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Programming with Shahan
Programming with Shahan

Posted on β€’ Edited on β€’ Originally published at freecodecamp.org

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I built a turtle racing game in Python

In this article, you'll learn how to build a racing game in Python using the Turtle library in just 39 lines of code.

Image if turtle racing game in python

Here's what we're going to create:

gif of turtle racing game

🧡 Prerequisites

Very basic knowledge of Python programming will be enough to go through this tutorial. Also, I assume that you don't know anything about this turtle library. I will teach you everything from scratch.

Image of turtle racing game

πŸ›  Tools we'll use

First, if you don't have Python installed on your machine, go to python.org to download the latest version of Python and then install it right away.

For writing the program, we will be using PyCharm, which is the most popular integrated development environment (IDE) for Python. After installing PyCharm on your machine, you are ready to build this amazing game from scratch.

β›³ Project Goals

Image if turtle racing game project goals

Concretely, we'll write a program that moves a turtle object horizontally until it reaches our calculated finish line. 🏁

Then we will create seven unique replicas of this turtle object using a for loop along with different colors and random moving speeds.

We'll also add a background image (roads with lanes for the turtles to race in) to create something like a real racing environment.

Then we'll compute different values along the vertical or Y-axis to define their starting locations.

Finally, we will prompt the user to enter their bet (turtle color) so that if a user's bet color matches our winner's turtle color, we will display "Winner!" on the screen. Otherwise, we'll display "You Lost!" on the screen.

Note: For screen readers or anyone who is interested in getting the full source code of this project, you can access it in my GitHub Repository here.

So, are you excited to build this game? I'm too. Let's begin!

πŸ‘©β€πŸ’» How to Set Up the Project

Open your PyCharm IDE. Then click New Project.

https://www.freecodecamp.org/news/content/images/2022/01/Screenshot-2022-01-25-185042.png

Let's call it racing-game and click create.

https://www.freecodecamp.org/news/content/images/2022/01/2-5.png

Then, add a new Python file called main.py.

πŸ“‚ How to Use the Turtle Library

Now, let's go to turtle-graphics python documentation. Here you will find the full details about this library.

I recommend reading this documentation at least once before jumping into the code. But don't worry, I will simplify it for you while we're writing the program.

https://www.freecodecamp.org/news/content/images/2022/01/3-5.png

Import the Library

So let's import Turtle and Screen from the turtle module.

Call this Screen in a new variable called screen. Then, call the screen.exitonclick() function to stop the program when we click on the screen.

https://www.freecodecamp.org/news/content/images/2022/01/4-3.png

πŸ›£οΈ Designing Game Canvas

Image of turtle racing game design

Now, let's work with the screen object to define our game canvas.

So, let's set the width to 800 pixels and height to 600 pixels.

https://www.freecodecamp.org/news/content/images/2022/01/5-4.png

Here is the result:

https://www.freecodecamp.org/news/content/images/2022/01/6-1.png

🏁 Adding Background Graphics

It's time to load our background image for our canvas. So let's drag our road.gif file into our racing-game project. 

Image of turtle racing game background graphics

You can download this background image from here

Let's add this image using screen.bgpic('road.gif')`.

https://www.freecodecamp.org/news/content/images/2022/01/7-1.png

Here is the result:

https://www.freecodecamp.org/news/content/images/2022/01/8-1.png

🐒 Working with Turtle Objects

Image of turtle objects

Now, let's create a turtle instance using the Turtle() method with the shape called turtle.

But it will seem really small. So we need define shapesize(2).

Turtle Location

Now we need to change our turtle's location to the left bottom corner using goto(x=-350, y=-260).

So here we set x for moving the turtle horizontally and y for vertically along with the computed values with respect to our canvas.

https://www.freecodecamp.org/news/content/images/2022/01/9-1.png

https://www.freecodecamp.org/news/content/images/2022/01/10-1.png

Here you can see that the turtle has moved to our desired location.

So, we can take the y position in a global variable and add different types of values for positioning our turtles on their respective roads.

Turtle replicas

Now, we have to create seven different types of turtle objects. For this reason, we will use a for loop.

So for index in range(0, 7) and then move our existing turtle instance in this loop. And of course, we have to change y to our global y positions variable and get their indexes in order.

https://www.freecodecamp.org/news/content/images/2022/01/11-4.png

Here is the result:

https://www.freecodecamp.org/news/content/images/2022/01/12-1.png

Turtle color

So as you can see, we have seven turtle instances created equally with different y locations. Let's add some random colors by using a global colors variable as we did for the y positions. Then use the color(colors[index]) method with their indexes.

https://www.freecodecamp.org/news/content/images/2022/01/13-2.png

Here is the result – beautiful!

https://www.freecodecamp.org/news/content/images/2022/01/14-2.png

The ugly lines

You may see that there are some ugly lines that point towards the middle, and the move direction is very slow. So we can use the speed('fastest') and penup() methods to solve these problems. Have a look!

https://www.freecodecamp.org/news/content/images/2022/01/15-2.png

Move the turtles forward

Now, what else do we need? Yeah, you got it! We need to define a random pace for every turtle. But before doing that, how can we move a single turtle forward?

