wasm-2048

An implementation of Gabriele Cirulli's 2048 on Rust-WASM and HTML Canvas

This project was kickstarted using wasm-pack-template

The wasm bundle has been published on npm, which can be found here.

Implementation

Direction

An enum that represents the player input movement direction.

It has four possible values: Up, Down, Left, and Right.

GameBoard

This struct implements the game logic and gameboard structure.

Fields

size: u8

The game board size.

cells: Vec

A vector that holds the game cells value as powers of two.

It's initialized as an u8 vector of size size * size filled with zeroes.

rng: ThreadRng

A single RNG thread to be used whenever a new cell is generated.

game_over: bool

A boolean that is used to check if the game is in a "game over" state.

It is updated using the merge_prediction generated after every new cell generation.

If true, the move_cells method aborts before executing any logic.

merge_prediction: HashMap<Direction, Vec>

A HashMap that holds the possible game states depending on the user input.

Its keys are the four possible Direction enum values, while its values are of type Vec, and hold the game state predictions (see Gameboard cells).

Whenever the player moves, the GameBoard's cells value is updated to reflect the prediction according to the input Direction.

Whenever a new cell is generated, the HashMap is updated to represent the new possible game states.

Public methods

new(s: usize) -> GameBoard

The GameBoard constructor method.

It receives an integer s, initializing a GameBoard with size s filled with zeroes.

cells -> *const u8

A getter that returns a pointer to the GameBoard cells Vector.

It can be converted to an Uint8Array in JavaScript.

is_game_win -> bool

A getter that returns true if there's a cell in the GameBoard with a value of 11 (2^11 = 2048).

is_game_over -> bool

A getter that returns the GameBoard's game_over value.

generate

A method that generates a new cell in an empty space.

It has a 63/64th chance of generating a new cell of power 1, and a 1/64th chance of generating a new cell of power 2.

If the board is empty, it generates two new cells instead.

move_cells(dir: Direction)

A method that receives a Direction and updates the GameBoard's state accordingly.

It uses the GameBoard's merge_prediction value to update the GameBoard's cells value, calls the generate method to generate a new cell, generates a new merge_prediction HashMap, and then checks if the game is over.