Gemmer Engine

Gemmer (formerly you-js) is a lightweight, modern 2D game engine built with JavaScript, Vite, and Electron. It features a robust Entity-Component-System (ECS) architecture designed for simplicity and ease of use.

Features

- ECS Architecture: Flexible Entity, Component, and System structure.
- Rendering: Canvas-based SpriteRenderer with support for anchors, pivots, and layers.
- Animation: Frame-based Animator system.
- Physics: AABB collision detection via BoxCollider.
- Input: Unified InputManager for Keyboard and Mouse.
- Audio: AudioManager for background music and sound effects.
- Cross-Platform: Builds for Web and Desktop (via Electron).

Getting Started

$3

``bash
npm install gemmer
`

_(Note: Currently in local development. Clone the repository to use.)_

$3

1. Initialize the Game:

`javascript
import { Game } from 'gemmer';

const game = new Game({
width: 800,
height: 600,
backgroundColor: '#333',
});

game.start();
`

2. Create an Entity:

`javascript
import { Entity, SpriteRenderer, Sprite, Vector2 } from 'gemmer';

// Create a player entity
const player = new Entity('Player');
player.position = new Vector2(400, 300);

// Add a sprite
const sprite = new Sprite('assets/player.png');
player.addComponent(new SpriteRenderer(sprite));

// Add to game
game.addEntity(player);
`

3. Create a Custom Component:

`javascript
import { Component, input } from 'gemmer';

class PlayerController extends Component {
update(dt) {
const speed = 200;

if (input.isKeyDown('ArrowRight')) {
this.entity.x += speed * dt;
}
if (input.isKeyDown('ArrowLeft')) {
this.entity.x -= speed * dt;
}
}
}

player.addComponent(new PlayerController());
`

Architecture Overview

$3

- Game: The central hub that manages the game loop, scenes (entities), and systems.
- Entity: A general-purpose object in the game world. Has a Transform (position, rotation, scale) by default.
- Component: Data or logic attached to an Entity (e.g., SpriteRenderer, BoxCollider).

$3

- InputManager (input): Handles user input.
- input.isKeyDown(key)
- input.mouse (Vector2)
- AudioManager (audio): Handles sound.
- audio.play('bgm')
- audio.playOneShot('sfx')

Development

$3

- npm run dev: Start the Vite development server.
- npm run dev-test: Launch the browser test suite.
- npm run electron: Launch the Electron desktop app.
- npm run test: Run headless unit tests.
- npm run build:lib: Build the engine library for distribution (npm).
- npm run dist`: Build and package the game as a desktop application (.exe, .dmg).

License

MIT