Introduction

In this project, you will create a tower defense game called Ants Vs. SomeBees. As the ant queen, you populate your colony with the bravest ants you can muster. Your ants must protect their queen from the evil bees that invade your territory. Irritate the bees enough by throwing leaves at them, and they will be vanquished. Fail to pester the airborne intruders adequately, and your queen will succumb to the bees' wrath. This game is inspired by PopCap Games' Plants Vs. Zombies.

This project combines functional and object-oriented programming paradigms, focusing on the material from Chapter 2.5 of Composing Programs. The project also involves understanding, extending, and testing a large program.

The ants.zip archive contains several files, but all of your changes will be made to ants.py.

• ants.py: The game logic of Ants Vs. SomeBees
• ants_gui.py: The original GUI for Ants Vs. SomeBees
• gui.py: An new GUI for Ants Vs. SomeBees
• graphics.py: Utilities for displaying simple two-dimensional animations
• state.py: Abstraction for gamestate for gui.py
• utils.py: Some functions to facilitate the game interface
• ucb.py: Utility functions for CS 61A
• assets: A directory of images and files used by gui.py
• img: A directory of images used by ants_gui.py
• ok: The autograder
• proj3.ok: The ok configuration file
• tests: A directory of tests used by ok

This is a partner project, so both partners should read, think about, and understand the solution to all questions. If you choose to do this project without a partner, you must complete all problems by yourself.

Logistics

This is a 9-day project. You may work with one other partner. You should not share your code with students who are not your partner or copy from anyone else's solutions. In the end, you will submit one project for both partners.

Remember that you can earn an additional bonus point by submitting the project at least 24 hours before the deadline.

The project is worth 27 points. 25 points are assigned for correctness, and 2 points for the overall composition of your program.

You will turn in the following files:

• ants.py

You do not need to modify or turn in any other files to complete the project. To submit the project, run the following command:

python3 ok --submit

You will be able to view your submissions on the OK dashboard.

For the functions that we ask you to complete, there may be some initial code that we provide. If you would rather not use that code, feel free to delete it and start from scratch. You may also add new function definitions as you see fit.

However, please do not modify any other functions. Doing so may result in your code failing our autograder tests. Also, please do not change any function signatures (names, argument order, or number of arguments).

Testing

Throughout this project, you should be testing the correctness of your code. It is good practice to test often, so that it is easy to isolate any problems. However, you should not be testing too often, to allow yourself time to think through problems.

We have provided an autograder called ok to help you with testing your code and tracking your progress. The first time you run the autograder, you will be asked to log in with your OK account using your web browser. Please do so. Each time you run ok, it will back up your work and progress on our servers.

The primary purpose of ok is to test your implementations, but there are two things you should be aware of.

First, some of the test cases are locked. To unlock tests, run the following command from your terminal:

python3 ok -u

This command will start an interactive prompt that looks like:

=====================================================================
Assignment: Ants Vs. SomeBees
OK, version ...
=====================================================================

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Unlocking tests

At each "? ", type what you would expect the output to be.
Type exit() to quit

---------------------------------------------------------------------
Question 0 > Suite 1 > Case 1
(cases remaining: 1)

>>> Code here
?

At the ?, you can type what you expect the output to be. If you are correct, then this test case will be available the next time you run the autograder.

The idea is to understand conceptually what your program should do first, before you start writing any code.

Once you have unlocked some tests and written some code, you can check the correctness of your program using the tests that you have unlocked:

python3 ok

Most of the time, you will want to focus on a particular question. Use the -q option as directed in the problems below.

python3 ok

We recommend that you submit after you finish each problem. Only your last submission will be graded. It is also useful for us to have more backups of your code in case you run into a submission issue.

The tests folder is used to store autograder tests, so do not modify it. You may lose all your unlocking progress if you do. If you need to get a fresh copy, you can download the zip archive and copy it over, but you will need to start unlocking from scratch.

If you do not want us to record a backup of your work or information about your progress, use the --local option when invoking ok. With this option, no information will be sent to our course servers.

New! Ok now has the ability to run a single test case! e.g. python3 ok -q 01 --suite 1 --case 2. Try it out if you ever get stuck on a specific case.

Core Concepts

A game of Ants Vs. SomeBees consists of a series of turns. In each turn, new bees may enter the ant colony. Then, new ants are placed. Finally, all insects (ants, then bees) take individual actions: bees sting ants, and ants throw leaves at bees. The game ends either when a bee reaches the ant queen (you lose), or the entire bee flotilla has been vanquished (you win).

