## Saturday 21 February 2015

### Minecraft - Code a Solar System

Update - I took this further and created a DeathStar to blow up planets too, in a Minecraft Star Wars animation.

Every wondered how big the Sun is? Well check out the picture below.

If the Earth was the size of 1 block in Minecraft the Sun would have a diameter of 109 blocks and if the distance was to scale 11728 blocks away!

What about the size and distance of the other planets in blocks?

PlanetDiameterDistance
Mercury0.384539.04
Venus0.958482.28
Earth1.011727.81
Mars0.5317866.1
Jupiter11.2161037.94
Saturn9.45112378.49
Uranus4.01225188.15
Neptune3.88352391.03
Pluto0.19460175.6

I didn't build this Solar System I coded it. I took information about the diameter and distance of the planets from Nasa's Planetary Fact Sheet and created a fairly simple program which created spheres of the right size based on a factor of Kilometers to Blocks.

The code is on github at github.com/martinohanlon/minecraft-solarsystem or you can download the Minecraft world.

You can change the ratio of the sun and planets by changing the constant KMTOBLOCK, which is the number of kilometers per block - be careful though, the sun will be VERY big if the value is too low. You might have to increase the height of your Minecraft world too.

```#Minecraft - Code a solar system
#Martin O'Hanlon

#import minecraft api library
import mcpi.minecraft as minecraft
import mcpi.block as block

# draw hollow sphere
def drawHollowSphere(mc, x1, y1, z1, radius, blockType, blockData=0):
# create sphere
if (x**2 + y**2 + z**2 < radius**2) and (x**2 + y**2 + z**2 > (radius**2 - (radius * 2))):
mc.setBlock(x1 + x, y1 + y, z1 +z, blockType, blockData)

# draw sphere
def drawSphere(mc, x1, y1, z1, radius, blockType, blockData=0):
# create sphere
if (x**2 + y**2 + z**2 < radius**2):
mc.setBlock(x1 + x, y1 + y, z1 +z, blockType, blockData)

#setup constants (all values in kilometers)
SUN = 1391684
#name, diameter, distance, blockId, blockData
PLANETS = (("mercury", 4879, 57900000, block.WOOL.id, 7),
("venus", 12104, 108200000, block.WOOL.id, 0),
("earth", 12756, 149600000, block.WOOL.id, 11),
("mars", 6792, 227900000, block.WOOL.id, 14),
("jupiter", 142984, 778600000, block.WOOL.id, 4),
("saturn", 120536, 1433500000, block.WOOL.id, 8),
("uranus", 51118, 2872500000, block.WOOL.id, 3),
("neptune", 49528, 4495100000, block.WOOL.id, 10),
("pluto", 2390, 5870000000, block.WOOL.id, 6))

#how many km's to a block
# change this value to have different sizes in the solar system
KMTOBLOCK = 12756.0

#middle of the minecraft sky, where the centre of the planets will be
MCMIDDLE = 75

#program
print("Minecraft Planets")
print("1 block = {} kilometers".format(KMTOBLOCK))

#connect to minecraft
mc = minecraft.Minecraft.create()

#set the middle of the solar system
pos = minecraft.Vec3(0,MCMIDDLE,0)

#create the sun
sunDiameter = round(SUN / KMTOBLOCK, 2)
print("Sun - Diameter = {} blocks".format(sunDiameter))
drawHollowSphere(mc, pos.x, pos.y, pos.z, sunRadius, block.WOOL.id, 1)
gapToLeave = (sunDiameter / 2) + 20
pos.z = pos.z + gapToLeave

#loop through the planets
for planet in PLANETS:
name = planet[0]
diameter = round(planet[1] / KMTOBLOCK, 2)
distance = round(planet[2] / KMTOBLOCK, 2)
print("{} - Diameter = {} blocks - Distance = {} blocks".format(name, diameter, distance))
#if the diameter is less than 1.5 draw a single block
if diameter < 1.5:
mc.setBlock(pos.x, pos.y, pos.z, planet[3], planet[4])
pass
else:
drawSphere(mc, pos.x, pos.y, pos.z, radius, planet[3], planet[4])
pass

gapToLeave = (diameter / 2) + 20
pos.z = pos.z + gapToLeave

#move the player to the sun
mc.player.setPos(0,0,0)
```

Have fun.