Minecraft Coding a Traffic Jam

I was doing a workshop on Minecraft Coding on the Rapsberry Pi for a group of teachers at Edge Hill University and I wanted to create a stretching challenge.

The idea of the workshop was that the starting point would be to create a working traffic light, which change through the colours in sequence e.g. Red, Red/Amber, Green, Amber, Red, but for those who completed the challenge early the stretch would be to expand on this to 2 traffic lights, a road and so on.

I created a series of programs in Python which would simulate a road system, traffic lights, junctions, cars, etc in Minecraft as examples which the attendees could take away.

My finished traffic jam.

I created 5 programs to show how I went from creating 1 traffic light to my traffic jam.  Each program led on from the next.  All the code is on github, https://github.com/martinohanlon/minecraft-traffic.

1light.py - is a really basic implementation of a traffic light, a single function which sets the blocks in turn.

#minecraft traffic lights - simple

#import the minecraft.py module from the minecraft directory
import minecraft.minecraft as minecraft
#import minecraft block module
import minecraft.block as block
#import time, so delays can be used
import time

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

#clear area
mc.setBlocks(-10,0,-10,60,50,50,block.AIR.id)
#put grass on the floor
mc.setBlocks(-10,-1,-10,60,-1,10,block.GRASS.id)

#build traffic light
# pole straight up
mc.setBlocks(0,0,0,0,5,0,block.IRON_BLOCK.id, 15)
# create 3 lights out of wool
# wool values (black - 15, red - 14, yellow - 4, green - 13)
# set all the lights to off (black)
mc.setBlock(1,5,0,block.WOOL.id,15)
mc.setBlock(1,4,0,block.WOOL.id,15)
mc.setBlock(1,3,0,block.WOOL.id,15)

#loop forever
while(True):
    #set to stop
    mc.setBlock(1,5,0,block.WOOL.id,14)
    mc.setBlock(1,4,0,block.WOOL.id,15)
    mc.setBlock(1,3,0,block.WOOL.id,15)
    # sleep for half a second
    time.sleep(0.5)
    #set to stop, prepare
    mc.setBlock(1,5,0,block.WOOL.id,14)
    mc.setBlock(1,4,0,block.WOOL.id,4)
    mc.setBlock(1,3,0,block.WOOL.id,15)
    time.sleep(0.5)
    #set to go
    mc.setBlock(1,5,0,block.WOOL.id,15)
    mc.setBlock(1,4,0,block.WOOL.id,15)
    mc.setBlock(1,3,0,block.WOOL.id,13)
    time.sleep(0.5)
    #set to prepare
    mc.setBlock(1,5,0,block.WOOL.id,15)
    mc.setBlock(1,4,0,block.WOOL.id,4)
    mc.setBlock(1,3,0,block.WOOL.id,15)
    time.sleep(0.5)
    #back to stop

1light-functions.py - is effectively the same program as 1light.py, but I have split the code into 3 functions:

• createTrafficLight() - creates the pole and 3 'lights' on the top
• go() - sets the traffic light to go
• stop() - sets the traffic light to stop

2lights.py - creates 2 traffic lights, which work in unison, one setting to stop, the other setting to go.  To do this I created a class called TrafficLight.  The main program then created 2 instances of this class and called stop, go methods of the class to change the lights

#minecraft traffic lights - classes

#import the minecraft.py module from the minecraft directory
import minecraft.minecraft as minecraft
#import minecraft block module
import minecraft.block as block
#import time, so delays can be used
import time

class TrafficLight():
    def __init__(self, mc, x, y, z):
        #build traffic light
        # pole straight up
        mc.setBlocks(x,y,z,x,y+5,z,block.IRON_BLOCK.id, 15)
        # create 3 lights out of wool
        # wool values (black - 15, red - 14, yellow - 4, green - 13)
        # set all the lights to off (black)
        mc.setBlock(x+1,y+5,z,block.WOOL.id,15)
        mc.setBlock(x+1,y+4,z,block.WOOL.id,15)
        mc.setBlock(x+1,y+3,z,block.WOOL.id,15)
        #set to stop
        mc.setBlock(x+1,y+5,z,block.WOOL.id,14)
        #store x,y,z
        self.x = x
        self.y = y
        self.z = z
        #store mc
        self.mc = mc
        