The Colony. The colony consists of several places that are chained together. The exit of each Place leads to another Place.

Placing Ants. There are two constraints that limit ant production. Placing an ant uses up some amount of the colony's food, a different amount for each type of ant. Also, only one ant can occupy each Place.

Bees. When it is time to act, a bee either moves to the exit of its current Place if no ant blocks its path, or stings an ant that blocks its path.

Ants. Each type of ant takes a different action and requires a different amount of food to place. The two most basic ant types are the HarvesterAnt, which adds one food to the colony during each turn, and the ThrowerAnt, which throws a leaf at a bee each turn.

The Code

Most concepts in the game have a corresponding class that encapsulates the logic for that concept. For instance, a Place in the colony holds insects and connects to other places. A Bee stings ants and advances through exits.

The game can be run in two modes: as a text-based game or using a graphical user interface (GUI). The game logic is the same in either case, but the GUI enforces a turn time limit that makes playing the game more exciting. The text-based interface is provided for debugging and development.

The files are separated according to these two modes. ants.py knows nothing of graphics or turn time limits.

To start a text-based game, run

python3 ants.py

To start a graphical game, run

python3 gui.py

To start an older version of the graphics, run

python3 ants_gui.py

When you start the graphical version, a new window should appear:

In the starter implementation, you have unlimited food and your ants only throw leaves at bees in their current Place. Try playing the game anyway! You'll need to place a lot of ThrowerAnts (the second type) in order to keep the bees from reaching your queen.

The game has several options that you will use throughout the project, which you can view with --help.

usage: ants.py [-h] [-d DIFFICULTY] [-w] [--food FOOD]

Play Ants vs. SomeBees

optional arguments:
  -h, --help     show this help message and exit
  -d DIFFICULTY  sets difficulty of game (easy/medium/hard/insane)
  -w, --water    loads a full layout with water
  --food FOOD    number of food to start with when testing

Phase 1

Problem 0 (0 pt)

Answer the following questions with your partner after you have read the entire ants.py file. If you cannot answer these questions, read the file again or ask a question in the Question 0 thread on Piazza.

1. What is the significance of an insect's armor attribute? What happens when armor reaches 0?
2. What are all of the attributes of the Ant class?
3. Is the armor attribute of the Ant class an instance attribute or class attribute?
4. Is the damage attribute of the Ant class an instance attribute or class attribute?
5. Which class do both Ant and Bee inherit from?
6. What attribute(s) do Ant and Bee inherit from their base class?

You can test your understanding by running

python3 ok -q 00 -u

Problem 1 (2 pt)

Add food costs and implement harvesters. Currently, there is no cost for deploying any type of Ant, and so there is no challenge to the game. You'll notice that Ant starts out with a base food_cost of zero. Override this value in each of the subclasses listed below with the correct costs.

Class	Food Cost	Armor
HarvesterAnt	2	1
ThrowerAnt	3	1

Now there's no way to gather more food! To fix this issue, implement the HarvesterAnt class. A HarvesterAnt is a type of Ant that adds one food to the colony.food total as its action.

Test your implementation before moving on:

python3 ok -q 01 -u
python3 ok -q 01

Remember: Ok now has the ability to run a single test case! e.g. python3 ok -q 01 --suite 1 --case 2. Try it out if you ever get stuck on a specific case.

Try playing the game again (python3 ants_gui.py). Once you have placed a HarvesterAnt, you should accumulate food each turn. Vanquishing the bees using the default game setup is now possible.

Problem 2 (2 pt)

Add code to the Place constructor that tracks entrances. Right now, a Place keeps track only of its exit. We would like a Place to keep track of its entrance as well. A Place needs to track only one entrance.

However, simply passing an entrance to a Place constructor will be problematic; we would need to have both the exit and the entrance before creating a Place! (It's a chicken or the egg problem.) To get around this problem, we will keep track of entrances in the following way instead. The Place constructor should specify that:

• A newly created Place always starts with its entrance as None.
• If the Place has an exit, then the exit's entrance is set to that Place.

Test your implementation before moving on:

python3 ok -q 02 -u
python3 ok -q 02

Phase 2: Water and Fire

Problem 3 (1 pt)

Add water to the colony. Currently there are only two types of places, the Hive and a basic Place. To make things more interesting, we're going to create a new type of Place called Water.

Only an ant that is watersafe can be deployed to a Water place. In order to determine whether an Insect is watersafe, add a new attribute to the Insect class named watersafe that is False by default. Since bees can fly, make their watersafe attribute True, overriding the default.

