Assignment 9: Snake

Assignment Setup

To create your repository go here. Then follow the same accept/import process described in the setup instructions.

Overview

For this assignment, we will be asking you to create the classic game Snake. This assignment is a bit more open ended than past assignments - no unit tests are given. This is to allow you a degree of creativity and flexibility. We expect some basic functionality from your game but you are otherwise encouraged you explore, expand, and improve upon the game to make it your own!

Requirements

To receive credit you must:

  • Have a Snake that is controlled by the keyboard

  • Randomly place food around the game screen

  • Grow the snake whenever it eats a piece of food

  • End the game once the snake collides with the edge of the screen

Code base

You will probably want to start with BodySegment and Food classes, as they are fairly simple. For Food you simply need to set the position of the food to a random spot within the boundary of the window. In BodySegment be sure to set the color instance variable, a ColorUtils class has been provided that you can use if you wish. Drawing each object as a circle makes collision detection a bit more straightforward, however you are welcome to draw each component in whatever way you wish.

Game and Snake will be where most of the work of this assignment is done. Start by noticing that the code to handle keyboard input has been provided for you. If you run the provided Game class, you can test the keyboard using the WASD keys and the console. We need to get the information from the keyboard to the Snake which can be done with the provided changeDirection() method in the Snake class.

Start with the constructor to Snake. We are using a LinkedList<BodySegment> to represent our Snake, so this must be initialized in the Snake constructor. We also want our new Snake to have at least one BodySegment, so within the constructor you should create a new BodySegment and add it to the list. Next, complete the draw() method in the Snake class by iterating through the list and telling each BodySegment to draw itself. Finally, start the move() method by retrieving the BodySegment representing the head of the snake from the LinkedList and updating its position by adding to the deltaX and deltaY values to its respective X and Y coordinates.

Moving to the Game class, within the constructor you should construct a new instance of Snake and Food and store them each in instance variables. Complete the updateDrawing() method such that it will clear the screen and redraw each of the game components. You can then update the loop within the play() method to incorporate your Snake: pass the direction to the Snake and tell it to move(), then updateDrawing(). If all goes well, you should have a (small) moving Snake!

The Food should cause your Snake to grow, but first you must complete the eat() method of the Snake class to determine if the head of the Snake overlaps the Food (refer to our previous Zombie assignments for a discussion of this concept). If the Snake successfully eats the Food then a new BodySegment should be added to the Snake. This will require you to go back and revisit the move() method to update the position of all of the BodySegment s in the list, not just the head. Hint: you may want to consider starting to move the snake from the back. Don’t forget to add your Food into the while loop in play() to make sure it works!

The final part of the game is to check whether the head of the Snake collides with the edge of the screen, which can be done with the isInbounds() method. Once this method is complete, update the while loop in play() to end the game appropriately.

Be Creative!

There are many ways upon which this game could be completed, and many ways upon which this simple version can be expanded upon. To recieve full credit on this assignment, you must choose one additional feature to add to your game. It does not have to be a complicated feature but it must be something functional, so simply changing the colors and cosmetics (while encouraged!) will not count towards this goal. Some simple ideas would include:

  • Intro / game over screens that display properly

  • Some kind of score that gets updated

  • Additional things the Snake can eat, perhaps to provide extra powers

  • Extra collision checks so the snake can’t collide with itself. Addition of walls to make the game more challenging.

This list is not intended to be exhaustive, we want you to be creative and pick something that interests you. Be sure to talk to an instructor or a TA if you have questions about this part!

Submitting your work

To submit your work come to office hours or class on an “Assignment day” and sign up for a demo via wustl-cse.help. Be prepared to show them the work that you have done and answer their questions about it!

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