14. Python in Minecraft

Note

The Minecraft Python library is made by David Whale and Martin O’Hanlon. I highly recommend their book Adventures in Minecraft which contains a great deal more programs.

14.1. Setup

You will need to own Minecraft Java Edition (not Bedrock edition).

If you already have a Mojang or Microsoft account, go to the Minecraft website and click login. If you haven’t accessed it for years you may need to reset your password. If you already own Minecraft it will then tell you. If you don’t have an account, create one, and buy Minecraft Java Edition.

14.1.1. Setup Java

You will need to download and install Java from adoptopenjdk.net.

I recommend the latest (currently OpenJDK 16) because it will be useful for other things, but if you have problems you can fall back to using OpenJDK 8. Choose HotSpot and click the button to download.

14.1.2. Setup Server

Download the Adventures In Minecraft Starter Kit from

https://adventuresinminecraft.github.io and unpack it in a folder on your desktop. There are videos on the site that explain how to set it up.

Use Notepad or SublimeText to edit the file Server/server.properties. Change this setting

level-type=flat

to generate a flat world. (But it’s up to you what sort of world you prefer!)

To run the server, double click the StartServer file. It will open a server console window, and ask you press space.

If you want to generate another world later you can change

level-name=world2

and then run the server again.

Once the server is running, to stop nighttime from happening I suggest you type this at the server console

gamerule doDaylightCycle false
time set day

If only we could do that in real life!

You must leave the server console window open at all times. When you want to quit, first type

stop

at the server console, so it saves your world.

Advanced Challenge

Setup a more modern Minecraft server, such as PaperMC.

Then try to get the Raspberryjuice plugin to work with it so you can use it with Python. This is not easy; I couldn’t do it!

14.1.3. Setup Minecraft

Run the Minecraft launcher you downloaded from minecraft.net. We will not be using the default which is the latest version of Minecraft. Instead we will be using version 1.12.

Run the Minecraft Launcher. Click Installations then New Installation, then select version release 1.12. Then click Create. Then click Play next to the new installation in the list.

Minecraft will run. Click multiplayer. Then add server. Enter the server address as

localhost

Click ‘done’. Click on your server to connect to it.

14.1.4. Setup Mu

Mu is the Python editor we have already been using, so you probably already have it installed. However you need to make sure you have the latest version. You can download it from the links at the top of https://codewith.mu/en/download.

Run Mu. Click Mode and select Python3. Then click the small gadget icon in the bottom right hand corner of the window. Click third party packages. Type

mcpi

into the box. Click OK. The library will download.

If you are not using Mu you can install mcpi from the command line like this:

pip3 install mcpi

14.1.5. Summary

You need to have the Minecraft server, Minecraft (the client) and Mu all running at the same time. It may be useful to arrange them in separate windows. Your Python program will talk to the server, and Minecraft will also talk to the server, allowing you to see the results of your program in Mincraft.

14.2. Hello Minecraft

This program tests you have a connection to the Minecraft server and displays a message on the client.

Program 14.1 Hello, Minecraft

from mcpi.minecraft import *
mc = Minecraft.create()
mc.postToChat("Hello Minecraft World")

14.3. Coordinates

This program gets the player’s co-ordinates and prints them to the chat.

Program 14.2 Getting player coordinates

from mcpi.minecraft import *
import time

mc = Minecraft.create()

while True:     # loop will make sure your game runs forever
    time.sleep(1)
    pos = mc.player.getTilePos()
    print(pos)
    mc.postToChat(pos)

14.4. Changing the player’s position

Find the coordinates of a location in your world, either by pressing F3 in the game, or running Program 14.2 Enter these coordinates in this program and run it to teleport to that location.

Program 14.3 Changing the player’s position

from mcpi.minecraft import *

mc = Minecraft.create()

# change these to where you want to go
x = 10
y = 11
z = 12

mc.player.setTilePos(x, y, z)

14.5. Build a teleporter

Before you run this program, build two tiles in the game to be your teleporters and write down their co-ordinates.

Program 14.4 Teleporter

from mcpi.minecraft import *

mc = Minecraft.create()

# CHANGE THESE NUMBERS TO THE CO-ORDS OF YOUR TELEPORTERS

teleporter_x = 742
teleporter_z = 955

destination_x = 735
destination_z = 956

while True:
    # Get player position
    pos = mc.player.getTilePos()
    print(pos)

    # Check whether your player is standing on the teleport
    if pos.x == teleporter_x and pos.z == teleporter_z:
        mc.postToChat("teleport!")
        pos.x = destination_x
        pos.z = destination_z
        mc.player.setTilePos(pos)

Exercise

Add this line to the end of the program:

time.sleep(5)

Then add another line that teleports the player somewhere else.