Now, implement the add_insect method for Water. First call Place.add_insect to add the insect, regardless of whether it is watersafe. Then, if the insect is not watersafe, reduce the insect's armor to 0 by invoking reduce_armor. Do not copy and paste code. Instead, use methods that have already been defined and make use of inheritance to reuse the functionality of the Place class.

Test your implementation before moving on:

python3 ok -q 03 -u
python3 ok -q 03

Once you've finished this problem, play a game that includes water. To access the wet_layout which includes water, add the --water option (or -w for short) when you start the game.

python3 ants_gui.py --water

Problem 4 (2 pt)

Implement the FireAnt. A FireAnt has a special reduce_armor method: when the FireAnt's armor reaches zero or lower, it will reduce the armor of all Bees in the same Place as the FireAnt by its damage attribute (defaults to 3).

Class	Food Cost	Armor
FireAnt	5	1

Hint: Damaging a bee may cause it to be removed from its place. If you iterate over a list, but change the contents of that list at the same time, you may not visit all the elements. As the Python tutorial suggests, "If you need to modify the sequence you are iterating over while inside the loop (for example to duplicate selected items), it is recommended that you first make a copy." You can copy a list by calling the list constructor or slicing the list from the beginning to the end.

Once you've finished implementing the FireAnt, give it a class attribute implemented with the value True. This attribute tells the game that you've added a new type of Ant.

Test your implementation before moving on:

python3 ok -q 04 -u
python3 ok -q 04

After implementing FireAnt, be sure to test your program by playing a game or two! A FireAnt should destroy all co-located Bees when it is stung. To start a game with ten food (for easy testing):

python3 ants_gui.py --food 10

Phase 3: Extended Range

Problem 5 (1 pt)

Implement the nearest_bee method for the ThrowerAnt class. In order for a ThrowerAnt to attack, it must know which bee it should hit. The provided implementation will only hit bees in the same Place. Your job is to fix it so that a ThrowerAnt will throw_at the nearest bee in front of it that is not still in the Hive.

The nearest_bee method returns a random Bee from the nearest place that contains bees. Places are inspected in order by following their entrance attributes.

• Start from the current Place of the ThrowerAnt.
• For each place, return a random bee if there is any, or consider the next place that is stored as the current place's entrance.

Hint: The random_or_none function provided in ants.py returns a random element of a sequence.

Test your implementation before moving on:

python3 ok -q 05 -u
python3 ok -q 05

After implementing nearest_bee, a ThrowerAnt should be able to throw_at a Bee in front of it that is not still in the Hive. Make sure that your ants do the right thing! To start a game with ten food (for easy testing):

python3 ants_gui.py --food 10

Problem 6 (2 pt)

Now that the ThrowerAnt has been completed, implement two subclasses of ThrowerAnt.

• The LongThrower can only throw_at a Bee that is found after following at least 5 entrance transitions. So the LongThrower can't hit Bees that are in the same Place as it or the first 4 Places in front of it. If there are two Bees, one too close to the LongThrower and the other within its range, the LongThrower should throw past the closer Bee, instead targeting the farther one, which is within its range.
• The ShortThrower can only throw_at a Bee that is found after following at most 3 entrance transitions. So the ShortThrower can only hit Bees in the same Place as it and 3 Places in front of it.

Neither of these specialized throwers can throw_at a Bee that is exactly 4 Places away. Placing a single one of these (and no other ants) should never win a default game.

Class	Food Cost	Armor
ShortThrower	2	1
LongThrower	2	1

A good way to approach the implementation to ShortThrower and LongThrower is to have it inherit the nearest_bee method from the base ThrowerAnt class. The logic of choosing which bee a thrower ant will attack is essentially the same, except the ShortThrower and LongThrower ants have maximum and minimum ranges, respectively.

To implement these behaviors, you may need to modify the nearest_bee method to reference min_range and max_range attributes, and only return a bee that is in range.

The ThrowerAnt has no minimum or maximum range, so make sure that its min_range and max_range attributes should reflect that. Then, implement the subclasses LongThrower and ShortThrower with appropriately constrained ranges and correct food costs.

Don't forget to set the implemented class attribute of LongThrower and ShortThrower to True.

Test your implementation before moving on:

python3 ok -q 06 -u
python3 ok -q 06

Phase 4: Seen and Unseen

With your Phase 2 ants, try python3 ants_gui.py -d easy to play against a full swarm of bees in a multi-tunnel layout and try -d normal, -d hard, or -d insane if you want a real challenge! If the bees are too numerous to vanquish, you might need to create some new ants.

