds to gravity and can flap its wings when the spacebar is pressed.
• A scrolling background using the cloning technique we learned.
• A scoring system that increases over time or when certain conditions are met.

Submission

When you've completed your game:

1. Save your project in Scratch.
2. Share your project and copy the project URL.
3. Submit the URL to your instructor or post it in our class forum.

Remember, creativity is encouraged! Feel free to add your own unique elements to the game. Have fun, and don't hesitate to ask for help if you get stuck!