Arcade Cabinet I

Review — where we got to 5 min

Two finished games, and both of them already have half of what we need.

• Jump Dash has a title screen: the flag builds it, when this sprite clicked starts the game.
• Paddle Bounce has a win screen, which is a screen by another name.

Quick-fire

Your project has two screens. How many sprites need to know about that?

Today’s Topic 3 min

• A screen is a broadcast, plus a rule for every sprite
• Buttons that send different messages
• A home button that works from anywhere
• Stopping a game properly when you leave it

Learning outcome

By the end of this lesson you will be able to:

1. Build a menu with three buttons on it.
2. Show and hide every sprite for every screen.
3. Leave a running game and come back to a clean menu.

Learnt — screens, buttons, and the way back 27 min

1 · A screen is a message

There is no screen block in Scratch. A screen is a broadcast, and every sprite in the project answers it with either show or hide.

1. Open a new project. Delete the cat and pick a plain backdrop.
2. Add two Button2 sprites, side by side.
3. On each, add when I receive [menu v] then show.
4. Add a second stack: when I receive [jump dash v] then hide.
5. On the flag, broadcast menu.

when flag clicked
broadcast [menu v]
            

2 · Buttons that lead somewhere

A button does two things: it says which screen it wants, and it gets out of the way.

1. Name your buttons Play1, Play2 and Scores.
2. On each: when this sprite clicked, a sound, and a broadcast of its own.
3. Use a different message name on each one.
4. Click each button and watch the buttons vanish.
5. Nothing else happens yet. That is correct.

when this sprite clicked
start sound [Pop v]
broadcast [jump dash v]
            

3 · Getting one game in, and getting back out

Now bring a game in. Its scripts do not change much — only the block at the top of each one.

1. Open your Jump Dash project and drag its sprites into the backpack, at the bottom of the editor.
2. Open the arcade project and drag them back out of the backpack.
3. On each of them, change every when flag clicked to when I receive [jump dash v].
4. Add a when I receive [menu v] stack to each one: stop [other scripts in sprite v], then hide.
5. Add a Home Button sprite in the top corner that broadcasts menu.
6. Play the game, click home, and check the menu is clean.

when I receive [menu v]
stop [other scripts in sprite v]
delete this clone
hide
            

Basic — build the menu 25 min

Build the empty cabinet first. A menu with nothing behind it still has to work.

Step 1 — the screens

1. New project, plain backdrop, cat deleted.
2. Decide your screen names now and write them down: menu, one per game, and scores.
3. Broadcast menu on the flag.

Step 2 — the buttons

1. Three buttons, evenly spaced, each with a name on it.
2. Give each one its show and hide stacks.
3. Give each one its clicked stack.
4. Click all three. The menu should empty every time.

Step 3 — the way home

1. Add the home button.
2. Hide it on the menu and show it everywhere else.
3. Click a button, then home, ten times.

Step 4 — one real game

1. Backpack your Jump Dash sprites over.
2. Change every hat block.
3. Add the menu stack to every one of them.

Step 5 — the round trip

1. Menu, game, home, menu, game, home. Five times.
2. Look at the menu each time. Nothing from the game should be on it.

Your cabinet

This is the front of everything you have made this year. Make it look like it.

• A name for your arcade.
• Three buttons a stranger could read.
• A backdrop that is not the plain white one.

Nothing left behind

Go through your project sprite by sprite and give every one of them a rule for every screen. Write the list out first.

• A written list: every sprite down one side, every screen along the top.
• Every box filled in with show or hide.
• The project matches the list.

The click test

Click everything, in any order, twenty times. A menu that only works if you use it politely is not finished.

• Twenty clicks, chosen carelessly.
• You never get stuck on a screen.
• Clicking a button twice quickly does not break anything.
• The green flag is never needed after the first press.

Buttons that answer the mouse

A button that changes when you point at it tells the player it is a button. Nothing else on the screen has to.

• A button grows or lights up when the mouse is over it.
• It goes back to normal when the mouse leaves.
• Two buttons are never both lit at once.
• They are their proper size again when you come back from a game.

Summary 4 min

No new game today, and the project is bigger than either of them.

1. A screen is a broadcast plus a rule for every sprite.
2. A button sends a message and then hides on that message.
3. A game brought in from another project only needs its hat blocks changed.
4. Leaving a game means stopping its scripts and deleting its clones.

Screen

A broadcast, and every sprite’s answer to it.

Menu

The screen everything else leads back to.

Backpack

Scratch’s way of carrying sprites from one project to another.

stop other scripts in sprite

Stops this sprite’s other stacks and leaves the rest of the project alone.

Next lesson: the other two buttons get games behind them, and two sprites called Ball cause trouble.