Problem 7 (1 pt)

We are going to add some protection to our glorious AntColony by implementing the WallAnt, which is an ant that does nothing each turn. A WallAnt is useful because it has a large armor value.

Class	Food Cost	Armor
WallAnt	4	4

Unlike with previous ants, we have not provided you with a class header. Implement the WallAnt class from scratch. Give it a class attribute name with the value 'Wall' (so that the graphics work) and a class attribute implemented with the value True (so that you can use it in a game).

Test your implementation before moving on:

python3 ok -q 07 -u
python3 ok -q 07

Problem 8 (2 pt)

Implement the NinjaAnt, which damages all Bees that pass by, but can never be stung.

Class	Food Cost	Armor
NinjaAnt	5	1

A NinjaAnt does not block the path of a Bee that flies by. To implement this behavior, first modify the Ant class to include a new class attribute blocks_path that is True by default. Set the value of blocks_path to False in the NinjaAnt class.

Second, modify the Bee's method blocked to return False if either there is no Ant in the Bee's place or if there is an Ant, but its blocks_path attribute is False. Now Bees will just fly past NinjaAnts.

Finally, we want to make the NinjaAnt damage all Bees that fly past. Implement the action method in NinjaAnt to reduce the armor of all Bees in the same place as the NinjaAnt by its damage attribute. Similar to the FireAnt, you must iterate over a list of bees that may change.

Test your implementation before moving on:

python3 ok -q 08 -u
python3 ok -q 08

For a challenge, try to win a game using only HarvesterAnt and NinjaAnt.

Phase 5: By Land and Sea

Problem 9 (1 pt)

Currently there are no ants that can be placed on Water. Implement the ScubaThrower, which is a subclass of ThrowerAnt that is more costly and watersafe, but otherwise identical to its base class. A ScubaThrower should not lose its armor when placed in Water.

Class	Food Cost	Armor
ScubaThrower	6	1

Unlike with previous ants, we have not provided you with a class header. Implement the ScubaThrower class from scratch. Give it a class attribute name with the value 'Scuba' (so that the graphics work) and a class attribute implemented with the value True (so that you can use it in a game).

Test your implementation before moving on:

python3 ok -q 09 -u
python3 ok -q 09

Problem 10 (2 pt)

We will now implement the new offensive unit called the HungryAnt, which will select a random Bee from its place and eat it whole. After eating a Bee, it must spend 3 turns digesting before eating again.

Class	Food Cost	Armor
HungryAnt	4	1

Give HungryAnt a time_to_digest class attribute that holds the number of turns that it takes a HungryAnt to digest (default to 3). Also, give each HungryAnt an instance attribute digesting that counts the number of turns it has left to digest (default is 0, since it hasn't eaten anything at the beginning).

Implement the action method of the HungryAnt to check if it's digesting; if so, decrement its digesting counter. Otherwise, eat a random Bee in its place by reducing the Bee's armor to 0 and restart the digesting timer.

Test your implementation before moving on:

python3 ok -q 10 -u
python3 ok -q 10

Phase 6

Problem 11 (4 pt)

Right now, our ants are quite frail. We'd like to provide a way to help them last longer against the onslaught of the bees. Enter the BodyguardAnt.

Class	Food Cost	Armor
BodyguardAnt	4	2

A BodyguardAnt differs from a normal ant because it is a container; it can contain another ant and protect it, all in one Place. When a Bee stings the ant in a Place where one ant contains another, only the container is damaged. The ant inside the container can still perform its original action. If the container perishes, the contained ant still remains in the place (and can then be damaged).

Each BodyguardAnt has an instance attribute ant that stores the ant it contains. It initially starts off as None, to indicate that no ant is being protected. The contain_ant method takes an Ant argument and sets the bodyguard's ant instance attribute.

You will need to make modifications throughout your program so that a container and its contained ant can both occupy the place at the same time (a maximum of two ants per place), but only if exactly one is a container.

1. Add an Ant.container class attribute that indicates whether a subclass of Ant is a container. For all Ant instances, except for BodyguardAnt instances, container should be False. The BodyguardAnt.container attribute should be True.

2. Add a method Ant.can_contain that takes the other ant as an argument and returns True when:

   • This ant is a container.
   • This ant does not already contain another ant.
   • The other ant is not a container.

3. Modify Place.add_insect to allow a container and a non-container ant to occupy the same place according to the following rules:

   • If the ant currently occupying a Place can contain the insect (an Ant) passed to add_insect, then it does.
   • If the insect (an Ant) passed to add_insect can contain the ant currently occupying a Place, then it does. Also, set the Place's ant to be the container insect.
   • If neither Ant can contain the other, raise the same AssertionError as before.