    def go(self):
        #set to stop, prepare        self.mc.setBlock(self.x+1,self.y+5,self.z,block.WOOL.id,14)
        self.mc.setBlock(self.x+1,self.y+4,self.z,block.WOOL.id,4)
        self.mc.setBlock(self.x+1,self.y+3,self.z,block.WOOL.id,15)
        time.sleep(0.5)
        #set to go
        self.mc.setBlock(self.x+1,self.y+5,self.z,block.WOOL.id,15)
        self.mc.setBlock(self.x+1,self.y+4,self.z,block.WOOL.id,15)
        self.mc.setBlock(self.x+1,self.y+3,self.z,block.WOOL.id,13)
        time.sleep(0.5)

    def stop(self):
        #set to prepare
        self.mc.setBlock(self.x+1,self.y+5,self.z,block.WOOL.id,15)
        self.mc.setBlock(self.x+1,self.y+4,self.z,block.WOOL.id,4)
        self.mc.setBlock(self.x+1,self.y+3,self.z,block.WOOL.id,15)
        time.sleep(0.5)
        #set to stop
        self.mc.setBlock(self.x+1,self.y+5,self.z,block.WOOL.id,14)
        self.mc.setBlock(self.x+1,self.y+4,self.z,block.WOOL.id,15)
        self.mc.setBlock(self.x+1,self.y+3,self.z,block.WOOL.id,15)
        # sleep for half a second
        time.sleep(0.5)

#MAIN PROGRAM

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

#clear area
mc.setBlocks(-5,0,-5,5,50,5,block.AIR.id)

#create traffic light
trafficLight1 = TrafficLight(mc,0,0,0)
trafficLight2 = TrafficLight(mc,0,0,3)

#loop forever
while(True):
    trafficLight2.stop()
    trafficLight1.go()
    time.sleep(2)
    trafficLight1.stop()
    trafficLight2.go()
    time.sleep(2)

road.py - to create a road and a junction I extended the program to include new classes for Road() and Junction(), the road now becomes the controlling class, allowing you to create junctions on the road.  In order to get the traffic lights changing in unison and allowing the elements of the road to work independently I also implemented threading.

car.py - is where I introduced the Car() class, again cars are controlled by the Road() class and every instance of the Car() class runs in its own thread.   Each car works independently checking before it moves whether it is going to enter a closed junction or go into the back of another car.  The main program creates a new car on the road every 3 seconds.

#minecraft traffic lights - class

#import the minecraft.py module from the minecraft directory
import minecraft.minecraft as minecraft
#import minecraft block module
import minecraft.block as block
#import time, so delays can be used
import time
#import threading so I can make asynchronous calls!
import threading
#import random so I can randomly create cars
import random

class Road():
    def __init__(self, mc, x, y, z, width, lenght):
        #create road
        mc.setBlocks(x, y-1, z, x+lenght, y-1, z+width-1, block.BEDROCK.id)
        #create line down the middle
        mc.setBlocks(x, y-1, z+(width/2), x+lenght, y-1, z+(width/2), block.WOOL.id, 0)
        #store values
        self.x = x
        self.y = y
        self.z = z
        self.width = width
        self.lenght = lenght
        #create empty junctions & cars list
        self.junctions = []
        self.cars= []

    def run(self):
        #start up junctions
        for junction in self.junctions:
            #tell the junction to run in the background
            junction.daemon
            junction.start()

    def stop(self):
        #stop junctions
        for junction in self.junctions: junction.stop()
        #stop cars
        for car in self.cars: car.stop()
        #wait for junctions to stop
        for junction in self.junctions: junction.join()
        #wait for cars to stop
        for car in self.cars: car.join()

    def createJunction(self, posDownRoad, timeOpen, timeClosed):
        #create junction at position down the road
        junction = Junction(mc, self.x+posDownRoad, self.y, self.z, self.x+posDownRoad+self.width, self.y, self.z+self.width-1, timeOpen, timeClosed)
        #add junction to collection
        self.junctions.append(junction)

