hbomb79 / Snake

2D Snake game implemented in Java

Snake Game

A simple classic snake game implemented in Java (OpenJDK 14.0.201) for a uni project (159.261 - Games Programming - Assignment 1).

All code is written by Harry Felton unless otherwise stated.

Features

Smooth snake movement

This snake game takes modern twist by using a gridless, pixel precise movement system. This system is fairly complex and is made possible by recording the players turns and having each, independantly moving part of the snake, react to these turns.

By doing away with the basic grid system, a new level of complexity is introduced to not only the gameplay, but also the development of the movement system, and the accompanying collision logic.

So, how does it work?

1. The game sends and update tick to the snake.

2. The snake begins to calculate it's next move. It scans ahead by the amount of distance it's planning to travel, and searches for any turns the player has made.

3. If a turn is found, it's executed. Of course, the snake won't always land exactly on a turn (as it's moving atleast 2 pixels at a time), so we take care of excess distance by moving it to the new direction.

   If no turn is found, the snake simply moves forward

4. The snake records it's movement in the form of a collision box to be checked later

5. After the snake has finished moving, the collision boxes generated are handed to the CollisionController attached to the SnakeGame instance, and the collision logic begins.

6. • If a snake is found to collide with an Apple, it's length is increased and the apple respawned.

   • If a snake collides head on with another snake (two-player mode only), then a tie is reached

   • If a snake collides with another (not head-on), then the collided-with snake is the winner.

7. The cycle starts all over again

This system was exceptionally intricate to implement, and involves checking collisions for intent to ensure the head of the snake isn't simply colliding with the snake body behind it. Using a simple linked list strategy (moving the last element to the front) would have saved a ridiculous amount of time and effort, but then, where's the fun in that?

Two player

This game features two-player. Simply select "Two Player" on the main menu and you and your opponent are launched in to the game.

In single player, either WASD, or the arrow keys can be used to control the single-snake. However, in two-player, the WASD keys are reserved from Player One, and the arrow keys, for player two.

Animations

When an apple is picked up, the user accumulates 10 points. These points are shown on the end screen and serve as a way to one-up yourself or your friends. Each time points are score, the point meter at the top glows yellow for 200ms, and a small fading text effect is spawned where the apple once was.

Simple, yet effectively retro.

Pause screen

Accessed by hitting escape. Hit the escape key again to.. escape, the pause screen.

When the game is paused all entity updates are paused and any user input aside from the escape key is ignored; also, a nice green overlay is displayed.

Design Choices

Fragments

Taking inspiration from Android development, I've created a very basic Fragment system (package fragment) that maximises code re-use and powers the UI of this game.

There are 4 fragments:

• DeathFragment Displayed when the game is over
• PauseFragment Displayed over the top of the game while it's paused, this is responsible for the overlay
• GameFragment Displays the current score of the player(s) above the game
• MenuFragment Provides the main menu UI

These fragments are dynamically activated based on the current state of the game. For example, if the game state is GAME, and the game instance is paused, then the GameFragment and PauseFragment will be active, and will therefore receive update ticks and redraw requests from the GameEngine superclass.

UI Library

Okay well maybe calling it a library is a little extreme, but to assist in the swift and effective design of the UI via the aforementioned Fragments, I have implemented a very rudimentary UI library to enable real buttons and labels to be displayed and interacted with by the user. These can be found in the ui package, and are used inside of Fragments by the UIController to construct menus and overlays that the user can hover and click on.

Controllers

As Java classes do not support multiple-inheritance (for good reason albeit), I've opted to use a controller-based approach to handling different aspects of the game.

There is a controller to handle the UI (UIController), the on-screen entities (EntityController), any animation effects (EffectController), and to check for collisions we have the CollisionController. Each are fundamental, but also simple, thanks to code encapsulation and re-use.

Documentation

All source code documentation is served here. This documentation is generated by the JavaDoc tool; all documentation on that page, or under the /doc directory, is plucked directly from the source code itself.

If you want to view the documentation locally, open /snake-game/doc/index.html in your web browser of choice.

You'll find that most of the inner-workings of this game are outlined inside of these comments.

How To Run

Simple. Just compile and run the code, starting with main.SnakeGame.

Alternatively, open inside of any Java-capable IDE and run. The entry point for this game is inside of the SnakeGame class.