85 lines
4.0 KiB
Markdown
85 lines
4.0 KiB
Markdown
## Introduction
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A Clojure library that provides a wrapper for [LibGDX](http://libgdx.badlogicgames.com/), allowing you to write 2D and 3D games that run on desktop OSes (Windows, OS X, and Linux) and mobile OSes (Android and iOS) with the same Clojure codebase.
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## Getting Started
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There are several different ways to get started:
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* Create a project with [Leiningen](https://github.com/technomancy/leiningen): `lein new play-clj hello-world`
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* Create a project with [Nightcode](https://nightcode.info/) by clicking "New Project", providing a name, and choosing the "Game" option
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* Create a project with [Nightmod](https://nightmod.net/) (easiest and most restrictive way)
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## Justification
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The best thing about making a game in Clojure is that you can modify it in a REPL while it's running. By simply reloading a namespace, your code will be injected into the game, uninhibited by the restrictions posed by tools like HotSwap. Additionally, a REPL lets you read and modify the _state_ of your game at runtime, so you can quickly experiment and diagnose problems.
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Clojure also brings the benefits of functional programming. This is becoming a big topic of discussion in gamedev circles, including by [John Carmack](http://www.altdevblogaday.com/2012/04/26/functional-programming-in-c/). Part of this is due to the prevalence of multi-core hardware, making concurrency more important. Additionally, there is a general difficulty of maintaining object-oriented game codebases as they grow, due to complicated class hierarchies and state mutations.
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## Documentation
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* Check out [the example games](https://github.com/oakes/play-clj-examples)
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* Read [the tutorial](TUTORIAL.md)
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* Read [the generated docs](http://oakes.github.io/play-clj)
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* Join the discussion on [/r/playclj](http://www.reddit.com/r/playclj/)
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* Look at this commented example:
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```clojure
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(ns game-test.core
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(:require [play-clj.core :refer :all]
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[play-clj.g2d :refer :all]))
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; define a screen, where all the action takes place
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(defscreen main-screen
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; all the screen functions get a map called "screen" containing various
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; important values, and a vector called "entities" for storing game objects
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; the entities vector is immutable, so in order to update it you must simply
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; return a new vector at the end of each screen function
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; this function runs only once, when the screen is first shown
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:on-show
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(fn [screen entities]
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; update the screen map to hold a tiled map renderer and a camera
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(update! screen
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:renderer (orthogonal-tiled-map "level1.tmx" (/ 1 8))
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:camera (orthographic))
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(let [; load a sprite sheet from your resources dir
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sheet (texture "tiles.png")
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; split the sheet into 16x16 tiles
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; (the texture! macro lets you call TextureRegion methods directly)
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tiles (texture! sheet :split 16 16)
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; get the tile at row 6, col 0
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player-image (texture (aget tiles 6 0))
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; add position and size to the player-image map so it can be drawn
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player-image (assoc player-image :x 0 :y 0 :width 2 :height 2)]
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; return a new entities vector with player-image inside of it
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[player-image]))
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; this function runs every time a frame must be drawn (about 60 times per sec)
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:on-render
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(fn [screen entities]
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; make the screen completely black
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(clear!)
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; render the tiled map, draw the entities and return them
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(render! screen entities))
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; this function runs when the screen dimensions change
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:on-resize
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(fn [screen entities]
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; make the camera 20 tiles high, while maintaining the aspect ratio
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(height! screen 20)
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; you can return nil if you didn't change any entities
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nil))
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; define the game itself, and immediately hand off to the screen
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(defgame game-test
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:on-create
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(fn [this]
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(set-screen! this main-screen)))
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```
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## Licensing
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All files that originate from this project are dedicated to the public domain. I would love pull requests, and will assume that they are also dedicated to the public domain.
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