#+TITLE: EON

[[file:logo.gif]]

An easy-to-use but flexible game framework based on [[https://www.raylib.com/][Raylib]] for Common Lisp.

* Introduction
EON is a game framework built upon and cooperating with [[https://github.com/bohonghuang/claw-raylib][claw-raylib]] (my high-level bindings for
Raylib), integrating commonly used facilities in game (especially old school style)
development. If you are familiar with Raylib, you should find it easy to get started with EON since
all interfaces of Raylib (including [[https://github.com/raysan5/raygui][Raygui]], Raymath, RLGL) can be used alongside EON. It is
important to note that EON was spun out from one of my retro game projects, mainly focusing on
optimizing and developing functionalities for console-style games without additional support for
modern PC games, for instance, the framework by default simulates the keyboard as gamepad input and
the built-in input events do not yet support mouse, although you can directly obtain mouse input
through Raylib. This project is still under development, so APIs are subject to change. EON and all
its dependencies can be loaded and run on SBCL, CCL, and ECL.
* Features
Along with the rich set of features of Raylib (such as support for various image,
audio, font formats, batch rendering, shape drawing, and collision
detection), EON offers many useful functionalities for game development:
1. *Asynchronous Support* \\
   A suite of built-in asynchronous functions allowing for quick writing
   of events and logic using ~async~ / ~await~ syntax.
2. *Asset Management* \\
   Unified API for loading and unloading assets, ensuring reusable
   assets are not repeatedly loaded, with non-reusable assets
   managed by the GC automatically, though manual management is also an
   option.
3. *Audio Management* \\
   Context-free, unified audio control API  and automatic audio stream resource management.
4. *Screen Management* \\
   Proper screen abstraction for managing scene/interface switching with transition animations.
5. *Viewport Support* \\
   Facilitates adaptation to different screen sizes and window dimensions.
6. *Scene System* \\
   Build 2D/3D scene node tree in your preferred way, transforming, rendering, and updating them together.
7. *GUI System* \\
   Based on the 2D scene system, the GUI system includes built-in
   widgets such as text, images, selection boxes, input boxes, dialogue
   boxes, and allows for easy creation of custom widgets, complete with
   a flexible GUI layout system and DSL for declarative UI construction.
8. *Particle Effect System* \\
   A particle effect system designed with logic and rendering
   separation, featuring abstract updaters and renderers for high
   customization and extension of particle systems.
9. *Tiled Map Renderer* \\
   An optimized built-in Tiled map renderer capable of rendering Tiled maps or any of their layers.
10. *More...* \\
    Scrolling backgrounds, key combos, focus management, shader uniform management, asynchronous job system, etc.
* Dependencies
Currently, the EON framework relies solely on =libraylib= as its foreign library, which should be ensured correctly installed on your machine.
Additionally, some libraries or their latest versions might not yet be included in the latest Quicklisp distribution.
You can find them in my repositories and clone them to a location where Quicklisp can find them:
- [[https://github.com/bohonghuang/claw-raylib][claw-raylib]] \\
  You also need to follow the [[https://github.com/bohonghuang/claw-raylib#build][build instruction of claw-raylib]] to automatically generate the bindings. 
- [[https://github.com/bohonghuang/cl-universal-tween-engine][cl-universal-tween-engine]]
- [[https://github.com/bohonghuang/cl-cont-optimizer][cl-cont-optimizer]]
- [[https://github.com/bohonghuang/promise-async-await][promise-async-await]]
- [[https://github.com/bohonghuang/cffi-ops][cffi-ops]]
- [[https://github.com/bohonghuang/cffi-object][cffi-object]]
* Get Started
To get started, you can refer to the [[https://www.raylib.com/examples.html][examples]] and [[https://www.raylib.com/cheatsheet/cheatsheet.html][cheatsheet]] to learn the interfaces of Raylib,
and familiarize yourself with the usage of EON by exploring the [[https://github.com/bohonghuang/eon-examples][eon-examples]].
Currently, most exported APIs should have docstrings to explain their arguments and usage.