14.6. Teleport player into the air

Program 14.5 Teleport player into the air

from mcpi.minecraft import *

mc = Minecraft.create()

# CHANGE THESE NUMBERS TO THE CO-ORDS OF YOUR TELEPORTERS

teleporter_x = 9
teleporter_z = 12

height = 30

while True:
    pos = mc.player.getTilePos()

    # Check whether your player is standing on the teleport
    if pos.x == teleporter_x and pos.z == teleporter_z:
        mc.postToChat("teleport!")
        pos.y += height  # up in the air!
        pos.x += 1  # move off the teleporter tile
        mc.player.setTilePos(pos)

14.7. Teleport jump

This program does a series of teleports in quick succession to give the effect of a jump.

Program 14.6 Teleport jump

from mcpi.minecraft import *
import time

mc = Minecraft.create()

# CHANGE THESE NUMBERS TO THE CO-ORDS OF YOUR TELEPORTERS

teleporter_x = 9
teleporter_z = 12

height = 20

while True:
    pos = mc.player.getTilePos()

    if pos.x == teleporter_x and pos.z == teleporter_z:
        mc.postToChat("teleport!")
        # move off the teleporter tile so we dont land on it again
        pos.x += 1
        for i in range(0, height):
            pos.y += 1  # move up a bit
            time.sleep(0.1) # short delay of 0.2 seconds
            mc.player.setTilePos(pos)

Exercise

Change the height of the jump.

Exercise

Make the jump faster.

Exercise

Move the player in X and Z directions as well as Y during the jump.

Advanced

Instead of checking if player is on a single teleporter tile, check if player is within a larger area. Use <, and, > operators.

14.8. Create a block

This program creates a block. Each type of block has it’s own number, but if we import mcpi.block we can use names instead remembering numbers.

Program 14.7 Create a block

from mcpi.minecraft import *
from mcpi.block import *

mc = Minecraft.create()
pos = mc.player.getTilePos()
x = pos.x
y = pos.y
z = pos.z
blocktype = 1
mc.setBlock(x, y, z, blocktype)

Exercise

Make the block appear a short distance from the player.

14.9. Types of block

AIR	BED	BEDROCK
BEDROCK_INVISIBLE	BOOKSHELF	BRICK_BLOCK
CACTUS	CHEST	CLAY
COAL_ORE	COBBLESTONE	COBWEB
CRAFTING_TABLE	DIAMOND_BLOCK	DIAMOND_ORE
DIRT	DOOR_IRON	DOOR_WOOD
FARMLAND	FENCE	FENCE_GATE
FIRE	FLOWER_CYAN	FLOWER_YELLOW
FURNACE_ACTIVE	FURNACE_INACTIVE	GLASS
GLASS_PANE	GLOWSTONE_BLOCK	GOLD_BLOCK
GOLD_ORE	GRASS	GRASS_TALL
GRAVEL	ICE	IRON_BLOCK
IRON_ORE	LADDER
LAPIS_LAZULI_ORE	LAVA	LAVA_FLOWING
LAVA_STATIONARY	LEAVES	MELON
MOSS_STONE	MUSHROOM_BROWN	MUSHROOM_RED
OBSIDIAN	REDSTONE_ORE	SAND
SANDSTONE	SAPLING	SNOW
SNOW_BLOCK	STAIRS_COBBLESTONE
STAIRS_WOOD	STONE	STONE_BRICK
STONE_SLAB	STONE_SLAB_DOUBLE	SUGAR_CANE
TNT	TORCH	WATER
WATER_FLOWING	WATER_STATIONARY	WOOD
WOOD_PLANKS	LAPIS_LAZULI_BLOCK	WOOL

14.10. Create a block inside a loop

This program creates a block over and over again in a loop. Move around to see it.

Program 14.8 Block loop

from mcpi.minecraft import *
from mcpi.block import *

mc = Minecraft.create()

while True:
    pos = mc.player.getTilePos()
    x = pos.x
    y = pos.y
    z = pos.z
    blocktype = WOOL
    mc.setBlock(x, y, z, blocktype)

Exercise

Make the block appear one meter below the player’s position.

Exercise

Change the block to something else, e.g. ICE

14.11. Create a tower of blocks

We will use a for loop to easily build a tower of blocks.

Program 14.9 Tower of blocks

from mcpi.minecraft import *

mc = Minecraft.create()
pos = mc.player.getTilePos()
x = pos.x + 3
y = pos.y
z = pos.z

for i in range(10):
    mc.setBlock(x, y + i, z, 1)

Exercise

How high can you make the tower?

