pxt-microbit
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micro:bit target for Microsoft MakeCode (PXT)
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# Blow Away
## {Introduction pt. 1 @unplugged}
👻 Oh, no! Your @boardname@ is being haunted by a ghost named Haven 👻
For this tutorial, we'll learn how to blow Haven away 🌬️
## {Haunted ghost setup}
A wild Haven has appeared!
■ From the ``||basic:Basic||`` category, find ``||basic:show icon [ ]||`` and add it to your ``||basic:on start||`` container.
■ Click the heart icon and set it to show a ghost.
💡 In the ``show icon`` dropdown menu options, you can hover to see what each design is called.
```blocks
// @highlight
basic.showIcon(IconNames.Ghost)
```
---
## {Loop setup}
■ From the ``||loops:Loops||`` category, find the ``||loops:repeat [4] times||`` loop and snap it into your empty ``||basic(noclick):forever||`` container.
💡 Why do we need a [__*repeat loop*__](#repeatLoop "repeat code for a given number of times") when we already have a ``forever`` container? Because ``forever`` has an embedded delay that we want to avoid!
```blocks
basic.forever(function () {
// @highlight
for (let index = 0; index < 4; index++) {
}
})
```
## {Conditional setup}
Haven hates noise and will blow away if things get too loud. Let's use an [__*if statement*__](#ifstatement "if this condition is met, do something") to check for sounds.
■ From ``||logic:Logic||``, grab an ``||logic:if <true> then||`` statement and snap it into your empty ``||loops(noclick):repeat [4] times do||`` loop.
■ Go back to ``||logic:Logic||`` to get a ``||logic:<[0] [=] [0]>||`` comparison.
■ Snap ``||logic:<[0] [=] [0]>||`` in to **replace** the ``||logic(noclick):<true>||`` condition for your ``||logic(noclick):if then||`` statement.
```blocks
basic.forever(function () {
// @highlight
for (let index = 0; index < 4; index++) {
// @highlight
if (0 == 0) {
}
}
})
```
## {Blow sound}
We'll be using a [__*sound threshold*__](#soundThreshold "a number for how loud a sound needs to be to trigger an event. 0 = silence to 255 = maximum noise") to act as Haven's ears.
■ From the ``||input:Input||`` category, drag ``||input:sound level||`` in to **replace** the **_left_ ``0``** of your ``||logic(noclick):<[0] [=] [0]>||`` comparison.
■ Using the dropdown in the **middle** of ``||logic(noclick):[sound level] [=] [0]||``, change the comparison to be **``>``** (greater than).
■ Finally, have the **right side** of the comparison say ``128`` so your full comparison reads: **``sound level > 128``**.
💡 This means Haven will hear any sound above ``128``.
```blocks
basic.forever(function () {
for (let index = 0; index < 4; index++) {
// @highlight
if (input.soundLevel() > 128) {
}
}
})
```
## {Making variables}
Let's create some [__*variables*__](#variable "a holder for information that may change") to keep track of Haven's movement.
■ In the ``||variables:Variables||`` category, click on ``Make a Variable...`` and make a variable named ``col``.
💡 ``col`` is short for "column".
■ Make **another** variable and name it ``row``.
## {Displacing LEDs part 1}
To show Haven is blowing away, we want to move a random set of lights sideways.
■ Your ``||variables:Variables||`` category should now have the option to ``||variables:set [row] to [0]||``. Drag that block into your empty ``||logic(noclick):if then||`` statement.
■ From the ``||math:Math||`` category, find ``||math:pick random [0] to [10]||`` and snap that in to **replace** the ``[0]`` in your ``||variables(noclick):set [row] to [0]||`` block.
■ Change the maximum number from ``10`` to **``4``**.
💡 We are setting the maximum random value to 4 because the lights on the @boardname@ are numbered 0, 1, 2, 3, and 4 for columns and rows.
```blocks
let row = 0
basic.forever(function () {
for (let index = 0; index < 4; index++) {
if (input.soundLevel() > 128) {
// @highlight
row = randint(0, 4)
}
}
})
```
## {Displacing LEDs part 2}
■ Go back into ``||variables:Variables||`` and drag out another ``||variables:set [row] to [0]||``. Place this one below the last one (at **the end**) of your `if then` statement.
■ Using the **dropdown menu**, set the new block to read ``||variables(noclick):set [col] to [0]||``.
■ From the ``||math:Math||`` category, grab another ``||math:pick random [0] to [10]||`` and snap that in to **replace** the ``[0]`` in your ``||variables(noclick):set [col] to [0]||`` block.
■ Change the maximum number from ``10`` to **``4``**.
```blocks
let col = 0
let row = 0
basic.forever(function () {
for (let index = 0; index < 4; index++) {
if (input.soundLevel() > 128) {
row = randint(0, 4)
// @highlight
col = randint(0, 4)
}
}
})
```
## {Conditioning on one point}
Time to move some lights around!
