Introduction

In this project, we’ll create a fireworks display over a city.

Step 1: Create a rocket that flies towards the mouse

Let’s import the different pictures for the game

Activity Checklist

Start a new Scratch project. Delete the cat by right clicking it and clicking Delete.
Replace the backdrop with outdoor/city-with-water.
Use the Upload sprite from file button to add a Rocket sprite to the project (use the Resources/Rocket.png costume).
Make the rocket hide when the green flag is clicked.
```
when FLAG clicked
    hide
```
Now we want to make the rocket move towards the mouse when the mouse is clicked. Add a when space key pressed control block, and under this make the rocket appear and glide towards the mouse.
```
when [space v] key pressed
    show
    glide (1) secs to x: (mouse x) y: (mouse y)
```

Test Your Project

Click the green flag, place your mouse over the stage and press the space bar.

Does the rocket appear and move to the mouse?
What happens if you move the mouse and press space again?

Activity Checklist

Fireworks don’t tend to fly from side to side, so lets make sure it always glides towards the mouse from the bottom of the screen. Before we show the rocket, use the go to block to tell it to move to below the bottom of the screen, but stay in the same place horizontally.
```
when FLAG clicked
    hide

when [space v] key pressed
    go to x: (mouse x) y: (-200)
    show
    glide (1) secs to x: (mouse x) y: (mouse y)
```

Test Your Project

Click the green flag, place your mouse over the stage and press the space bar.

Does the rocket fly towards the mouse from the bottom of the screen?
What happens if you move the mouse and press space again?

Activity Checklist

Finally, let’s make this work by using the mouse button instead of the space bar. To do this, we can wrap our script in a forever if mouse down block, then swap the when space key pressed control block for when flag clicked. And last but not least make sure the rocket is hidden when everything starts up.
```
when FLAG clicked
    hide
    forever
        if <mouse down?> then
            go to x: (mouse x) y: (-200)
            show
            glide (1) secs to x: (mouse x) y: (mouse y)
```

Test Your Project

Click the green flag, and then press the mouse button over the stage. Click again at another point.

Things to try

Try making some rockets a little slower or faster than others.
Try changing where the rocket moves to before gliding towards the mouse to make it arc a little.

Save your project

Step 2: Make the rocket explode

Activity Checklist

The first step to make the rocket explode is to make it play a ‘bang’ sound (Resources/bang.wav) before it starts moving, and then hide itself once it reaches the mouse. To import a sound go to the Sounds tab and click the Upload sound from file button.
```
when FLAG clicked
    hide
    forever
        if <mouse down?> then
            go to x: (mouse x) y: (-200)
            play sound [bang v]
            show
            glide (1) secs to x: (mouse x) y: (mouse y)
            hide
```

Next, make the rocket broadcast a new message when it explodes. We’ll listen for this message later on.

when FLAG clicked
    hide
    forever
        if <mouse down?> then
            go to x: (mouse x) y: (-200)
            play sound [bang v]
            show
            glide (1) secs to x: (mouse x) y: (mouse y)
            hide
            broadcast [explode v]

Test Your Project

Click the green flag. Make sure the rocket plays a noise and hides when it reaches the mouse.

Activity Checklist

Create new sprite from File, Resources/firework1.png
When it receives the explode message, it should hide itself and then move to the position of the rocket using the go to block, show itself, and then vanish again a second later.
```
when I receive [explode v]
    hide
    go to [rocket v]
    show
    wait (1) secs
    hide
```

Test Your Project

Send another rocket flying.

Does it get replaced with the explosion graphic when it explodes?
What happens if you hold the mouse button down whilst moving the mouse? (Don’t worry, we’ll fix this later on).

Save your project

Step 3: Make each explosion unique

Now we can make each explosion even more unique by using the set color effect block, and have it pick a random colour between 1 and 200 before showing it.
```
when I receive [explode v]
    hide
    set [color v] effect to (pick random (1) to (200))
    go to [rocket v]
    show
    wait (1) secs
    hide
```

Test Your Project

Click the green flag. Does each explosion have a different colour?

Activity Checklist

Lets add a number of different possible explosion graphics as costumes, using Resources/firework2.png and Resources/firework3.png, and switch between them for each rocket, again before showing it.

when I receive [explode v]
    hide
    switch costume to (pick random (1) to (3))
    set [color v] effect to (pick random (1) to (200))
    go to [rocket v]
    show
    wait (1) secs
    hide

Test Your Project

Click the green flag.

Does each rocket have a different explosion graphic?

Activity Checklist

Finally, Let’s make the explosion get bigger after the rocket explodes! Instead of waiting a second, set the size of the sprite to 5% before we show it, and then once it’s shown, increase the size by 2 fifty times, using a repeat block.

when I receive [explode v]
    hide
    switch costume to (pick random (1) to (3))      
    set [color v] effect to (pick random (1) to (200))
    go to [rocket v]
    show
    set size to (5) %
    repeat (50)
        change size by (2)
    end
    hide

Test Your Project

Click the green flag.

Does the explosion graphic spread out from the centre of the rocket and slowly grow?

Things to try

Why not try making each explosion more unique by altering the size and speed of growth for the explosion.

Save your project

Step 4: Fixing the Broadcast Bug

Remember earlier we had a bug involving holding down the mouse button? This occurs because when the rocket broadcasts its explosion, it will immediately repeat the if loop and move the rocket back to the bottom of the stage. This happens before the explosion has moved to the position of the rocket.

Activity Checklist

To fix this, we can replace the broadcast block with a broadcast and wait block. This way, the loop will not repeat until the explosion finishes exploding.

when FLAG clicked
    hide
    forever
        if <mouse down?> then
            go to x: (mouse x) y: (-200)
            play sound [bang v]
            show
            glide (1) secs to x: (mouse x) y: (mouse y)
            hide
            broadcast [explode v] and wait

Test Your Project

Click the green flag, hold down the mouse button and move the mouse around the stage.

Does the explosion graphic appear in the right place and at the right time?

Save your project

Well done, you’ve finished! Now you can enjoy your game!

Don’t forget you can share your game with all your friends and family by clicking on Share on the menu bar!

Search Results

Introduction

Step 1: Create a rocket that flies towards the mouse

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Test Your Project

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Things to try

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Step 2: Make the rocket explode

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Step 3: Make each explosion unique

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Things to try

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Step 4: Fixing the Broadcast Bug

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Hi there!