Exercise

Change the program to create three towers next to one another.

14.12. Clear space

The setBlocks() function lets us create a large cube of blocks. If we create blocks of type AIR this has the effect of removing all blocks! This is such a useful thing that we will need it in the future, therefore in this program we put it in its own function. Make sure to save the program as clear_space.py so you can import it into the next program.

Program 14.10 Clear space

from mcpi.minecraft import *
from mcpi.block import *

def clear_space(mc, size):
    pos = mc.player.getTilePos()
    mc.setBlocks(pos.x-size, pos.y, pos.z-size, pos.x+size, pos.y+size, pos.z+size,
                 AIR)

mc = Minecraft.create()

clear_space(mc, 10)

14.13. Build a house

Make sure you have saved the previous Program 14.10 to the same directory before you run this program because we are going to import the function from clear_space.py. Save this program as house.py.

Program 14.11 A simple house

from mcpi.minecraft import *
from mcpi.block import *

# This MUST be the name you gave to your clear space program!
from clear_space import *

def make_house(mc, x, y, z, width, height, length):
    mc.setBlocks(x, y, z, x + width, y + height, z + length, STONE)

    # What happens if we make AIR inside the cube?
    mc.setBlocks(x + 1, y + 1, z + 1,
                 x + width - 2, y + height - 2, z + length - 2, AIR)

mc = Minecraft.create()
pos = mc.player.getPos()
x = pos.x
y = pos.y
z = pos.z

width = 10
height = 50
length = 60

# Use the function from the other program
clear_space(mc, 10)
make_house(mc, x, y, z, width, height, length)

Exercise

Run the program and manually bash a hole in the wall to see what is inside and to give you a way to get into the building.

Exercise

Change the program so it automatically makes a hole for a door.

Exercise

Lower the floor in your house.

Exercise

Add some furniture, torches, windows.

Advanced

Make the windows get bigger if you increase the size of the house.

Exercise

Try filling a house with LAVA, or WATER, or TNT (Be careful with TNT, too much will crash your computer!)

14.14. Build a street of houses

Make sure you have saved the previous Program 14.11 to the same directory before you run this program because we are going to import the function from house.py.

Program 14.12 A street of houses

from mcpi.minecraft import *
from mcpi.block import *

# This MUST be the name you gave to your clear space program!
from clear_space import *
# This MUST be the name you gave to your house program!
from house import *

mc = Minecraft.create()
pos = mc.player.getTilePos()

x = pos.x
y = pos.y
z = pos.z

width = 10
height = 5
length = 6

clear_space(mc, 100)

for i in range(1, 100, 20):
    print(x+i, y, z)
    make_house(mc, x+i, y, z, width, height, length)

Exercise

How many houses are there? Make the street longer with more houses.

Exercise

Make the houses get taller as the street goes on.

Exercise

Add some towers to the street.

Advanced

Put a loop inside the loop to create multiple streets.

Advanced

Make some roads or fences.

Exercise

Make your houses out of TNT. Use flint tool on them.

14.15. Chat commands

This program can read chat messages posted by players. It builds a block next to any player who says “build”. This is the first example that will work for more than one player.

Program 14.13 Chat commands

from mcpi.minecraft import *

mc = Minecraft.create()

while True:
    events = mc.events.pollChatPosts()
    for event in events:
        print(event)
        if event.message == "build":
            id = event.entityId
            pos = mc.entity.getTilePos(id)
            x = pos.x
            y = pos.y
            z = pos.z
            mc.setBlock(x, y, z, 1)
            mc.postToChat("done building!")

Advanced

Build a house around the player if the player says “house”.

Advanced

Build a lava trap if the player says “trap”.

Advanced

use mc.getPlayerEntityId(“fred”) to get the id of a certain player named Fred (or whatever your friend’s player name is). Build something at the position of this player.

14.16. Turtle

This requires the minecraftstuff package to work. You can install it in Mu by clicking in the bottom right gadget and adding minecraftstuff to list of third party packages

In olden days at school we used robotic turtles to draw on paper. You may have done similar on the screen in Python or Scratch. This is the same but in Minecraft.

Program 14.14 Turtle

from mcpi.minecraft import *
from mcpi.block import *

from minecraftstuff import MinecraftTurtle

mc = Minecraft.create()
pos = mc.player.getTilePos()
pos.y += 1

turtle = MinecraftTurtle(mc, pos)

turtle.forward(5)
turtle.right(90)
turtle.forward(5)
turtle.right(90)
turtle.forward(5)
turtle.right(90)
turtle.forward(5)

Exercise

Draw a triangle, hexagon, etc.

Exercise

What do turtle.up(90) and turtle.down(90) do?