■ From ``||logic:Logic||``, grab another ``||logic:if <true> then||`` and snap it at the **inside and at the bottom of** your ``||loops(noclick):repeat [4] times do||`` loop, right below your ``||logic(noclick):if [sound level] [>] [128]||`` statement.
■ From the ``||led:Led||`` category, find ``||led:point x [0] y [0]||`` and drag it in to **replace** the ``||logic(noclick):<true>||`` condition in the **new** ``||logic(noclick):if then||`` statement.
💡 This block will test if the light is on at the the given ``x`` and ``y`` coordinate points.
```blocks
let col = 0
let row = 0
basic.forever(function () {
for (let index = 0; index < 4; index++) {
if (input.soundLevel() > 128) {
row = randint(0, 4)
col = randint(0, 4)
}
// @highlight
if (led.point(0, 0)) { }
}
})
```
## {Unplotting and replotting LEDs}
To create the animation effect of Haven blowing away, we will turn off (or ``unplot``) a light that is on and then turn it on again (``plot`` it) in a different spot.
■ From ``||led:Led||``, grab ``||led:unplot x [0] y [0]||`` and snap it inside the **empty** ``||logic(noclick):if <point x [0] y [0]> then||`` statement.
■ Go back to ``||led:Led||`` and get ``||led:plot x [0] y [0]||``. Snap that in **beneath** the ``||led(noclick):unplot x [0] y [0]||`` block that you just added.
```blocks
let col = 0
let row = 0
basic.forever(function () {
for (let index = 0; index < 4; index++) {
if (input.soundLevel() > 128) {
row = randint(0, 4)
col = randint(0, 4)
}
// @highlight
if (led.point(0, 0)) {
led.unplot(0, 0)
led.plot(0, 0)
}
}
})
```
## Setting variables
Notice how you have **three** blocks from the ``||led:Led||`` category. All three have ``||led(noclick):x||`` ``[0]`` and ``||led(noclick):y||`` ``[0]`` coordinates. In these **two** steps, we will set it so that every ``||led(noclick):x||`` is followed by the ``||variables:col||`` variable and every ``||led(noclick):y||`` is followed by the ``||variables(noclick):row||`` variable.
■ From ``||variables:Variables||``, get three copies of ``||variables:col||``, and use them to **replace the ``x`` values** in the following three blocks:
**1.** ``||led(noclick):point x [0] y [0]||``
**2.** ``||led(noclick):unplot x [0] y [0]||``
**3.** ``||led(noclick):plot x [0] y [0]||``
■ Go into ``||variables:Variables||``, get three copies of ``||variables:row||``, and use them to **replace the ``y`` values** in the same three blocks.
```blocks
let col = 0
let row = 0
basic.forever(function () {
for (let index = 0; index < 4; index++) {
if (input.soundLevel() > 128) {
row = randint(0, 4)
col = randint(0, 4)
}
// @highlight
if (led.point(col, row)) {
led.unplot(col, row)
led.plot(col, row)
}
}
})
```
## {Moving LEDs}
Right now, we are unplotting and replotting in the same spot. What we want to do is move the lights we're turning back on just a smidge to the right every time until there's nothing left on the grid.
■ From ``||math:Math||``, find the ``||math:[0] [+] [0]||`` operation and use it to **replace** ``||variables(noclick):col||`` in your ``||led(noclick):plot x [col] y [row]||`` block.
💡 If you move your entire ``||basic(noclick):forever||`` container, you should find a greyed out ``col`` variable in your workspace.
■ Take the greyed out ``||variables(noclick):col||`` variable (or get a new one) and use it to **replace** the **_first_ ``[0]``** so the operation reads ``||math(noclick):[col] [+] [0]||``.
■ Replace the **_second_ ``[0]``** with **``[1]``** so the operation reads ``||math(noclick):[col] [+] [1]||``.
```blocks
let col = 0
let row = 0
basic.forever(function () {
for (let index = 0; index < 4; index++) {
if (input.soundLevel() > 128) {
row = randint(0, 4)
col = randint(0, 4)
}
// @highlight
if (led.point(col, row)) {
led.unplot(col, row)
led.plot(col + 1, row)
}
}
})
```
## {Testing in the simulator}
Check out the simulator!
■ Click on the pink bar underneath the microphone icon. Drag it above the sound number you chose (we used ``128``!) to blow Haven away.
■ If you have a new @boardname@ (the one with the **shiny gold** logo at the top), download this code and try it out!
💡 Blow close to the @boardname@ and watch Haven swoosh away 💨
💡 Use your @boardname@'s reset button (it's on the back!) to bring Haven back 👻
```blocks
let col = 0
let row = 0
basic.showIcon(IconNames.Ghost)
basic.forever(function () {
for (let index = 0; index < 4; index++) {
if (input.soundLevel() > 128) {
row = randint(0, 4)
col = randint(0, 4)
}
if (led.point(col, row)) {
led.unplot(col, row)
led.plot(col + 1, row)
}
}
})
```
```validation.global
# BlocksExistValidator
```