    def startCar(self, direction):
        #create car
        car = Car(mc, self, direction)
        #add car to collection
        self.cars.append(car)
        #tell car to run in background
        car.daemon
        car.start()

class Car(threading.Thread):
    def __init__(self, mc, road, direction):
        #store variables
        self.mc = mc
        self.road = road
        self.direction = direction
        #set x,y,z
        #set z & x position, left or right side, top or bottom of road depending on direction
        if direction == 1:
            self.x = road.x
            self.z = road.z + 1
        if direction == -1:
            self.x = road.x + road.lenght
            self.z = road.z + road.width - 2
        self.y = road.y
        #setup threading
        threading.Thread.__init__(self)

    def run(self):
        lenghtOfCar = 4
        self.running = True
        ableToMove = True
        #find the end of the road, depending on which way the car is going
        endOfRoad = self.road.x
        if self.direction == 1: endOfRoad = endOfRoad + self.road.lenght
        #loop until i meet the end of the road
        while(self.x != endOfRoad and self.running == True):
            #draw the car
            if ableToMove: self.drawCar()
            #sleep for a bit
            time.sleep(0.5)
            #move the car
            #where will the car be moving too?
            frontOfCar = self.x + self.direction
            #if im going forwards add 3 to the x, as my car's x is at the back
            if self.direction == 1: frontOfCar = frontOfCar + lenghtOfCar
            ableToMove = True
            #am I going to enter a junction which is closed?
            for junction in self.road.junctions:
                if self.direction == 1 and junction.x1 == frontOfCar and junction.open == False: ableToMove = False
                if self.direction == -1 and junction.x2 == frontOfCar and junction.open == False: ableToMove = False
            #am I going to hit another car?
            for car in self.road.cars:
                if self.direction == 1 and frontOfCar >= car.x and frontOfCar <= (car.x + lenghtOfCar) and self.z == car.z and car.running == True: ableToMove = False
                if self.direction == -1 and frontOfCar <= (car.x + lenghtOfCar) and frontOfCar >= car.x and self.z == car.z and car.running == True: ableToMove = False
            #clear car and add 1 to the car's position
            if ableToMove:
                self.clearCar()
                self.x = self.x + self.direction

        self.running = False

    def stop(self):
        self.running = False
    
    def drawCar(self):
        self.mc.setBlocks(self.x, self.y, self.z, self.x + 3, self.y + 2, self.z, block.IRON_BLOCK.id)
        self.mc.setBlock(self.x, self.y, self.z, block.WOOL.id, 15)
        self.mc.setBlock(self.x+3, self.y, self.z, block.WOOL.id, 15)

    def clearCar(self):
        self.mc.setBlocks(self.x, self.y, self.z, self.x + 3, self.y + 2, self.z, block.AIR.id)

class Junction(threading.Thread):
    def __init__(self, mc, x1, y1, z1, x2, y2, z2, timeOpen, timeClosed):
        #create junction
        mc.setBlocks(x1,y1-1,z1,x2,y2-1,z2,block.BEDROCK.id)
        #create lines
        mc.setBlocks(x1,y1-1,z1,x2,y2-1,z1,block.WOOL.id,0)
        mc.setBlocks(x2,y1-1,z1,x2,y2-1,z2,block.WOOL.id,0)
        mc.setBlocks(x2,y1-1,z2,x1,y2-1,z2,block.WOOL.id,0)
        mc.setBlocks(x1,y1-1,z2,x1,y2-1,z1,block.WOOL.id,0)
        #create traffic lights
        self.trafficLight1 = TrafficLight(mc, x1, y1, z1-1, -1)
        self.trafficLight2 = TrafficLight(mc, x2, y2, z2+1, 1)
        #set to open
        self.openJunction()
        #store times
        self.timeOpen = timeOpen
        self.timeClosed = timeClosed
        #setup threading
        threading.Thread.__init__(self)
        #store variables
        self.x1 = x1
        self.y1 = y1
        self.z1 = z1
        self.x2 = x2
        self.y2 = y2
        self.z2 = z2
        
