Crate game_gem 

game-gem

A blazing-fast, ergonomic 2D game library for Rust — no macros, no magic, just gems.

Why game-gem?

game-gem is designed as a modern, modular alternative to macroquad with:

• No proc macros — Plain trait GameState + Game::run() instead of #[macroquad::main]
• Explicit context — All state passed via &mut Context, no global variables
• Feature-gated modules — Only compile what you use (audio, UI, particles, etc.)
• Built-in systems that macroquad lacks entirely:
  • Scene management with transitions
  • Particle system with emitters
  • Tweening with 30+ easing functions
  • Sprite animation with state machine
  • Collision detection (AABB, circle, ray casting, spatial hash)
  • Immediate-mode UI toolkit
  • Spatial audio with 2D positioning
  • Camera system with shake, follow, and split-screen
  • Asset management with hot-reload support
• Zero-cost abstractions — Feature flags mean unused modules don’t exist in your binary
• Proper error handling — Result types instead of panics

Quick Start

use game_gem::prelude::*;

struct MyGame;

impl GameState for MyGame {
    fn update(&mut self, ctx: &mut Context) {
        if ctx.input.keyboard.is_pressed(KeyCode::Escape) {
            ctx.quit();
        }
    }

    fn render(&mut self, ctx: &mut Context) {
        ctx.graphics.clear(Color::SKY_BLUE);
        ctx.graphics.draw_rect(100.0, 100.0, 200.0, 150.0, Color::GOLD);
        ctx.graphics.draw_text("Hello, game-gem!", 50.0, 50.0, 32.0, Color::WHITE);
    }
}

fn main() {
    Game::new()
        .window_title("Hello game-gem!")
        .window_size(800, 600)
        .run(MyGame);
}

Module Overview

Module	Feature flag	Description
math	(always)	Vec2, Rect, Transform, Angle, Lerp
color	(always)	Color with HSL/HSV, hex parsing, named constants
time	(always)	Delta time, FPS tracking, Timer, fixed timestep
input	(always)	Keyboard, mouse, gamepad, remappable actions
camera	(always)	Multi-camera, follow, shake, split-screen
engine	(always)	Game loop, Context, GameState trait, WindowConfig
collision	collision	AABB, circle, ray, spatial hash
particles	particles	Emitters, shapes, easing, pooling
tween	tween	30+ easing functions, TweenManager
animation	animation	Sprite sheet animation, events
scene	(always)	Scene stack, transitions
ui	ui	Buttons, sliders, text input, layouts
assets	(always)	Asset handles, ImageAsset, SpriteSheet
audio	audio	Spatial audio, music/SFX channels, fade

Feature Flags

[dependencies]
game-gem = { version = "0.1", features = ["audio", "ui", "particles", "animation", "tween", "collision"] }

All features are enabled by default. Disable what you don’t need:

game-gem = { version = "0.1", default-features = false, features = ["collision"] }

Modules

animation

Sprite animation system.

assets

Asset management system.

audio

Audio system (feature-gated behind audio feature).

camera

Camera / viewport system with multiple camera support.

collision

Collision detection module.

color

Color types with comprehensive construction and manipulation.

engine

Engine core: Context, game loop, and window configuration.

input

Input handling: keyboard, mouse, and gamepad.

math

game-gem Math

particles

Particle system for visual effects.

prelude

Convenience prelude — import everything you need with one line.

scene

Scene management system.

time

Time management: delta time, FPS tracking, timers, and time utilities.

tween

Tweening and easing functions.

ui

Immediate-mode UI toolkit.