Intro

Nuklear Is a really cool library for programing Graphical User Interfaces (GUIs) using C or C++. The library itself is written in ‘pure’ C but, the best part about it: it’s a single header file. That means no installation, no weird dlls, just copy the nuklear.h into your project and include it.

Unfortunately this simplicity is a bit deceptive, as you need to know a bit about the library and what its doing before you can actually even get started with it.

I thought I would make a quick post about how I was able to get an example from the Nuklear demos folder compiling and running using cmake and in a linux environment.

You will need to have a couple of things set-up to follow along:

  • SDL2 (SDL is usually included with most linux distros)
  • CMake (CMake will create a makefile for us. Most linux distros have a cmake package available)

Why SDL??

Nuklear is back-end agnostic meaning that it doesn’t actually draw anything directly but uses whatever back-end you tell it to. Examples of different Nuklear back-ends can be found on the Nuklear Github. OpenGL, SFML, SDL/opengl are options but for simplicity in this post, I am just going to use the example for SDL2 using its built-in renderer. This way we can avoid adding more dependencies such as GLAD etc.

Create Project Folder

You can really do this a lot of different ways. For this example I’m going to create the following structure inside of a directory called nuke-test:

├── src
│   ├── main.c
├── include
│   ├── nuklear.h
│   ├── nuklear_sdl_renderer.h
│   
└── CMakeLists.txt

Copy Files

  • Go to the Nuklear sdl_renderer demo folder and copy the main.c file into the src directory.

  • Next copy the nuklear_sdl_renderer.h into the include directory.

  • Then go to Nuklear main branch and copy the nuklear.h file into the include directory.

Modify Example Files

We will need to modify two of the example files.

nuklear_sdl_renderer.h and main.c

nuklear_sdl_renderer.h

add:

#include "nuklear.h"

near line 16 change:

#define NK_SDL_RENDERER_SDL_H <SDL.h>

to:

#define NK_SDL_RENDERER_SDL_H <SDL2/SDL.h>

We need to include the nuklear library in the rendering backend header, and when the sdl library is defined we need to make sure that the compiler can find where our install is (your path might be different depending on where it is installed).

main.c

near line 25 change:

#include "../../nuklear.h"
#include "nuklear_sdl_renderer.h"

to:

#include "../include/nuklear_sdl_renderer.h"

We dont need to include nuklear.h again because it is included with nuklear_sdl_renderer.h so we can delete that line and replace the second line with the proper path to our nuklear_sdl_renderer.h.

Create CMakeLists

Now we need to make a CMakeLists.txt file in the top directory. This will tell CMake how to go about creating a makefile. This is a pretty straightforward config, we just need to make sure that SDL can be found and that the math library is included:

#minimum required cmake version
#cmake --version

cmake_minimum_required(VERSION 3.2)

#set project name
project (NUKE_TEST)

find_package(SDL2 REQUIRED)

#create sources variable
set(SOURCES
  src/main.c
)

#add excutable with sources
add_executable(${PROJECT_NAME} ${SOURCES})

target_link_libraries(${PROJECT_NAME} SDL2 m)

#directories included
target_include_directories(${PROJECT_NAME}
  PRIVATE
    ${PROJECT_SOURCE_DIR}/include
  )

Test

First things first run cmake . in the top directory of the project to initialize cmake, and have it create the makefile.

Next run make

If there are no errors then try running the excutable that is created by typing ./NUKE_TEST

If it didn’t work try this:

  • go over paths/file modifications carefully.
  • look for typos.
  • google compiler error messages and codes.

Congrats

If everything worked NICCEEEE now you can play around in main.c and change up the example or create your own using the provided backend.

Of course this is nothing but getting the backend running on a simple example. Part of the cool factor of Nuklear is that it is so flexible and customizable. Once you get the hang of it there are countless ways to incorporate it into a project.

go back.