CPPND: Capstone Snake Game

This is an extended version of the Snake Game, a project in the Udacity C++ Nanodegree Program.

As the original README states, "The code for this repo was inspired by this excellent StackOverflow post and set of responses."

How I chose this project

Truthfully, I didn't intend to use this, but as I had experimented immediately after first seeing it, I had some ideas about changes I thought would be fun to try. Namely, adding another snake to compete against.

There's another snake...

I assumed I'd be able to find a way to use multiple threads in order to run a computer player, and starting poking that idea. Originally, I had started with the intent that there could perhaps be more than just one, but in the end, I stayed with just the one competitor. I just wanted to see if I could get a snake running and finding food autonimously.

I also wondered how changing the goal would impact the way I needed to code it. Instead of growing, the snakes, get smaller (and faster).

The game has a few ways to end, so I also strugged with how to send the right messages to the queue, and when, to ensure that threads were closed down as the program needed to end. I went down a few git branches trying various ideas, and backtracked a number of times, before make a version that is a bit simpler than some of my attempts, but I feel would still statify much of the projects goals.

Running the programs

The original dependancies are still present. See the dependency section below.

1. Clone this repo.
2. cd into the folder you cloned (it should have this README.md file).
3. cd into the build folder.
4. Use the command "cmake .." followed by "make" to compile the src folder into an executable.
5. There should now be an executable called SnakeGame.
6. Run the file from your terminal with the command ./SnakeGame

Code structure

Much of the oringal code structure remains, with the addition of class to extend the Snake class, to make a ComputerSnake.

All source files are in the {project root}/src directory. Most classes have a distinct headder file(.h) and code file (.cpp). There's a simple gameDebug.h file that doesn't hava a .cpp file to go along.

The main.cpp file contains the main function, and includes the game.h header, render.h and, and controller.h. Main initials the Game::Run function.

The game.h file included most other headers for the rest of the classes.

Satisfying the rubric

• The project compiles and runs, not only on my local system, but also in the dev environment provided for the project. It compiles utilizing cmake and make, as suggested.

• The project code is organized into classes with class attributes to hold the data, and class methods to perform tasks.

Loops and IO

• The project accepts input from a user as part of the necessary operation of the program.

  • Input is required to move the snake.

• A variety of control structures are used in the project.

• The project code is clearly organized into functions.

  • While I'm sure it could be inmproved, examples of this are found in the game.cpp. I separated the Update functions, breaking out smaller functions, and functiones needed for the computer snake, vs the player. See also the Game::GameOver() function, and Game::PlaceFood() function, as some examples.

Object Orientated Programming

• The project code is organized into classes with class attributes to hold the data, and class methods to perform tasks.

• The Snake class holds a '_won' boolean value, with a public IsWinner() function to retrieve it.

• All class data members are explicitly specified as public, protected, or private.

  • The "Snake" class shows some example of this. protected was used to enable ineheritance where needed.

• All class members that are set to argument values are initialized through member initialization lists.

  • There are few left TODO here.

• Appropriate data and functions are grouped into classes. Member data that is subject to an invariant is hidden from the user. State is accessed via member functions.

• One function is overloaded with different signatures for the same function name.

  • Renderer::Render() has two signatures.

• Inheritance hierarchies are logical. Composition is used instead of inheritance when appropriate. Abstract classes are composed of pure virtual functions. Override functions are specified.

  • The ComputerSnake needs to use most of the features of the SnakeClass, and augment or change.
    • It adds new functions, Release() and UpdateLastKnownFoodPoint().
    • However, it also overrides the ShrinkBody() function to effect the computer snake with unique changes.

• One function is declared with a template that allows it to accept a generic parameter.

  • See the MessageQueue. Its utilized by the Game class to send and receive gameMessages of type FoodStatus.

Memory Managment

• At least two variables are defined as references, or two functions use pass-by-reference in the project code.
  • ComputerSnake::UpdateLastKnownFoodPoint passes a reference to a food object.
  • Game::UpdateComp passes a reference to the Snake object.

Concurancy

• The project uses multiple threads in the execution.

  • See ComputerSnake::Release(), and Game::Run(), line 32.

• A mutex or lock (e.g. std::lock_guard or `std::unique_lock) is used to protect data that is shared across multiple threads in the project code.

  • See ComputerSnake::Hunt(), Game::Update().

• A std::condition_variable is used in the project code to synchronize thread execution.

  • See the use of the MessageQueue.
  • Also these functions Game::EatFood() Game::waitForFoodEaten() Game::GameOver()

Dependencies for Running Locally

• cmake >= 3.7
  • All OSes: click here for installation instructions
• make >= 4.1 (Linux, Mac), 3.81 (Windows)
  • Linux: make is installed by default on most Linux distros
  • Mac: install Xcode command line tools to get make
  • Windows: Click here for installation instructions
• SDL2 >= 2.0
  • All installation instructions can be found here

  Note that for Linux, an apt or apt-get installation is preferred to building from source.

• gcc/g++ >= 5.4
  • Linux: gcc / g++ is installed by default on most Linux distros
  • Mac: same deal as make - install Xcode command line tools
  • Windows: recommend using MinGW

Basic Build Instructions

1. Clone this repo.
2. Make a build directory in the top level directory: mkdir build && cd build
3. Compile: cmake .. && make
4. Run it: ./SnakeGame.

CC Attribution-ShareAlike 4.0 International

Shield:

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

This code was adapted and changed by Beau Kinstler for fun (and hopefully a nanodegree.)