Test your implementation before moving on:

python3 ok -q 11 -u
python3 ok -q 11

Problem 12 (1 pt)

The BodyguardAnt provides great defense, but they say the best defense is a good offense. The TankAnt is a container that protects an ant in its place and also deals 1 damage to all bees in its place each turn.

Class	Food Cost	Armor
TankAnt	6	2

You should not need to modify any code outside of the TankAnt class. If you find yourself needing to make changes elsewhere, look for a way to write your code for the previous question such that it applies not just to BodyguardAnt and TankAnt objects, but to container ants in general.

Test your implementation before moving on:

python3 ok -q 12 -u
python3 ok -q 12

Problem 13 (4 pt)

Implement the QueenAnt. The queen is a waterproof ScubaThrower that inspires her fellow ants through her bravery. The QueenAnt doubles the damage of all the ants behind her each time she performs an action. Once an ant's damage has been doubled, it is not doubled again for subsequent turns.

Class	Food Cost	Armor
QueenAnt	7	1

However, with great power comes great responsibility. The QueenAnt is governed by three special rules:

1. If the queen ever has its armor reduced to 0, the bees win. The bees also still win if any bee reaches the end of a tunnel.
2. There can be only one true queen. Any queen instantiated beyond the first one is an impostor, and should have its armor reduced to 0 upon taking its first action, without doubling any ant's damage or throwing anything. If an impostor dies, the game should still continue as normal.
3. The true (first) queen cannot be removed. Attempts to remove the queen should have no effect (but should not cause an error). You will need to modify the remove_insect method of Place to enforce this condition.

Some suggestions:

• Call bees_win() to signal to the simulator that the game is over.
• You can find each Place in a tunnel behind the QueenAnt by starting at the ant's place.exit and then repeatedly following its exit.
• To detect whether a Place is at the end of a tunnel, check whether its exit is None.
• To make sure that you don't double the damage of the same ant twice, maintain a list of all the ants that have been doubled.

• You may find the isinstance function useful for checking if something is an instance of an object. For example:

  >>> a = Foo()
  >>> isinstance(a, Foo)
  True

Test your implementation before moving on:

python3 ok -q 13 -u
python3 ok -q 13

Extra Credit (2 pt)

Implement two final thrower ants that do zero damage, but instead produce a temporary "effect" on the action method of a Bee instance that they throw_at. This effect is an alternative action that lasts for a certain number of .action(colony) calls, after which the Bee's action reverts to its original behavior.

We will be implementing two new ants that subclass ThrowerAnt.

• SlowThrower applies a slow effect for 3 turns.
• StunThrower applies a stun effect for 1 turn.

Class	Food Cost	Armor
SlowThrower	4	1
StunThrower	6	1

In order to complete the implementations of these two ants, you will need to set their class attributes appropriately and implement the following three functions:

1. make_slow is an effect that takes an action method and returns a new action method that performs the original action on turns where colony.time is even and does nothing on other turns.
2. make_stun is an effect that takes an action method and returns a new action method that does nothing.
3. apply_effect takes an effect (either make_slow or make_stun), a Bee, and a duration. It uses the effect on the Bee's .action method to produce a new action method, and then arranges to have the new method become the bee's action method for the next duration times that .action is called, after which the previous .action method is restored.

You can run some provided tests, but they are not exhaustive:

python3 ok -q EC -u
python3 ok -q EC

Make sure to test your code! Your code should be able to apply multiple effects on a target; each new effect applies to the current (possibly affected) action method of the bee.

You are now done with the project! If you haven't yet, you should try playing the game! There are two GUIs that you can use. The first is a new browser GUI that has fancy graphics and animations. The command to run it is:

python3 gui.py [-h] [-d DIFFICULTY] [-w] [--food FOOD]

The second is an older, but tried-and-true interface that we have been using over the past few years. The command to run it is:

python3 ants_gui.py [-h] [-d DIFFICULTY] [-w] [--food FOOD]

Acknowledgments: Tom Magrino and Eric Tzeng developed this project with John DeNero. Jessica Wan contributed the original artwork. Joy Jeng and Mark Miyashita invented the queen ant. Many others have contributed to the project as well!

Colin Schoen developed the new browser GUI. The beautiful new artwork was drawn by the efforts of Alana Tran, Andrew Huang, Emilee Chen, Jessie Salas, Jingyi Li, Katherine Xu, Meena Vempaty, Michelle Chang, and Ryan Davis.