eeschneider / hello_lwjgl

simple lwjgl clojure example

hello_lwjgl

How to get LWJGL3 working with Leiningen & Clojure.

Now with automatic downloads!

In this pull request euccastro provides an elegant way to download the native libraries easily. While I have some concern that this might break 32-bit compatibility, it would seem that there is less interest in maintaining that pathway. So, I can delete the old, complicated instructions that were here and now you can just look at the top of project.clj and configure LWJGL3 to download & use the libraries & version you want in a very simple manner.

Application Setup

If you want to create your own application using Clojure & LWJGL, here's what I did:

> lein new app hello_lwjgl
> cd hello_lwjgl

See project.clj and the source code for more info. Hopefully it is easy to follow.

Usage

All of these are very basic examples.

alpha

A spinning triangle that uses OpenGL 1.1

beta

A spinning triangle that uses OpenGL 3.2

gamma

A fullscreen spinning triangle that uses OpenGL 1.1 and you can move with a keyboard. The triangle also rotates to follow the mouse.

To run these examples, just add the name to the lein run commandline. E.g. to run the 'alpha' test:

> lein run alpha

REPL Usage

Because of interations between the GLFW and AWT window system and Mac OS X, using the REPL on Mac OS X is a bit different than on PC/Linux. On PC/Linux, I think you can just use lein repl as you would normally. But, on Mac, we need to start the nREPL server ourselves in a separate thread. See Issue #6 for details and thanks to @antoinevg for his efforts in figuring this out.

For Mac OS X, you should add the Emacs cider-nrepl package into your ~/.lein/profiles.clj file in order to get a REPL working. I'm not sure about other external tools, so for now cider-nrepl is the way to get a REPL on the Mac. To start this, add cider after the name of the example. E.g. lein alpha cider will create a cider-nrepl server and report this on startup. Something like this:

> lein run alpha cider
Hello, Lightweight Java Game Library! V 3.0.0b SNAPSHOT
Run example Alpha
Starting Cider Nrepl Server Port 7888
OpenGL version: 2.1 NVIDIA-10.4.2 310.41.35f01

In emacs, use M-x cider-connect and use port 7888 to connect. A repl pane shoudl open up. Now, you can adjust the code live, for example, adjust the angle of the triangle.

user> (in-ns 'hello-lwjgl.alpha)
#namespace[hello-lwjgl.alpha]
hello-lwjgl.alpha> (swap! globals assoc :angle 0.0)

Please note that you may need to adjust the cider-nrepl package version to match your local install. It changes often.

Running from the commandline

First create the 'uberjar'

> lein uberjar
...
Created .../hello_lwjgl/target/hello_lwjgl-0.4.0-standalone.jar

Then you can run it with a commandline.

> java -jar target/hello_lwjgl-0.4.0-SNAPSHOT-standalone.jar

Notes

• found this helpful example: https://github.com/honeytree/clojure-lwjgl
• found this discussion: https://groups.google.com/forum/#!msg/leiningen/MAFbNqDYT78/Ub2scaa4RCoJ
• See this issue for some background. technomancy/leiningen#898
• If you get an error similar to this, update to Java 8: java.lang.UnsupportedClassVersionError: org/lwjgl/opengl/GL : Unsupported major.minor version 52.0

License

Copyright © 2013-2018 Roger Allen.

Distributed under the Eclipse Public License, the same as Clojure.