Step 1: Adding a start line

To draw the start line as a vertical line on the left hand side of the screen, we will need to use the following (x,y) coordinates to tell the computer where does the start line starts and ends:

You will can add the following code to the above trinket to draw the start line:

#Let's draw the start line
myPen.penup()
myPen.goto(-160, 150)
myPen.pendown()
myPen.goto(-160, 0)

Step 2: Adding a finish line

It’s now your turn to use very similar code, this time to draw the finish line using the following (x,y) coordinates:

View Solution!

#Let's draw the finish line
myPen.penup()
myPen.goto(180, 150)
myPen.pendown()
myPen.goto(180, 0)

Step 3: Adding four turtles on the start line

We are now going to add the four competitors on the start line. We will have four turtles that we will need to position using the following (x,y) coordinates:

Here is the code to add the red turtle at position (-180, 140):

#Let's add our turtles
redTurtle = turtle.Turtle()
redTurtle.shape('turtle')
redTurtle.color('red')
redTurtle.pensize(2)
redTurtle.penup()
redTurtle.goto(-180, 140)
redTurtle.pendown()

Can you add some more lines of code to add 3 more turtles using the following coordinates:

• Green Turtle at position (-180,110)
• Blue Turtle at position (-180,80)
• Yellow Turtle at position (-180,50)

#Let's add our turtles
redTurtle = turtle.Turtle()
redTurtle.shape('turtle')
redTurtle.color('red')
redTurtle.pensize(2)
redTurtle.penup()
redTurtle.goto(-180, 140)
redTurtle.pendown()

greenTurtle = turtle.Turtle()
greenTurtle.shape('turtle')
greenTurtle.color('green')
greenTurtle.pensize(2)
greenTurtle.penup()
greenTurtle.goto(-180, 110)
greenTurtle.pendown()

blueTurtle = turtle.Turtle()
blueTurtle.shape('turtle')  
blueTurtle.color('blue')
blueTurtle.pensize(2)
blueTurtle.penup()
blueTurtle.goto(-180, 80)
blueTurtle.pendown()

yellowTurtle = turtle.Turtle()
yellowTurtle.shape('turtle')
yellowTurtle.color('orange')
yellowTurtle.pensize(2)
yellowTurtle.penup()
yellowTurtle.goto(-180, 50)
yellowTurtle.pendown()

Step 4: Animating the turtles to race across the screen

It’s now time for our turtles to race across the screen. To do so we will use an infinite while loop. Within each iteration of the loop, we will move each turtle forward by a randomly generated number of pixels between 1 and 8.

Here is the code to use for our infinite loop…

#Let's start the race!
while True:
  redTurtle.forward(random.randint(1,8))
  greenTurtle.forward(random.randint(1,8))
  blueTurtle.forward(random.randint(1,8))
  yellowTurtle.forward(random.randint(1,8))

Step 5: And the winner is…

As you can see with step 4, the four turtles carry on racing even after crossing the finish line. They even disappearing off screen!

Our aim is now to check, within each iteration of the while loop, to see if one of the four turtles has reached the finish line. To do so, we will need to check the x coordinate of each turtle. A turtle with an x coordinate greater than 180 has crossed the finish line!

Here is the final code for our racing loop!

#Let's start the race!
while True:
  redTurtle.forward(random.randint(1,8))
  greenTurtle.forward(random.randint(1,8))
  blueTurtle.forward(random.randint(1,8))
  yellowTurtle.forward(random.randint(1,8))
  
  if redTurtle.xcor()>180:
    print("Red Turtle wins!")
    break
  elif greenTurtle.xcor()>180:
    print("Green Turtle wins!")
    break
  elif blueTurtle.xcor()>180:
    print("Blue Turtle wins!")
    break
  elif yellowTurtle.xcor()>180:
    print("Yellow Turtle wins!")
    break