207 lines
4.5 KiB
Markdown
207 lines
4.5 KiB
Markdown
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# Rock Paper Scissors
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### ~avatar avatar
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Build a Rock Paper Scissors game with the BBC micro:bit! You can play
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the game with a friend who has it on a micro:bit. You can also play
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it with friends who are just using their hands. (The game is built
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like a coin flipper, but with three choices instead of two.)
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### ~
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## Step 1: Getting started
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We want the micro:bit to choose rock, paper, or scissors when you
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shake it. Try creating an ``on shake`` block so when you shake the
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micro:bit, it will run part of a program.
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Clear up the blocks and add the blocks below.
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```blocks
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input.onGesture(Gesture.Shake, () => {
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})
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```
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Next, when you shake the micro:bit, it should pick a random number from `0` to `2`
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and store it in the variable `item`.
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Add a ``set`` block with a variable. Then add a ``pick random`` block,
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and store the random number in the variable,
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like this:
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```blocks
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input.onGesture(Gesture.Shake, () => {
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let item = Math.random(3)
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})
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```
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### ~hint
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No one can predict random numbers. That's what makes them great for Rock Paper Scissors!
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### ~
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Each possible number these blocks can make (`0`, `1`, or `2`) means a different picture.
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We will show the right picture for that number on the LED screen.
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## Step 2: Picking paper
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Put an ``if`` block after the ``let`` block that checks whether
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`item` is `0`. Make sure the ``if`` block has an ``else if`` part
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and an ``else`` part.
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Next, add a ``show leds`` block that shows a
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picture of a piece of paper:
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```blocks
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input.onGesture(Gesture.Shake, () => {
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let item = Math.random(3)
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if (item == 0) {
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basic.showLeds(`
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# # # # #
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# . . . #
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# . . . #
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# . . . #
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# # # # #
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`)
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} else if (false) {
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} else {
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}
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})
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```
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## Step 3: A random rock
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Now we are going to add a new picture for the micro:bit to show
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when another random number comes up.
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Make the ``else if`` part check if the variable `item` is `1`.
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Then add a ``show leds`` block with a picture of a rock.
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```blocks
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input.onGesture(Gesture.Shake, () => {
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let item = Math.random(3)
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if (item == 0) {
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basic.showLeds(`
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# # # # #
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# . . . #
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# . . . #
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# . . . #
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# # # # #
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`)
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} else if (item == 1) {
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basic.showLeds(`
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. . . . .
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. # # # .
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. # # # .
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. # # # .
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. . . . .
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`)
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} else {
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}
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})
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```
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## Step 4: Suddenly scissors
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Add a ``show leds`` block with a picture of scissors to the ``else`` part:
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```blocks
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input.onGesture(Gesture.Shake, () => {
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let item = Math.random(3)
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if (item == 0) {
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basic.showLeds(`
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# # # # #
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# . . . #
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# . . . #
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# . . . #
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# # # # #
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`)
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} else if (item == 1) {
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basic.showLeds(`
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. . . . .
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. # # # .
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. # # # .
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. # # # .
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. . . . .
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`)
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} else {
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basic.showLeds(`
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# # . . #
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# # . # .
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. . # . .
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# # . # .
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# # . . #
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`)
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}
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})
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```
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### ~hint
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You don't need to check if `item` is `2` because `2` is the only number left out of `0`, `1`, and `2`.
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That's why you can use an ``else`` instead of an ``else if``.
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### ~
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Your game is ready!
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Click **Compile** to move your program to the BBC micro:bit!
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Have fun!
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## Step 5: Are you the greatest?
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Here is a way you can make your Rock Paper Scissors game better.
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When button ``A`` is pressed,
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the micro:bit will add `1` to your score.
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Open the ``Game`` drawer, and then add the block ``change score by 1`` to your program,
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like this:
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```blocks
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input.onButtonPressed(Button.A, () => {
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game.addScore(1)
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})
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```
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## Step 6: Prove you're the greatest!
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After your micro:bit can add `1` to the score, show how many wins you have.
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```blocks
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input.onButtonPressed(Button.A, () => {
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game.addScore(1)
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basic.showString("WINS:")
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basic.showNumber(game.score())
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})
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```
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## Step 7: Staying honest
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Success! Your micro:bit can track wins!
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But what about losses?
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Use the ``Game`` drawer to subtract `1` from your score when you press button `B`.
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Here are all the blocks you will need:
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```shuffle
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input.onButtonPressed(Button.B, () => {
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game.addScore(-1)
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basic.showString("LOSSES:")
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basic.showNumber(game.score())
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})
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```
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Click **Compile** to move your program to the BBC micro:bit!
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# Want to do more?
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There are [10 great projects](/projects) waiting for you.
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