Change the view

You may find it hard to use the default first-person view, which puts the camera in front of your player’s eyes. It’s kind of clumsy, and it’s hard to see where you are.

To change the view, press Esc and click the second button at the top left of the window. When the icon changes to a rectangle with lines leading to a pair of blocks, click Back to Game.

Now the camera is behind your player. Some people prefer this view because it’s easier to see what’s happening.

Change the world

Minecraft is all about changing your world. To remove a block, click the left mouse button to swing your sword. After you hit a block a few times, it breaks into pieces and disappears.

It’s hard to aim in Minecraft. You have to practice to work out which block your sword is going to hit.

If nothing happens when you left-click, move your player until a block is in front of you.

To build something new, press E to see all the blocks and other items you can use. Click one to select it. If it’s a block and not a weapon, right-click to add it to the world. You can keep right-clicking, turning, and moving to add more and more blocks, as shown in Figure 13-3.

Understand the Minecraft API

The Minecraft API built into the Pi version is much simpler than the Twitter API, but you can still do some cool things with it. Here are some possibilities:

• Find out where your player is.
• Teleport your player to a new location.
• Build complicated shapes with blocks.
• Remove blocks with code — maybe to clear a big area.

Look at the Minecraft API

All APIs have a reference website with a list of commands — also known as API calls, or just calls for short.

The Minecraft API Reference is at www.stuffaboutcode.com/p/minecraft-api-reference.html.

As shown in Figure 13-4, API reference pages often look complicated, but often that’s because you get a list of calls and not quite enough explanation of what each call does, or how to use it, with examples.

The Minecraft API Reference has good examples, but the explanations are not very detailed. You have to do some guessing — which is normal when you’re using an API.

Another missing feature is priority. All the calls get equal space, so you have no idea which calls are used a lot and which are hardly used at all.

That’s normal, too. It’s up to you to decide which calls you want to use. It’s a good idea to look through the list and copy/paste or make a note of calls that look interesting or useful. Then you can experiment with them. If you need to know more about them, you can look online for other examples.

Never try to learn all of an API before using it. You’d need a brain the size of a planet — which would make it hard to get out of bed in the morning — and a perfect memory. It’s fine to keep looking stuff up. If you use an API a lot, you often learn the most useful calls without really trying.

Use an API call

Here’s a simple example showing how to use an API call:

1. Choose Menu⇒Programming⇒Python 2 to launch the Python 2 editor.
2. Choose File⇒New Window to make a new file.

3. Type the following code:

   from mcpi import minecraft

   mc = minecraft.Minecraft.create()

   x, y, z = mc.player.getPos()

   print x, y, z

   Can you guess what this does?

4. Save the file as wherami.py.
5. Launch Minecraft if it’s not already running.
6. Move around inside the game for a bit.
7. Then click the code window in the Python editor again and press F5 to run the code.

8. Move the player again and run the code again.

   Figure 13-5 shows what you can get.

The code tells you where your player is in the Minecraft world! It uses three numbers. Table 13-2 shows you what they mean.

There’s no big arrow pointing north in Minecraft, so x and z are just for guidance. Even so, north is always in the same direction. It’s not usually the direction you’re facing.

Teleport in Minecraft

You can use a different API call to move around in Minecraft:

1. Change the code so that it looks like this:

   from mcpi import minecraft

   mc = minecraft.Minecraft.create()

   x, y, z = mc.player.getPos()

   mc.player.setPos(x, y + 100, z)

   The setPos() API call moves your player to a new location.

2. Move to another location, if you’d like.

   You can do some basic math to the x, y, and z numbers to move from your current location to a new one. Or you can use some other numbers — maybe random numbers — to jump to some other place.

3. Save the file as jump.py and press F5 to run it.

   Figure 13-6 shows an example. The code makes you jump straight up by 100 grid blocks. If you’re flying, you stay there. If you’re not flying, you crash straight back down again.

You don’t die when you crash. Your player is made of very tough blocks.

Remove blocks

Hacking away at blocks with a sword is a really slow way to change the world. Is there a faster way?

If you look through the API, you won’t find a deleteBlock() call, but there is a setBlock() call. It turns a block into a different kind of block.

Can you work out how to make blocks disappear now? You have to use a trick. In Minecraft, the entire world is made of blocks, across, left, right, up and down, in every direction, so there are no missing blocks.

The trick? Empty blocks are made of air. You can use setBlock() to turn stone and other blocks into air blocks to make them disappear.

Here’s some code:

from mcpi import minecraft

from time import sleep

    mc = minecraft.Minecraft.create()

while True:

    x, y, z = mc.player.getPos()

    mc.setBlock(x, y - 1, z, 0)

    sleep (0.1)

The game is called Minecraft, so you can make a mine. The code removes the block your player is standing on. It loops forever, so it keeps removing blocks. The player falls into a bottomless shaft that gets deeper and deeper.

Save it as death_dig.py and run it. You may need to nudge your character into a hole to make the mineshaft appear. Eventually, you see the screen in Figure 13-7.

If you dig deep enough. Minecraft decides you’ve fallen out of the bottom of the earth and kills you.

The 0 at the end of the setBlock() call makes the block an air block. Minecraft has lots of different block types, and they all have a different number. If you scroll through the API reference, you can find a list of block types, with the number of each.

Make buildings

Of course, you can also take an air block and turn it into a stone or water block. Try the following:

from mcpi import minecraft

import random

mc = minecraft.Minecraft.create()

x, y, z = mc.player.getPos()

x = x + random.randint(-10, 10)

z = z + random.randint(-10, 10)

for i in range(0, 21):

    mc.setBlock(x, y + i, z, random.randint(1, 8))

Can you work out what this code does? The random.randint(a, b) calls produce a random — unpredictable — number between the first and second numbers in the brackets. For example,

random.randint(-10, 10)

makes a number between –10 and 10. You get a different number every time you run this code. It’s supposed to be unpredictable, so you never know what you’ll get.

Random code is a good way to add surprises. You can give the code an outline of something, and it fills in the details in surprising ways.

Here, the x and z positions are random so they stay close to the player, but not likely to be on top of the player.

Why does this matter? Because the rest of the code makes a simple building on the random position. It turns air blocks into other blocks.

The small 1, 8 range of randomness more or less guarantees that one of the blocks will be flowing water. Figure 13-8 shows what happens when you put everything together — you get a fountain!

Minecraft makes the water pour off the fountain onto the ground, and into the sea. Because the blocks are random, the fountain is a little different every time you run the code.