CSCI 111 Lab 8- SNAKE! Solution

File names: Names of files, functions, and variables, when specified, must be EXACTLY as specified. This includes simple mistakes such as capitalization.
Pygame: First, make sure you know how pygame works. For our purposes, it’s probably best to go through the tutorial that results in the original (buggy) snake game:
https://www.edureka.co/blog/snake-game-with-pygame/
It is a very good tutorial and explains all the concepts you need to get going. There are many other tutorials on the web that you can consult if you need more help: https://www.pygame.org/wiki/tutorials
Hand in: You will write just one module for this, snake.py, which will start with my version in the lab folder on github. Add your name and class information below mine. It is always good practice to preserve the lineage of a program by keeping all developers names at the top.
Snake: The modified snake game is provided in the lab folder, and includes my improvements to the original one on the web.
You will make the following improvements and additions to the game. Add the following features in the following order. Do not go on to the next feature without making sure the previous one works.
Game modes: Currently the game has three modes: playing, loser, and quit. These are controlled by the booleans loser and quitGame (why didn’t I use the name quit?).
You will get rid of these booleans and have one, gameMode which can take on several values:
# Game states
PLAYING = ’Playing mode’
MENU = ’Menu mode’
LOSER = ’Loser mode’ QUIT = ’Quit mode’
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The constants (in all caps) are easier to type than the strings, and also make sure you have fewer spelling mistakes.
Now, for example, where my code has:
if quitGame:
return()
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you will use
if gameMode == QUIT:
return()
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This will make it easier to control the several modes we have available.
Implement this step before going on.
Overall game loop structure: For minimum pain you might want to use this structure:
while not gameMode == QUIT:
clock.tick(speed) for event in pygame.event.get():
# handle user events:
# keyboard, quit, mouse, controller, whatever
if gameMode == X:
# update things X
# display things X if gameMode == Y:
# update things Y
# display things Y if gameMode == Z:
# update things Z
# display things Z
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In particular note:
• There is only one while loop!
• There is only one place where we get the event queue!
• Code updating and displaying each mode separate from other modes!
Starting (and losing) menu: When the game begins or when the player loses a game (there is no winning this game) there will be a menu allowing the user to set various parameters of the game that looks a bit like this:

After a loss, the only thing that changes is the top line, which changes from ”Welcome” to ”You lost!”
This screen will allow the user to set various configuration parameters for the game, as follows.
startSnakeLength : This has a default value of 5. Can be set to any positive integer with the left/right arrows. Note that in your keyboard handling you will have to distinguish between gameModes to handle the arrows correctly.
nSnakes : Starting value of 1, can be toggled between 1 and 2 with the S key. poisonApples : Starting value of False, can be toggled to True with the P key.
Implement this feature before going on. The toggling and changing will change the variables, but of course nothing in the game will change. You can check that your menu is working by just printing out the values of the variables each time they are changed.
Poison apples: The game is a bit more interesting with more kinds of food to eat. A simple one is a food item of a different color. If the snake eats this food, the game is over.
If the user selects this feature from the menu, add it to the game. This is the easiest feature to add, so do this first.
It is straightforward to add a food item of a different color, and end the game if the snake eats it. To make it a bit more interesting the poison apple will appear and disappear at random times. Here is how we accomplish that.
We will introduce some new global variables: poisonX and poisonY, which tell us where to draw the poison apple, and also poisonOn initialized to False, and poisonCount initialized to a random integer between 10*speed and 20*speed.
If poisonOn is True, then we draw the poison apple at the position specified by poisonX and poisonY. If it is False then we don’t draw it.
Every time through the game loop, the counter is decremented by one. When the counter gets to zero, several things happen:
• We choose new random values for poisonX, poisonY and poisonCount in the appropriate ranges.
• We toggle poisonOn to the opposite value.
The result of these operations is that the poison apple will appear for 10 to 20 seconds at a random location, then disappear for 10 to 20 seconds, then reappear at a new location for 10 to 20 seconds, and so on.
Naturally, if the snake collides with poisonX and poisonY the game is over only if poisonOn is True!
Pick a nice ugly color for the poison apple, so the user knows which kind of food is good and which is bad.
Implement this feature before going on!
Starting snake length: The game is more interesting after the snake has some length. After the menu, create the snake of the length specified by the user.
Create the initial snake with head at the center of the board, and tail stretching off to the left, like before. You will need to create a function that creates a snake of that length. After the user enters their choice in the menu, you will have to run this function for the snake before beginning game play.
Note that you will have to change the starting behavior of the snake. What happens if you just start the existing game with a longer snake? For example, instead of:
snake = [(x1,y1)]
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you put:
snake = [(x1-40,y1), (x1-30,y1), (x1-20,y1), (x1-10,y1), (x1,y1)]
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what happens? Why?
How can you fix this? A simple way is to start the game with the snake moving (by changing the initial x1Change value, for instance), throwing the player en media res.
For this lab, you can do that, or you can make it so the snake does not move until the player enters the first direction. You will have to modify a bit of code to do this.
What happens if the user starts with a number so big the tail goes off the board? What can you do about that? I see two approaches: prohibit such long snakes, or allow them but don’t draw any part of the snake that is off the board. Your choice. By the way, pygame automatically ignores requests to draw something off the board, so if you choose that path, you’re good.
Implement this feature before going on. Make sure you handle very long snakes!
Multiple snakes: If the user selects two snakes, then two snakes should appear so that two players can play competitively. They should have different colors so they can be visually distinguished.
For two people to play they will have to sit side by side and use the same keyboard. One player will use the arrow keys as usual, the other will use the WASD keys. These are standard keys used in many games so that the left hand can control direction while the right hand uses the mouse (no mouse needed in this game).
The mapping should be obvious from the layout: W=UP, A=LEFT, S=DOWN, and D=RIGHT.
The score for each player is kept and updated and displayed at the top of the screen. The color of the score text should match the color of the snake so we know who’s score is who’s.
If either snake runs into a wall or the body of a snake (either one), or eats a poison apple, the game is over.
This will be the hardest feature to implement, so save this for last.
Going further: That’s all that’s required for this lab. There are, of course, infinitely many directions you can go with this. Some examples:
• Add sounds. A crunchy noise when the snake eats something. A crash of broken glass when it hits the wall, followed by a sad “Wa-wa-waaaaa” for the loser screen. A dying scream when a poison apple is eaten.
If you google “free game sound effects” you should find plenty. Consult the pygame documentation to find out about loading and playing sounds.
• Background music. What game isn’t identified with signature music? You can also find free game-style music on the web.
• Lives. This game only gives you one life. Most cool games give you a finite number of lives before ending. • It’s a bit unfair to end the game with two snakes when only one snake dies. That way, if you’re ahead, you can guarantee a win by crashing into something deliberately.
Fix this so that, when one snake dies, the other keeps going and can run up their score.
• More kinds of food? Power-ups to increase your speed? Give you invinicibility for a limited time? Power-ups that give you free points without adding to your tail length? Power-downs that deduct from your opponent’s score?
• Surely you’ve got some ideas of your own.
• Game design is fun! Look into CSCI 319.