CJIT for graphical applications

Be welcome to the exciting world of graphical C applications using SDL (Simple DirectMedia Layer). SDL, originally developed by Sam Lantinga in 1998, is a powerful, cross-platform library designed to provide low-level access to audio, keyboard, mouse, and graphics hardware via OpenGL and Direct3D.

WARNING

This part of the tutorial may be incomplete for Apple/OSX, please help testing and refining it!

Download the cjit-demo package

From now on this tutorial will guide you to launch more complex applications, showing how to use libraries that are installed on your system and shipped along with the source code.

To set up the demo environment you can simply run the command below:

MS/Windows

iex ((New-Object System.Net.WebClient).DownloadString('https://dyne.org/cjit/demo'))

GNU/Linux & Apple/OSX

curl -sL https://dyne.org/cjit/demo.sh | bash

The Beauty of Random

Execute sdl2_noise.c passing the source file as argument to CJIT, and since we are also using the SDL2 library we also need an extra parameter:

MS/Windows

.\cjit.exe examples/sdl2_noise.c SDL2.dll

GNU/Linux & Apple/OSX

./cjit examples/sdl2_noise.c -lSDL2

INFO

This preview looks blurred because video compression cannot deal well with randomness.

Have a look inside sdl2_noise.c, and see the first line of code:

The "hashbang"

#!/usr/bin/env cjit

The source file can be launched as a script, when the CJIT interpreter is found in PATH.

WARNING

The hashbang works only on Apple/OSX and GNU/Linux, where scripts can be made executable with chmod +x.

The pragma lib

Also see this pre-processor directive:

#pragma comment(lib, "SDL2")

This line tells CJIT to link the SDL2 shared library. It is the equivalent of SDL2.dll on the command line, with the only difference that it can be specified inside the source code.

INFO

On Windows the DLL files need to be in the same directory of execution, or installed system-wide.

Three Dimensions

To draw accelerated graphics and 3D objects we'll use OpenGL libraries, which need to be installed on the system.

MS/Windows

Install the Windows SDK which is distributed gratis by Microsoft.

Apple/OSX

Not sure yet. Help testing this please.

GNU/Linux

sudo apt-get install libopengl-dev

Then run CJIT passing the file examples/opengl.c as argument, along with the same parameter to link SDL2.

For more details on using OpenGL and SDL2 in C with shaders, read the multi-platform-modern-opengl-demo-with-sdl2 tutorial on which our example code is based.

Nuklear widgets

Nuklear is a minimal, immediate-mode graphical user interface toolkit written in ANSI C and licensed under public domain. It is designed to be lightweight and highly customizable, and provides a wide range of components, including buttons, sliders, text input fields, and more, all of which can be integrated seamlessly with CJIT.

This time the code of our example is distributed across multiple files. This is a quick overview of what is found inside the examples folder:

.
├── nuklear
│   ├── calculator.c
│   ├── canvas.c
│   ├── node_editor.c
│   ├── overview.c
│   └── style.c
├── nuklear.c
└── nuklear.h

The main code of our example is examples/nuklear.c and by default it will just start all modules.

Fire it up as usual with ./cjit.exe examples/nuklear.c on MS/Windows or ./cjit examples/nuklear.c on GNU/Linux and Apple/OSX.

And enjoy Nuklear!