    def run(self):
        #start the Junction
        self.running = True
        while(self.running):
            self.openJunction()
            time.sleep(self.timeOpen)
            self.closeJunction()
            time.sleep(self.timeClosed)

    def stop(self):
        #stop the junction
        self.running = False

    def openJunction(self):
        #set lights to go
        light1 = self.trafficLight1.go()
        light2 = self.trafficLight2.go()
        #wait for lights to finish changing
        light1.join()
        light2.join()
        #set open status to True
        self.open = True

    def closeJunction(self):
        #set lights to stop
        light1 = self.trafficLight1.stop()
        light2 = self.trafficLight2.stop()
        #wait for lights to finish changing
        light1.join()
        light2.join()
        #set open status to False
        self.open = False

class TrafficLight():
    def __init__(self, mc, x, y, z, direction):
        #build traffic light
        # pole straight up
        mc.setBlocks(x,y,z,x,y+5,z,block.IRON_BLOCK.id, 15)
        # create 3 lights out of wool
        # wool values (black - 15, red - 14, yellow - 4, green - 13)
        # set all the lights to off (black)
        mc.setBlock(x+direction,y+5,z,block.WOOL.id,15)
        mc.setBlock(x+direction,y+4,z,block.WOOL.id,15)
        mc.setBlock(x+direction,y+3,z,block.WOOL.id,15)
        #set to stop
        mc.setBlock(x+direction,y+5,z,block.WOOL.id,14)
        #store x,y,z
        self.x = x
        self.y = y
        self.z = z
        #store direction
        self.direction = direction
        #store mc
        self.mc = mc
        
    def go(self):
        thread = threading.Thread(target=self.setToGo)
        thread.start()
        return thread

    def setToGo(self):
        #set to stop, prepare
        self.mc.setBlock(self.x+self.direction,self.y+5,self.z,block.WOOL.id,14)
        self.mc.setBlock(self.x+self.direction,self.y+4,self.z,block.WOOL.id,4)
        self.mc.setBlock(self.x+self.direction,self.y+3,self.z,block.WOOL.id,15)
        time.sleep(0.5)
        #set to go
        self.mc.setBlock(self.x+self.direction,self.y+5,self.z,block.WOOL.id,15)
        self.mc.setBlock(self.x+self.direction,self.y+4,self.z,block.WOOL.id,15)
        self.mc.setBlock(self.x+self.direction,self.y+3,self.z,block.WOOL.id,13)
        time.sleep(0.5)

    def stop(self):
        thread = threading.Thread(target=self.setToStop)
        thread.start()
        return thread

    def setToStop(self):
        #set to prepare
        self.mc.setBlock(self.x+self.direction,self.y+5,self.z,block.WOOL.id,15)
        self.mc.setBlock(self.x+self.direction,self.y+4,self.z,block.WOOL.id,4)
        self.mc.setBlock(self.x+self.direction,self.y+3,self.z,block.WOOL.id,15)
        time.sleep(0.5)
        #set to stop
        self.mc.setBlock(self.x+self.direction,self.y+5,self.z,block.WOOL.id,14)
        self.mc.setBlock(self.x+self.direction,self.y+4,self.z,block.WOOL.id,15)
        self.mc.setBlock(self.x+self.direction,self.y+3,self.z,block.WOOL.id,15)
        time.sleep(0.5)

if __name__ == "__main__":
    #MAIN PROGRAM

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

    #clear area
    mc.setBlocks(-10,0,-10,60,50,10,block.AIR.id)
    #put grass on the floor
    mc.setBlocks(-10,-1,-10,60,-1,10,block.GRASS.id)

    #create road
    road = Road(mc, 0,0,0,9,50)
    #create junction, 20 blocks down, open for 10 seconds, closed for 5
    road.createJunction(20,10,5)
    #start the road
    road.run()
    #loop until Ctrl C
    try:
        while(True):
            #create a car in a random direction, unless its 0 then we wont create a car
            direction = random.randint(-1, 1)
            if direction != 0:
                road.startCar(direction)
            #sleep for a bit
            time.sleep(3)
    except KeyboardInterrupt:
        print("stopped")
    finally:
        #stop everything
        road.stop()