Well, you can use the forward() method to do this.

Let's say we need to move our turtles forward 30 pixels.

https://www.freecodecamp.org/news/content/images/2022/01/17.png

Here is the result:

https://www.freecodecamp.org/news/content/images/2022/01/18.png

But they are not moving continuously. What else can we do here? Think about it and come back to see my solutions.

So, to solve this problem, we take a variable called is_on and set it to True. Now we will continuously execute our program until we break it using a while loop.

Now, we have the opportunity to move our turtle forward continuously with 30 pixels in every step.

https://www.freecodecamp.org/news/content/images/2022/01/7-2.png

Here is the result:

https://www.freecodecamp.org/news/content/images/2022/01/9-2.png

It's moving like a plane because we set forward to 30. 🀣

For now, let's keep it like that. We will fix it after all turtles be able to run together and then adjust the speed accordingly.

Run multiple turtles in sync

Now we need to target all the turtle objects, not just a single one. But how can we do it? Think about it and come back to see my solution.

So, we can take a global variable called all_turtle and set it to an empty list. Now, in the for loop, after creating seven new turtle instances, we can append our new born turtle to this global all_turtle list. This way we can access them in other code blocks.

https://www.freecodecamp.org/news/content/images/2022/01/19.png

Now we have all our turtles. So, while our is_on variable in true, we can say all_turtle.forward(10). Also, here we need to use a for loop again to get each turtle from this all_turle global variable and then move them forward by 10 pixels.

https://www.freecodecamp.org/news/content/images/2022/01/20-1.png

Let's see the result up until now:

https://www.freecodecamp.org/news/content/images/2022/01/21.png

Setting random moving speed

So, we solved our turtle moving problem. But they're running infinitely – there is no ending point.

Also all turtles are moving at the same speed. Think about this problem, and try to solve it on your own.

So let's take a new variable random_pace and set it to random.randint(0, 7). It will return value between zero to seven randomly. You have to import random at the top. Finally pass this random_pace variable to the forward() method like forward(random_pace).

https://www.freecodecamp.org/news/content/images/2022/01/22.png

Here is the result:

https://www.freecodecamp.org/news/content/images/2022/01/23.png

🏁 How to Set the Finish Line

Now, we need to define our finish line in this canvas. To solve this problem, we check if turtle.xcor() > 330, set is_on = False, else we need to continue executing our program.

https://www.freecodecamp.org/news/content/images/2022/01/24.png

πŸ™Žβ€β™‚οΈ How to Prompt the User to Enter Their Bet

We are done with the UI. Now, we need to define some logic to let the user enter their bet and compare their bet with our programmed result.

To let the user enter their bet, we can write screen.textinput and with a placeholder 'Enter your bet'. We'll also prompt the user "which turtle color" and store it in a global variable user_bet.

Then we take a variable winner. We check if winner == user_bet which will come from the user's input color. We print You Won, Otherwise, You lost with the turtle winner's color. That's why we have to use an f-string to pass the variable in the print method.

https://www.freecodecamp.org/news/content/images/2022/01/25.png

🎐 How to Show the Results on the Screen

Now, I want you to show this print text in the canvas with their responsive turtle color after touching the finish line. How can you implement this? You will see my solution next.

So, here in the top. We take two global variables ALIGN = "right" and FONT = ("Courier", 28, "bold"). We will write to align the text on the right, and also make the font family courier and font size 28, bold.

Now, we'll use them when we want to show the user the racing results. So when the winner turtle color is equal to the user_bet color, we have to show the text in the canvas instead of printing it in the terminal.

To do this, we write turtle.write() and past the print statement along with font=FONT and align=ALIGN. Else, we need to show the text "You lost" with the same variable FONT and ALIGN. See, this is the benefit of using global variables.

https://www.freecodecamp.org/news/content/images/2022/01/26.png

Finally, let's run this code one more time. Let's say that the red turtle will be the winner. But, as you can see below – Oops, the yellow turtle is the winner. So, you can see the bold yellow font displayed next to this turtle. This is why we used align = "right" and set the turtle color using the turtle.pencolor() method.

https://www.freecodecamp.org/news/content/images/2022/01/turtle-overview.gif

And there you have it - we've built our turtle racing game. If you want to watch this tutorial in video form, here's a full video tutorial for you:

πŸ“Ή Full video tutorial: How to make racing game in python

πŸ‘ Conclusion

So, we are at the end of this racing game project. If you liked this article, feel free to follow me for daily programming news and productivity.

Read More: Why we need math in programming

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